A 2 V 150 MHz CMOS digital phase modulator for fast-switching frequency synthesis

A 2 V 145 mW 150 MHz CMOS digital phase modulator is fabricated using a 0.6 /spl mu/m CMOS technology. The modulator is used to control a PLL to form a frequency synthesizer. Fine frequency resolution is achieved by phase interpolation and /spl Delta//spl Sigma/ oversampling. High-speed frequency switching is achieved by loop bandwidth adaptation. Settling time of a PLL with 109 kHz natural frequency can be reduced from 830 /spl mu/s to 94 /spl mu/s.