Super-Schottky Mixer Performance at 92 GHz

As part of a program to explore the behavior of superconducting Schottky mixers at high frequencies (nu_RF≥90 GHz), the mixing and video performance of several super-Schottky diodes have been tested at 92 GHz. The diodes used (~3-mu m active diameter, doping concentration ~2x 10¹⁹ cm^-3) were identical to those recently developed at Aerospace for use in a 31-GHz mixer. The WR-10 mixer mount, designed specifically for this experiment, utilizes a quartz stripline assembly for the diode, whisker, and IF choke, suspended across quarter-height RF wavegnide. At 92 GHz, video responsivities were typically ~80 A/W (corrected for RF mismatch). Conversion loss(corrected for both RF and IF mismatches) was typically measured to he ≳18 dB. As expected, T_diode was small (< 5K). Video responsivity and conversion loss were also measured at an RF frequency of 3.95 GHz. These data were used with the measured I- V characteristics of the diodes to compare theoretical predictions of diode performance at 92 GHz in both the video and mixing modes, with the high-frequency data.