Preface

The book in front of you has been written specifically for those of you who have mastered Ohm's law and Kirchhoff's laws, have the basic knowledge of electrical components and their applications, who often explore phenomena inside various analog circuits. It is designed for those who do not dread either to analyse problems by means of pen and paper or to make computer experiments, and for those who have enough internal motivation to become really knowledgeable users of present commercial simulation programs, without studying reams of unreadable manuals. However, if you do not conform to some of the above provisions, it need not to be an obstacle, as will be obvious from a glance at the contents with titles of individual chapters.

On the following pages you can find large volumes of information from the area of efficient methods of analysis of analog circuits. However, a "bonding compound" of this information - a chain of solved problems - is no less important than the information itself. The examples will guide you through both "hand-and-paper" and computer-aided analysis methods.

How to read this book so that it can be most useful to you?

Before offering any directions, let me give a couple of supporting facts. This book has three parts. The first two parts discuss methods of "hand-and-paper" and computer-aided analyses, the third one contains appendixes. For those of you who want to learn to analyse electronic circuits really well, I recommend reading from the very beginning. In other words, you would in the first place study solving simpler circuit by "hand-and-paper" methods, be led by your effort to understand how this or that circuit operates, and after that you may study "automated" computer-aided analysis. In this second stage, it is advisable to download the installation software for the SNAP and MicroCap programs together with a set of electronic sample examples from the website from the BEN publisher webpage www.BEN.cz.

 Present-day simulation programs are mostly based on modified nodal analysis. That is why this method is discussed in detail already in the introductory chapters, which are devoted to "hand-and-paper" analysis, just after heuristic methods, which are tailored for people who are used to solving problems "in their own original style", creatively utilizing the basic laws and principles of Electrical Engineering. The procedures of fast analysis of circuits containing classical and modern circuit elements (various OpAmp types including transimpedance OpAmps and OTAs, current conveyors, etc.) are discussed in detail. These methods are explained clearly in a number of examples, both in the matrix and signal flow graph forms. Some of them have not been published anywhere. This is also true of the somewhat "exotic" methods of signal flow graphs. Their mastering can lead to notable effects, for instance, to writing analysis results immediately from a circuit diagram inspection, i.e. without any side-computing.

Through Chapter 4 you enter the world of computer analysis and simulation of electrical circuits. Here, on just about 200 pages, you can familiarize yourself with an alphabet whose mastering will open your way to working efficiently with any of today's "SPICE-family" circuit simulators. If you manage to finish this chapter and interlace reading with experiments on your computer, verify the described experiments on sample examples, and deliberate on the results generated by the SNAP and MicroCap programs, then you will have done a lot for your "way to the top" to be as honest as possible and not only because of the formula:

MicroCap = SPICE + "something beyond".

You will be initiated into computer simulation step-by-step, from relatively simple programs based on symbolic computations (SNAP) to commercial "numerical" simulators (MicroCap). We have developed the SNAP program exactly for students who need to promptly master the first steps in computer simulation of circuits. An unconventional chapter 4.5 should help you significantly to master the above alphabet. In this chapter, three thematically linked-up lectures of computer simulation in the SNAP program are concentrated. To raise the overall "tutorial" effect, this part is formally arranged rather differently from the other chapters (graphical information predominates over the text, figure numbering is omitted, etc.). Suggestions how to experiment individually in the SNAP may be found here. You can continue in solving a set of 123 electronic examples after downloading them to your computer from http://shop.ben.cz/detail.asp?id=121177 . Their description is given in Appendix P9. Examples cover a broad range of problems. They are sorted into the following categories: "Basics of EE", "Amplifiers", "Oscillators", "Synthetic elements", "Filters", "RF circuits ". However, this preliminary part is warmly recommended also for advanced users of commercial simulators. The SNAP program offers - in contrast to SPICE-family simulators - results in so-called symbolic form. It will enable you to obtain some solutions, which commercial simulators simply cannot do.

Though the follow-up chapters about "numerical" simulation programs can be studied independently of the foregoing parts, going through the preceding "basics" is more efficient. The above "skip" can be recommended perhaps only to more advanced users of some commercial simulators. You learn to "move" through a professional schematic editor, you meet the basic terms and rules how to work with models of circuit components, with libraries, how to utilize correctly the .MODEL and .DEFINE commands, etc. You become familiar with assorted types of analysis, with various analyzing modes and regimes. Depending on your needs, you can have such a command of these problem that will satisfy you: In addition to the basic types of analysis, which are of the same nature in various simulation programs, further useful practices are also described in detail (for example various "interactive" analyses, the sensitivity analysis, animations, etc.). You will have an opportunity to understand - via concrete examples- some procedures offered by various simulation programs, which are usually "clouded in secret" for common users, who have not time enough to read large manuals. We are talking now about spectral analysis of waveforms, about rules for applying the forward and the inverse Fast Fourier Transform (FFT) in circuit simulators, about setting initial conditions in various types of analysis, about enabling/disabling the DC operating point, about a correct utilization of .IC and .NODESET commands, about noise analysis, about generalized DC analysis, how get familiar with "simulation temperatures" or whit various methods of parameter stepping, how to use the Monte Carlo method in practice, how to work properly in the optimization mode and, in particular, how to overcome various problems during computer simulation, including problems with the convergence of internal algorithms, etc. By virtue of this "concentrated experience", the book could be also interesting for more advanced users of some professional simulation programs.

Let us go back to the opening question, " How to read this book so that it can be most useful to you?" Severally, depending on "how far you are from the top", with the awareness that "the way is not straight". Study - according to the content - the parts you are interested in. The book contains a number of cross-references both to foregoing chapters and to the appendix section. From appendices you may gather some basic theoretical knowledge which was purposely included here instead of the technical chapters. Simultaneously, they can serve you as brief reference manuals, especially as regards concrete working with the component models.

Many thanks are due to my co-workers. This book could not have been written without team-work solution of a number of research projects from the area of analysis and synthesis of analog circuits. My thanks also go to Dr. Zdeněk Kolka, Ph.D., the main author of SNAP program and special thanks to Prof. Karel Hájek for invaluable discussions over the manuscript. Let me express my thanks also to my students, whose mistakes and lapses in experimental and computer labs have moulded my experience. I would like to inscribe this book to them above all.

In conclusion, I also thank you, my former teachers of circuit theory. For Prof. Josef Čajka, author of the famous COCO program, I wrote Chapter 2.3 about the matrix methods of analysis. Without the COCO program, its successor SNAP would not have come into being. Furthermore, I would also like to thank Prof. Ján Mikula, who had initiated me into the mystique of signal flow graphs. Chapter 2.4 about graph algorithmic methods is inscribed to his memory.

Readers can send all inquiries or comments and suggestions directly to the author to his email address dalibor.biolek@unob.cz or to the address of BEN publishers.

In Brno, August 2003

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