Auto-calibrating resistor string in a data converter

Abstract

A data converter (20) comprising an input (I0′-I2′) for receiving an input signal and an output (VOUT′) for providing an output signal formed in response to the input signal. The converter also includes a string of series-connected resistive elements (12′) having in total a string resistance (DENOM) and providing a plurality of voltage taps (T0′-T7′), wherein at least one of the voltage taps is accessible in response to the input signal and for forming the output signal. The converter further includes a calibration circuit (22). The calibration circuit includes a plurality of trimming transistors (TT0-TT6) connected in parallel to selected ones of the plurality of voltage taps. Each of the trimming transistors has an adjustable resistance. Finally, the calibration circuit includes adjustment circuitry (28, 26) for selectively adjusting the adjustable resistance of a trimming transistor connected in parallel to two of the plurality of voltage taps in response to a ratio of a resistance between the two of the plurality of voltage taps (NUM) relative to the string resistance.

Dependencies are inferred from the claim text.