AGC circuit and radio receiver
AssigneeSocionext Inc.
InventorsKoichiro Tanaka, Takeaki Watanabe
Life of this patent
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Abstract
An AGC circuit for a radio receiver includes a detector converting a high frequency signal into a baseband signal. To reduce generation of a DC offset, the AGC circuit includes: a variable gain amplifier having an amplifier circuit and a high-pass filter, the amplifier circuit amplifying the baseband signal with a variable gain and the high-pass filter coupled to the amplifier circuit and having a cut-off frequency which is variable; a controller supplying a gain control signal; and a blocker temporarily blocking the high frequency signal. Using the block control signal, the controller causes the blocker to start blocking the high frequency signal, before the cut-off frequency of the high-pass filter is switched from high to low.
Claims10
An automatic gain control (AGC) circuit for a radio receiver having a detector for converting a high frequency signal into a baseband signal, the AGC circuit comprising:
- a variable gain amplifier including an amplifier circuit and a high-pass filter, the amplifier circuit amplifying the baseband signal with a variable gain, and the high-pass filter being coupled to the amplifier circuit and having a cut-off frequency which is variable;
- a controller supplying a gain control signal to the amplifier circuit and a cut-off frequency control signal to the high-pass filter of the variable gain amplifier;
- and
- a switch temporarily blocking the high frequency signal from being supplied to the detector, wherein
- the controller further causes the switch to start blocking the high frequency signal before the cut-off frequency of the high-pass filter is switched from high to low from the cut-off frequency control signal.
A radio receiver comprising:
- a detector converting a high frequency signal into a baseband signal;
- a variable gain amplifier including an amplifier circuit and a high-pass filter, the amplifier circuit amplifying the baseband signal with a variable gain, and the high-pass filter being coupled to the amplifier circuit and having a cut-off frequency which is variable;
- a controller supplying a gain control signal to the amplifier circuit and a cut-off frequency control signal to the high-pass filter of the variable gain amplifier;
- and a switch temporarily blocking the high frequency signal from being supplied to the detector, wherein
- the controller further causes the switch to start blocking the high frequency signal before the cut-off frequency of the high-pass filter is switched from high to low from the cut-off frequency control signal.
Dependencies are inferred from the claim text.