MESFET drain mixers: analysis and design

A general and efficient nonlinear/linear analysis technique for MESFET drain mixers is presented. The study of conversion gain and matching impedances of the mixer is based on the Z-parameter conversion matrix. Using the approach, all the nonlinearities in the FET large-signal equivalent circuit can be included and any number of local oscillator (LO) harmonics and mixing products can be considered. LO level and DC bias conditions for maximum gain are predicted. The proposed program set, MIXAN (mixer analysis), is based on the output results of SPICE transient analysis. This tool was used for the design and optimization of X-band drain mixers. An example is presented for which the experimental and simulated results are in close agreement.<>