Broadband Differential Phase-Shifter Design Using Bridged T-Type Bandpass Network

In this paper, a family of broadband differential phase shifters using bridged T-type bandpass networks and their design procedures are presented. Conventional high/low-pass networks are widely applied in 22.5 °-90 ° phase shifters. However, the tradeoff must be made between the bandwidths of return loss and phase error, which are limited to less than 90%. The proposed bridged T-type bandpass network can improve the bandwidth of phase error while keeping good return loss. Theoretically, the fractional bandwidth of a phase shifter using a bridged T-type bandpass network can be improved by more than 40 percentage points as compared with a conventional high-pass network. 22.5 °, 45 °, and 90 ° phase shifters are demonstrated on FR4 using discrete surface mounted device (SMD) L/C components. Due to limited discrete SMD component values, the phase and return-loss bandwidths of the realized three phase shifters are slightly reduced, but still larger than 125% and are better than 18 dB from 0.55 to 2.51 GHz.