A transmitter based on a frequency synthesizer includes an LC tank of a digitally controlled oscillator with various arrays of capacitors. The first and second algorithms actively generate stimulation parameters during each cardiac cycle, but the stimulation parameters generated by the second algorithm are only permitted to result in actual stimulation therapy if those parameters fall within parameter ranges that are calculated to be allowable for stimulation by the first algorithm. Several of the pads can be used simultaneously, and each can be controlled individually.