The analysis of microwave mixers using commercial CAD software packages

The analysis of frequency conversion properties of mixers is a non-trivial problem. Schottky diodes are the most commonly used nonlinear elements in mixers and many analytical methods have been used, mainly using the diode current-voltage characteristics and switching function analysis, to study their performance. In particular, with the increasing applications of broad bandwidth enhanced dynamic range systems, the prediction of intermodulation(IM) distortion has become extremely important since the performance degradation caused by IM products can be reduced if the frequency and power levels of the IM products are known. The simulation of the mixer performance, without any simplifying assumptions, requires a fully numerical approach with the power levels of IM products being obtained by a full nonlinear analysis. Harmonic balance (HB) techniques are recognised as the preferred methods for analysing mixers and a number of application specific analysis packages have been reported. The authors discuss the applicability of the HB method as available in Supercompact Microwave Harmonica and EEsof LIBRA software packages to the analysis of microwave diode mixers