AMPLIFICATION CIRCUIT, AND RECEPTION DEVICE AND COMMUNICATION DEVICE USING THE SAME

摘要

PROBLEM TO BE SOLVED: To provide an amplification circuit that controls a gain in response to a variation in the amplitude of an input signal.

SOLUTION: The amplification circuit includes: a variable gain amplifier circuit 10 for amplifying a first signal S1 input thereinto to output a second signal S2; a detection circuit 20 for detecting the first signal S1 to output a third signal S3; and a converter circuit 30 for receiving the third signal S3 to output a fourth signal S4 having a voltage varying exponentially relative to the voltage of the third signal S3, and controls the gain of the variable gain amplifier circuit 10 with the fourth signal S4. Even when the amplitude of the first signal S1 input varies greatly, the amplification circuit can control the gain in response to the variation in the amplitude of the first signal S1. This can reduce a variation in the amplitude of the second signal S2 even when the amplitude of the first signal S1 varies greatly.

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