Dynamic element matching in digital-to-analog converters with code-dependent output resistance

Abstract

Ihis paper evaluates the pertormance ot dynamic element matching (DEM) in digital-to-analog-converters, when the unit conversion cells of the converter have finite output resistance. DEM is already known to be effective against the static amplitude, timing and pulse shaped mismatches. However, the effect of output resistance and its mismatches has not been studied. A comprehensive code-dependent output resistance model for the current-steering DAC is presented. System level simulations show that the non-linearity caused by the output resistance, in the absence of mismatches, is not shaped by the DEM encoder since the output resistance is same for all the conversion cells. In this paper we demonstrate that, in the presence of mismatches, the DEM encoder is able to shape the non-linearity they cause since the output resistance now varies among different conversion cells.