An embodiment of a pumped substrate system includes an oscillator, capacitive pump, comparing circuit, and a level shifter. The level shifter is coupled between the substrate and the positive input lead of the comparator and shifts the voltage level present on the substrate by a voltage Vbg. The comparator compares ground potential to the shifted substrate voltage. The oscillator, capacitive pump and comparing circuit form a negative feedback loop which operates to maintain the substrate voltage substantially equal to -Vbg. In one embodiment, the level shifter includes a band gap reference.