A 0.5–9.5-GHz, 1.2- $\mu \text{s}$ Lock-Time Fractional-N DPLL With ±1.25%UI Period Jitter in 16-nm CMOS for Dynamic Frequency and Core-Count Scaling

Abstract

A phase-locked loop (PLL) architecture is proposed for improved efficiency of power and thermal management techniques in system-on-chips (SoCs). PLL architecture introduces two techniques: a dual-stage phase-acquisition loop filter that enables fast lock time of 1.2 $\mu \text{s}$ without any frequency overshoots and a nonlinear DCO that enables a wide frequency range of 0.5–9.5 GHz and a low period jitter of ±1.25%UI p-p with a single wideband tuning. With this proposed PLL architecture, SoC can continue its operation without any interruption caused by frequency overshoots during power and thermal management techniques like dynamic core-count scaling and dynamic voltage frequency scaling. The PLL achieves 0.45 ps rms period jitter at 3.25 GHz in fractional-N mode operation, while consuming a total power of 7.1 mW.