Frequency-independent fast-lock register-controlled DLL with wide-range duty cycle adjuster

A fast-lock all-digital register-controlled delay-locked loop (RCDLL) with wide-range duty cycle adjuster is presented. The architecture of the proposed fast-lock RCDLL uses the initial delay monitor without the delay line, which shares with the register controlled delay line for high accuracy of initial delay. Also, the duty cycle corrector of the DLL has achieved wide correction range to a small delay of the duty cycle adjuster. The proposed RCDLL with wide-range duty cycle adjuster has been designed with a 0.18um CMOS process and operates over a frequency range from 250MHz to 1.2GHz with a 1.8V supply voltage. The lock-time of the DLL is 10cycles independent to the input frequency.