An 80MHz-BW 640MS/s Time-Interleaved Passive Noise- Shaping SAR ADC in 22nm FDSOI Process

Abstract

Recently, both the number of smart devices and the amount of data transfered to and from these devices have grown at unprecedented rates. To provide users with a highquality experience, wireless LAN plays a key role among various wireless standards. Wi-Fi 6E extends the available bandwidth, enhances spectral efficiency, increases data rate, and serves more users simultaneously in public areas. To support 1024-QAM in bandwidths up to 160MHz while maintaining sufficient EVM, the ADC has to achieve inband DR of 63-70dB over 80MHz baseband bandwidth. SAR ADCs are used extensively in Wi-Fi receivers due to their low power consumption and small area. But for DR >60 dB, quantization noise and comparator noise become the dominant noise sources. Noise shaping embedded within a SAR ADC has been utilized to suppress these noise sources with minimal overhead [1]–[2]. The maximum reported conversion rate of 10 to 12b 1b/step SAR ADCs is $\sim 400$ MS/s, and hence the available bandwidth is limited to 50MHz given an OSR of 4-6. The NS pipeline-SAR ADC [3] was introduced to overcome this limitation by virtue of its superior speed, but at the cost of an active amplifier and calibration. To enlarge the bandwidth and increase the SNR of a SAR ADC, a timeinterleaved noise-shaping SAR (TINS-SAR) architecture is a promising solution [4]. This work presents a passive TI noise-shaping technique to enable a power-efficient, PVT-robust ADC for 80MHz BW and 70dB DR.