V-band pHEMT dual-conversion down-converter with Schottky diode RF mixer and analog Gilbert IF mixer

A V-band dual-conversion down-converter with the Schottky-diode first conversion mixer and the analog Gilbert second conversion mixer is demonstrated using 0.15-μm pseudomorphic high electron mobility transistor (pHEMT) technology. The diode mixer based on quarter-wavelength design methodology occupies a reasonable real estate at millimeter-wave frequency while the analog IF mixer has the size advantage at low microwave frequency. A trifilar transformer is employed in the first mixer to have balanced RF/LO/IF signals for the anti-parallel diode-pairs while a Marchand balance converts the RF signal into the balanced one. Analog I/Q Gilbert mixers driven by the poly-phase filter in the LO port achieve precise I/Q IF output. As a result, this work achieves a wideband conversion gain around -1 dB from 54-64 GHz, -5 dBm of IP_1dB, and 6 dBm of IIP₃.