A first-order low distortion sigma-delta modulator using split DWA technique and SAR quantizer

摘要

This paper presents a comparator-based OTA first-order discrete-time low-distortion sigma-delta modulator. A split data weighted averaging (DWA) algorithm logic is proposed to release the heavy burden of digital circuit while a 6 bit DAC is implemented in this work. In addition, a comparator-based OTA is used to reduce the power consumption. On the top of that, to achieve lower power consumption, a power efficient SAR quantizer with embedded analog passive adder is proposed to eliminate additional operational amplifier for summation. The modulator core occupies an active area of 0.0275 mm in TSMC 90-nm 1P9M CMOS process. Experimental results show that the proposed modulator achieves 59.90 dB SNDR with 0.58 mW power consumption under 1.0 V supply voltage, an OSR of 16 at 65 MHz sampling frequency and 500kHz input frequency.