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A circuit technique for compensating the device-to-device variation in bandgap voltage references is presented. The circuit senses the variation of Vbe of the transistor with process and pumps into the emitter a PTAT current in direction opposite to the variation to bring it back to the right value. It also exploits the temperature coeff. of MOS Vt to compensate for higher order temperature variations. Silicon results show a variation of 60 mV across different lots and less than 50 PPM across temperature (-40° to 130°C). The prototype was built in a 0.18u CMOS digital process with low β PNP transistors.