A Practical Load-optimized VCO Design for Low-jitter 5V 500 MHz Digital Phase-locked Loop

摘要

In high-speed digital systems and high-resolution display devices, the jitter effect ofphase-locked loops (PLL) limits the system performance. Power supply noise coupling isone of the major causes of PLL jitter problems, especially with mixed-signal systems.The paper presents a targeted 5.0V 500 MHz PLL which is implemented by a 0.6 um1P3M digital CMOS technology. The features of the proposed design include a load-optimized3-stage VCO, a frequency limiter RC circuit, and a ratioed VCO controllingcurrent mirror. The jitter, thus, is reduced to 72.693 ps at 600 MHz at the presence ofsupply noise, while the sensitivity is limited to 286.6 ps/V. This high-noise immunitydesign allows that the PLL can be integrated with digital circuits.