Patent ID: 9172332
Filing Date: 2015-10-27
Classification: G06G,H03F

Abstract:
1. An operational amplifier circuit for amplifying a difference between signals input to input terminals and outputting the amplified difference from an output terminal, the operational amplifier circuit comprising: a first amplifier stage connected to the input terminals of the operational amplifier circuit; a first chopper circuit that is connected to the input terminals of the operational amplifier circuit and controlled by a first clock, the first chopper circuit having a function of modulating input signals; a second amplifier stage connected to output terminals of the first chopper circuit; a second chopper circuit that is connected to output terminals of the second amplifier stage and controlled by the first clock, the second chopper circuit having a function of demodulating input signals; an integrating circuit that is connected to output terminals of the second chopper circuit and has a function of integrating input signals; an FIR filter connected to output terminals of the integrating circuit; a third amplifier stage connected to output terminals of the FIR filter; and a fourth amplifier stage that is connected to an output terminal of the first amplifier stage and an output terminal of the third amplifier stage, and has an output terminal connected to the output terminal of the operational amplifier circuit; wherein the FIR filter comprises: a first weighting circuit that is connected to input terminals of the FIR filter and has a fixed gain; a delay circuit that is connected to the input terminals of the FIR filter and has a function of delaying an input signal for a fixed period of time and outputting the delayed signal; a second weighting circuit that is connected to output terminals of the delay circuit and has a fixed gain; and an adder circuit that is connected to an output terminal of the first weighting circuit and an output terminal of the second weighting circuit, and has a function of adding input signals.