A 1.3V–1.8V configurable phase locked loop with an adaptive charge pump

Abstract

In this manuscript, we propose a robust phase locked loop (PLL) using an adaptive, low current-mismatch charge pump in 180nm UMC MPW RF process targeted for internet of things (IoT) applications. The PLL operates over a supply voltage range of 1.3V-1.8V, generating locking frequencies in the range 500 MHz to 1.5 GHz. The proposed charge pump limits the variation in charging and discharging currents to 0.03% of its biasing value, which is designed to be 34.7uA, for change in control voltage from 0.4 V to 1.1 V. Power consumption of the PLL is limited to 2.3mW at 1.8V supply voltage and reduces to 0.9mW for a supply voltage of 1.3V. A 10bit successive approximation register analog to digital converter (SAR ADC) is operated using the proposed PLL and the effect of variation in frequency on its output is demonstrated.