A mode-configurable analog baseband for Wi-Fi 11ac direct-conversion receiver utilizing a single filtering ΔΣ ADC

A mode-configurable filtering ΔΣ ADC is utilized as the analog baseband in a Wi-Fi 11ac direct-conversion receiver (RX). The filtering ΔΣ ADC providing both 2nd-order out-of-band filtering and 3rd-order in-band noise shaping is realized with only two opamps. A SAR-quantizer with built-in discrete-time (DT) excess-loop delay (ELD) compensation technique is also adopted. The filtering ΔΣ ADC is clocked at 480 MHz or 960 MHz and achieves 77-to-58 dB dynamic range (DR) in 10 MHz – 80 MHz bandwidth. With the aid of the filtering ability, the interferer DR at 4× bandwidth is at least 71.3 dB over modes. This work is fabricated in 28-nm low-power (LP) technology with 0.06 mm2 of active area. It consumes 3.97 mW or 6.39 mW over different clock rates, resulting a highest Schreier's FoM of 171 dB (BW20) and a best 4×-bandwidth Walden's FoM [2] of 13.3 fJ/c (BW160) among all modes.