Study of modified noise-shaper architectures for oversampled sigma-delta DACs

In this paper, modified low-complex, hybrid architectures for digital, oversampled sigma-delta digital-to-analog converters (ΣΔDACs) are explored in terms of signal-to-noise ratio (SNR) and subDAC complexity. The studied techniques illustrate the trade-off in terms of noise-shaper and DAC implementation complexity and loss in SNR. It is found that a fair amount of improvement in SNR is achieved by maintaining low-complexity of noise shaper. The complexity of the subDAC is yet a parameter, directly related to the number of output bits from the noise shaper. Two different architectures are investigated with respect to subDAC complexity and noise shaper complexity. It is shown that the required number of DAC unit elements (DUE) can be reduced to half.