AGC circuit
AssigneeMatsushita Electric Industrial Co., Ltd.
InventorTakuma Ishida
Life of this patent
Estimating the term…
Abstract
An AGC circuit includes: a variable gain amplifier circuit having a gain controlled with a gain control signal; a rectifier circuit for rectifying an output signal of the variable gain amplifier circuit; a voltage comparator for comparing a rectified signal with a threshold voltage; an up/down counter that switches between up-counting and down-counting according to the level of an output voltage of the voltage comparator; and a D/A converter circuit for outputting a voltage corresponding to a count value of the up/down counter. The gain control signal supplied to the variable gain amplifier circuit corresponds to the voltage output from the D/A converter circuit, and the threshold voltage for the voltage comparator is a voltage corresponding to the voltage output from the D/A converter circuit.
Claims2
An AGC circuit comprising:
- a variable gain amplifier circuit having a gain controlled with a gain control signal;
- a rectifier circuit for rectifying an output signal of the variable gain amplifier circuit;
- a first voltage comparator for comparing a rectified signal from the rectifier circuit with a threshold voltage;
- a first up/down counter that switches between up-counting and down-counting according to an output voltage of the first voltage comparator;
- a first D/A converter circuit for outputting a voltage corresponding to a count value of the first up/down counter;
- a second up/down counter that switches between up-counting and down-counting according to a given voltage level;
- a second D/A converter circuit for outputting a voltage corresponding to a count value of the second up/down counter;
- a second voltage comparator for comparing the output voltage of the first D/A converter circuit with the output voltage of the second D/A converter circuit;
- and
- a clock switch circuit for switching a frequency of a count clock for the first up/down counter based on an output voltage of the second voltage comparator,
- wherein the second up/down counter is configured to switch between the up-counting and the down-counting according to the output voltage of the second voltage comparator, and
- the gain control signal supplied to the variable gain amplifier circuit corresponds to the voltage output from the first D/A converter circuit, and the threshold voltage for the first voltage comparator corresponds to the voltage output from the first or second D/A converter circuit.
Dependencies are inferred from the claim text.