Multi-bit DAC with noise-shaped element mismatch

By a process similar to delta-sigma modulation, the noise caused by static mismatch in a multi-level unit-element DAC can be attenuated in a narrow frequency band. This paper explores the circuit considerations for switched-current and switched-capacitor realizations of the unit-element DAC. The switched-current DAC is found to be relatively simple and capable of high-speed operation. The switched-capacitor circuit is more complex and likely to be somewhat slower, but it is nonetheless robust and provides a simple interface. A dynamic range of 110 dB with a third-order 17-level DAC is expected, even if the DAC elements suffer from 1% mismatch.