PLL charge pump with adaptive body-bias compensation for minimum current variation

A novel charge pump with adaptive body-bias compensation to minimise the current variation over a wide output voltage range is proposed. With 1.2 V supply voltage, the proposed charge pump demonstrates a constant current of 140 μA across the output voltage from 0.2 to 1.0 V. The current variation is less than 1.20 μA or 0.9 over output range, which helps keep the loop bandwidth of the charge pump phase-locked loop (PLL) fixed and maximise the dynamic range. Extremely low power adaptive bias circuits are proposed to provide body-bias compensation at different output voltage levels. It is believed that the current variation is the minimum among the published results of PLL charge pumps.