A 1.8GHz wideband open-loop phase modulator with TDC based non-linearity calibration in 0.13µm CMOS

A non-linearity calibration technique is proposed for an open loop RF phase modulator. The phase modulator integrates a digital phase-locked loop, LO distribution network and digital calibration. A prototype was implemented in 0.13-μm CMOS 1.8-GHz GFSK transmitter integrated circuit. Measurements on the prototype show that out-of-band quantization noise is 56-dB lower than the signal when transmitting 20-Mb/s GFSK signal and the r.m.s. error is only 3.2%. The power consumption of the phase modulator is 18 mW.