A portable digital DLL architecture for CMOS interface circuits

A digital DLL was developed which achieves infinite phase range and 40 ps worst-case phase resolution at 400 MHz. The architecture uses dual delay lines with an end-of-cycle detector, phase blenders, and duty cycle correctors. This more easily process-portable DLL achieves jitter performance comparable to a more complex analog DLL, when placed into identical high-speed interface circuits fabricated on the same die in a 0.4 /spl mu/m CMOS process.