Signal Amplification Circuit and Signal Amplification Determination Circuit Including the Signal Amplification Circuit

摘要

A signal amplification circuit (41) includes an input terminal; a first chopper modulation circuit (12); a first amplifier (14) including an amplification circuit (140) and a chopper demodulation circuit (15) connected to a second output terminal of the amplification circuit (14), a capacitance feedback circuit (170), including a second chopper modulation circuit (18), connected to an output terminal of the chopper demodulation circuit (15) to an input terminal of the amplification circuit (140) via a feedback point, a first switch (SW0e, SW0f), connected to a first output terminal of the amplification circuit (15), constituting a voltage follower circuit with the amplification circuit (15); a second switch (SW0a, SW0b, SW0c, SW0d); a second amplifier (21) to convert an amplified signal from the second output terminal of the amplification circuit (140) into a single-end signal; and a filter (22, 24) to pass at least a predetermined frequency component of a chopping frequency from the single-end signal output from the second amplifier (21) to output an output signal.