Influence Analysis of Mismatch on Nonlinearity in Hybrid RC-DACs

In this paper, an influence analysis of mismatch on nonlinearity in a N-bit segmented hybrid RC-digital-to-analog converter is introduced. In the considered structure, segment for the most significant bits is capacitive and binary, whereas segment for the least significant bits is resistive and unary. Such a segmented structure allows reducing number of buffers and, consequently, power consumption. Moreover, a lower capacitive segment resolution decreases total wire length and distortion induced by parasitic wires parameters. As digital-to-analog converter is heterogeneous, unit elements in segments have different area, and the optimal ratio of segments should be investigated. An expression for the optimal segment resolutions providing area minimization is proposed. For the analysis, a parametric mathematical model of the considered converter is developed in MATLAB. Arrays with random errors are generated to estimate influence on the differential and integral nonlinearities. Simulation results show lower contribution to nonlinearity of the resistive segment against the capacitive one. Additionally, an increase of capacitive segment resolution improves yield.