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ABSTRACT
AbstractIn this book, switched-capacitor (SC) techniques are proposed which allow the attainment of higher intrinsic analogue accuracies than previously possible in such application areas as analogue filter and analogue-to-digital converter (ADC) design. The design philosophy is to create the required functionality without relying on trimming or digital calibration means but instead to develop methods which have reduced dependence on both component matching (especially capacitor matching) and parasitic effects (especially parasitic capacitance).At a system level, orthogonal design procedures are employed which ensure that artefacts due to expected circuit imperfections are avoided in the system transfer function. For instance, in SC filter design, orthogonal-hardware-modulation helps alleviate the effects of Npath mismatch through the introduction of an extra degree of freedom, where the number of hardware paths N (hardware modulation) is decoupled from the functional modulation factor n, as introduced by the transformation . In algorithmic ADC design, both cyclic and pipelined, conventional techniques make use of multiplying digital-to-analogue converters (or MDACs) which require SC circuits with accurate capacitor ratios to implement accurate signal multiplication. On the other hand, in this book, the ADC function is decomposed into the simple sub-functions of signal addition and level shifting which can be implemented using SC techniques which don't rely on accurate capacitor ratios.At circuit level, delta-charge flow techniques are employed to realize SC circuits with more accurate transfers than their conventional charge-transfer (QT) counterparts. Unlike QT SC circuits, SC circuits do not require signal charge transfer from capacitor to capacitor via the amplifier virtual earth node. Instead, only a delta charge flows in the virtual earth node due to the presence of parasitic capacitors at the amplifier input terminals. In SC filter design, delta-charge-redistribution is a means for the accurate implementation of filter transfer functions using passive charge redistribution between capacitors in the feedback path of an amplifier, instead of active charge transfer between capacitors through the active intervention of an amplifier in QT SC filters. In ADC design, a highly accurate method (C+C) for the stacking of capacitor voltages is proposed which uses a floating-hold-buffer for implementation. The accuracy of signal addition is practically insensitive to the matching and linearity of the signal capacitors as well as the presence of parasitic terminal capacitance.A number of ...
