A four pointer data weighted averaging (FPDWA) algorithm is presented to reduce the nonlinearity of the feedback multi-bit digital-to-analog converter (DAC) for delta-sigma modulators. By utilizing the proposed algorithm, the noise power caused by element mismatch can be reduced. A nine-level second-order delta-sigma modulator has been implemented in a double-poly double-metal 0.35 μm CMOS process. Experimental results indicate the peak SNDR reaches 86.59 dB within bandwidth of 22 kHz. The maximum input amplitude is −7 dB below the full scale with 10-kHz input frequency, the sampling frequency is 5 MHz, and the OSR is around 113. The power consumption is 6.27 mW for a power supply of 3.3 V.
Analog Integrated Circuits and Signal Processing 33(3), pp.289-300