An All-Digital 90-Degree Phase-Shift DLL with Loop-Embedded DCC for 1.6Gbps DDR Interface

An all-digital 90° phase-shift DLL is proposed for 1.6Gbps DDR interface by using a loop-embedded DCC and a binary phase detector with the lock range extended to 0~4π radians. The DCC has a small delay and the fixed rising-edge property for loop-embedding. The chip fabricated with a 0.13μm CMOS process gives the DLL data rate of 667Mbps~1.6Gbps and the output duty cycle of 47.8%~49% for the input duty cycle of 23%~76%, at 1.6Gbps and 1.2V.