V-band dual-conversion down-converter with Schottky-diode ring-mixer using 0.35?m SiGe BiCMOS process

A V-band dual-conversion downconverter using 0.35μm SiGe BiCMOS process is demonstrated in this paper. This downconverter contains three sub-circuits, a V-band Schottky-diode RF mixer with Marchand balun, a 15-GHz low-noise IF buffer amplifier, and an IF Gilbert mixer. The Schottky diode has high cutoff frequency because of the n+ buried layer in the SiGe BiCMOS process. Thus, a fundamental ring-mixer is employed as the RF mixer. A Marchand balun has a broadband feature, and the feature has been used to achieve converter for high frequency circuit applications. In addition to this, a low-noise buffer amplifier is used to provide enough gain performance. By combining these advantages, a dual-conversion downconverter is successfully achieved. The downconverter has about 6 dB conversion loss, 18 GHz RF bandwidth, 800 MHz IF bandwidth and about -6 dBm IP_1dB when LO₁ power is 5 dBm and LO₂ power is 8 dBm.