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A low-power delta–sigma modulator based on inverter operational-transconductance amplifiers (OTAs) using correlated level shifting technique (CLS) is presented. The CLS technique boosts the DC gain of inverter-based OTA from 42 to 79 dB and extends the linear output swing from 55 to 80% of the full scale. Simulation results show that design in 180 nm CMOS technology, the proposed second-order delta–sigma modulator achieves a signal-to-quantisation-noise ratio improvement of 10.4 dB compared to a conventional inverter-based modulator implementing the identical loop filter with the same oversampling ratio.
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Inverter-based low-power delta–sigma modulator using correlated level shifting technique