Analysis of the effect of radio frequency interference on the DC performance of bipolar operational amplifiers

Fourier-series approximations are obtained for the input/output characteristic of the bipolar differential amplifier with active load and the asymmetrical differential amplifier. Using these approximations, the DC voltage offset of a differential amplifier subjected to radio-frequency interference (RFI) can be studied and analytical expressions are obtained. These expressions can help in optimizing the parameters of the differential amplifier to minimize the offset voltage resulting from the RFI.