A digital calibration for a 16-bit, 400-MHz current-steering DAC

A digital calibration for current-steering D/A converters is presented. The calibration corrects errors originating from mismatched thermometer decoded MSB current sources. The calibration principle is to measure the mismatches and skip over transfer function discontinuations. Four redundant MSB sources compensate the reduced input range cause by the skipping action. The mismatches are measured by using a simple comparator. Manners for extending the calibration range, thus enhancing linearity, are straightforward. Simulation show that the errors caused by the MSB sources are cancelled resulting in clear improvement in static linearity.