Nonlinear bipolar transistor modelling for high frequency amplifiers
Nonlinear bipolar transistor modelling for high frequency amplifiers
Computer Aided Design of high frequency circuits requires a coherent component modelling strategy if it is to successfully assist the circuit designer in his task. This report describes techniques for modelling u.h.f. bipolar transistors, using lumped circuit equivalents based on the physical processes of device operation. A suitable model topology is selected, and by incorporating some novel measurement methods in a general modelling procedure, a linear circuit model of the transistor is derived which is then computer optimized for best agreement with device measurements. Nonlinear elements in the device model are characterized from terminal measurements and incorporated into the equivalent circuit. The transistor model is analysed in the frequency domain using Volterra series techniques, and is particularly suited to low order prediction of intermodulation distortion, which is especially troublesome in many contemporary applications. The accuracy of the modelling technique is checked by distortion measurements on two common types of silicon bipolar transistor operating up to 1 GHz. Distortion as a function of signal level, frequency, temperature and bias level is considered, and the models are shown to be accurate in predicting distortion in tuned amplifiers where differing load impedances are involved. Methods of reducing distortion in high frequency amplifiers are considered, and the technique of out-of-band impedance matching is introduced. This technique is studied in detail and is applied to two practical amplifier designs to show how distortion levels can be affected by selective modification of terminating impedances outside the amplifier passband.
University of Southampton
1983
Redfern, Stephen William
(1983)
Nonlinear bipolar transistor modelling for high frequency amplifiers.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
Computer Aided Design of high frequency circuits requires a coherent component modelling strategy if it is to successfully assist the circuit designer in his task. This report describes techniques for modelling u.h.f. bipolar transistors, using lumped circuit equivalents based on the physical processes of device operation. A suitable model topology is selected, and by incorporating some novel measurement methods in a general modelling procedure, a linear circuit model of the transistor is derived which is then computer optimized for best agreement with device measurements. Nonlinear elements in the device model are characterized from terminal measurements and incorporated into the equivalent circuit. The transistor model is analysed in the frequency domain using Volterra series techniques, and is particularly suited to low order prediction of intermodulation distortion, which is especially troublesome in many contemporary applications. The accuracy of the modelling technique is checked by distortion measurements on two common types of silicon bipolar transistor operating up to 1 GHz. Distortion as a function of signal level, frequency, temperature and bias level is considered, and the models are shown to be accurate in predicting distortion in tuned amplifiers where differing load impedances are involved. Methods of reducing distortion in high frequency amplifiers are considered, and the technique of out-of-band impedance matching is introduced. This technique is studied in detail and is applied to two practical amplifier designs to show how distortion levels can be affected by selective modification of terminating impedances outside the amplifier passband.
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Published date: 1983
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Local EPrints ID: 459422
URI: http://eprints.soton.ac.uk/id/eprint/459422
PURE UUID: 880a8877-2229-44d8-87bc-02e31615a7b8
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Date deposited: 04 Jul 2022 17:10
Last modified: 04 Jul 2022 17:10
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Author:
Stephen William Redfern
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