High-Resolution All-Digital Duty-Cycle Corrector in 65-nm CMOS Technology

Abstract

In high-speed data transmission applications, such as double data rate memory and double sampling analog-to-digital converter, the positive and negative edges of the system clock are utilized for data sampling. Thus, these systems require an exact 50% duty cycle of the system clock. In this paper, two wide-range all-digital duty-cycle correctors (ADDCCs) with output clock phase alignment are presented. The proposed phase-alignment ADDCC (PA-ADDCC) not only achieves the desired output/input phase alignment, but also maintains the output duty cycle at 50% with a short locking time. In addition, the proposed high-resolution ADDCC (HR-ADDCC) without a half-cycle delay line can improve the delay resolution and mitigate the delay mismatch problem in a nanometer CMOS process. Experimental results show that the frequency range of the proposed ADDCCs is 263-1020 MHz for the PA-ADDCC and 200-1066 MHz for the HR-ADDCC with a DCC resolution of 3.5 and 1.75 ps, respectively. In addition, the proposed PA-ADDCC and HR-ADDCC are implemented in an all-digital manner to reduce circuit complexity and leakage power in advanced process technologies and, thus, are very suitable for system-on-chip applications.