Full-custom all-digital phase locked loop for clock generation

Abstract

A novel approach of constructing an All-Digital Phase Locked Loop (ADPLL) is presented in this paper. A 3-Step symmetric Time-to-Digital Converter (TDC) is proposed with both long dynamic range and high resolution. The Upper-and-Lower-boundaries-Cut-off-Determination (ULCD) logic is presented for a full-custom digital loop filter. With this method, an all-digital PLL can be designed without synthesis procedures. The Digitally-Controlled Oscillator is designed by ring architecture with periodic variation linear. The dynamic range of the TDC is 7.7 ns and the finest resolution of the TDC is only 12.7 ps. System locked time is only 1.62 us. The rms jitter and P-P jitter is 4.68 ps and 38.68 ps in the measurement results. And the power dissipation is only 7.55 mW.