A HIGH-PASS/LOWPASS PHASE SHIFTER WITH RESISTIVE MATCHING NETWORKS

This paper proposes a high-pass/lowpass phase shifter with improved reflection and phase-shift characteristics using resistive matching networks. The circuit configuration, reflection characteristics, phase-shift error-reduction methods, and the design results are described. The relationship between the reflection of the single-pole, double-throw (SPDT) switch and the phase-shift error is discussed in the high-pass/lowpass phase shifter using filters to switch the SPDT switch. The reflection of the SPDT switch caused by the parasitic resistance of the switching device is investigated, and an impedance matching method using the resistive matching networks is proposed to reduce reflection. The calculation results for an S-band phase shifter with the resistive matching networks show that the matching can be achieved even for switching devices with resistance and that the phase-shift error can be reduced. An S-band, 90° single-bit phase shifter has been designed and a low return loss of better than 19 dB and a phase-shift error of less than 4° are achieved, which confirms the usefulness of the resistive matching networks.