BPSK modulator for 2-18 GHz Vector Modulator

In this contribution, an active fully monolithic BPSK modulator with small phase error and small differential insertion loss is presented. The proposed topology consists of a split-loaded amplifier and a symmetrical absorptive SPDT switch. A test vehicle adopting this topology is designed using a 0.18 μm GaAs pseudomorphic HEMT technology. A phase error of 15° and a differential insertion loss lower than 1.8 dB covering the entire 2-18 GHz frequency band has been achieved. A phase error of only ±2.5° around 186.8° over the 4-18 GHz sub-band has been also obtained. Return loss resulted better than 10 dB at both input and output ports. The proposed structure can be exploited as BPSK modulator for ultra-wideband vector modulators.