A 7.3 mW 200 MHz-BW 4-element Passive-Beamforming Continuous-Time ΔΣ ADC with >30dB Spatial Interferer Suppression

This paper proposes a novel BF-$\Delta \Sigma M$ concept, which integrates passive vector modulators within the $\Delta \Sigma M$ loop filter to suppress spatial blockers and hence greatly reduce the dynamic range requirements of the ADC. To enhance phased-array receiver performance, a CT-$\Delta \Sigma M$ with embedded R-2R based vector modulators as feed-in coefficients is proposed. Resistive vector modulators can provide accurate phase shifting and amplitude scaling, enabling beam-steering and null-steering. This 4-element 40 nm CMOS BF-$\Delta \Sigma M$ achieves $\gt30 \mathrm{~dB}$ suppression of interferers up to three spatial interferers, 200MHz-bandwidth and $\gt70 \mathrm{~dB}$ spatial blocker DR with only 7.3 mW. The BF-$\Delta \Sigma M$ obtains $7 \mathrm{fJ} / \mathrm{cs}$ and 177 dB BF-ADC equivalent Walden FoM and Schreier FoM.