A 4.6GHz PLL with automatic frequency calibration based on multiple-pass ring oscillator

A good-performance high-frequency Phase Locked Loop using a ring oscillator is described. A Voltage Controlled Oscillator with automatic calibration of frequency fluctuated by process and temperature variations is proposed. The VCO adopts new multiple-pass loop to improve frequency with unchangeable stages (phases). The circuit is implemented with TSMC 0.18um standard CMOS technology and power supply is 1.8V. Cadence and Matlab tools are both used to present credible transistor and behavior simulation results.