A Wide-Range All-Digital Duty Cycle Corrector with a Period Monitor

A wide-range all-digital duty cycle corrector (DCC) with a period monitor is presented. It corrects the duty cycle within four cycles. It generates the output clock of 50% duty cycle when the input duty cycle is within 10% ~ 90%. After this DCC locked, a closed-loop monitor continuously tracks the period of input clock to keep 50% duty-cycle in every eight cycles. The proposed circuit has been fabricated in a 0.18 um CMOS technology. The measured duty cycle error is between 1.3% and 1.6% and the measured frequency range is from 1GHz to 1.6 GHz.