A multioctave active GaAs MMIC quadrature phase shifter

A GaAs monolithic quadrature phase shifter based on a phase-locked-loop system which covers a 0.1- to 4.5-GHz frequency range is presented. It provides about 8 dB of gain, and its phase error and amplitude mismatch are respectively, less than 2.5° and 0.4 dB over the band. When the phase shifter is integrated into a single-sideband receiver, a sideband rejection of at least 30 dB is achieved. The results also show that design methods based on voltage amplification instead of power amplification, without any impedance matching between stages, can be extended up to the microwave domain