An inductorless electrical-balance 360° phase shifter for 0.5-1.15GHz in 0.18μm CMOS

This paper presents an integrated phase shifter based on electrical-balance operation. The phase shift of the circuit is set through the difference in impedance between two on-chip tunable impedances. Each impedance consists of a parallel combination of a tunable resistor and a tunable capacitor. Measurements of the inductorless, 0.12mm2 prototype implemented in 0.18μm CMOS show a tunable range of >360° of phase shift across 0.5-1.15GHz with >12-bit tuning accuracy, while the 15 to 40dB insertion loss is acceptable for the target application of auxiliary self-interference cancellation loops in in-band full-duplex capable transceivers. The phase shifter has maximum phase/gain errors of 0.42° and 0.27dB per MHz, respectively.