MOSFET Nonlinear Incremental Model for NCAP

Abstract

A four-terminal nonlinear incremental MOSFET model for EMI analysis is described. For normal MOSFET opera­ tion the model simplifies to a three-terminal model. A BiMOS op amp circuit was investigated to determine how well the model could predict how API-modulated RF sig­ nals are demodulated in MOS circuits to cause undesired low frequency responses. The experimental and calcu­ lated values for demodulation RFI agreed quite well over the RF frequency range 50 kHz to 100 MHz. The agreement demonstrates the usefulness of the nonlinear incremental MOSFET model described in the paper.