A 62.5–625-MHz Anti-Reset All-Digital Delay-Locked Loop

An anti-reset all-digital delay-locked loop (DLL) is presented. When the input clock frequency changes significantly, the dynamic frequency detector re-locks the DLL without any external reset signal. The proposed binary time-to-digital converter (BTDC) reduces effectively the hardware, compared with a conventional TDC. Unlike many previous all-digital DLLs, this one is a closed feedback loop that can track environmental variations. The input frequency range can be operated from 62.5-625 MHz. It spends at most six cycles to synchronize the input and output clocks.