A 30 kHz - 3 GHz Clock Duty-Cycle Corrector Circuit for CMOS Integrated Digital Electronic Systems

This paper reports on a Duty-Cycle Corrector (DCC) circuit that employs a closed-loop scheme paradigm capable to provide a real time 50% duty-cycle control of the generated output clock signal. A control voltage generated by a feedback circuit allows to estimate the values of the duty-cycles of the input and output clock signals. This control voltage provides and regulates the values of two currents that charge and discharge, even asymmetrically, a load to adjust the output clock signal duty-cycle. The DCC circuit has been designed in TSMC 180 nm CMOS technology with a 1.8 V single supply voltage and requires a total Si area of about 0.017 mm(2) with a power consumption of 0.46 mW/GHz. The reported post-layout simulations validated the DCC circuit performances to suitable correct the input clock signal duty-cycle for values ranging from 30 % to 70 % so providing a 50 % duty-cycle of the output clock signal with an error smaller than +/- 1 %. Furthermore, the proposed simple DCC circuit handles input clock waveforms with frequencies ranging from 3 GHz down to 30 kHz. This makes the DDC circuit suitable for a variety of applications such as clock generators, transceivers, serial interfaces, Phase-Locked Loop, Delay-Locked Loop, RAM memories, and data links.