180$^{\circ}$ and 90$^{\circ}$ Reflection-Type Phase Shifters Using Over-Coupled Lange Couplers

Reflection-type phase shifters (RTPSs) of 180° and 90° using over-coupled Lange couplers to obtain multioctave bandwidth are presented. A thorough theoretical analysis of the effect of coupler parameters on the RTPS performance is provided. The impact of coupler parameters on the RTPS performance is further illustrated with vector plots. Each measured phase shifter is comprised of an over-coupled Lange coupler, two low-loss single-pole double-throw switches, and two pairs of LC reflection loads on a Rogers RO4003C substrate with a thickness of 0.8 mm (32 mil) and 1.5 mm (60 mil). By using the 1.5-mm substrate, the coupling can be increased. Phase shifts of 90° and 180° using Lange couplers with 2-3-dB coupling in steps of 0.2 dB are designed, fabricated, and measured. The experimental results show that an over-coupling of 2.2 dB is able to obtain a return loss larger than 10 dB over a 127% bandwidth from 550 to 2450 MHz for all states. Worst case measured insertion loss and phase error on the 0.8-mm substrate with an over-coupling of 2.8 dB is 2.0±0.8 dB and ±5.8°, respectively, for both 180° and 90°phase states. On the 1.5-mm substrate with an over-coupling of 2.4 dB, they are 1.8 ±1 dB and ±16°, respectively, for both phase states.