Patent attributes
Startup charge balancing circuits and methods for capacitive charge pumps that avoid large in-rush currents and resulting voltage spikes. Embodiments include a charge balance circuit coupled to a corresponding charge pump capacitor of a charge pump. The charge balance circuit includes a comparator that compares the output voltage of the charge pump to a feedback voltage derived from the voltage across the corresponding charge pump capacitor. In response, either a constant current source or a constant current sink is coupled to the charge pump capacitor. Current sourcing or sinking continues until the voltage across the corresponding charge pump capacitor approximates a target voltage, at which point the comparator output toggles, which results in uncoupling of the coupled current source or current sink from the corresponding charge pump capacitor. Embodiments only need one current sink and one current source per charge pump capacitor, and charge balancing is independent of leakage currents.
