Nonlinear Analysis of Millimeter-Wave Schottky Diode Mixers

Abstract

A calculation technique based on the equivalent circuit method is developed for the gain-transfer characteristic of the mm-wave Schottky diode mixers. The proposed mixer equivalent circuit adequately describes all the processes taking place in the mm-wave mixer mounts. This has been proved for the 3mm-wave mixer by our comparison of the calculated and measured dependencies of its rectified current vs. local oscillator frequency. The proposed mm-wave mixer model permits to compute for the specifically used Schottky diode the limiting conversion loss and conditions of their attainment (local oscillator power, dc bias voltage and diode current, input and output load impedances, characteristics of mixer mount elements, etc.). Using the proposed technique, the conversion loss and impedance performance were computed for several Schottky diodes that allowed to select the optimal type of a diode for the 3mm wavelength operation. For this diode, the optimum conversion loss and operating characteristics (dc bias voltage and diode current) vs. local oscillator power were measured at 100 GHz in the developed 3mm-wave mixer mount. A close agreement between the measured and calculated characteristics is shown.