Digitally Controlled Leakage-Based Oscillator and Fast Relocking MDLL for Ultra Low Power Sensor Platform

This paper presents an all-digital multiplying delay-locked loop (MDLL) with a leakage-based oscillator for ultra-low-power sensor platforms. The proposed digital control of channel leakage current achieved ultra-low-power consumption in frequency generation with a fine resolution. The leakage based oscillator was modeled as an RC-based oscillator, analyzed, and the analyses were verified by simulation. The proposed oscillator was applied to the MDLL with a fast frequency relocking scheme which adaptively performs an optimal lock process according to the amount of frequency drift during the sleep state. The MDLL was implemented in 65 nm CMOS and consumed 423 nW for 3.2 MHz generation, and had an energy efficiency FoM of 0.132 μW/MHz.