Simulation of intermodulation distortion in passive CMOS FET mixers

The simulation of third-order intermodulation distortion in a passive CMOS FET mixer will typically predict a fictitious 2:1 slope using the industry standard EKV, BSIM3 and BSIM4 models. This phenomenon has been attributed to the discontinuity in the second-order derivatives of the drain-current and the terminal charge model. This paper establishes the connection between the discontinuous derivatives and the resulting intermodulation distortion slope and provides experimental verification.