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# What You Need to Know About Desoer Basic Circuit Theory PDF 45 - The Best Book for Circuit Theory

## Desoer Basic Circuit Theory PDF 45: A Comprehensive Guide

If you are interested in learning the fundamentals of electrical circuits, you may have come across the book Basic Circuit Theory by Charles A. Desoer and Ernest S. Kuh. This book is one of the classic texts on circuit analysis, covering a wide range of topics from linear and nonlinear circuits to Laplace transform and Fourier series. In this article, we will give you a comprehensive guide on what this book is about, who are the authors, what is the PDF 45 version of the book, and why it is useful for electrical engineering students and professionals.

## What is basic circuit theory?

Basic circuit theory is the branch of electrical engineering that deals with the analysis and design of electric circuits. An electric circuit is a network of components, such as resistors, capacitors, inductors, sources, switches, etc., that are connected by wires or other conductors. The main goal of basic circuit theory is to understand how electric currents and voltages behave in different circuits, how to calculate them using various methods and laws, how to model them using mathematical tools, and how to apply them to practical problems.

## Who are Desoer and Kuh?

Charles A. Desoer (1923-2010) was a Belgian-American electrical engineer and professor at the University of California, Berkeley. He was a pioneer in the fields of circuit theory, systems theory, feedback control, nonlinear systems, and neural networks. He authored or co-authored over 200 papers and several books, including Basic Circuit Theory, Theory of Linear Active Networks, Linear System Theory, Feedback Systems: Input-Output Properties, and Basic Electronics.

Ernest S. Kuh (1928-2015) was a Chinese-American electrical engineer and professor at the University of California, Berkeley. He was a leader in the fields of circuit theory, electronic design automation, computer-aided design, VLSI design, bioengineering, and education. He authored or co-authored over 300 papers and several books, including Basic Circuit Theory, Theory of Linear Active Networks, Introduction to VLSI Systems, Electronic Design Automation: Synthesis, Verification, and Test, and Engineering Education for the 21st Century.

## What is the PDF 45 version of their book?

The PDF 45 version of their book is a digital copy of the original 1969 edition of Basic Circuit Theory. It is available online for free download from various sources, such as Google Drive, Internet Archive, and Google Books. The PDF 45 version has 876 pages and contains all the chapters, sections, examples, problems, and solutions of the original book. It also has some additional features, such as bookmarks, hyperlinks, and searchable text. The PDF 45 version is a convenient and accessible way to read and study the book on your computer, tablet, or smartphone.

## Why is it useful for electrical engineering students and professionals?

The book Basic Circuit Theory by Desoer and Kuh is useful for electrical engineering students and professionals for several reasons. First, it covers a comprehensive range of topics in circuit analysis, from basic concepts and definitions to advanced techniques and applications. It provides a solid foundation for further studies in electrical engineering, such as electronics, signals and systems, communication, control, power, etc. Second, it explains the theory and methods in a clear and rigorous way, with many examples and problems to illustrate and practice. It also connects the theory with the physical reality of circuits, using intuitive explanations and analogies. Third, it is written by two eminent experts in the field, who have made significant contributions to the development and teaching of circuit theory. Their book reflects their deep knowledge and experience in the subject, as well as their passion and enthusiasm for it.

## Basic Concepts and Definitions

In this section, we will review some of the basic concepts and definitions that are essential for circuit analysis. We will introduce the notions of linear and nonlinear circuits, Kirchhoff's laws, network topology, and network functions.

### Linear and nonlinear circuits

A circuit is said to be linear if it satisfies two properties: homogeneity and superposition. Homogeneity means that if the input (source) is multiplied by a constant factor, the output (response) is also multiplied by the same factor. Superposition means that if there are multiple inputs (sources), the output (response) is equal to the sum of the outputs (responses) due to each input (source) separately. A circuit that does not satisfy these properties is called nonlinear.

Linear circuits are easier to analyze than nonlinear circuits because they obey simple mathematical rules and principles. Most of the methods and techniques that we will learn in this book are applicable to linear circuits. However, nonlinear circuits are also important because they can exhibit complex and interesting behaviors that linear circuits cannot, such as oscillations, chaos, switching, etc. Some examples of nonlinear components are diodes, transistors, relays, etc.

### Kirchhoff's laws

Kirchhoff's laws are two fundamental laws that govern the behavior of electric currents and voltages in any circuit. They are based on the conservation of charge and energy in a closed system. They are stated as follows:

• Kirchhoff's current law (KCL): The algebraic sum of the currents entering any node (junction point) in a circuit is zero.

• Kirchhoff's voltage law (KVL): The algebraic sum of the voltages around any closed loop (path) in a circuit is zero.

Kirchhoff's laws can be used to write equations that relate the currents and voltages in a circuit. These equations can then be solved to find the unknown currents and voltages.

### Network topology

Network topology is the study of the structure and arrangement of a circuit. It involves identifying the elements (components), nodes (junction points), branches (connections), loops (closed paths), meshes (independent loops), cutsets (sets of branches that divide the network into two parts), etc., of a circuit. Network topology helps us to simplify and organize a circuit for analysis.

### Network functions

Network functions are mathematical expressions that describe the relationship between the input and output variables of a circuit. For example, if we have a voltage source Vs as the input and a voltage Vo across a load as the output of a circuit, we can define a network function H(s) = Vo(s)/Vs(s), where s is a complex variable. This network function is called the transfer function or voltage gain of the circuit. Similarly, we can define other network functions as well, such as impedance function, admittance function, hybrid function, etc., depending on the choice of input and output variables.

## Analysis of Resistive Circuits

In this section, we will learn how to analyze circuits that contain only resistors and independent sources. Resistors are passive components that oppose the flow of electric current and dissipate energy as heat. Independent sources are active components that provide a constant voltage or current regardless of the rest of the circuit. We will use some of the methods and techniques that are based on Kirchhoff's laws and network topology, such as node-voltage method, mesh-current method, Thevenin's and Norton's theorems, and superposition principle.

### Node-voltage method

The node-voltage method is a systematic way to find the voltages at each node (junction point) in a circuit. The steps are as follows:

• Choose a reference node (usually the one connected to the most branches) and assign it a voltage of zero.

• Assign voltage variables to the other nodes and label their polarities.

• Apply KCL at each node (except the reference node) and write an equation for the sum of the currents entering or leaving the node.

• Express the currents in terms of the node voltages and the resistances using Ohm's law.

• Solve the system of equations for the unknown node voltages.

The node-voltage method can be applied to any circuit that contains only resistors and independent sources. It can also be extended to circuits that contain dependent sources by introducing additional variables for the controlling quantities.

### Mesh-current method

The mesh-current method is another systematic way to find the currents in each branch of a circuit. A mesh is an independent loop that does not contain any other loops within it. The steps are as follows:

• Identify all the meshes in the circuit and assign a mesh current to each one. The direction of the mesh current is arbitrary, but it is usually chosen to be clockwise.

• Apply KVL around each mesh and write an equation for the sum of the voltages around the loop.

• Express the voltages in terms of the mesh currents and the resistances using Ohm's law.

• Solve the system of equations for the unknown mesh currents.

The mesh-current method can be applied to any circuit that contains only resistors and independent sources. It can also be extended to circuits that contain dependent sources by modifying the equations for the meshes that contain them.

### Thevenin's and Norton's theorems

Thevenin's and Norton's theorems are useful tools for simplifying complex circuits into equivalent circuits that are easier to analyze. They state that any linear circuit with two terminals can be replaced by an equivalent circuit that consists of either a voltage source in series with a resistor (Thevenin's theorem) or a current source in parallel with a resistor (Norton's theorem). The steps to find the equivalent circuit are as follows:

• Remove the load (the component connected to the two terminals) from the original circuit.

• Find the open-circuit voltage Voc across the two terminals by applying any of the methods discussed before.

• Find the short-circuit current Isc through the two terminals by applying any of the methods discussed before.

• Find the Thevenin resistance Rth by dividing Voc by Isc.

• Find the Thevenin voltage Eth by multiplying Rth by Isc, or by using Voc.

• Find the Norton current In by dividing Voc by Rth, or by using Isc.

• Find the Norton resistance Rn by using Rth.

• Reconnect the load to the equivalent circuit and analyze it.

Thevenin's and Norton's theorems can be applied to any linear circuit with two terminals. They can also be extended to circuits that contain dependent sources by modifying the steps for finding Voc, Isc, and Rth.

### Superposition principle

The superposition principle is a technique that can be used to analyze linear circuits that contain multiple independent sources. It states that the response (current or voltage) in any branch of a circuit is equal to the algebraic sum of the responses caused by each independent source acting alone, while all other independent sources are turned off (replaced by their internal impedances). The steps are as follows:

• Select one independent source and turn off all other independent sources.

• Analyze the circuit and find the response due to the selected source.

• Repeat steps 1 and 2 for each independent source in the circuit.

• Add up all the responses to get the total response.

The superposition principle can be applied to any linear circuit that contains multiple independent sources. It can also be combined with other methods and techniques, such as node-voltage method, mesh-current method, Thevenin's theorem, etc., to simplify the analysis.

## Analysis of Dynamic Circuits

In this section, we will learn how to analyze circuits that contain capacitors and inductors, in addition to resistors and sources. Capacitors and inductors are passive components that store energy in electric and magnetic fields, respectively. They introduce dynamics (time-dependence) into the circuit behavior, as their currents and voltages depend on how they are charged or discharged over time. We will use some of the methods and techniques that are based on Kirchhoff's laws and network functions, such as first-order circuits, second-order circuits, sinusoidal steady-state analysis, etc.

### Capacitors and inductors

A capacitor is a device that consists of two conductive plates separated by an insulator (dielectric). It can store electric charge on its plates when connected to a voltage source. The amount of charge Q on a capacitor is proportional to the voltage V across it, according to the equation Q = CV, where C is the capacitance of the capacitor. The capacitance is a measure of how much charge a capacitor can store per unit voltage. It depends on the physical characteristics of the capacitor, such as the area and distance of the plates, and the type of dielectric. The unit of capacitance is farad (F).

An inductor is a device that consists of a coil of wire wrapped around a core (air or magnetic material). It can store magnetic flux (linked with electric current) in its coil when connected to a current source. The amount of flux Φ in an inductor is proportional to the current I through it, according to the equation Φ = LI, where L is the inductance of the inductor. The inductance is a measure of how much flux an inductor can store per unit current. It depends on the physical characteristics of the inductor, such as the number of turns, the area and length of the coil, and the type of core. The unit of inductance is henry (H).

The current-voltage relationship for a capacitor is given by the equation I = C dV/dt, where I is the current through the capacitor, C is the capacitance, and dV/dt is the rate of change or the slope of the voltage across the capacitor. This equation shows that the current through a capacitor is proportional to the rate of change of the voltage across it. If the voltage is constant, the current through the capacitor is zero, and the capacitor behaves like an open circuit.

The current-voltage relationship for an inductor is given by the equation V = L dI/dt, where V is the voltage across the inductor, L is the inductance, and dI/dt is the rate of change or the slope of the current through the inductor. This equation shows that the voltage across an inductor is proportional to the rate of change of the current through it. If the current is constant, the voltage across the inductor is zero, and the inductor behaves like a short circuit.

### First-order circuits

A first-order circuit is a circuit that contains only one energy storage element (capacitor or inductor) and one resistor. A first-order circuit can be analyzed using a first-order differential equation that relates either the current or voltage to its derivative with respect to time. A first-order circuit can be either a series RC circuit (a resistor and a capacitor connected in series) or a series RL circuit (a resistor and an inductor connected in series).

A series RC circuit can be used to model a charging or discharging capacitor. When a capacitor is connected to a DC voltage source through a resistor, it starts to charge up until it reaches its final voltage, which is equal to the source voltage. The charging process follows an exponential curve that depends on the time constant τ = RC, where R is the resistance and C is the capacitance. The time constant τ determines how fast the capacitor charges or discharges. The charging or discharging process follows an exponential curve that depends on the initial and final voltages of the capacitor.

A series RL circuit can be used to model an energizing or de-energizing inductor. When an inductor is connected to a DC voltage source through a resistor, it starts to build up current until it reaches its final current, which is equal to the source voltage divided by the resistance. The energizing process follows an exponential curve that depends on the time constant τ = L/R, where L is the inductance and R is the resistance. The time constant τ determines how fast the current rises or falls. The energizing or de-energizing process follows an exponential curve that depends on the initial and final currents of the inductor.

### Second-order circuits

A second-order circuit is a circuit that contains two energy storage elements (capacitors or inductors) and one or more resistors. A second-order circuit can be analyzed using a second-order differential equation that relates either the current or voltage to its second derivative with respect to time. A second-order circuit can be either a series RLC circuit (a resistor, an inductor, and a capacitor connected in series) or a parallel RLC circuit (a resistor, an inductor, and a capacitor connected in parallel).

A series RLC circuit can be used to model a resonant circuit that can oscillate at a natural frequency or respond to an external driving frequency. When a series RLC circuit is connected to a DC voltage source through a switch, it starts to oscillate between charging and discharging the capacitor and building up and collapsing the magnetic field of the inductor. The oscillation process follows a sinusoidal curve that depends on the natural frequency ω0 = 1/(LC), where L is the inductance and C is the capacitance. The natural frequency ω0 determines how fast the oscillation occurs. The oscillation process also depends on the damping factor α = R/2L, where R is the resistance. The damping factor α determines how quickly the oscillation dies out due to energy dissipation.

A parallel RLC circuit can also be used to model a resonant circuit that can oscillate at a natural frequency or respond to an external driving frequency. When a parallel RLC circuit is connected to a DC current source through a switch, it starts to oscillate between charging and discharging the capacitor and building up and collapsing the magnetic field of the inductor. The oscillation process follows a sinusoidal curve that depends on the natural frequency ω0 = 1/(LC), where L is the inductance and C is the capacitance. The natural frequency ω0 determines how fast the oscillation occurs. The oscillation process also depends on the damping factor α = 1/2R(C/L), where R is the resistance. The damping factor α determines how quickly the oscillation dies out due to energy dissipation.

Sinusoidal steady-state analysis is a technique that can be used to analyze circuits that are driven by sinusoidal sources with a constant frequency. Sinusoidal sources are common in AC circuits, such as power supply systems, audio systems, radio systems, etc. Sinusoidal sources can be represented by phasors, which are complex numbers that encode the amplitude and phase of a sinusoid. Phasors can be manipulated using complex arithmetic, which simplifies the analysis of AC circuits.

When a circuit is driven by a sinusoidal source, the currents and voltages in the circuit will also be sinusoidal with the same frequency as the source, but possibly with different amplitudes and phases. The circuit will reach a steady state after a transie