K-band reflection-type phase shifter using phase-shift range enhancement technique

This letter presents a simple but efficient phase shift range enhancement technique for a reflection type phase shifter (RTPS). The proposed structure consists of a 3-dB coupler and a pair of back-to-back diodes connected with a pair of series and parallel inductors and a pair of parallel resistors. The parallel inductors are inserted to widen relative phase shift range compared to regularly used RTPS and Lange coupler is used as the 3-dB coupler. The proposed circuit is implemented in 0.15 -μm GaAs low noise pHEMT process and provides a measured phase shifting range of 227° at 24 GHz with a measured insertion loss of 4.6 ± 1.3 dB. The input and output return losses are better than 18 dB and 17 dB, respectively. The size of the fabricated phase shifter MMIC chip is 2.2×1.5 mm² including test pads.