AMPLIFICATION CIRCUIT, AND RECEIVING DEVICE AND COMMUNICATION DEVICE USING SAME

摘要

[Problem] To provide an amplification circuit the gain of which can be controlled in response to fluctuation in amplitude of an input signal. [Solution] Provided is an amplification circuit which comprises: a variable gain amplification circuit (3) for amplifying an input first signal (S1) to output a second signal (S2); a first control circuit (4) which outputs a third signal (S3) that is used for controlling the gain of the variable gain amplification circuit (3) in accordance with the amplitude of the first signal (S1); a second control circuit (5) which outputs a fourth signal (S4) that is used for controlling the gain of the variable gain amplification circuit (3) in accordance with the amplitude of the second signal (S2); and a third control circuit (6) which adds the input third signal (S3) and fourth signal (S4) to output a fifth signal (S5) that controls the gain of the variable gain amplification circuit (3). The third control circuit (6) weights and adds the third signal (S3) and fourth signal (S4) in accordance with the amplitude of the first signal (S1).