Sensitivity Analysis of Continuous-Time $Delta Sigma$ ADCs to Out-of-Band Blockers in Future SAW-Less Multi-Standard Wireless Receivers

摘要

The increasing demand for integrating multiple wireless services in one multi-standard handset, exemplified by the software-defined radio (SDR) model, calls for digitizing wireless receivers in a quest for flexibility. Radio-frequency (RF) front-end and analog baseband filters need to be exchanged for digital processing at the expense of a highly challenging analog-to-digital converter (ADC) specifications. In this paper, the sensitivities of continuous-time (CT) delta-sigma $(Delta Sigma)$ ADCs, which are candidate architectures for multi-standard receivers and SDRs, to out-of-band (OOB) blockers at the ADC input are investigated. This analysis addresses the problems and performance limitations that can result from large OOB blockers appearing at the input of CT $Delta Sigma$ modulators in a digitized multi-standard receiver. Analysis and discussions given in different sections of the paper are verified by CT system-level simulations.