| One audio signal processing SIGMA-DELTA(∑-△)A naolog to Digital Converter (ADC) is introduced in paper, which has 16 bits resolution. The DCG nonlinearity of the integrators ,which is not considered in many∑-△modulators'modeling attempts,is analyze ,estimated ,and modeled by the paper. Precise behavioral modeling of switched-capacitor modulators is presented,considering noise( switches'and op-amps thermal noise),clock jitter, nonidealities of integrators and op-amps including finite dc-gain(DCG)and unity gain band width et.it is shown that negleting this parameter would lead to a significant underestimation of the modulators'behavior and increase the noise floor as well as the harmonic distortion at the output of the modulator. The design in this paper uses a lot of technologies to decrease the power dissipation of the modulator and digital filter in the ADC system: Uses a Cascode class AB voltage OP in the modulator, because of its much smaller operating current than the OTP OP's. And a dynamic comparator with no DC power dissipation is used in the modulator. In the digital filter it find the most simplified fram work and the most optimized length of the filter coefficients, so can simplify the caculater and reduce the power dissipation in the digital circuits. |
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