An Infinite Phase Shift Delay-Locked Loop With Voltage-Controlled Sawtooth Delay Line

A wide-range delay-locked loop (DLL) with infinite phase shift and digital-controlled duty cycle is presented. By changing the polarity of the input clock of the voltage-controlled sawtooth delay, this proposed DLL achieves infinite phase shift by only a single loop. The proposed DLL has been fabricated in a 0.18 mum CMOS process and the core area is 0.45×0.3 mm². The measurement results show the proposed DLL operates from 50 to 500 MHz. The duty cycle of the output clock can be adjusted from 30% to 60% in the step of 5%. At 500 MHz, the measured rms jitter and peak-to-peak jitter is 1.43 and 11.1 ps, respectively. Its power consumption is 6 mW for a supply of 1.5 V.