US20070224960A1 - Radio receiver and radio signal processing method - Google Patents
Radio receiver and radio signal processing method Download PDFInfo
- Publication number
- US20070224960A1 US20070224960A1 US11/750,598 US75059807A US2007224960A1 US 20070224960 A1 US20070224960 A1 US 20070224960A1 US 75059807 A US75059807 A US 75059807A US 2007224960 A1 US2007224960 A1 US 2007224960A1
- Authority
- US
- United States
- Prior art keywords
- gain
- amplifier
- change
- signal
- vga
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Images
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/06—Receivers
- H04B1/10—Means associated with receiver for limiting or suppressing noise or interference
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03G—CONTROL OF AMPLIFICATION
- H03G3/00—Gain control in amplifiers or frequency changers without distortion of the input signal
- H03G3/20—Automatic control
- H03G3/30—Automatic control in amplifiers having semiconductor devices
- H03G3/3052—Automatic control in amplifiers having semiconductor devices in bandpass amplifiers (H.F. or I.F.) or in frequency-changers used in a (super)heterodyne receiver
- H03G3/3068—Circuits generating control signals for both R.F. and I.F. stages
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03D—DEMODULATION OR TRANSFERENCE OF MODULATION FROM ONE CARRIER TO ANOTHER
- H03D3/00—Demodulation of angle-, frequency- or phase- modulated oscillations
- H03D3/007—Demodulation of angle-, frequency- or phase- modulated oscillations by converting the oscillations into two quadrature related signals
- H03D3/008—Compensating DC offsets
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/06—Receivers
- H04B1/16—Circuits
- H04B1/30—Circuits for homodyne or synchrodyne receivers
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/32—Carrier systems characterised by combinations of two or more of the types covered by groups H04L27/02, H04L27/10, H04L27/18 or H04L27/26
- H04L27/34—Amplitude- and phase-modulated carrier systems, e.g. quadrature-amplitude modulated carrier systems
- H04L27/38—Demodulator circuits; Receiver circuits
- H04L27/3809—Amplitude regulation arrangements
Definitions
- the present invention relates to a radio receiver and a radio signal processing method.
- radio communication devices have widely spread. As a result, it is increasingly demanded to reduce the number of components and the manufacture cost for a radio circuit and manufacture the radio circuit as a monolithic IC. In order to cope with this demand, the direct conversion scheme is adopted for the radio circuits.
- FIG. 8 is a block diagram of a conventional receiver adopting the direct conversion scheme.
- An antenna 10 receives an RF (Radio Frequency) signal, and an LNA (Low Noise Amplifier) 20 amplifies this RF signal.
- a quadrature demodulator 30 multiplies the amplified RF signal by an LO (Local Oscillator) signal supplied from a local oscillator (not illustrated). As a result, the RF signal is directly converted to a baseband signal.
- An LPF (Low Pass Filer) 40 conducts waveform shaping on the baseband signal, and a VGA (Variable Gain Amplifier) 50 amplifies this baseband signal.
- a demodulator 70 demodulates this baseband signal to a digital signal. In this way, the receiver using the direct conversion scheme converts the RF signal to a digital signal, and then demodulates it by using digital signal processing.
- the baseband signal amplified by the VGA 50 is input not only to the demodulator 70 but also to a gain controller 60 and a DC offset canceller 94 .
- a signal strength detector 80 measures the strength of the baseband signal.
- a gain selector 90 decides whether to switch the gain of the LNA 20 and the gain of the VGA 50 on the basis of the measured value of the baseband signal.
- a gain control signal generator 92 outputs a gain control signal to the LNA 20 and the VGA 50 to switch the gain in accordance with the decision made by the gain selector 90 . In this way, the gain controller 60 effects feedback control on the strength of the baseband signal.
- the DC (Direct Current) offset canceller 94 removes a DC offset component from the baseband signal amplified by the VGA 50 , and feeds back this to the VGA 50 .
- problems concerning the DC offset component are described in “Research development tendency of mixer for direct conversion receiver(“Mission Impossible ? A Review of Mixers for Direct-Conversion Receivers”)” written by Hiroshi Tanimoto, The Transactions of the Institute of Electronics, Information, and Communication Engineers, section C, Vol. J84-C, No. 5, pp. 337-348, May 2001.
- FIGS. 9A and 9B are graphs showing gains of the LNA 20 and the VGA 50 , respectively.
- FIG. 9C is a graph showing a transient response component of a DC offset in the output of the VGA 50 .
- the gains of the LNA 20 and the VGA 50 are simultaneously switched.
- the VGA 50 is switched simultaneously from a low gain to a high gain. In some cases, therefore, DC offsets of both the LNA 20 and the VGA 50 overlap eachother, and a very large transient response component occurs, resulting in a degraded reception performance. This is because the LNA 20 is disposed in a stage in the radio circuit preceding the VGA 50 , and consequently the transient response component of the DC offset generated in the LNA 20 is amplified by the high gain obtained after the change in the VGA 50 .
- An advantage of an aspect of the present invention is to provide a radio receiver of direct conversion scheme in which degradation of the reception performance caused by the transient response component of the DC offset is suppressed.
- a radio receiver of an embodiment accordance with the instant invention comprises a first amplifier to amplify a received radio signal; a demodulation circuit line comprising a quadrature demodulator to demodulate the radio signal amplified by said first amplifier and to generate a baseband signal, a second amplifier to amplify the baseband signal, and a demodulator to demodulate the baseband signal amplified by said second amplifier; and a gain controller to control timing of a change in a gain of said second amplifier, in case that the gain of said first amplifier and the gain of said second amplifier are changed, on the basis of a gain of said first amplifier before and after the change.
- a radio receiver of another embodiment accordance with the instant invention comprises a radio receiver comprising: a first amplifier to amplify a received radio signal; a quadrature demodulator to demodulate the radio signal amplified by said first amplifier and to generate a baseband signal; a second amplifier to amplify, after changing a gain of said first amplifier, the baseband signal with a gain based on a gain of said first amplifier obtained before and after the change; and a demodulator to demodulate the baseband signal amplified by said second amplifier.
- a radio receiver of further embodiment accordance with the instant invention comprises a first amplifier to amplify a received radio signal; a quadrature demodulator to demodulate the radio signal amplified by said first amplifier and to generate a baseband signal; a second amplifier to amplify the baseband signal; a demodulator to demodulate the baseband signal amplified by said second amplifier; and a gain controller to delay timing of a change in a gain of said second amplifier as compared with timing of a change in a gain of said first amplifier, in case that the gain of said first amplifier is changed from a high gain to a low gain and the gain of said second amplifier is changed from a low gain to a high gain.
- a radio signal processing method of an embodiment accordance with the instant invention comprises: receiving a radio signal; amplifying the radio signal; demodulating the amplified radio signal to a baseband signal; amplifying the baseband signal; demodulating the amplified baseband signal; determining timing of a change in a gain of said first amplifier and a gain of said second amplifier, in case that the gain of said first amplifier and the gain of said second amplifier are changed, on the basis of the gain of said first amplifier obtained before and after the change; and changing the gain of said first amplifier and the gain of said second amplifier in accordance with the determined timing.
- FIG. 1 is a block diagram showing an embodiment according to the present invention
- FIG. 2 is a block diagram showing a concrete example of a change timing controller 196 ;
- FIGS. 3A to 3 F are time charts showing gains of the LNA 120 and VGA 150 , and signal strength of a baseband signal;
- FIGS. 4A to 4 H are time charts showing gains of the LNA 120 and VGA 150 during phasing and signal strengths of a received signal and a baseband signal;
- FIG. 5 is a flow diagram showing operation of a radio receiver in an embodiment
- FIG. 6 is a flow diagram showing details of operation of a gain controller 160 at a step S 70 ;
- FIG. 7 is a graph showing a DC offset component induced when the gain of the LNA 120 is changed from a high gain to a low gain and the gain of the VGA 150 is changed from a low gain to a high gain;
- FIG. 8 is a block diagram of a conventional receiver.
- FIGS. 9A to 9 C are graphs showing gains of conventional LNA 20 and VGA 50 .
- the gain of the LNA and the gain of the VGA can be changed respectively at points in time that are different from each other. As a result, the transient response component of the DC offset in the output of the VGA is reduced.
- FIG. 1 is a block diagram of a radio receiver 100 according to an embodiment of the present invention.
- the radio receiver 100 is a radio receiver using the direct conversion scheme.
- the direct conversion scheme is a scheme in which an RF signal having a high frequency is converted to a baseband signal having a low frequency without using an intermediate frequency.
- the radio receiver 100 includes an antenna 110 , an LNA 120 , a quadrature demodulator 130 , an LPF 140 , a VGA 150 , a gain controller 160 , a demodulator 170 and a DC offset canceller 194 .
- the DC offset canceller 194 is, for example, a circuit formed by connecting an amplifier having a constant gain and an integrator (low pass filter) in cascade. Owing to such a configuration, the DC offset canceller 194 can remove the DC offset component.
- the DC offset canceller 194 removes a DC offset component contained in the baseband signal, and then feeds back this baseband signal to the VGA 150 .
- the DC offset component is induced by a component of an LO signal that leaks to the antenna 110 and the LNA 120 and undergoes frequency conversion as an input of the quadrature demodulator 130 .
- Each of the LNA 120 and the VGA 150 is formed so as to be able to be changed stepwise in gain.
- the gain of the LNA 120 can be changed to two levels, i.e., a high-gain level and a low-gain level.
- the gain of the VGA 150 can be changed to multiple levels between a high gain and a low gain inclusive thereof.
- the gain controller 160 is formed so as to effect feedback control on the gains of the LNA 120 and the VGA 150 in order to keep a baseband signal supplied from the VGA 150 at a predetermined signal strength.
- the gain controller 160 includes a signal strength detector 180 , a gain selector 190 , a change timing controller 196 , a gain control signal generator 192 and a delay controller 198 .
- the signal strength detector 180 detects the signal strength of the baseband signal amplified by the VGA 150 .
- the gain selector 190 conducts selection on the gain of the LNA 120 and the gain of the VGA 150 so as to keep the signal strength of the baseband signal detected by the signal strength detector 180 at a constant signal strength.
- the change timing controller 196 controls timing at which the gain of the VGA 150 should be changed, on the basis of the gain of the LNA 120 selected by the gain selector 190 and the actual gain of the LNA 120 at the current point in time.
- the quadrature demodulator 130 , the VGA 150 and the demodulator 170 are connected in series. Hereafter, this is referred to as a demodulation circuit line.
- two demodulation circuit lines are connected in parallel after the LNA 120 , and used for an I-axis component and a Q-axis component of a received signal, respectively.
- One gain controller 160 is connected to the two demodulation circuit lines to control the two VGAs 150 in common.
- the gain controller 160 changes gains of the two VGAs 150 by the same period of time after changing the gain of the LNA 120 .
- the gain controller 160 changes gains of the two VGAs 150 by the same quantity. In this way, the gain controller 160 controls a plurality of demodulation circuit lines in common.
- the radio receiver 100 can demodulate the I-axis component and the Q-axis component of the received signal in common.
- FIG. 2 shows a concrete example of the change timing controller 196 .
- the change timing controller 196 includes a gain comparator 201 and a delay control signal generator 203 .
- the gain comparator 201 compares the actual gain of the LNA 120 at the current point in time with the gain of the LNA 120 selected by the gain selector 190 .
- the gain comparator 201 previously stores a certain threshold concerning the gain of the LNA 120 .
- the high gain of the LNA 120 is a gain larger than the threshold, and the low gain is a gain smaller than the threshold.
- the gain comparator 201 compares the gain of the LNA 120 before a change with the gain of the LNA 120 after the change. Then, with the comparison result, the gain comparator 201 decides whether the gain of the LNA 120 is changed from the high gain to the low gain, the gain of the LNA 120 is changed from the low gain to the high gain, or the gain of the LNA 120 is not changed.
- the gain of the LNA 120 before the change means the actual gain of the LNA 120 at the current point in time
- the gain of the LNA 120 after the change means the gain of the LNA 120 selected by the gain selector 190 .
- changing the gain means switching the gain stepwise.
- the gain comparator 201 also previously stores a certain threshold concerning the gain of the VGA 150 .
- the high gain of the VGA 150 is a gain larger than the threshold, and the low gain of the VGA 150 is a gain smaller than the threshold.
- the delay control signal generator 203 generates a delay control signal that indicates a delay time used to delay the change in gain of the VGA 150 .
- the delay control signal generator 203 In the case where the gain of the LNA 120 is changed from the high gain to the low gain, the delay control signal generator 203 generates a delay control signal when the gain of the VGA 150 is changed from the low gain to the high gain. This delay control signal is output to the delay controller 198 .
- the delay control signal generator 203 does not generate the delay control signal when the gain of the VGA 150 is changed.
- the gain control signal generator 192 is supplied with the gain selected in the gain selector 190 via the change timing controller 196 .
- the gain control signal generator 192 outputs a gain control signal to the LNA 120 and the delay controller 198 on the basis of the gains of the LNA 120 and the VGA 150 selected by the gain selector 190 .
- the gain control signal is a signal indicating the gains respectively of the LNA 120 and the VGA 150 selected by the gain selector 190 .
- the delay controller 198 outputs the gain control signal to the VGA 150 , after a predetermined delay time has elapsed since a point in time at which the delay controller 198 receives the gain control signal, in accordance with the delay control signal. Since the gain control signal is transmitted directly to the LNA 120 , the gain of the VGA 150 is changed with a delay to the gain of the LNA 120 . On the other hand, in the case where the delay control signal is not output from the delay control signal generator 203 , the delay controller 198 outputs the gain control signal to the VGA 150 without delaying the gain control signal.
- the gain controller 160 is formed so as to control the timing at which the gain of the VGA 150 is changed on the basis of the gain of the LNA 120 before and after the change.
- the timing at which the gain of the VGA 150 is changed is controlled on the basis of the gain of the LNA 120 before and after the change.
- the timing at which the gain of the VGA 150 is changed may be controlled on the basis of the gains of the LNA 120 and the VGA 150 before and after the change.
- FIGS. 3A to 3 F are time charts showing gains of the LNA 120 and the VGA 150 , and the signal strength of the baseband signal. With reference to FIGS. 3A to 3 F, operation of the LNA 120 and the VGA 150 will now be described in further detail.
- the gain of the LNA 120 is changed from the low gain to the high gain as shown in FIG. 3A
- the gain of the VGA 150 is changed from the high gain to the low gain as shown in FIG. 3B
- the gains of the LNA 120 and the VGA 150 are changed at a point in time t 20 .
- a transient response characteristic of the DC offset induced at this time is relatively small as shown in FIG. 3C .
- the gain of the LNA 120 is changed from the high gain to the low gain as shown in FIG. 3D
- the gain of the VGA 150 is changed from the low gain to the high gain as shown in FIG. 3E .
- the gain of the LNA 120 is changed at a point in time t 21 . If at this time the gain of the VGA 150 is changed simultaneously with the change in the gain of the LNA 120 as represented by a broken line in FIG. 3E , a large transient response component of the DC offset is induced as represented by a broken line in FIG. 3F .
- the gain of the VGA 150 is changed from the low gain to the high gain with a delay time Td after the change in the gain of the LNA 120 as represented by a solid line in FIG. 3E .
- the delay time Td is larger than 0, and smaller than a repetition period ( ⁇ t shown in FIG. 9 ) of the change in gains of the LNA 120 and the VGA 150 .
- the gain of the VGA 150 is changed with a delay to the change in the gain of the LNA 120 , in the present embodiment. Therefore, the transient response component of the DC offset can be reduced.
- an area S B of a region surrounded by a straight line L and the solid line is obviously smaller than an area S A of a region surrounded by the straight line L and the broken line.
- the DC offset component per unit time is smaller than that in the conventional technique. Since, as described above, the error rate in the reception characteristics is proportionate to an accumulation value of an area S per unit time, the present embodiment has a smaller error rate in the reception performance than that of the conventional technique. In the present embodiment, therefore, the reception performance becomes better than that in the conventional technique.
- the gain of the LNA 120 can be changed to two levels, it is also permissible that the gain of the LNA can be changed to three or more levels.
- FIGS. 4A to 4 H are time charts showing gains of the LNA 120 and VGA 150 in the case where the received electric field strength (so called “RSSI (received signal strength indicator))changes monotonously, and time charts showing signal strengths of the received signal and signal strengths of the baseband signal.
- RSSI received electric field strength indicator
- the gain of the VGA 150 gradually rises stepwise from the point in time t 10 as shown in FIG. 4C under the feedback control of the gain controller 160 .
- the amplification factor for the received signal rises even if the signal strength of the received signal falls. Therefore, the signal strength of the baseband signal is kept constant as shown in FIG. 4D .
- the gain of the VGA 150 there is an upper limit in the gain of the VGA 150 . If the gain of the VGA 150 arrives at a vicinity of its upper limit at the point in time t 20 , therefore, the gain of the LNA 120 is changed from the low gain to the high gain as shown in FIG. 4B , and the gain of the VGA 150 is changed from the high gain to the low gain as shown in FIG. 4C .
- the gain change widths of the LNA 120 and the VGA 150 are nearly equal to each other. As a result, the fall in the gain of the VGA 150 can be compensated by the increase in the gain of the LNA 120 .
- the transient response characteristic of the DC offset induced at this time is relatively small as shown in FIG. 4D .
- the gain of the VGA 150 is changed in a larger number of steps as compared with the gain of the LNA 120 as shown in FIGS. 4B, 4C , 4 F and 4 G. Even if the received signal strength changes linearly as shown in FIG. 4A , therefore, the signal strength of the baseband signal can be kept constant in the present embodiment.
- the signal strength of the received signal further continues to fall.
- the signal strength of the baseband signal can be kept constant by making the gain of the VGA 150 further rise stepwise.
- the transient response component of the DC offset caused by the stepwise gain switching of the VGA 150 is omitted, because it is small.
- the gain of the VGA 150 gradually falls stepwise from the point in time t 11 as shown in FIG. 4G under the feedback control of the gain controller 160 .
- the amplification factor for the received signal falls even if the signal strength of the received signal rises. Therefore, the signal strength of the baseband signal is kept constant as shown in FIG. 4H .
- the gain of the VGA 150 arrives at a vicinity of its lower limit at the point in time t 21 , therefore, the gain of the LNA 120 is changed from the high gain to the low gain as shown in FIG. 4F . If at this time the gain of the VGA 150 is changed simultaneously with the change in the gain of the LNA 120 , a large transient response component of the DC offset occurs at the point in time t 21 as represented by a broken line in FIG. 4H .
- the gain of the VGA 150 is changed from the low gain to the high gain with a delay time Td after the change in the gain of the LNA 120 as represented by a solid line in FIG. 4G .
- a transient response component of the DC offset induced at the point in time t 21 becomes smaller as compared with the transient response component in the conventional technique as shown in FIG. 4H .
- the delay time Td is a value that is larger than 0 and that is smaller than a repetition period (At shown in FIG. 9 ) of the change in gains of the LNA 120 and the VGA 150 .
- the signal strength of the received signal further continues to rise.
- the signal strength of the baseband signal can be kept constant by making the gain of the VGA 150 fall gradually.
- the gain of the VGA 150 is changed with a delay to the change in the gain of the LNA 120 , and consequently effects similar to those of the embodiment shown in FIGS. 3A to 3 F can be obtained.
- the gain of the VGA 150 is changed between the points in time t 21 and t 31 as represented by a broken line in FIG. 4G .
- the gain of the VGA 150 is not changed during the delay time Td, i.e., between the points in time t 21 and t 31 .
- the width of the gain of the VGA 150 changed at the point in time t 31 in the present variant is smaller than that at the point in time t 21 in the conventional technique. Therefore, the transient response component of the DC offset induced in the present variant is relatively small.
- the width of the gain of the VGA 150 changed at the point in time t 31 is equal to that changed at the point in time t 21 in the conventional technique.
- a peak P 2 Of the transient response component of the DC offset induced at the point in time t 31 in the present variant becomes further smaller than a peak P 1 of the transient response component induced at the point in time t 31 in the embodiment shown in FIGS. 3A to 3 F.
- the gain of the VGA 150 is changed singly without changing the gain of the LNA 120 in some cases.
- the transient response component of the DC offset is relatively small similarly as in FIG. 4D , and consequently no problems are posed.
- FIG. 5 is a flow diagram showing operation of the radio receiver 100 in the embodiment.
- An RF signal is received by the antenna 110 (S 10 ).
- the received signal is amplified by the LNA 120 (S 20 ).
- the quadrature demodulator 130 converts the RF signal having a high frequency to the baseband signal (S 30 ).
- the baseband signal is subjected to waveform shaping in the LPF 140 (S 40 ), and amplified in the VGA 150 (S 50 ).
- the DC offset canceller 194 removes the DC offset component from this baseband signal (S 60 ).
- the gain controller 160 is supplied with the baseband signal output from the VGA 150 , and the gain controller 160 effects feedback control on the LNA 120 and the VGA 150 (S 70 ).
- the demodulator 170 demodulates the baseband signal to the digital signal (S 80 ).
- FIG. 6 is a flow diagram showing details of operation conducted by the gain controller 160 at the step S 70 . If the baseband signal is input to the gain controller 160 , the signal strength detector 180 detects the signal strength of the baseband signal (S 70 - 1 ).
- the gain selector 190 selects gains of the LNA 120 and the VGA 150 so as to keep the signal strength of the baseband signal constant (S 70 - 3 ).
- the change timing controller 196 compares the actual gain state of the LNA 120 at the current point in time with the selected gain of the LNA 120 (S 70 - 5 ). As a result of this comparison, it is determined whether the gain of the LNA 120 passes through a threshold previously stored in the change timing controller 196 before and after a change (S 70 - 6 ).
- the change timing controller 196 furthermore judges the gain state of the LNA 120 at the current point in time (S 70 - 7 ). Judgment on the gain state of the LNA 120 can be conducted by determining whether the gain of the LNA 120 is higher than this threshold (S 70 - 8 ). If the gain of the LNA 120 at the current point in time is the high gain as a result of this decision, the change timing controller 196 outputs the delay control signal to the delay controller 198 (S 70 - 9 ).
- the gain control signal generator 192 outputs the gain control signal to the LNA 120 and the delay controller 198 on the basis of the gains of the LNA 120 and the VGA 150 selected by the gain selector 190 (S 70 - 11 ).
- the delay controller 198 is supplied with the gain control signal and the delay control signal, and the delay controller 198 delays the gain control signal and outputs the delayed gain control signal to the VGA 150 .
- the gain of the VGA 150 is changed with a delay to the change in the gain of the LNA 120 (S 70 - 13 ).
- the change timing controller 196 does not output the delay control signal. Since the delay control signal is not output, the delay controller 198 outputs the gain control signal to the VGA 150 without delaying it. As a result, the gain of the VGA 150 is changed simultaneously with a change in the gain of the LNA 120 (S 70 - 15 ).
- the change timing controller 196 further makes a decision whether to change the gain of the VGA 150 (S 70 - 17 ). In this decision, the gain comparator 201 previously stores a threshold located between the low gain and the high gain of the VGA 150 , and judges a gain higher than the threshold to be the high gain and judges gain lower than the threshold to be the low gain. If the gain of the VGA 150 passes through this threshold before and after the change, the change timing controller 196 decides to change the gain of the VGA 150 (S 70 - 18 ).
- the gain control signal generator 192 outputs the gain control signal to the VGA 150 via the delay controller 198 to change the gain of the VGA 150 . Since the delay control signal is not issued from the change timing controller 196 , the delay controller 198 passes the gain control signal to the VGA 150 without delaying it. As a result, the gain of the VGA 150 is changed (S 70 - 19 ).
- the delay controller 198 does not change the gain of VGA 150 .
- FIG. 7 is a graph showing a DC offset component actually measured when the gain of the LNA 120 is changed from the high gain to the low gain and the gain of the VGA 150 is changed from the low gain to the high gain.
- FIG. 7 corresponds to the graph shown in FIG. 4H in which the signal strength of the baseband signal has been obtained by actually measuring it.
- a curve A shows a DC offset component measured when the gain of the LNA 120 and the gain of the VGA 150 are changed simultaneously in the same way as the conventional technique.
- a curve B shows a DC offset component measured when the gain of the VGA 150 is changed with a delay to a change in the gain of the LNA 120 according to the embodiment.
- the transient response component of the DC offset output from the VGA 150 is approximately 70 mV maximum.
- the transient response component of the DC offset output from the VGA 150 is approximately 30 mV maximum. Therefore, the transient response component in the curve B is obviously lower than the transient response component in the curve A.
- the probability in the embodiment that the DC offset component exceeds the threshold becomes lower as compared with the conventional technique.
- An area S B of a region surrounded by a curve B and a broken line is obviously smaller than an area S A of a region surrounded by a curve A and the broken line.
- the DC offset component per unit time is smaller as compared with the conventional technique. Since the error rate in the reception characteristic is proportionate to the accumulation value of the area S per unit time as described earlier, the error rate in the reception characteristic in the embodiment is smaller as compared with the conventional technique. As a result, the embodiment becomes better in reception performance than the conventional technique.
Abstract
A radio receiver comprises a first amplifier to amplify a received radio signal; a quadrature demodulator to demodulate the radio signal amplified by said first amplifier and thereby generate a baseband signal; a second amplifier to amplify the baseband signal; a demodulator to demodulate the baseband signal amplified by said second amplifier; and a gain controller to control timing of a change in a gain of said second amplifier, in case that changing the gain of said first amplifier and the gain of said second amplifier, on the basis of a gain of said first amplifier before and after the change.
Description
- This application is a Divisional of and claims the benefit of priority under 35 USC § 120 from U.S. Ser. No. 10/819,288, filed Apr. 7, 2004, claims the benefit of priority under 35 U.S.C. §119 from the prior Japanese Patent Application No. 2003-122316, filed on Apr. 25, 2003, the entire contents of which are incorporated herein by reference.
- 1. Field of the Invention
- The present invention relates to a radio receiver and a radio signal processing method.
- 2. Related Background Art
- In recent years, radio communication devices have widely spread. As a result, it is increasingly demanded to reduce the number of components and the manufacture cost for a radio circuit and manufacture the radio circuit as a monolithic IC. In order to cope with this demand, the direct conversion scheme is adopted for the radio circuits.
-
FIG. 8 is a block diagram of a conventional receiver adopting the direct conversion scheme. Anantenna 10 receives an RF (Radio Frequency) signal, and an LNA (Low Noise Amplifier) 20 amplifies this RF signal. Aquadrature demodulator 30 multiplies the amplified RF signal by an LO (Local Oscillator) signal supplied from a local oscillator (not illustrated). As a result, the RF signal is directly converted to a baseband signal. An LPF (Low Pass Filer) 40 conducts waveform shaping on the baseband signal, and a VGA (Variable Gain Amplifier) 50 amplifies this baseband signal. In addition, ademodulator 70 demodulates this baseband signal to a digital signal. In this way, the receiver using the direct conversion scheme converts the RF signal to a digital signal, and then demodulates it by using digital signal processing. - The baseband signal amplified by the
VGA 50 is input not only to thedemodulator 70 but also to again controller 60 and aDC offset canceller 94. In thegain controller 60, asignal strength detector 80 measures the strength of the baseband signal. Again selector 90 decides whether to switch the gain of theLNA 20 and the gain of theVGA 50 on the basis of the measured value of the baseband signal. A gaincontrol signal generator 92 outputs a gain control signal to theLNA 20 and theVGA 50 to switch the gain in accordance with the decision made by thegain selector 90. In this way, thegain controller 60 effects feedback control on the strength of the baseband signal. - The DC (Direct Current)
offset canceller 94 removes a DC offset component from the baseband signal amplified by theVGA 50, and feeds back this to theVGA 50. By the way, problems concerning the DC offset component are described in “Research development tendency of mixer for direct conversion receiver(“Mission Impossible ? A Review of Mixers for Direct-Conversion Receivers”)” written by Hiroshi Tanimoto, The Transactions of the Institute of Electronics, Information, and Communication Engineers, section C, Vol. J84-C, No. 5, pp. 337-348, May 2001. -
FIGS. 9A and 9B are graphs showing gains of theLNA 20 and theVGA 50, respectively.FIG. 9C is a graph showing a transient response component of a DC offset in the output of theVGA 50. The gains of the LNA 20 and the VGA 50 are simultaneously switched. - When the LNA 20 is switched from a high gain to a low gain at a point t1 in time, the VGA 50 is switched simultaneously from a low gain to a high gain. In some cases, therefore, DC offsets of both the
LNA 20 and theVGA 50 overlap eachother, and a very large transient response component occurs, resulting in a degraded reception performance. This is because the LNA 20 is disposed in a stage in the radio circuit preceding theVGA 50, and consequently the transient response component of the DC offset generated in theLNA 20 is amplified by the high gain obtained after the change in theVGA 50. - An advantage of an aspect of the present invention is to provide a radio receiver of direct conversion scheme in which degradation of the reception performance caused by the transient response component of the DC offset is suppressed.
- A radio receiver of an embodiment accordance with the instant invention comprises a first amplifier to amplify a received radio signal; a demodulation circuit line comprising a quadrature demodulator to demodulate the radio signal amplified by said first amplifier and to generate a baseband signal, a second amplifier to amplify the baseband signal, and a demodulator to demodulate the baseband signal amplified by said second amplifier; and a gain controller to control timing of a change in a gain of said second amplifier, in case that the gain of said first amplifier and the gain of said second amplifier are changed, on the basis of a gain of said first amplifier before and after the change.
- A radio receiver of another embodiment accordance with the instant invention comprises a radio receiver comprising: a first amplifier to amplify a received radio signal; a quadrature demodulator to demodulate the radio signal amplified by said first amplifier and to generate a baseband signal; a second amplifier to amplify, after changing a gain of said first amplifier, the baseband signal with a gain based on a gain of said first amplifier obtained before and after the change; and a demodulator to demodulate the baseband signal amplified by said second amplifier.
- A radio receiver of further embodiment accordance with the instant invention comprises a first amplifier to amplify a received radio signal; a quadrature demodulator to demodulate the radio signal amplified by said first amplifier and to generate a baseband signal; a second amplifier to amplify the baseband signal; a demodulator to demodulate the baseband signal amplified by said second amplifier; and a gain controller to delay timing of a change in a gain of said second amplifier as compared with timing of a change in a gain of said first amplifier, in case that the gain of said first amplifier is changed from a high gain to a low gain and the gain of said second amplifier is changed from a low gain to a high gain.
- A radio signal processing method of an embodiment accordance with the instant invention comprises: receiving a radio signal; amplifying the radio signal; demodulating the amplified radio signal to a baseband signal; amplifying the baseband signal; demodulating the amplified baseband signal; determining timing of a change in a gain of said first amplifier and a gain of said second amplifier, in case that the gain of said first amplifier and the gain of said second amplifier are changed, on the basis of the gain of said first amplifier obtained before and after the change; and changing the gain of said first amplifier and the gain of said second amplifier in accordance with the determined timing.
-
FIG. 1 is a block diagram showing an embodiment according to the present invention; -
FIG. 2 is a block diagram showing a concrete example of achange timing controller 196; -
FIGS. 3A to 3F are time charts showing gains of the LNA 120 andVGA 150, and signal strength of a baseband signal; -
FIGS. 4A to 4H are time charts showing gains of the LNA 120 andVGA 150 during phasing and signal strengths of a received signal and a baseband signal; -
FIG. 5 is a flow diagram showing operation of a radio receiver in an embodiment; -
FIG. 6 is a flow diagram showing details of operation of again controller 160 at a step S70; -
FIG. 7 is a graph showing a DC offset component induced when the gain of the LNA 120 is changed from a high gain to a low gain and the gain of theVGA 150 is changed from a low gain to a high gain; -
FIG. 8 is a block diagram of a conventional receiver; and -
FIGS. 9A to 9C are graphs showing gains of conventional LNA 20 andVGA 50. - Hereafter, embodiments according to the present invention will be described with reference to the drawings. These embodiments do not restrain the present invention. In a radio receiver of a direct conversion scheme according to embodiments of the present invention, the gain of the LNA and the gain of the VGA can be changed respectively at points in time that are different from each other. As a result, the transient response component of the DC offset in the output of the VGA is reduced.
-
FIG. 1 is a block diagram of aradio receiver 100 according to an embodiment of the present invention. Theradio receiver 100 is a radio receiver using the direct conversion scheme. The direct conversion scheme is a scheme in which an RF signal having a high frequency is converted to a baseband signal having a low frequency without using an intermediate frequency. Theradio receiver 100 includes anantenna 110, an LNA 120, aquadrature demodulator 130, anLPF 140, aVGA 150, again controller 160, ademodulator 170 and aDC offset canceller 194. - The
DC offset canceller 194 is, for example, a circuit formed by connecting an amplifier having a constant gain and an integrator (low pass filter) in cascade. Owing to such a configuration, the DC offsetcanceller 194 can remove the DC offset component. The DC offsetcanceller 194 removes a DC offset component contained in the baseband signal, and then feeds back this baseband signal to theVGA 150. The DC offset component is induced by a component of an LO signal that leaks to theantenna 110 and theLNA 120 and undergoes frequency conversion as an input of thequadrature demodulator 130. - Each of the
LNA 120 and theVGA 150 is formed so as to be able to be changed stepwise in gain. In the present embodiment, the gain of theLNA 120 can be changed to two levels, i.e., a high-gain level and a low-gain level. The gain of theVGA 150 can be changed to multiple levels between a high gain and a low gain inclusive thereof. - The
gain controller 160 is formed so as to effect feedback control on the gains of theLNA 120 and theVGA 150 in order to keep a baseband signal supplied from theVGA 150 at a predetermined signal strength. - The configuration of the
gain controller 160 will now be described in more detail. Thegain controller 160 includes asignal strength detector 180, again selector 190, achange timing controller 196, a gaincontrol signal generator 192 and adelay controller 198. Thesignal strength detector 180 detects the signal strength of the baseband signal amplified by theVGA 150. Thegain selector 190 conducts selection on the gain of theLNA 120 and the gain of theVGA 150 so as to keep the signal strength of the baseband signal detected by thesignal strength detector 180 at a constant signal strength. Thechange timing controller 196 controls timing at which the gain of theVGA 150 should be changed, on the basis of the gain of theLNA 120 selected by thegain selector 190 and the actual gain of theLNA 120 at the current point in time. - The
quadrature demodulator 130, theVGA 150 and thedemodulator 170 are connected in series. Hereafter, this is referred to as a demodulation circuit line. In the present embodiment, two demodulation circuit lines are connected in parallel after theLNA 120, and used for an I-axis component and a Q-axis component of a received signal, respectively. Onegain controller 160 is connected to the two demodulation circuit lines to control the twoVGAs 150 in common. For example, thegain controller 160 changes gains of the twoVGAs 150 by the same period of time after changing the gain of theLNA 120. Thegain controller 160 changes gains of the twoVGAs 150 by the same quantity. In this way, thegain controller 160 controls a plurality of demodulation circuit lines in common. As a result, theradio receiver 100 can demodulate the I-axis component and the Q-axis component of the received signal in common. -
FIG. 2 shows a concrete example of thechange timing controller 196. Thechange timing controller 196 includes again comparator 201 and a delaycontrol signal generator 203. - The
gain comparator 201 compares the actual gain of theLNA 120 at the current point in time with the gain of theLNA 120 selected by thegain selector 190. Thegain comparator 201 previously stores a certain threshold concerning the gain of theLNA 120. The high gain of theLNA 120 is a gain larger than the threshold, and the low gain is a gain smaller than the threshold. Thegain comparator 201 compares the gain of theLNA 120 before a change with the gain of theLNA 120 after the change. Then, with the comparison result, thegain comparator 201 decides whether the gain of theLNA 120 is changed from the high gain to the low gain, the gain of theLNA 120 is changed from the low gain to the high gain, or the gain of theLNA 120 is not changed. Here, the gain of theLNA 120 before the change means the actual gain of theLNA 120 at the current point in time, and the gain of theLNA 120 after the change means the gain of theLNA 120 selected by thegain selector 190. Furthermore, in the present embodiment, changing the gain means switching the gain stepwise. By the way, thegain comparator 201 also previously stores a certain threshold concerning the gain of theVGA 150. The high gain of theVGA 150 is a gain larger than the threshold, and the low gain of theVGA 150 is a gain smaller than the threshold. - The delay
control signal generator 203 generates a delay control signal that indicates a delay time used to delay the change in gain of theVGA 150. In the case where the gain of theLNA 120 is changed from the high gain to the low gain, the delaycontrol signal generator 203 generates a delay control signal when the gain of theVGA 150 is changed from the low gain to the high gain. This delay control signal is output to thedelay controller 198. On the other hand, in the case where the gain of theLNA 120 is changed from the low gain to the high gain or the gain of theLNA 120 is not changed, the delaycontrol signal generator 203 does not generate the delay control signal when the gain of theVGA 150 is changed. - The gain
control signal generator 192 is supplied with the gain selected in thegain selector 190 via thechange timing controller 196. The gaincontrol signal generator 192 outputs a gain control signal to theLNA 120 and thedelay controller 198 on the basis of the gains of theLNA 120 and theVGA 150 selected by thegain selector 190. The gain control signal is a signal indicating the gains respectively of theLNA 120 and theVGA 150 selected by thegain selector 190. - The
delay controller 198 outputs the gain control signal to theVGA 150, after a predetermined delay time has elapsed since a point in time at which thedelay controller 198 receives the gain control signal, in accordance with the delay control signal. Since the gain control signal is transmitted directly to theLNA 120, the gain of theVGA 150 is changed with a delay to the gain of theLNA 120. On the other hand, in the case where the delay control signal is not output from the delaycontrol signal generator 203, thedelay controller 198 outputs the gain control signal to theVGA 150 without delaying the gain control signal. - In this way, the
gain controller 160 is formed so as to control the timing at which the gain of theVGA 150 is changed on the basis of the gain of theLNA 120 before and after the change. - When the gain of the
LNA 120 is changed, it is evident in the present embodiment that the gain change of theVGA 150 is brought about. Therefore, the timing at which the gain of theVGA 150 is changed is controlled on the basis of the gain of theLNA 120 before and after the change. - In the case where it is not evident that the gain change of the
VGA 150 is brought about when the gain of theLNA 120 is changed, however, the timing at which the gain of theVGA 150 is changed may be controlled on the basis of the gains of theLNA 120 and theVGA 150 before and after the change. -
FIGS. 3A to 3F are time charts showing gains of theLNA 120 and theVGA 150, and the signal strength of the baseband signal. With reference toFIGS. 3A to 3F, operation of theLNA 120 and theVGA 150 will now be described in further detail. - First, the gain of the
LNA 120 is changed from the low gain to the high gain as shown inFIG. 3A , and the gain of theVGA 150 is changed from the high gain to the low gain as shown inFIG. 3B . The gains of theLNA 120 and theVGA 150 are changed at a point in time t20. A transient response characteristic of the DC offset induced at this time is relatively small as shown inFIG. 3C . - Subsequently, the gain of the
LNA 120 is changed from the high gain to the low gain as shown inFIG. 3D , and the gain of theVGA 150 is changed from the low gain to the high gain as shown inFIG. 3E . The gain of theLNA 120 is changed at a point in time t21. If at this time the gain of theVGA 150 is changed simultaneously with the change in the gain of theLNA 120 as represented by a broken line inFIG. 3E , a large transient response component of the DC offset is induced as represented by a broken line inFIG. 3F . - In the present embodiment, therefore, the gain of the
VGA 150 is changed from the low gain to the high gain with a delay time Td after the change in the gain of theLNA 120 as represented by a solid line inFIG. 3E . The delay time Td is represented by Td=t31−t21. As a result, the transient response component of the DC offset induced at the point in time t21 becomes smaller than the transient response component induced in the conventional technique. The delay time Td is larger than 0, and smaller than a repetition period (Δt shown inFIG. 9 ) of the change in gains of theLNA 120 and theVGA 150. - In this way, the gain of the
VGA 150 is changed with a delay to the change in the gain of theLNA 120, in the present embodiment. Therefore, the transient response component of the DC offset can be reduced. - Furthermore, in
FIG. 3F , an area SB of a region surrounded by a straight line L and the solid line is obviously smaller than an area SA of a region surrounded by the straight line L and the broken line. In the present embodiment, therefore, the DC offset component per unit time is smaller than that in the conventional technique. Since, as described above, the error rate in the reception characteristics is proportionate to an accumulation value of an area S per unit time, the present embodiment has a smaller error rate in the reception performance than that of the conventional technique. In the present embodiment, therefore, the reception performance becomes better than that in the conventional technique. - Although in the present embodiment the gain of the
LNA 120 can be changed to two levels, it is also permissible that the gain of the LNA can be changed to three or more levels. -
FIGS. 4A to 4H are time charts showing gains of theLNA 120 andVGA 150 in the case where the received electric field strength (so called “RSSI (received signal strength indicator))changes monotonously, and time charts showing signal strengths of the received signal and signal strengths of the baseband signal. A variant for the embodiment shown inFIGS. 3A to 3F will now be described with reference toFIGS. 4A to 4H. - First, the case where the signal strength of the received signal supplied from the
antenna 110 falls between a point in time t10 and a point in time t30 as shown inFIG. 4A will now be described. The gain of theVGA 150 gradually rises stepwise from the point in time t10 as shown inFIG. 4C under the feedback control of thegain controller 160. As a result, the amplification factor for the received signal rises even if the signal strength of the received signal falls. Therefore, the signal strength of the baseband signal is kept constant as shown inFIG. 4D . - However, there is an upper limit in the gain of the
VGA 150. If the gain of theVGA 150 arrives at a vicinity of its upper limit at the point in time t20, therefore, the gain of theLNA 120 is changed from the low gain to the high gain as shown inFIG. 4B , and the gain of theVGA 150 is changed from the high gain to the low gain as shown inFIG. 4C . The gain change widths of theLNA 120 and theVGA 150 are nearly equal to each other. As a result, the fall in the gain of theVGA 150 can be compensated by the increase in the gain of theLNA 120. The transient response characteristic of the DC offset induced at this time is relatively small as shown inFIG. 4D . In the present embodiment, the gain of theVGA 150 is changed in a larger number of steps as compared with the gain of theLNA 120 as shown inFIGS. 4B, 4C , 4F and 4G. Even if the received signal strength changes linearly as shown inFIG. 4A , therefore, the signal strength of the baseband signal can be kept constant in the present embodiment. - Between the points in time t20 and t30, the signal strength of the received signal further continues to fall. In such a case, the signal strength of the baseband signal can be kept constant by making the gain of the
VGA 150 further rise stepwise. InFIG. 4D andFIG. 4H described later, the transient response component of the DC offset caused by the stepwise gain switching of theVGA 150 is omitted, because it is small. - Subsequently, the case where the signal strength of the received signal rises between a point in time t11 and a point in time t31 as shown in
FIG. 4E will now be described. The gain of theVGA 150 gradually falls stepwise from the point in time t11 as shown inFIG. 4G under the feedback control of thegain controller 160. As a result, the amplification factor for the received signal falls even if the signal strength of the received signal rises. Therefore, the signal strength of the baseband signal is kept constant as shown inFIG. 4H . - However, there is a lower limit in the gain of the
VGA 150. If the gain of theVGA 150 arrives at a vicinity of its lower limit at the point in time t21, therefore, the gain of theLNA 120 is changed from the high gain to the low gain as shown inFIG. 4F . If at this time the gain of theVGA 150 is changed simultaneously with the change in the gain of theLNA 120, a large transient response component of the DC offset occurs at the point in time t21 as represented by a broken line inFIG. 4H . - In the present variant, the gain of the
VGA 150 is changed from the low gain to the high gain with a delay time Td after the change in the gain of theLNA 120 as represented by a solid line inFIG. 4G . At this time, the gain change widths of theLNA 120 and theVGA 150 are nearly equal to each other. The delay time Td is represented by Td=t31−t21. As a result, a transient response component of the DC offset induced at the point in time t21 becomes smaller as compared with the transient response component in the conventional technique as shown inFIG. 4H . The delay time Td is a value that is larger than 0 and that is smaller than a repetition period (At shown inFIG. 9 ) of the change in gains of theLNA 120 and theVGA 150. - Between the points in time t21 and t31, the signal strength of the received signal further continues to rise. In this case, the signal strength of the baseband signal can be kept constant by making the gain of the
VGA 150 fall gradually. - Thus, in the present variant, the gain of the
VGA 150 is changed with a delay to the change in the gain of theLNA 120, and consequently effects similar to those of the embodiment shown inFIGS. 3A to 3F can be obtained. - In the conventional technique, the gain of the
VGA 150 is changed between the points in time t21 and t31 as represented by a broken line inFIG. 4G . This means that the gain of theVGA 150 is being controlled when the transient response component of the DC offset is occurring. Therefore, the gain of theVGA 150 is changed largely at the point in time t21. - On the other hand, in the present variant, the gain of the
VGA 150 is not changed during the delay time Td, i.e., between the points in time t21 and t31. As a result, the width of the gain of theVGA 150 changed at the point in time t31 in the present variant is smaller than that at the point in time t21 in the conventional technique. Therefore, the transient response component of the DC offset induced in the present variant is relatively small. Furthermore, according to the embodiment shown inFIGS. 3A to 3F, the width of the gain of theVGA 150 changed at the point in time t31 is equal to that changed at the point in time t21 in the conventional technique. Therefore, a peak P2 Of the transient response component of the DC offset induced at the point in time t31 in the present variant becomes further smaller than a peak P1 of the transient response component induced at the point in time t31 in the embodiment shown inFIGS. 3A to 3F. - In the present variant, the gain of the
VGA 150 is changed singly without changing the gain of theLNA 120 in some cases. In this case, however, the transient response component of the DC offset is relatively small similarly as inFIG. 4D , and consequently no problems are posed. -
FIG. 5 is a flow diagram showing operation of theradio receiver 100 in the embodiment. An RF signal is received by the antenna 110 (S10). The received signal is amplified by the LNA 120 (S20). Thequadrature demodulator 130 converts the RF signal having a high frequency to the baseband signal (S30). The baseband signal is subjected to waveform shaping in the LPF 140 (S40), and amplified in the VGA 150 (S50). The DC offsetcanceller 194 removes the DC offset component from this baseband signal (S60). Thegain controller 160 is supplied with the baseband signal output from theVGA 150, and thegain controller 160 effects feedback control on theLNA 120 and the VGA 150 (S70). In addition, thedemodulator 170 demodulates the baseband signal to the digital signal (S80). -
FIG. 6 is a flow diagram showing details of operation conducted by thegain controller 160 at the step S70. If the baseband signal is input to thegain controller 160, thesignal strength detector 180 detects the signal strength of the baseband signal (S70-1). - Subsequently, the
gain selector 190 selects gains of theLNA 120 and theVGA 150 so as to keep the signal strength of the baseband signal constant (S70-3). Subsequently, thechange timing controller 196 compares the actual gain state of theLNA 120 at the current point in time with the selected gain of the LNA 120 (S70-5). As a result of this comparison, it is determined whether the gain of theLNA 120 passes through a threshold previously stored in thechange timing controller 196 before and after a change (S70-6). - If the gain of the
LNA 120 passes through this threshold before and after the change, thechange timing controller 196 furthermore judges the gain state of theLNA 120 at the current point in time (S70-7). Judgment on the gain state of theLNA 120 can be conducted by determining whether the gain of theLNA 120 is higher than this threshold (S70-8). If the gain of theLNA 120 at the current point in time is the high gain as a result of this decision, thechange timing controller 196 outputs the delay control signal to the delay controller 198 (S70-9). - Subsequently, the gain
control signal generator 192 outputs the gain control signal to theLNA 120 and thedelay controller 198 on the basis of the gains of theLNA 120 and theVGA 150 selected by the gain selector 190 (S70-11). Thedelay controller 198 is supplied with the gain control signal and the delay control signal, and thedelay controller 198 delays the gain control signal and outputs the delayed gain control signal to theVGA 150. As a result, the gain of theVGA 150 is changed with a delay to the change in the gain of the LNA 120 (S70-13). - If the gain of the
LNA 120 at the current point in time is the low gain at the step S70-8, thechange timing controller 196 does not output the delay control signal. Since the delay control signal is not output, thedelay controller 198 outputs the gain control signal to theVGA 150 without delaying it. As a result, the gain of theVGA 150 is changed simultaneously with a change in the gain of the LNA 120 (S70-15). - If the gain of the
LNA 120 does not pass through the threshold before and after the change at the step S70-6, the delay control signal is not output. Thechange timing controller 196 further makes a decision whether to change the gain of the VGA 150 (S70-17). In this decision, thegain comparator 201 previously stores a threshold located between the low gain and the high gain of theVGA 150, and judges a gain higher than the threshold to be the high gain and judges gain lower than the threshold to be the low gain. If the gain of theVGA 150 passes through this threshold before and after the change, thechange timing controller 196 decides to change the gain of the VGA 150 (S70-18). - If the gain of the
VGA 150 is decided to be changed, the gaincontrol signal generator 192 outputs the gain control signal to theVGA 150 via thedelay controller 198 to change the gain of theVGA 150. Since the delay control signal is not issued from thechange timing controller 196, thedelay controller 198 passes the gain control signal to theVGA 150 without delaying it. As a result, the gain of theVGA 150 is changed (S70-19). - If the gain of the
VGA 150 is decided not to be changed, thedelay controller 198 does not change the gain ofVGA 150. -
FIG. 7 is a graph showing a DC offset component actually measured when the gain of theLNA 120 is changed from the high gain to the low gain and the gain of theVGA 150 is changed from the low gain to the high gain.FIG. 7 corresponds to the graph shown inFIG. 4H in which the signal strength of the baseband signal has been obtained by actually measuring it. A curve A shows a DC offset component measured when the gain of theLNA 120 and the gain of theVGA 150 are changed simultaneously in the same way as the conventional technique. A curve B shows a DC offset component measured when the gain of theVGA 150 is changed with a delay to a change in the gain of theLNA 120 according to the embodiment. These graphs are data showing actual measured results obtained when an RF signal from a signal generator is input to theLNA 120 and a baseband signal output from theVGA 150 is observed on a digital oscilloscope. - In the curve A, the transient response component of the DC offset output from the
VGA 150 is approximately 70 mV maximum. On the other hand, in the curve B, the transient response component of the DC offset output from theVGA 150 is approximately 30 mV maximum. Therefore, the transient response component in the curve B is obviously lower than the transient response component in the curve A. - In the case where a threshold is provided for the DC offset component, the probability in the embodiment that the DC offset component exceeds the threshold becomes lower as compared with the conventional technique.
- An area SB of a region surrounded by a curve B and a broken line is obviously smaller than an area SA of a region surrounded by a curve A and the broken line. In the embodiment, therefore, the DC offset component per unit time is smaller as compared with the conventional technique. Since the error rate in the reception characteristic is proportionate to the accumulation value of the area S per unit time as described earlier, the error rate in the reception characteristic in the embodiment is smaller as compared with the conventional technique. As a result, the embodiment becomes better in reception performance than the conventional technique.
- Other embodiments of the present invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and example embodiments will be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following.
Claims (7)
1-20. (canceled)
21. A radio signal processing method in a radio receiver, the radio receiver comprising a first amplifier, a second amplifier and a gain controller controlling gains of the first and the second amplifier, the method comprising:
receiving a radio signal;
amplifying a received radio signal in the first amplifier;
demodulating the amplified radio signal to a baseband signal;
amplifying the baseband signal in the second amplifier;
demodulating the amplified baseband signal;
controlling timing, in the gain controller, of a change in a gain of the first amplifier, in case that the gain of the first amplifier and the gain of the second amplifier are changed, on the basis of a gain of the first amplifier before and after the change;
detecting strength of the baseband signal;
selecting the gain of the first amplifier and the gain of the second amplifier at the gain controller on the basis of the strength of the baseband signal;
comparing actual gains of the first amplifier and the second amplifier with the selected gain of the first amplifier and the selected gain of the second amplifier;
determining timing of a change in the gain of the second amplifier on the basis of a result of the comparison;
generating a control signal to change the gain of the first amplifier and the gain of the second amplifier; and
transmitting the control signal to the second amplifier in accordance with the determined timing.
22. The method according to claim 21 , wherein
in a case that said gain controller changes the gain of said first amplifier from a high gain to a low gain and changes the gain of said second amplifier from a low gain to a high gain,
the gain controller transmits the control signal to said second amplifier a delay after transmission of the control signal to said first amplifier.
23. The radio receiver according to claim 21 , wherein a delay time is shorter than a repetition period of the changes in the gain of said first amplifier and the gain of said second amplifier, said delay time being a period from the change in the gain of said first amplifier until the change in the gain of said second amplifier.
24. A method of processing a radio signal in a radio receiver, the radio receiver comprising a first amplifier, a second amplifier and a gain controller controlling a gain of the first and the second amplifier, the method comprising:
receiving a radio signal;
amplifying a received radio signal in the first amplifier;
demodulating the amplified radio signal to a baseband signal;
amplifying the baseband signal in the second amplifier, after changing a gain of said first amplifier, with a gain based on a gain of said first amplifier obtained before and after the change; and
demodulating the amplified baseband signal, wherein
in a case that the gain of said first amplifier is changed from a high gain to a low gain and the gain of said second amplifier is changed from a low gain to a high gain, timing of the change in the gain of said second amplifier is delayed as compared with timing of the change in the gain of said first amplifier.
25. The method according to claim 24 , wherein a delay time is shorter than a repetition period of the changes in the gain of said first amplifier and the gain of said second amplifier, said delay time being a period from the change in the gain of said first amplifier until the change in the gain of said second amplifier.
26. A radio signal processing method comprising:
receiving a radio signal;
amplifying the radio signal;
demodulating the amplified radio signal to a baseband signal;
amplifying the baseband signal;
demodulating the amplified baseband signal;
determining timing of a change in a gain of the radio signal amplification and a gain of the baseband signal amplification, in case that the gain in the radio signal amplification and the gain in the baseband signal amplification are changed, on the basis of the gain in the radio signal amplification obtained before and after the change; and
changing the gain in the radio signal amplification and the gain in the baseband signal amplification in accordance with the determined timing,
wherein in a case where the gain in the radio signal amplification is changed from a high gain to a low gain and the gain in the baseband signal amplification is changed from a low gain to a high gain, in a case that the timing of the change in the gain is determined, the gain in the baseband signal amplification is changed with a delay to the change in the gain in the radio signal amplification.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US11/750,598 US20070224960A1 (en) | 2003-04-25 | 2007-05-18 | Radio receiver and radio signal processing method |
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2003122316A JP3906179B2 (en) | 2003-04-25 | 2003-04-25 | Radio receiver and radio signal processing method |
JP2003-122316 | 2003-04-25 | ||
US10/819,288 US7245894B2 (en) | 2003-04-25 | 2004-04-07 | Radio receiver and radio signal processing method with controlling gain |
US11/750,598 US20070224960A1 (en) | 2003-04-25 | 2007-05-18 | Radio receiver and radio signal processing method |
Related Parent Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US10/819,288 Division US7245894B2 (en) | 2003-04-25 | 2004-04-07 | Radio receiver and radio signal processing method with controlling gain |
Publications (1)
Publication Number | Publication Date |
---|---|
US20070224960A1 true US20070224960A1 (en) | 2007-09-27 |
Family
ID=32959712
Family Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US10/819,288 Expired - Fee Related US7245894B2 (en) | 2003-04-25 | 2004-04-07 | Radio receiver and radio signal processing method with controlling gain |
US11/750,598 Abandoned US20070224960A1 (en) | 2003-04-25 | 2007-05-18 | Radio receiver and radio signal processing method |
Family Applications Before (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US10/819,288 Expired - Fee Related US7245894B2 (en) | 2003-04-25 | 2004-04-07 | Radio receiver and radio signal processing method with controlling gain |
Country Status (5)
Country | Link |
---|---|
US (2) | US7245894B2 (en) |
EP (1) | EP1471633A3 (en) |
JP (1) | JP3906179B2 (en) |
KR (1) | KR100615022B1 (en) |
CN (1) | CN100359810C (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20090058531A1 (en) * | 2007-08-31 | 2009-03-05 | Nanoamp Solutions Inc. (Cayman) | Variable gain amplifier |
US20120274398A1 (en) * | 2011-04-26 | 2012-11-01 | Analog Devices, Inc. | RF AGC Control |
Families Citing this family (55)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP3852919B2 (en) * | 2001-12-25 | 2006-12-06 | 株式会社東芝 | Wireless receiver |
JP3906179B2 (en) * | 2003-04-25 | 2007-04-18 | 株式会社東芝 | Radio receiver and radio signal processing method |
DE102004024875B4 (en) * | 2004-05-19 | 2006-09-07 | Infineon Technologies Ag | Amplifier arrangement and method for compensating a signal component in an amplifier arrangement |
GB2424326B (en) * | 2005-03-18 | 2008-01-16 | Motorola Inc | Receiver for receipt and demodulation of a frequency modulated RF signal and method of operation therein |
US8340944B2 (en) | 2005-11-30 | 2012-12-25 | The Invention Science Fund I, Llc | Computational and/or control systems and methods related to nutraceutical agent selection and dosing |
US8000981B2 (en) | 2005-11-30 | 2011-08-16 | The Invention Science Fund I, Llc | Methods and systems related to receiving nutraceutical associated information |
US10296720B2 (en) | 2005-11-30 | 2019-05-21 | Gearbox Llc | Computational systems and methods related to nutraceuticals |
US20080241910A1 (en) * | 2007-03-27 | 2008-10-02 | Searete Llc, A Limited Liability Corporation Of The State Of Delaware | Devices for pathogen detection |
US7827042B2 (en) | 2005-11-30 | 2010-11-02 | The Invention Science Fund I, Inc | Methods and systems related to transmission of nutraceutical associated information |
US7974856B2 (en) | 2005-11-30 | 2011-07-05 | The Invention Science Fund I, Llc | Computational systems and methods related to nutraceuticals |
US20080241909A1 (en) * | 2007-03-27 | 2008-10-02 | Searete Llc, A Limited Liability Corporation Of The State Of Delaware | Microfluidic chips for pathogen detection |
US20080178692A1 (en) * | 2007-01-29 | 2008-07-31 | Searete Llc, A Limited Liability Corporation Of The State Of Delaware | Fluidic methods |
US20080103746A1 (en) | 2005-11-30 | 2008-05-01 | Searete Llc, A Limited Liability Corporation | Systems and methods for pathogen detection and response |
US20080179255A1 (en) * | 2007-01-29 | 2008-07-31 | Searete Llc, A Limited Liability Corporation Of The State Of Delaware | Fluidic devices |
US8297028B2 (en) | 2006-06-14 | 2012-10-30 | The Invention Science Fund I, Llc | Individualized pharmaceutical selection and packaging |
US7927787B2 (en) | 2006-06-28 | 2011-04-19 | The Invention Science Fund I, Llc | Methods and systems for analysis of nutraceutical associated components |
JP2008011027A (en) * | 2006-06-28 | 2008-01-17 | Fujitsu Ltd | Receiver |
US8642093B2 (en) * | 2007-10-30 | 2014-02-04 | The Invention Science Fund I, Llc | Methods and systems for use of photolyzable nitric oxide donors |
US7862598B2 (en) * | 2007-10-30 | 2011-01-04 | The Invention Science Fund I, Llc | Devices and systems that deliver nitric oxide |
US20090110933A1 (en) * | 2007-10-30 | 2009-04-30 | Searete Llc, A Limited Liability Corporation Of The State Of Delaware | Systems and devices related to nitric oxide releasing materials |
US20090112197A1 (en) | 2007-10-30 | 2009-04-30 | Searete Llc | Devices configured to facilitate release of nitric oxide |
US8221690B2 (en) * | 2007-10-30 | 2012-07-17 | The Invention Science Fund I, Llc | Systems and devices that utilize photolyzable nitric oxide donors |
US20110190604A1 (en) * | 2006-12-22 | 2011-08-04 | Hyde Roderick A | Nitric oxide sensors and systems |
JP4734262B2 (en) * | 2007-01-26 | 2011-07-27 | 株式会社東芝 | Receiving device, wireless device, offset canceling method |
US20080245740A1 (en) * | 2007-01-29 | 2008-10-09 | Searete Llc, A Limited Liability Corporation Of The State Of Delaware | Fluidic methods |
US20080180259A1 (en) * | 2007-01-29 | 2008-07-31 | Searete Llc, A Limited Liability Corporation Of The State Of Delaware | Devices for allergen detection |
US20080181821A1 (en) * | 2007-01-29 | 2008-07-31 | Searete Llc, A Limited Liability Corporation Of The State Of Delaware | Microfluidic chips for allergen detection |
US20090050569A1 (en) * | 2007-01-29 | 2009-02-26 | Searete Llc, A Limited Liability Corporation Of The State Of Delaware | Fluidic methods |
US20080181816A1 (en) * | 2007-01-29 | 2008-07-31 | Searete Llc, A Limited Liability Corporation | Systems for allergen detection |
US10001496B2 (en) | 2007-01-29 | 2018-06-19 | Gearbox, Llc | Systems for allergen detection |
US8617903B2 (en) * | 2007-01-29 | 2013-12-31 | The Invention Science Fund I, Llc | Methods for allergen detection |
JP2008205956A (en) * | 2007-02-21 | 2008-09-04 | Toshiba Corp | Receiver, wireless apparatus, and offset canceling method |
US20090215157A1 (en) * | 2007-03-27 | 2009-08-27 | Searete Llc | Methods for pathogen detection |
US7817750B2 (en) * | 2007-05-21 | 2010-10-19 | Seiko Epson Corporation | Radio receiver including a delay-locked loop (DLL) for phase adjustment |
US8980332B2 (en) | 2007-10-30 | 2015-03-17 | The Invention Science Fund I, Llc | Methods and systems for use of photolyzable nitric oxide donors |
US7897399B2 (en) | 2007-10-30 | 2011-03-01 | The Invention Science Fund I, Llc | Nitric oxide sensors and systems |
US8877508B2 (en) * | 2007-10-30 | 2014-11-04 | The Invention Science Fund I, Llc | Devices and systems that deliver nitric oxide |
US20090112193A1 (en) * | 2007-10-30 | 2009-04-30 | Searete Llc, A Limited Liability Corporation Of The State Of Delaware | Systems and devices that utilize photolyzable nitric oxide donors |
US8349262B2 (en) * | 2007-10-30 | 2013-01-08 | The Invention Science Fund I, Llc | Nitric oxide permeable housings |
US10080823B2 (en) | 2007-10-30 | 2018-09-25 | Gearbox Llc | Substrates for nitric oxide releasing devices |
US20090112055A1 (en) * | 2007-10-30 | 2009-04-30 | Searete Llc, A Limited Liability Corporation Of The State Of Delaware | Sleeves configured to facilitate release of nitric oxide |
US20090259217A1 (en) * | 2008-04-09 | 2009-10-15 | Searete Llc, A Limited Liability Corporation Of The State Of Delaware | Methods and systems associated with delivery of one or more agents to an individual |
US20090259214A1 (en) * | 2008-04-09 | 2009-10-15 | Searete Llc, A Limited Liability Corporation Of The State Of Delaware | Agent delivery device |
CN102025667B (en) * | 2010-08-31 | 2013-11-20 | 上海南麟电子有限公司 | Circuit and method for eliminating direct current offset and radio frequency receiving chip |
US8986337B2 (en) | 2012-02-24 | 2015-03-24 | Elwha Llc | Devices, systems, and methods to control stomach volume |
JP5887433B2 (en) * | 2012-03-06 | 2016-03-16 | フラウンホッファー−ゲゼルシャフト ツァ フェルダールング デァ アンゲヴァンテン フォアシュンク エー.ファオ | Receive stage and receive method |
US9589106B2 (en) | 2012-05-04 | 2017-03-07 | Elwha Llc | Devices, systems, and methods for automated data collection |
US9375145B2 (en) | 2012-12-19 | 2016-06-28 | Elwha Llc | Systems and methods for controlling acquisition of sensor information |
US10141073B2 (en) | 2012-12-19 | 2018-11-27 | Elwha Llc | Systems and methods for controlling acquisition of sensor information |
US10289806B2 (en) | 2013-11-14 | 2019-05-14 | Elwha Llc | Devices, systems, and methods for automated medical product or service delivery |
US9864842B2 (en) | 2013-11-14 | 2018-01-09 | Elwha Llc | Devices, systems, and methods for automated medical product or service delivery |
US9654159B2 (en) * | 2013-12-20 | 2017-05-16 | Motorola Solutions, Inc. | Systems for and methods of using a mirrored wideband baseband current for automatic gain control of an RF receiver |
JP2015231148A (en) * | 2014-06-05 | 2015-12-21 | 船井電機株式会社 | Receiver |
CN104393845B (en) * | 2014-10-21 | 2018-03-13 | 东南大学 | A kind of current-mode variable gain amplifier |
US11209520B2 (en) * | 2019-05-24 | 2021-12-28 | Electronics And Telecommunications Research Institute | Radar, signal processing circuit, and signal processing method |
Citations (14)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6205189B1 (en) * | 1996-09-13 | 2001-03-20 | Samsung Electronics Co., Ltd. | Digital automatic gain control method and device for use in communication terminal of mobile radio communication system |
US20020086651A1 (en) * | 2001-01-02 | 2002-07-04 | Prentice John S. | Precision automatic gain control circuit |
US6459889B1 (en) * | 2000-02-29 | 2002-10-01 | Motorola, Inc. | DC offset correction loop for radio receiver |
US20030064696A1 (en) * | 2001-09-28 | 2003-04-03 | Yukinori Akamine | Wireless communication receiver |
US20030207675A1 (en) * | 2002-05-03 | 2003-11-06 | Motorola, Inc. | Automatic gain control system having a wide range of continuous gain control |
US20040097209A1 (en) * | 2002-11-14 | 2004-05-20 | Haub David R. | Automatic gain control apparatus and methods |
US6748200B1 (en) * | 2000-10-02 | 2004-06-08 | Mark A. Webster | Automatic gain control system and method for a ZIF architecture |
US20050070240A1 (en) * | 2001-06-29 | 2005-03-31 | Bernd Adler | Receiver device comprising an alternating current coupling |
US6885852B2 (en) * | 2002-05-02 | 2005-04-26 | Motorola, Inc. | Method and apparatus in a wireless communication device for mitigating a received power overload |
US20050186928A1 (en) * | 1999-03-18 | 2005-08-25 | Matsushita Electric Industrial Co., Ltd. | Automatic gain control circuit and receiver device having the automatic gain control circuit, and automatic gain control method |
US20050208919A1 (en) * | 2001-02-16 | 2005-09-22 | Brett Walker | Serial bus interface for direct conversion receiver |
US6950641B2 (en) * | 2003-01-31 | 2005-09-27 | Nokia Corporation | Apparatus, and an associated method, for increasing receiver sensitivity of a direct conversion receiver |
US6963733B2 (en) * | 2001-10-31 | 2005-11-08 | Telefonaktiebolaget L M Ericsson (Publ) | Method and apparatus for reducing the effect of AGC switching transients |
US7245894B2 (en) * | 2003-04-25 | 2007-07-17 | Kabushiki Kaisha Toshiba | Radio receiver and radio signal processing method with controlling gain |
Family Cites Families (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP3180682B2 (en) * | 1996-09-19 | 2001-06-25 | 日本電気株式会社 | Receiving machine |
JP3475037B2 (en) * | 1997-03-14 | 2003-12-08 | 株式会社東芝 | transceiver |
EP0920766B1 (en) * | 1997-05-23 | 2005-02-23 | Koninklijke Philips Electronics N.V. | Receiver with controllable amplifier means |
US6442380B1 (en) | 1999-12-22 | 2002-08-27 | U.S. Philips Corporation | Automatic gain control in a zero intermediate frequency radio device |
JP2002076805A (en) | 2000-08-29 | 2002-03-15 | Sharp Corp | Agc amplifier circuit and receiver employing it |
JP2002094346A (en) | 2000-09-14 | 2002-03-29 | Mitsubishi Electric Corp | Receiver provided with variable gain amplifier, and its control method |
-
2003
- 2003-04-25 JP JP2003122316A patent/JP3906179B2/en not_active Expired - Fee Related
-
2004
- 2004-02-24 KR KR1020040012294A patent/KR100615022B1/en not_active IP Right Cessation
- 2004-03-01 CN CNB2004100639825A patent/CN100359810C/en not_active Expired - Fee Related
- 2004-03-31 EP EP04251939A patent/EP1471633A3/en not_active Withdrawn
- 2004-04-07 US US10/819,288 patent/US7245894B2/en not_active Expired - Fee Related
-
2007
- 2007-05-18 US US11/750,598 patent/US20070224960A1/en not_active Abandoned
Patent Citations (15)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6205189B1 (en) * | 1996-09-13 | 2001-03-20 | Samsung Electronics Co., Ltd. | Digital automatic gain control method and device for use in communication terminal of mobile radio communication system |
US20050186928A1 (en) * | 1999-03-18 | 2005-08-25 | Matsushita Electric Industrial Co., Ltd. | Automatic gain control circuit and receiver device having the automatic gain control circuit, and automatic gain control method |
US6459889B1 (en) * | 2000-02-29 | 2002-10-01 | Motorola, Inc. | DC offset correction loop for radio receiver |
US6748200B1 (en) * | 2000-10-02 | 2004-06-08 | Mark A. Webster | Automatic gain control system and method for a ZIF architecture |
US20020086651A1 (en) * | 2001-01-02 | 2002-07-04 | Prentice John S. | Precision automatic gain control circuit |
US20050208919A1 (en) * | 2001-02-16 | 2005-09-22 | Brett Walker | Serial bus interface for direct conversion receiver |
US7076225B2 (en) * | 2001-02-16 | 2006-07-11 | Qualcomm Incorporated | Variable gain selection in direct conversion receiver |
US20050070240A1 (en) * | 2001-06-29 | 2005-03-31 | Bernd Adler | Receiver device comprising an alternating current coupling |
US20030064696A1 (en) * | 2001-09-28 | 2003-04-03 | Yukinori Akamine | Wireless communication receiver |
US6963733B2 (en) * | 2001-10-31 | 2005-11-08 | Telefonaktiebolaget L M Ericsson (Publ) | Method and apparatus for reducing the effect of AGC switching transients |
US6885852B2 (en) * | 2002-05-02 | 2005-04-26 | Motorola, Inc. | Method and apparatus in a wireless communication device for mitigating a received power overload |
US20030207675A1 (en) * | 2002-05-03 | 2003-11-06 | Motorola, Inc. | Automatic gain control system having a wide range of continuous gain control |
US20040097209A1 (en) * | 2002-11-14 | 2004-05-20 | Haub David R. | Automatic gain control apparatus and methods |
US6950641B2 (en) * | 2003-01-31 | 2005-09-27 | Nokia Corporation | Apparatus, and an associated method, for increasing receiver sensitivity of a direct conversion receiver |
US7245894B2 (en) * | 2003-04-25 | 2007-07-17 | Kabushiki Kaisha Toshiba | Radio receiver and radio signal processing method with controlling gain |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20090058531A1 (en) * | 2007-08-31 | 2009-03-05 | Nanoamp Solutions Inc. (Cayman) | Variable gain amplifier |
US20120274398A1 (en) * | 2011-04-26 | 2012-11-01 | Analog Devices, Inc. | RF AGC Control |
US8965317B2 (en) * | 2011-04-26 | 2015-02-24 | Analog Devices, Inc. | RF AGC control |
Also Published As
Publication number | Publication date |
---|---|
EP1471633A2 (en) | 2004-10-27 |
CN100359810C (en) | 2008-01-02 |
CN1571287A (en) | 2005-01-26 |
EP1471633A3 (en) | 2007-09-05 |
JP3906179B2 (en) | 2007-04-18 |
US7245894B2 (en) | 2007-07-17 |
JP2004328494A (en) | 2004-11-18 |
KR100615022B1 (en) | 2006-08-25 |
KR20040092383A (en) | 2004-11-03 |
US20050009489A1 (en) | 2005-01-13 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US7245894B2 (en) | Radio receiver and radio signal processing method with controlling gain | |
US7515890B2 (en) | Radio receiver and radio receiving method | |
US6806844B2 (en) | Calibration system for array antenna receiving apparatus | |
US7961821B2 (en) | Communication semiconductor integrated circuit, radio communication system, and adjustment method of gain and offset | |
US6226504B1 (en) | Receiving apparatus | |
JP6225041B2 (en) | Receiver | |
US20030027538A1 (en) | Receiving apparatus and a receiver system having the receiving apparatus | |
US8660221B2 (en) | Fast and robust AGC apparatus and method using the same | |
US8804882B2 (en) | Receiving apparatus, and computer readable memory medium that stores a program | |
JP2004215246A (en) | In-phase composite diversity receiving apparatus and method for the same | |
JP2005210261A (en) | Wireless communication system and high frequency ic | |
US7920840B2 (en) | Wireless receiver apparatus provided with gain control amplifier | |
US8301172B2 (en) | Mobile communication system and method for estimating moving speed of mobile terminal | |
US20050129151A1 (en) | Wireless receiving device suppressing occurrence of reception error | |
EP0687080B1 (en) | Receive signal level detection system | |
JP2009177568A (en) | Receiver, and electronic apparatus using the same | |
JP2000216836A (en) | Dc offset adjusting circuit and method | |
JPH06338796A (en) | Receiver | |
US8767894B2 (en) | Wireless device and receiving method | |
JP2004064525A (en) | Feedback gain control circuit and radio communication equipment | |
JPH1155138A (en) | Receiver | |
JPH04337931A (en) | Diversity reception system | |
JPH088667A (en) | Demodulating circuit | |
JP2006129161A (en) | Radio receiver | |
JPH09294080A (en) | Am radio receiver |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
STCB | Information on status: application discontinuation |
Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION |