L-band 90° hybrid-coupled phase shifter using UHF band p-i-n diodes

The design, development, and testing of a low-cost L-band hybrid-coupled 90° phase shifter are presented. The developed phase shifter uses a compact branch line coupler to minimize its size, and employs low-cost UHF band p-i-n switching diodes to minimize its production cost. The diodes in a stand-alone configuration feature large stray capacitance, which make them a poor-quality open circuit in the reverse-bias state. An LC compensation technique is applied to tune out this capacitance and make the diodes applicable to L-band. The developed phase shifter exhibits less than 1.0 dB insertion loss, more than 15 dB RL, and ±8° phase deviation over 225 MHz centered at 1.6 GHz.