Precision, temperature and supply independent CMOS current source with no external components

A precision, CMOS current generation circuit, using no external components, which is independent of temperature and supply voltage, is described. The only process parameter which affects it is the oxide thickness, which, typically, varies less than +/-10%. The operation utilises charging an on-chip capacitor within a clock defined time period by a feedback controlled current to a reference voltage. The clocking noise is effectively isolated from the output by three orders of magnitude.