2.45-GHz CMOS Reflection-Type Phase-Shifter MMICs With Minimal Loss Variation Over Quadrants of Phase-Shift Range

CMOS reflection-type phase shifters with minimal insertion-loss variation over quadrants of phase-shift range are presented. Two performance enhancement techniques are proposed. First, the 3-dB; quadrature hybrid is designed with a phase-compensated inductively coupled hybrid. Second, an impedance-transformed pi-resonated varactor network is presented to provide a full 360 degrees phase range, using a MOSFET varactor with limited reactance variation range. The design considerations and simulation are described. Two experimental 2.45-GHz phase shifters were implemented in 0.18-mu m CMOS technology. One has a measured phase-shift range of 120 degrees with the insertion loss of 5.6 +/- 1.2 dB in 2.33-2.60 GHz and the other has a phase range larger than 340 degrees with the insertion loss (of 10.6 +/- 2 dB in 2.44 +/- 2.55 GHz. Both chips are extremely compact with sizes of 0.72 and 0.66 mm(2), respectively, and consume zero dc power.