A drive frequency source with two selectable output frequencies connected to two charge pump arrays. A first array of basic charge pump units is connected to the first output frequency and a second array of basic charge pump units is connected to the output frequency. One or more of the basic charge pump units making up the aforementioned first and second charge pump arrays has an enable input allowing its output current contribution to be added or subtracted from the total array output. The output of the first array is coupled to a P-type substrate and the output of the second array is coupled to an N-well residing in the P-type substrate. A controller may be coupled to the drive frequency source for selecting the output frequencies, and an output monitor may be coupled between the array outputs and the controller to provide feedback.