Quadrature Mismatch Shaping Techniques for Fully Differential Circuits

Quadrature ΣΔ ADCs require a feedback path for both the I and the Q part of the complex feedback signal. A complex DAC could give this feedback with near-perfect I/Q balance. Still, the mismatch between the unit elements of the complex DAC introduces mismatch noise that should be shaped out of the s...

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Bibliographic Details
Published in2007 IEEE International Symposium on Circuits and Systems (ISCAS) pp. 3614 - 3617
Main Authors Reekmans, Stijn, Rombouts, Pieter, Weyten, Ludo
Format Conference Proceeding
LanguageEnglish
Published IEEE 01.05.2007
Subjects
Circuit noise
Digital modulation
Energy consumption
Feedback
Hardware
Logic
Noise shaping
Quantization
Signal generators
Tree data structures
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Summary:Quadrature ΣΔ ADCs require a feedback path for both the I and the Q part of the complex feedback signal. A complex DAC could give this feedback with near-perfect I/Q balance. Still, the mismatch between the unit elements of the complex DAC introduces mismatch noise that should be shaped out of the signal band with dynamic element-matching (DEM) techniques. In literature, only quadrature DEM techniques for 3-state (I, Q, 0) unit elements are considered. However, in fully differential circuit, also 5-state unit elements are available. In this case, each unit element can be selected ±1, ±Q or 0. When using these 5-state unit elements, the amount of hardware and power consumption can be reduced significantly. In this paper it is shown how the tree structure, the data directed swapper and the vector quantizer structure can be adapted for the use in fully differential circuits with such 5-state unit elements.
ISBN:1424409209
9781424409204
ISSN:0271-4302
2158-1525
DOI:10.1109/ISCAS.2007.378535