A low-jitter phase-locked loop architecture for clock generation in Analog to Digital Converters

This paper presents the circuit level implementation and analysis of the Phase Locked Loop (PLL) architecture for clock generation in Analog to Digital Converters (ADCs). The PLLs are required to generate low-noise or low-jitter clock signals and at the same time need to achieve fast locking. The Analog to Digital Converters require a clock generator whose clock output should have jitter less than 1 ps to have higher Effective Number Of Bits (ENOB). Catering the needs of the ADC, low-jitter PLL architecture is proposed which consist of pre-charged phase-frequency detector, charge pump, second order loop filter and a current-starved inverter based Voltage Controlled Oscillator (VCO) circuit. The integrated PLL architecture is implemented and simulated using CADENCE Analog Design Environment. It is synthesized using TSMC 0.18µm, six-metal technology. The lock range (operating frequency range) of the PLL is 95MHz to 145 MHz with a center frequency of 100 MHz and a jitter of around 700 fs are obtained as a result of its verification at all process corners.