A method and apparatus for generating a reference signal involves (i) generating a CTAT voltage and a PTAT voltage, (ii) generating a first digital signal and a second digital signal having an amplified difference dependent on a difference between the CTAT voltage and the PTAT voltage, and (iii) dependent on the first digital signal and the second digital signal, adding or subtracting charge from the reference signal, where the reference signals controls the conductivity of devices that drive current through the devices that are used to generate the CTAT and PTAT voltages.