Analysis and modeling of low-frequency noise in resistive FET mixers

A complete analysis of the low-frequency (LF) noise is performed on resistive field-effect transistor (FET) mixers, where LF noise is created due to the self-mixing process of the local oscillator. First, a new scalable noise model for FETs in an ohmic channel bias regime (U_ds≈0 V) has been developed, which uses fluctuating resistances, instead of noise voltage or noise current sources. Measurements on a hybrid single-ended mixer prove a good accuracy of the proposed model and reveal a method to distinguish between the different noise sources. Further investigations discuss the LF noise in balanced mixers and explain the mechanisms of noise generation. All mixers under test operate in X-band (8, ..., 12 GHz) with IF below 1 MHz.