Patent ID: 9584079
Date: 2017-02-28
CPC Classifications: H03F

Claim:
1. An operational amplifier comprising: a first chopper for modulating an input signal pair; a first signal processing path on a stage subsequent to the first chopper, having at least one circuit unit set or multiple circuit unit sets connected in series, the circuit unit set being constituted by one high-pass filter and one differential amplifier to amplify output signals from the high-pass filter, wherein output nodes of the high-pass filter of each set are biased to a potential within a common-mode range that enables operation of the differential amplifier of that circuit unit set; a second chopper for signal demodulation provided on the output side of the first signal processing path; a second signal processing path including one differential amplifier connected to the output nodes of the first chopper; a summing means for summing an output signal from the first signal processing path and an output signal from the second signal processing path; and an amplifier that amplifies the signal generated by the summing means and supplied via the second chopper and outputs the amplified signal as an output signal of the operational amplifier.