Radio receiver and radio receiving method

• US 7,555,274 B2
• Filed: 11/17/2005
• Issued: 06/30/2009
• Est. Priority Date: 12/25/2001
• Status: Expired due to Fees

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Yoshida, Hiroshi, Kato, Takayuki, Toyoda, Takehiko
• Primary Examiner(s): Urban; Edward
• Assistant Examiner(s): Hannon; Christian A
• Application Number:
  US11/280,315
• Publication Number:
  US 20060068734A1
• Time in Patent Office: 1,321 Days
• Field of Search: 455/230, 455/231, 455/232.1, 455/234.1, 455/234.2, 455/235.1, 455/239.1, 455/240.1, 455/241.1
• US Class Current: 455/239.1
• CPC Class Codes: H03G 3/3052 in bandpass amplifiers (H.F. or I.F.) or in frequency-changers used in a (super)heterodyne receiver H03G3/32, H03G3/34 take precedence
• CPC Class Codes: H03G 3/3068 Circuits generating control signals for both R.F. and I.F. stages
• CPC Class Codes: H04B 1/30 for homodyne or synchrodyne receivers demodulator circuits H03D1/22

Abstract

A radio receiver comprises an LNA which amplifies An RF signal, a quadrature demodulator which directly demodulates the amplified RF signal into a B/B signal, using a LO signal, a VGA which amplifies the B/B signal, a DC offset canceller which executes feedback control on the amplified B/B signal, and a gain controller which controls at least the gain of the LNA, the gain controller including a signal intensity detector which detects the intensity of the amplified B/B signal, a gain selector which selects a desired one of preset gains on the basis of the detected intensity, a timing controller which controls timing of switching to the selected desired gain, and a gain control signal generator which changes, in accordance with the controlled timing, the interval at which an LNA gain control signal is generated.

Claims

1. A radio receiver comprising:

a low noise amplifier which amplifies a radio signal;

a quadrature demodulator which demodulates the amplified radio signal into a baseband signal;

a variable gain amplifier which amplifies the baseband signal;

an executing unit configured to execute feedback of the amplified baseband signal; and

a first gain controller which controls a first gain of the low noise amplifier and a second gain of the variable gain amplifier, the first gain controller comprising,

a signal intensity detector which detects an intensity of the amplified baseband signal,

a gain selector which selects a preset gain from a plurality of preset gains which are set for the low noise amplifier, based on the detected intensity,

a timing controller which controls timing of switching the first gain and the second gain to the selected preset gain, and

a gain control signal output unit configured to output a gain control signal which controls the first gain according to the selected preset gain at a time-interval according to the controlled timing; and

a second gain controller which controls the second gain if the time-interval is not longer than a present time-interval;

wherein the timing controller comprises,

a measurement unit configured to measure time when an intensity of a received signal crosses a threshold value, and calculate a time-interval elapsing from a previous adjacent time when the intensity of the received signal crossed a threshold value to the measured time, and

a comparator configured to compare the time-interval with the preset time-interval; and

the gain control signal output unit outputting the gain control signal to the low noise amplifier if the time-interval is longer than the preset time-interval.

2. The radio receiver according to claim 1, wherein the time-interval is a time-interval elapsing from a previous adjacent time when an intensity of the baseband signal crossed a threshold value to the time when an intensity of the baseband signal crosses a threshold value.

3. The radio receiver according to claim 1, wherein the time-interval is a time-interval elapsing from a previous adjacent time when a signal from the selector was input to the measurement unit to a time when the signal is input to the measurement unit.

4. The radio receiver according to claim 1, wherein the preset time-interval is set such that even if gain of the low noise amplifier is switched, a block error rate does not degrade to a degree higher than a maximum allowable block error rate as a standard for a radio communication system.

5. The radio receiver according to claim 1, wherein the preset time-interval is 7680 times or more as long as a chip rate.

6. A radio receiving method comprising:

amplifying a radio signal using a low noise amplifier;

demodulating the amplified radio signal into a baseband signal;

amplifying the baseband signal;

executing feedback of the amplified baseband signal;

controlling a first gain of the low noise amplifier and a second gain of the variable gain amplifier;

detecting an intensity of the amplified baseband signal;

selecting a preset gain from a plurality of preset gains which are set for the low noise amplifier, based on the detected intensity;

controlling timing of switching the first gain and the second gain to the selected preset gain;

outputting a gain control signal which controls the first gain according to the selected preset gain at a time-interval according to the controlled timing; and

controlling the second gain and failing to control the first gain if the time-interval is not longer than a present time-interval;

wherein controlling the timing comprises,

measuring time when an intensity of a received signal crosses a threshold value, and calculating a time-interval elapsing from a previous adjacent time when the intensity of the received signal crossed a threshold value to the measured time,

comparing the time-interval with the preset time-interval, and

outputting the gain control signal to the low noise amplifier if the time-interval is longer than the preset time-interval.