High resolution digital-to-analog converter

A digital-to-analog converter, e.g. for converting 16-bit digital signals, comprises a cascaded two-stage device wherein the first stage consists of a segment converter (10) with a series- connected string (14) of resistors and switches (16) operable by a set of higher-order input bits for selecting the voltage across any one of the resistors. Buffer amplifiers (A1, A2) direct the selected voltage to the input of a second-stage converter (12) comprising a CMOS DAC with an R/2R ladder controlled by a set of lower order bits to interpolate between the limits of the selected voltage from the first stage. The switches (16) for the first stage function to interchange the roles of the buffer amplifiers (A1, A2) for each step up (or down) the resistor string (14) so as to eliminate or minimize differential non-linearity errors due to offset mismatch between the buffer amplifiers (A1, A2). The polarity reversals arising from role changing are compensated by switches 30, which alternate the connections between supply leads 32, 34 and the corresponding ladder elements.