A digital bandgap reference

A digital bandgap reference that provides a programmable reference voltage output is presented. It uses the same idea as an analog bandgap circuit except that the three operations of differencing, scaling and addition are done in the digital domain after converting the operands, the analog junction-diode voltages, into numbers. Digital signal processing provides both precision and programmability. The computed result is converted back to obtain the analog output voltage. The voltage drop across one of the current-biased diodes is used as reference in performing both the analog to digital and digital to analog conversions. Both of these conversions are done in a short time period to ensure that the reference voltage remains constant. Thus the reference voltage value cancels and becomes immaterial. It also becomes easier to address issues like curvature correction in the digital domain. Simulation results are presented for a nominal digital bandgap reference 1.2V with a variation of <;0.22% over -40 to 125μC.