US Patent 9602111 Delay locked loop (DLL) locked to a programmable phase

An asynchronous digital logic is used to provide a pulse. A pulse train is filtered to determine an analog measurement based at least in part on the duty cycle of the pulse. The analog measurement is compared with a tunable reference associated with a programmable locked delay for the DLL. A digital code is sequenced based at least in part on the comparison. A digitally controlled delay line is programmed based at least in part on the digital code.