Mismatch-shaped pseudo-passive two-capacitor DAC

A simple mismatch-shaping scheme is proposed for a two-capacitor DAC. Unlike in other mismatch-shaping systems, the shaped error is generated by direct filtering of a well-defined bounded signal, which can be generated as white noise. The operation is closely related to a specific digital interpolation filter, but arbitrary properties of the overall interpolation characteristic can be assured. Simulations indicate that the scheme can be used for the realization of DACs with 16-bit linearity and SNR performance, with only 0.1% capacitance accuracy. The DAC is pseudo-passive, i.e. an active element is required only to buffer the output signal. Hence, it is potentially a very low-power circuit, suitable for portable applications.