An All-analogue Duty Cycle Corrector with High Accuracy, Wide Correction Range and Configurable Crossing

Abstract

Duty cycle correctors (DCCs) are utilized in most high-speed circuits to correct the duty cycle of the output clock at 50% and reduce the phase noise introduced by the duty cycle distortion. An all-analogue feedback duty cycle corrector (DCC) with high precision, wide correction range and configurable crossing is proposed in this paper. The duty cycle adjustor (DCA) calibrates the duty cycle by regulating the common mode level of the differential clock signal complementary with both wide correction range and high speed. The duty cycle detector (DCD) has an excellent performance with a high gain to achieve the high correction accuracy and a narrow bandwidth to restrain the deterministic jitter and other noises. Besides, a configurable clock crossing adjustor (CCA) is employed to alter the clock crossing voltage flexibly. The DCC has been implemented in 65nm SMIC CMOS technology with a power supply of 1.8V. The simulation results prove that the output duty cycle is corrected to 50±0.1% over the input duty cycle range of 20%~80% for 1~5GHz, and the crossing voltage can be adjusted over a span of ±180mV centered about the mid-supply point. The DCC consumes 3.2mW at 3GHz and occupies an area of only 0.005mm2.