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 mu A across the output voltage from 0.2 to 1.0 V. The current variation is less than 1.20 mu A 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.