An automatically placed-and-routed ADPLL for the medradio band using PWM to enhance DCO resolution

An all-digital phase-locked loop for the MedRadio bands is presented. This ring oscillator based ADPLL was entirely designed and placed-and-routed using digital design flows and was fabricated in a 65 nm CMOS process. Pulse width modulation of the DCO control signals is introduced as a technique to improve the resolution of the DCO to 59 kHz/LSB. This ADPLL operates as a subsampling integer-N frequency synthesizer from 400 to 460 MHz, and consumes 2.1 mA from a 1 V supply, with an rms jitter of 13.3 ps.