A band gap voltage reference circuit includes a high accuracy band gap (BG) circuit that generates a BG voltage potential V_bgH. A low accuracy BG circuit includes a variable resistance and outputs a BG voltage potential V_bgL that is related to a value of the variable resistance. A calibration circuit communicates with the high and low accuracy BG circuits, adjusts the variable resistance based on a difference between the BG voltage potential V_bgH and the BG voltage potential V_bgL, and shuts down the high accuracy BG circuit when the BG voltage potential V_bgL is approximately equal to the BG voltage potential V_bgH.