A 40-75GHz Balanced Vector Modulator MMIC With A Compact Broadside Coupler

This paper presents a 40-75 GHz balanced vector modulator using a 0.15μm GaAs pHEMT technology for quadrature phase shift keying modulation. In order to enhance operation bandwidth, balanced vector modulator with a compact broadside coupler is proposed. To miniaturize the parasitic effects, a balanced or a push-pull topology is adopted, where two bi-phase amplitude modulators with 180° phase difference are co-designed to realize the bi-phase function. Thus, the influence of parasitic parameters is canceled out due to the out of phase signal combination. The designed prototype has simulated results of a 35 GHz operation bandwidth centered at 58 GHz, the amplitude and phase errors within ±1 dB and ±3°, insertion loss of less than 14 dB and input return loss is better than 11 dB.