A higher-order programmable amplitude and timing error shaping bandpass DEM for Nyquist-rate D/A converters

This paper presents a programmable amplitude and timing error shaping bandpass dynamic- element-matching (DEM) for Nyquist-rate D/A converters. Amplitude and timing-skew errors are shaped using two different loop-filters employed within the DEM structure. The systematic-duty-cycle errors are eliminated from the DAC spectrum using a controlled set of 'ON' transitions for any choice of the input-signal over the Nyquist band. The loop-filter order within the DEM can be selected to 2, 4 or 6 and the DAC errors can be shaped over a narrow or wide band for any choice of center-frequency. This work demonstrates that for a 12­bit segmented Nyquist DAC (5T-7B), the in-band SFDR and IMD3 is >80dBs for the DEM configurations