Wideband low-distortion sigma-delta ADC for WLAN

This work presents a wideband low-distortion sigma- delta analog-to-digital converter (ADC) for wireless local area network (WLAN) standard. The proposed converter makes use of low-distortion swing suppression SDM architecture which is highly suitable for low oversampling ratios to attain high linearity over a wide bandwidth. The modulator employs a 2-2 cascaded sigma-delta modulator with feedforward path with a single-bit quantizer in the first stage and 4-bit in the second stage. The modulator is designed in TSMC 0.18 um CMOS technology and operates at 1.8 V supply voltage. Simulation results show that, a peak SNDR of 57 dB and a spurious free dynamic range (SFDR) of 66 dB is obtained for a 10 MHz signal bandwidth, and an oversampling ratio of 8.

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