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Systematic Design of Linear Feedback Amplifiers

Lantz, Martin LU (2002) 29.
Abstract
This work adds a quantitative description of distortion to the structured design method of negative-feedback amplifiers. It constitutes a power-series representation of the feedback amplifier, which may include dynamic (memory) effects, where the design parameters appear explicitly. These results have been incorporated into the systematic design method. It now includes design steps for calculating the required number of amplifying stages, and the optimal bias current allocation.



The power-series representation of negative-feedback amplifiers models several properties of active devices. The effects of collector-base current tracking (current drive), high-level injection of BJTs, and the presence of base resistance... (More)
This work adds a quantitative description of distortion to the structured design method of negative-feedback amplifiers. It constitutes a power-series representation of the feedback amplifier, which may include dynamic (memory) effects, where the design parameters appear explicitly. These results have been incorporated into the systematic design method. It now includes design steps for calculating the required number of amplifying stages, and the optimal bias current allocation.



The power-series representation of negative-feedback amplifiers models several properties of active devices. The effects of collector-base current tracking (current drive), high-level injection of BJTs, and the presence of base resistance influences on the nonlinear distortion performance are described. Furthermore, mobility reduction, and channel length modulation of FETs are modeled. Moreover, the power-series representation also allows the mismatch of balanced stages to be considered.



This power-series representation explicitly states the conditions for achieving the desired nonlinear distortion performance of negative-feedback amplifiers. One of the main findings is that the current/voltage gain of an amplifying stage is more important than its intrinsic nonlinearity in this regard. The intrinsic nonlinearity of an amplifying stage is represented by nonlinearity coefficients. The coefficients are, in general, of the same order of magnitude for all technologies and configurations. Therefore, the ability of amplifying stages to contribute to the loop gain is more important.



What is more, in contrast to common belief, applying local feedback does not improve the nonlinear distortion performance of negative-feedback amplifiers. The linearity loss can be slight, assuming that local feedback is applied to the amplifying stage that dominates the linearity performance. The least harmful place for local feedback is, therefore, often the output stage. (Less)
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author
opponent
  • Nordholt, Ernst, Holland
organization
publishing date
type
Thesis
publication status
published
subject
keywords
Signal processing, Volterra series, dynamic distortion, clipping, nonlinear distortion, systematic design, feedback amplifier, Signalbehandling
volume
29
pages
280 pages
publisher
Department of Electroscience, Lund University
defense location
E:1406, E-huset
defense date
2002-11-22 13:15
ISSN
1402-8662
ISBN
91-628-5395-3
language
English
LU publication?
yes
id
eab6398d-5fc9-43d7-9ebc-7f92de9b93ce (old id 20856)
date added to LUP
2007-05-28 13:43:10
date last changed
2016-09-19 08:44:55
@phdthesis{eab6398d-5fc9-43d7-9ebc-7f92de9b93ce,
  abstract     = {This work adds a quantitative description of distortion to the structured design method of negative-feedback amplifiers. It constitutes a power-series representation of the feedback amplifier, which may include dynamic (memory) effects, where the design parameters appear explicitly. These results have been incorporated into the systematic design method. It now includes design steps for calculating the required number of amplifying stages, and the optimal bias current allocation.<br/><br>
<br/><br>
The power-series representation of negative-feedback amplifiers models several properties of active devices. The effects of collector-base current tracking (current drive), high-level injection of BJTs, and the presence of base resistance influences on the nonlinear distortion performance are described. Furthermore, mobility reduction, and channel length modulation of FETs are modeled. Moreover, the power-series representation also allows the mismatch of balanced stages to be considered.<br/><br>
<br/><br>
This power-series representation explicitly states the conditions for achieving the desired nonlinear distortion performance of negative-feedback amplifiers. One of the main findings is that the current/voltage gain of an amplifying stage is more important than its intrinsic nonlinearity in this regard. The intrinsic nonlinearity of an amplifying stage is represented by nonlinearity coefficients. The coefficients are, in general, of the same order of magnitude for all technologies and configurations. Therefore, the ability of amplifying stages to contribute to the loop gain is more important.<br/><br>
<br/><br>
What is more, in contrast to common belief, applying local feedback does not improve the nonlinear distortion performance of negative-feedback amplifiers. The linearity loss can be slight, assuming that local feedback is applied to the amplifying stage that dominates the linearity performance. The least harmful place for local feedback is, therefore, often the output stage.},
  author       = {Lantz, Martin},
  isbn         = {91-628-5395-3},
  issn         = {1402-8662},
  keyword      = {Signal processing,Volterra series,dynamic distortion,clipping,nonlinear distortion,systematic design,feedback amplifier,Signalbehandling},
  language     = {eng},
  pages        = {280},
  publisher    = {Department of Electroscience, Lund University},
  school       = {Lund University},
  title        = {Systematic Design of Linear Feedback Amplifiers},
  volume       = {29},
  year         = {2002},
}