A programmable current-mode digital-to-analog converter with correction of nonlinearity of input-output characteristics

The paper presents a concept of a programmable digital-to-analog converter (DAC) with the correction mechanism of a non-linearity of the input-output characteristics. The motivation behind the research presented in this work is an earlier project of a 10-bits two stage current mode DAC, whose basic block is a two-stage multi-output current mirror with binary weighted branches. The laboratory measurements of this converter were carried out, during which a certain non-linearity of the input-output characteristics was observed. Particular branches of the DAC theoretically should offer gains of the input trimming of 1, 2, 4, 8, ..., 512, respectively. In fact, in several sections this gain differs by several percent from the assumed values. The result of these observations is the proposition of a programmable correction mechanism, suitable for current mode converters.