A 3 MHz-to-1.8 GHz 94 μW-to-9.5 mW 0.0153-mm2 all-digital delay-locked loop in 65-nm CMOS

It is challenging to design a closed-loop all-digital delay-locked loop (ADDLL) that also has a small area, low power, and fast locking for a wide frequency range operation. In this work a cyclic half-delay-line architecture with the same type of delay lines for cyclic delay deduction and coarse locking is proposed to achieve the design goals of small area and fast locking for a wide frequency range operation. In addition to clock gating, which is used to reduce power consumption in the lock-in state regardless of the clock frequency, automatic bypassing of the cyclic operation is developed to reduce power consumption for high-frequency operations. Based on these proposed techniques, a 3 MHz-to-1.8 GHz 94 μW-to-9.5 mW 0.0153-mm2 closed-loop ADDLL is realized in 65-nm CMOS.