A Low Power High Performance Register-Controlled Digital DLL for 2Gbps x32 GDDR SDRAM

A new low power high performance register-controlled digital delay locked loop (LPRCDLL) is presented. The circuit has fine delay compensation ability, fast delay compensation according to external voltage variation, and inherent duty correction. The digital DLL used for 2Gbps 8M times 32 GDDR3 SDRAM is fabricated using a 0.10mum technology. Experimental results show less than plusmn1% duty correction from external duty error of plusmn5%, less than 400 cycle locking time, 1GHz operation frequency at 1.5V, 38mW at 1.5V/1GHz, and a wide locking range from 250MHz to 1GHz