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2021 | Book

Engineering Mathematics Read chapter Read first chapter

Wireless Communication Electronics by Example

Author: Prof. Robert Sobot

Publisher: Springer International Publishing

Part of: Springer Professional "Wirtschaft+Technik" , Springer Professional "Technik"

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About this book

This book is intended for senior undergraduate and graduate students as well as practicing engineers who are involved in design and analysis of radio frequency (RF) circuits. Fully-solved, tutorial-like examples are used to put into practice major topics and to understand the underlying principles of the main sub-circuits required to design an RF transceiver and the whole communication system.

Starting with review of principles in electromagnetic (EM) transmission and signal propagation, through detailed practical analysis of RF amplifier, mixer, modulator, demodulator, and oscillator circuit topologies, as well as basics of the system communication theory, this book systematically covers most relevant aspects in a way that is suitable for a single semester university level course. Readers will benefit from the author’s sharp focus on radio receiver design, demonstrated through hundreds of fully-solved, realistic examples, as opposed to texts that cover many aspects of electronics and electromagnetic without making the required connection to wireless communication circuit design.

Offers readers a complete, self-sufficient tutorial style textbook;Includes all relevant topics required to study and design an RF receiver in a consistent, coherent way with appropriate depth for a one-semester course;Uses hundreds of fully-solved, realistic examples of radio design technology to demonstrate concepts;Explains necessary physical/mathematical concepts and their interrelationship.

Table of Contents

Frontmatter

Basic Concepts and Definitions

Frontmatter
Chapter 1. Engineering Mathematics
Abstract
Being fluent in the very basic techniques and definitions in engineering mathematics is prerequisite if one is to work on circuit design and analysis, specifically, the basic operations with complex numbers, vectors, and trigonometry identities and their equivalent geometrical interpretations. Mastery of these mathematical techniques is essential for rapid analysis of circuits and systems that are routinely used by working engineers.
Robert Sobot
Chapter 2. Introduction
Abstract
Wireless transmission of information over vast distances is one of the finest examples of Clarke’s third law, which states that “any sufficiently advanced technology is indistinguishable from magic”. Even though a radio represents one of the most ingenious achievements of humankind and is now taken for granted; for the majority of the modern human population (including some of its highly educated members), this phenomenon still appears to be magical. In order to understand this magic, it is important to review some of fundamental concepts and definitions in physics, mathematics, and engineering.
Robert Sobot
Chapter 3. Basic Behavioural and Device Models
Abstract
At the system level, analysis and design of electronic circuits are based on the set of fundamental building blocks represented by their behavioural models. In the initial phase of the design, it is important to validate the intended functionality of the overall circuit at the level of mathematics, without regard for the implementation details. Therefore, the knowledge of functionality of fundamental devices, namely, a switch, voltage, and current sources, and RLC devices as well as their respective impedances is the prerequisite for the next phase in the design process.
Robert Sobot
Chapter 4. Multistage Interface
Abstract
Over the time, we have developed what is known as “top-to-bottom then bottom-to-top design flow”, that is to say that a complicated system is designed hierarchically; during its development stage, systems are often split into more than ten levels of hierarchy. Once the hierarchy chain is established and each of the stages is replaced by its equivalent Thévenin or Norton model, each of the blocks is considered to be a “black box” described by its input and output impedances and its transfer function.
Robert Sobot
Chapter 5. Basic Semiconductor Devices
Abstract
Three terminal active devices are capable of controlling large current flow at its output terminal if a small input signal is applied to its input terminal. That is to say, large waveform at the output terminal is faithful replica of the small input side waveform, thus the amplification. Key point, however, is that the device merely controls the output current flow. The signal energy used both at the input and output sides is provided by the external energy sources, battery, for example. In a mechanical analogy, function of three terminal devices is similar to a water tap that controls water flow (it does not create it).
Robert Sobot
Chapter 6. Transistor Biasing
Abstract
Active devices pose a design challenge due to their non-linear voltage–current characteristics. Inherently, there are two very different resistances that are found at each point of the V–I transfer characteristics, one static and the other one dynamic. When fixed voltage/current stimulus is applied at the terminals of an active device, then by Ohm’s law, we find static (i.e. DC) resistance at the given point simply by calculating V/I ratio. However, when this stimulus signal varies around its static value, resistance to that change is then calculated by using the first derivative mathematical operation. Depending on the specific shape of a non-linear function, this dynamic (i.e. AC) resistance is very much dependent on the function’s curvature at the given static point, that is to say on its derivative.
Robert Sobot
Chapter 7. Review of Basic Amplifiers
Abstract
After a weak radio frequency (RF) signal has arrived at the antenna, it is channeled to the input terminals of the RF amplifier through a passive matching network that enables maximum power transfer of the receiving signal by equalizing the antenna impedance with the RF amplifier input impedance. Then, it is job of the RF amplifier to increase the power of the received signal and prepare it for further processing. Aside from their operating frequency, for all practical purposes, there is not much difference between the schematic diagrams of RF and IF amplifiers.
Robert Sobot
Chapter 8. Introduction to Frequency Analysis of Amplifiers
Abstract
Frequency independent analysis is based on a simple assumption that the circuit is capable to accept and process signals whose frequency spectrum includes all frequencies, from minus infinity to plus infinity. Nonetheless, we already know that elements capable to store energy need a finite amount of time to change their internal states. For slow changes this time delay is negligible, thus “low frequency” approximation produces acceptable results. However, as the signal frequency increases, the impedances of frequency dependent components drastically change.
Robert Sobot
Chapter 9. Electrical Noise
Abstract
Any electrical signal that makes recovery of the information signal more difficult is considered noise. For example, “white snow” on a TV picture and “hum” in an audio signal are typical electrical noise manifestations. Noise mainly affects receiving systems, where it sets the minimum signal level that it is possible to recover before it becomes swamped by the noise. We note that amplifying a signal already mixed with noise does not help the signal recovery process at all. Once it enters the amplifier, noise is also amplified, which is to say that the ratio of signal to noise (S/N) power does not improve and that is what matters. When the power of the noise signal becomes too large relative to the power of the information signal, information content may be irreversibly lost.
Robert Sobot

Radio Receiver Circuit

Frontmatter
Chapter 10. Radio Receiver Architecture
Abstract
Wireless communication systems are result of multidisciplinary research that exploits various mathematical, scientific, and engineering principles in a very creative manner. The inner structure of signal waveforms (such as a voice, for example) is revealed by Fourier transformations, which enables us to design appropriate filters and amplifiers. By using Fourier theory we are able to both synthesize and decompose waveform that are continuous (i.e. analog) or sampled (i.e. digital). By using Maxwell’s theory we explain the creation and propagation of EM waves. By using mathematical theorems, such as basic trigonometry identities, for example, we are able to manipulate signals at the system level. By using circuit theory and techniques, we are able to practically implement the underlying theoretical equations and therefore create “wireless communication system”.
Robert Sobot
Chapter 11. Electrical Resonance
Abstract
In the most familiar form of mechanical oscillations, the pendulum, the total system energy constantly bounces back and forth between the kinetic and potential forms. In the absence of friction (i.e. energy dissipation), a pendulum would oscillate forever. Similarly, after two ideal electrical elements capable of storing energy (a capacitor and an inductor) are connected in parallel then the total initial energy of the system bounces back and forth between the electric and magnetic energy forms. This process is observed as electrical oscillations and the parallel LC circuit is said to be in resonance. The phenomenon of electrical resonance is essential to wireless radio communications technology because without it, simply put, there would be no modern communications.
Robert Sobot
Chapter 12. Matching Networks
Abstract
In this chapter, we study a simple basic methodology for interfacing two stages in the signal processing chain which, is commonly used in the design of RF electronic systems, with the main criterion being maximum power transfer between the stages. This approach is justified by the argument that wireless RF signals that have arrived at the system input terminals (e.g. at the antenna) are very weak, thus subsequent power loss would have broad consequences for the overall system performance. This objective is achieved by using “power matching” techniques.
Robert Sobot
Chapter 13. RF and IF Amplifiers
Abstract
After a weak radio frequency (RF) signal has arrived at the antenna, it is channeled to the input terminals of the RF amplifier through a passive matching network. The matching network is made to enable maximum power transfer of the receiving signal by equalizing the antenna impedance with the RF amplifier input impedance. After that, it is the job of the RF amplifier to increase the power of the received signal and prepare it for further processing. In the first part of this chapter, we review the basic principles of linear baseband amplifiers and common circuit topologies. In the second part of the chapter, we introduce RF and IF amplifiers. Aside from their operating frequency, for all practical purposes, there is not much difference between the schematic diagrams of RF and IF amplifiers.
Robert Sobot
Chapter 14. Sinusoidal Oscillators
Abstract
Communication transceivers require oscillators that generate pure electrical sinusoidal signals (i.e. stable time reference signals) for further use in modulators, mixers, and other circuits. Although oscillators may be designed to deliver other waveforms as well, e.g. square, triangle, and sawtooth waveforms, if intended for applications in wireless radio communications, the sinusoidal and square waveforms are the most important ones. A good sinusoidal oscillator is expected to deliver either a voltage or a current signal that is stable both in amplitude and frequency. Because a variety of oscillator structures are available that are suitable for generation of periodic waveforms, circuit designers make the choice mostly based on their personal preference for one particular type of oscillator.
Robert Sobot
Chapter 15. Frequency Shifting
Abstract
In this chapter, we focus on the mathematical operation of “frequency shifting” that is fundamental to wireless communication systems. Frequency shifting (or “frequency translation”) is complementary to the frequency tuning mechanism used in VCOs. However, as will be shown, it is a much broader concept with a much wider range of applications. As it turns out, mathematical multiplication of two sinusoidal waveforms with given frequencies results in waveforms that contain both higher and lower frequencies. This phenomenon is known as “frequency shifting”, where the term “up-conversion” refers to the process of shifting of lower frequency tone to the upper frequency range (used in RF transmitters), while “down-conversion” refers to the frequency shifting from higher to lower frequency ranges (used in RF receivers). Hence, in a complete wireless communication system, the information-carrying signal is shifted in both directions.
Robert Sobot
Chapter 16. Modulation
Abstract
In a broad sense, the term “modulation” implies a change in time of a certain parameter, where the “change” itself is the message being transmitted. For instance, while listening to a steady single-tone signal with constant amplitude and frequency coming out of a speaker, we merely receive the simplest message that conveys information only about the existence of the signal source and nothing else. If the source is turned off, then we cannot even say if there is a signal source out there or not. For the purpose of transmitting a more sophisticated message, the communication system must use at least the simplest modulation scheme, based on time divisions, i.e. turning on and off the signal source. By listening to short and long beeps, we can decode complicated messages letter by letter. As slow and inefficient as it is, Morse code does work and is used even today in special situations, for example, in a very low SNR environment.
Robert Sobot
Chapter 17. AM and FM Signal Demodulation
Abstract
When a modulated signal arrives at the receiving antenna, the embedded information must somehow be extracted by the receiver and separated from the HF carrier signal. This information recovery process is known as “demodulation” or “detection”. It is based on an underlying mechanism similar to the one used in mixers, where a non-linear element is used to multiply two waves and accomplish the frequency shifting. However, the demodulation process is centred around the carrier frequency ω 0 and the signal spectrum is shifted downward to the baseband and returned to its original position in the frequency domain. Both modulation and demodulation involve a frequency shifting process; both processes shift the frequency spectrum by a distance ω 0 on the frequency axis; and both processes require a non-linear circuit to accomplish the task. Although very similar, the two processes are different in very subtle but important details. In the modulating process the carrier wave is generated by the LO circuit, and then combined with the baseband signal inside the mixer. In the demodulating process, however, the carrier signal is already contained in the incoming modulated signal and it can be recovered at the receiving point.
Robert Sobot
Chapter 18. RF Receivers
Abstract
In a general sense, radio receiver is an electronic system that is expected to detect the existence of a single, very specific EM wave in the overcrowded air space, to separate it from the rest of the frequency spectrum, and to extract the message. Hence, the literal implementation of the receiver function, which is known as a TRF receiver, consists only of a receiving antenna, an RF amplifier, and an audio amplifier. On the contrary, advanced radio receiver versions include one or more mixers and VCO blocks, which are meant to perform either a single-step frequency down-conversion (also known as a “heterodyne receiver”) or multiple step frequency down-conversions (also known as a “super-heterodyne receiver”) in order to shift the HF wave down to the baseband. In this chapter, we review basic definitions and receiver specification parameters.
Robert Sobot
Backmatter
Metadata
Title
Wireless Communication Electronics by Example
Author
Prof. Robert Sobot
Copyright Year
2021
Electronic ISBN
978-3-030-59498-5
Print ISBN
978-3-030-59497-8
DOI
https://doi.org/10.1007/978-3-030-59498-5