A reversible successive approximation register (RSAR) controlled all-digital delay-locked loop (ADDLL) is proposed to achieve fast-lock and wide range operation. The modified binary search algorithm of RSAR scheme is presented. With improved RSAR control-circuits, it could achieve adaptive bandwidth in wide range operation and eliminate the dead lock problem of conventional SAR DLL. The maximal lock-in cycles are reduced down to 42 for the 11-bit RSAR DLL, and its frequency range is from 30 MHz to 1 GHz in post layout simulation. The layout is done in SMIC 0.13 um CMOS technology, and an active area of 0.2 mm by 0.1 mm is occupied.
['Lei Wang', 'Leibo Liu', 'Hongyi Chen']
A fast-locking and wide-range reversible SAR DLL