A W-band low conversion loss single balanced mixer with planar GaAs Schottky diodes

A W-band low conversion loss single balanced mixer using planar microstrip circuit and commercially available GaAs Schottky barrier flip-chip diodes has been developed for 94 GHz receiver applications. The RF signals and LO signals are introduced by low insertion loss waveguide-to-microstrip probe transition and coupling by an improved branch-line hybrid. After calculating the embedding impedance of the diodes in harmonic balance method, an input matching network of the diodes is designed. The IF mixing product is extracted via a typical stepped impedance low pass filter. By optimizing the structural parameters of diode matching networks, good performance of the mixer has been achieved. Measured result of the conversion loss in the band of 91GHz~97GHz is less than 10.5dB, and the minimum is 8.5dB.