Patent ID: 9246446
Filing Date: 2016-01-26
CPC Classification: H03F

Claim Text:
1. A chopper amplifier comprising: a chopper modulator to modulate a certain detection signal and a bias voltage by a certain control signal and output a chopper modulation signal; a first differential amplifier to differentially amplify the chopper modulation signal from the chopper modulator and output a differential modulation signal; a chopper demodulator to demodulate the differential modulation signal from the first differential amplifier by the control signal and output a demodulation signal; a second differential amplifier to extract a detection signal component from the demodulation signal; and a plurality of filters connected at an input terminal of the second differential amplifier and having different cutoff frequencies from each other relative to the demodulation signal, wherein the filters include a first highpass filter and a second highpass filter having different cutoff frequencies which satisfy the following relation: where F c1 is the cutoff frequency of the first highpass filter, F c2 is the cutoff frequency of the second highpass filter, F in is a frequency of the detection signal, and F chop is a frequency of the control signal.