A 2.45 GHz Polar Vector Modulator Phase Shifter With Varactor Diode-Based Amplitude Control Capability for Energy-Efficient Systems

This letter presents a varactor-based polar vector modulator phase shifter (Polar-VMPS) with amplitude control capability. The proposed design combines a single control voltage varactor-based balanced biphase variable attenuator and a 180° reflection-type phase shifter (RTPS) in a cascaded configuration. Measured results demonstrate a 360° phase shift range, an amplitude control range exceeding 20 dB, an insertion loss of 3.6 dB, a return loss better than 23.6 dB, a root-mean-square (rms) phase error of 0.75°, and an rms gain error of 0.02 dB at 2.45 GHz. With zero dc power consumption and the potential to reuse attenuated energy, this VMPS provides an energy-efficient alternative to p-i-n diode and transistor-based designs. These features make it well suited for energy-efficient systems, including phased array antennas (PAAs) for wireless power transfer (WPT) and battery-powered devices.