Blocker-Tolerant Wideband Continuous-Time Delta Sigma ADC Using Embedded Minimally-Invasive Filtering

This paper proposes a technique to improve the blocker-tolerance of continuous-time Delta Sigma modulators (CTDSMs) by embedding a third-order minimally-invasive filter (MIF) in the Delta Sigma loop. The noise-transfer-function (NTF) restoration is achieved by re-using the same filter network, eliminating the need for a matched filter. We present detailed system-level analysis and design choices. We also present simulation results of the proposed technique on a 170 MHz BW, 11-bit ENOB, 4th-order cascaded-integrator-feed-forward (CIFF) loop-filter based CTDSM with loop filter and DACs implemented at the schematic level in a 40nm CMOS technology.