Radio receiver and radio receiving method

• US 20030119464A1
• Filed: 12/24/2002
• Published: 06/26/2003
• Est. Priority Date: 12/25/2001
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Yoshida, Hiroshi, Kato, Takayuki, Toyoda, Takehiko
• Granted Patent: US 7,272,371 B2
• Time in Patent Office: Days
• US Class Current: 455/245.1
• 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 directly demodulates the radio signal amplified into a baseband signal;

a variable gain amplifier which amplifies the baseband signal;

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

a gain controller which controls a gain of the low noise amplifier, the gain controller comprising;

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

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

a timing controller which controls timing of switching the gain to the desired preset gain selected; and

a gain control signal output unit configured to output a gain control signal to the low noise amplifier at a time-interval according to the timing controlled.

2. The radio receiver according to claim 1, wherein:

the gain controller also controls a gain of the variable gain amplifier;

the gain selector also selects a desired preset gain from a plurality of preset gains which are set for the variable gain amplifier, based on the intensity detected; and

the gain control signal output unit selectively outputs a first gain control signal and a second gain control signal to the variable gain amplifier,

the first gain control signal making the gain of the variable gain amplifier lower than a value if a first state in which the gain of the low noise amplifier is set high is maintained,

and the second gain control signal making the gain of the variable gain amplifier higher than the value if a second state in which the gain of the low noise amplifier is set low is maintained.

3. The radio receiver according to claim 1, wherein:

the timing controller comprises;

a measurement unit configured to measure time when the gain of the low noise amplifier is switched, and calculate a time-interval elapsing from a previous adjacent time when the gain of the low noise amplifier was switched to the time measured; and

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

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

4. The radio receiver according to claim 3, wherein the preset time-interval is set such that even if the 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 3, wherein the preset time-interval is 7680 times or more as long as a chip rate.

6. The radio receiver according to claim 1, 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 time measured;

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

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

7. The radio receiver according to claim 6, 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.

8. The radio receiver according to claim 6, 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.

9. The radio receiver according to claim 6, 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.

10. The radio receiver according to claim 6, wherein the preset time-interval is 7680 times or more as long as a chip rate.

11. A radio receiving method comprising:

amplifying a radio signal;

directly demodulating the radio signal amplified into a baseband signal;

amplifying the baseband signal;

executing feedback control on the baseband signal amplified;

detecting an intensity of the baseband signal amplified;

selecting a desired preset gain from a plurality of preset gains based on the intensity detected;

controlling timing of switching the gain to the desired preset gain selected; and

outputting a gain control signal at a time-interval according to the timing controlled.