CONVERSION LOSS IN MICROWAVE BALANCED MIXERS WITH JUNCTION DIODES.

The behavior of microwave balances mixers is analyzed and compared with that of single-ended mixers, which has been dealt with in a previous paper. To perform this study the mixer diodes are modeled by means of a constant resistance in series with the parallel combination of an exponential conductance and a constant capacitance, which schematizes the barrier capacitance. The results refer to the available conversion loss of four mixer configurations, namely G, H, Z and Y. The mixers are supposed to be driven by a sinusoidal pump waveform (voltage and current). The image frequency is considered in the two extreme situations of short-circuit and open-circuit. The results are presented in a very compact way as a function of a quality factor Q of the diode, which is the main diode parameter affecting the mixer conversion loss. The results show that the presence of the barrier capacitance in the diode model causes a deterioration in the mixer performances.