Design investigation of a compact broadband reflection-type PIN phase shifter

This paper presents the design strategies and performances of a broadband reflection-type phase shifter, implemented with the termination circuits composed of lumped capacitors and the junction capacitor of PIN Diodes. A wideband slot-coupled hybrid coupler is designed and used for the realization of the phase shifter, with which the phase shift of the phase shifter is nearly frequency-insensitive in a wide frequency band, saying, the phase shift almost has no change in the whole band of our interest. Analytical formulas of phase shift for the proposed phase shifter are derived, from which the capacitances of junction capacitor of the PIN diode and the lumped capacitor can be found. Two phase shifters of 90° and 45° are designed. Simulation results from commercial software Advanced Design System (ADS) indicate wide bandwidth, low insertion loss and high return loss in all states, demonstrating the validity of the proposed design strategies.