Amplifiers and Oscillators

Optimization by Simulation

François de Dieuleveult, François De Dieuleveult

• Publisher: ISTE Press - Elsevier
• Year: 2018
• Print ISBN: 9781785482410
• eBook ISBN: 9780081023419
• Topic: Technology & Engineering
• Subtopic: Physics
• Index: Physics

Amplifiers and Oscillators Optimization by Simulation provides a comprehensive resource on the topic, including theory and simulation. The book presents a panorama of electronic patterns, from the simple, to the more complicated. Comparisons of different structures and their advantages and disadvantages are included, making this the go-to book for engineers who need to quickly find the characteristics of a circuit and the method of calculation and dimensioning of components that fit a particular design.- Explains the theory of amplifiers and oscillators in detail- Includes examples and comparisons of different structures- Provides the go-to book for engineers who want to quickly find the characteristics of a circuit and the method of calculation and dimensioning of components that fit a particular design

1

The Transistor

Abstract

The transistor is the basic component and building block that is inevitable for the development of complex functions. The two main devices are amplifiers and oscillators, and there are many others as well, such as multipliers.

Keywords

Amplification; Ebers-Moll model; Giacoletto model; Hyperbolic tangent function; Modeling of transistors; Scattering parameters; S/X parameters; Spice-type modeling

The transistor is the basic component and building block that is inevitable for the development of complex functions. The two main devices are amplifiers and oscillators, and there are many others as well, such as multipliers.

In the case of a bipolar transistor or an MOS field effect transistor, these are modeled by a four pole network, receiving the input voltage and having a current output related to the input voltage.

In order to understand, elaborate and calculate a subset such as an amplifier or an oscillator, it is necessary to derive the equations describing a particular circuit using the transistor model.

In this first chapter, we will cover the different models starting from the simplest one and examine the effects of parasitic components added to the basic schematic.

Please rest assured that establishing the different equations of the circuit is not complicated. Common sense is all that is required to derive the equations. An understanding of how to solve the problems of linear algebra suffices to find the solution of the derived equations. Powerful, modern computer tools such as computer algebra software relieve the engineer, and the mathematical solution can be obtained without mathematical skills.

1.1 Modeling of transistors

The objective of this chapter is to examine the different ways of modeling transistors with configurations of increasing complexity. The higher the frequency, the more complex the equivalent schematics are. The approximation methods of the transistor are classified starting from schematics that are valid for low and medium frequencies, with which we can perform analytical calculation of the more complex models intended for the simulators and finally construct tables of values, like the S matrix, that can be used either analytically or with a simulator.

1.1.1 An input resistance and a linked source

The equivalent diagram of the transistor can be represented using one of the two models shown in Figure 1.1. In fact, these two representations are equivalent. The transistor’s gain, denoted as β or g _m , is known with a high percentage of inaccuracy, with a value of 50% being a good common example. For example, for a BC547B-type transistor, the average gain is 200, which varies between 100 and 300.

Figure 1.1 Replacement of the amplifier by its transistor model

The diagram in Figure 1.1 is presented to first year engineering students. The engineer’s work can be summarized in this simple stage of the circuit’s description, which results in the establi...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• Preface
• 1: The Transistor
• 2: Amplifiers
• 3: Differential Amplifiers
• 4: Amplifier Output Stage
• 5: Study and Analysis of Certain Amplifiers
• 6: Study and Analysis of Oscillators
• 7: Low Frequency Oscillators
• 8: High Frequency Oscillators
• 9: Differential Oscillators
• 10: Bonus Oscillators
• Bibliography
• Index