A 48GHz-78GHz MMIC sub-harmonic pumped image rejection mixer

The paper presents the design of a 48-78GHz sub-harmonic pumped image rejection mixer (SHIRM) based on a 3μm GaAs technology. The SHIRM contains two identical 2^nd APDP-Based SHP mixers, a modified quadrature-phase RF Lange coupler and an in-phase LO Wilkinson power divider. The quasi-lumped topology is utilized with the compact size of 1.7×1.6 mm². The conversion gain of -14±1dB and the minimum image rejection radio of 20dB over the frequency range 48-78GHz covering the whole V-band are simulated, with fixed IF of 1GHz and the LO input power of 12dBm. The 3dB bandwidth is superior to 30GHz. The LO-to-RF and 2LO-to-RF isolations are superior to 25dB and 70dB, respectively. The 2nd harmonic component of LO signal is suppressed by the symmetrical structure.