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

Abstract

A wide-range delay-locked loop (DLL) with infinite phase shift and duty cycle control is presented. A voltage-controlled sawtooth delay line provides not only the delay control but also duty cycle control. The proposed DLL achieves infinite phase shift by using a single loop. Therefore, it has the benefits of good jitter and wide range compared with the conventional dual-loop DLL. The proposed DLL has been fabricated in a 0.18-mum CMOS process and the core area is 0.45 times 0.3 mm2. The measurement results show the proposed DLL operates from 50 MHz 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 peak-to-peak jitter is 11.1 ps and the power consumption is 6 mW.