Intermodulation Distortion Analysis of FET Mixers under Multitone Excitation

This paper presents an extension of the time-varying Volterra-series technique for evaluating intermodulation distortion (IMD) in FET mixers when excited by multitone signals. The mentioned nonlinear analysis tool is properly combined with an accurate device characterization in order to reproduce and control the FET distortion performance when it is employed for frequency conversion in small-signal regime. Good spectral regrowth and noise power ratio (NPR) predictions on a resistive mixer and on a class A amplifier confirm the validity of the proposed approach not only for time-varying but also for time-invariant applications.