A flexible resonation-based cascade ΣΔ modulator with simplified cancellation logic

This paper presents a new two-stage cascade ΣΔ modulator architecture that uses inter-stage resonation to increase its effective resolution as compared to conventional cascades and avoids the need for digital filtering in the error cancellation logic. The combination of these two strategies, together with the use of unity signal transfer function in all stages, make the presented modulator highly tolerant to noise leakages, very robust to non-linearities and mismatches of the loop-filter circuitry, and especially suited for low-voltage implementations at low oversampling ratios. In addition, the use of loop filters based on Forward-Euler integrators, instead of Backward-Euler integrators, simplifies the switched-capacitor implementation of the resonation and makes the presented architecture very suited for reconfigurable multi-standard applications. As an illustration, a Beyond-3G case study is shown to demonstrate the benefits of the presented approach.