In addition to one or more of the features described herein, or as an alternative, further embodiments include operating each current source of the plurality of stages as a current mirror, wherein the current is equal to or proportional to a reference current.

In addition to one or more of the features described herein, or as an alternative, further embodiments include coupling a voltage differential amplifier to the capacitor of the plurality of stages and providing the output to the comparator.

According to another embodiment, a system is provided that includes a constant current source, and a charge pump circuit including a plurality of stages. Each of the plurality of stages include a capacitor configured to be charged to a predetermined voltage; a current source operable to charge the capacitor; a switch; and a controller that is configured to control switching of the switch for each of the plurality of stages based at least in part on an output current of the charge pump.

In addition to one or more of the features described herein, or as an alternative, further embodiments include a comparator that is configured to compare a reference voltage and the capacitor voltage at each of the plurality of stages, wherein the comparison is used to charge the capacitor.

In addition to one or more of the features described herein, or as an alternative, further embodiments include a controller that is configured to adapt a reference current and the reference voltage of the comparator.

In addition to one or more of the features described herein, or as an alternative, further embodiments include a controller that is configured to increase the output current by increasing the reference voltage of the comparator and decrease the output current by decreasing the reference voltage of the comparator.