Nonlinear effects of RF interference in MOS operational amplifiers

The effect of radio frequency interference in MOS operational amplifiers is dealt with. In order to obtain analytical expressions which can be useful for design purposes, a second-order nonlinear circuit analysis has been performed. This approach grants a good insight in the nonlinear mechanisms involved in the RFI induced DC offset shift in operational amplifiers and allows us to relate this behavior to design parameters and parasitics. The validity of the proposed model is discussed, comparing theoretical predictions with computer simulations and experimental measurements.