A Wide Operating Frequency Range Delay-Locked Loop Using a Recursive D/A Converter

A wide operating frequency range, false-lock free delay-locked loop with mixed-mode calibration is presented. The recursive D/A converter in the auxiliary circuit expands the operating frequency range with minimum hardware by controlling the capacitive loading of a delay cell. Moreover, the sampling phase detector with the D/A converter automatically tracks the false-lock free condition. The proposed DLL with equally spaced 14-phase clock outputs is implemented in 0.18-mum, 3.3V digital CMOS process, and its operating frequency ranges from 15MHz to 270MHz. The measured peak-to-peak jitter and rms jitter at 270MHz are 33.3psec and 3.93psec, respectively. The DLL occupies 0.22mm² and consumes 19mA