Continuous-time cascaded sigma-delta modulators for VDSL: a comparative study

Ramon Tortosa; Jose M. de la Rosa; Angel Rodriguez-Vazquez; Francisco V. Fernandez

doi:10.1117/12.607923

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30 June 2005 Continuous-time cascaded ΣΔ modulators for VDSL: a comparative study

Ramon Tortosa, Jose M. de la Rosa, Angel Rodriguez-Vazquez, Francisco V. Fernandez

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Proceedings Volume 5837, VLSI Circuits and Systems II; (2005) https://doi.org/10.1117/12.607923
Event: Microtechnologies for the New Millennium 2005, 2005, Sevilla, Spain

Abstract

This paper describes new cascaded continuous-time ΣΔ modulators intended to cope with very high-rate digital subscriber line specifications, i.e. 12-bit resolution within a 20-MHz signal bandwidth. These modulators have been synthesized using a new methodology that is based on the direct synthesis of the whole cascaded architecture in the continuous-time domain instead of using a discrete-to-continuous time transformation as has been done in previous approaches. This method allows to place the zeroes/poles of the loop-filter transfer function in an optimal way and to reduce the number of analog components, namely: transconductors and/or amplifiers, resistors, capacitors and digital-to-analog converters. This leads to more efficient topologies in terms of circuitry complexity, power consumption and robustness with respect to circuit non-idealities. A comparison study of the synthesized architectures is done considering their sensitivity to most critical circuit error mechanisms. Time-domain behavioral simulations are shown to validate the presented approach.

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Ramon Tortosa, Jose M. de la Rosa, Angel Rodriguez-Vazquez, and Francisco V. Fernandez "Continuous-time cascaded ΣΔ modulators for VDSL: a comparative study", Proc. SPIE 5837, VLSI Circuits and Systems II, (30 June 2005); https://doi.org/10.1117/12.607923

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