Op Amps for Everyone, Second Edition

by Bruce Carter

The operational amplifier ("op amp") is the most versatile and widely used type of analog IC, used in audio and voltage amplifiers, signal conditioners, signal converters, oscillators, and analog computing systems. Almost every electronic device uses at least one op amp. This book is Texas Instruments' complete professional-level tutorial and reference to operational amplifier theory and applications. Among the topics covered are basic op amp physics (including reviews of current and voltage division, Thevenin's theorem, and transistor models), idealized op amp operation and configuration, feedback theory and methods, single and dual supply operation, understanding op amp parameters, minimizing noise in op amp circuits, and practical applications such as instrumentation amplifiers, signal conditioning, oscillators, active filters, load and level conversions, and analog computing. There is also extensive coverage of circuit construction techniques, including circuit board design, grounding, input and output isolation, using decoupling capacitors, and frequency characteristics of passive components. The material in this book is applicable to all op amp ICs from all manufacturers, not just TI. Unlike textbook treatments of op amp theory that tend to focus on idealized op amp models and configuration, this title uses idealized models only when necessary to explain op amp theory. The bulk of this book is on real-world op amps and their applications; considerations such as thermal effects, circuit noise, circuit buffering, selection of appropriate op amps for a given application, and unexpected effects in passive components are all discussed in detail.

*Published in conjunction with Texas Instruments
*A single volume, professional-level guide to op amp theory and applications
*Covers circuit board layout techniques for manufacturing op amp circuits.

Genres: Reference

472 pages, Paperback

First published March 1, 2003

Reviews

[Jonatron · Rating 1 out of 5]

Beware: The guide on how to calculate noise of op-amp amplifiers is full of errors, which resulted in great confusion as I tried to learn this topic and my calculations disagreed depending on which instructions I followed.

First big mistake: They combine the noise of the resistors with the output noise of the op-amp:

Instead, they should be combining the noise of the resistors with the input noise of the op-amp, and then multiplying this by the (noise) gain to get the output noise.

Second big mistake: They sum the noise of parallel resistors together. Instead, they should be calculating the equivalent resistance seen by the source, and then using that. For instance, they combine a 10 MΩ resistor and a 100 kΩ resistor as if they were in series (10.1 MΩ → 57.1 μV), but they should be combining them as if they are in parallel (99 kΩ → 5.6 μV).


And no, that equation doesn't match the text describing it, either. There are a number of other miscalculation/typo errors in this section, making it useless for learning how to calculate noise.

There are other fundamental errors, too: In another part of the book, they claim that "unity gain stable" means that an inverting amplifier with gain less than unity is unstable, so you have to attenuate first and then amplify:

This is the most often misdesigned circuit of all the cases. Many inexperienced designers create an unstable stage by attempting to extrapolate an inverting gain stage to the attenuation case by making RG greater than RF. The easiest fix for this problem is to use a voltage divider followed by a unity gain buffer, as described in Section 5.2. If inverting gain is absolutely required, then a similar solution can be implemented by adding a voltage divider to the input of an inverting gain stage.

This is wrong, but it's still being echoed around the internet, confusing n00bs. There is nothing unstable about making Rg greater than Rf. The truth is that "unity gain stable" applies to the noise gain, not the inverting signal gain. Noise gain of this circuit can never drop below unity. Their proposed solution increases both parts count and noise for no reason:



(And that equation is wrong, too. It should be m = (Rf * Ratten)/(Rin*(Rin + 2*Ratten)).)

So yeah, don't trust anything you read in this book until you've double-checked it.

[Keith · Rating 4 out of 5]

I have used several editions of OpAmps for Everyone. The latest free download version is 2; the latest paper edition is 4. This is a very good overview of op amps. Ron Mancini suggests novices read chapters 1 through 9. As others have observed, most people can skip the chapters on current feedback op amps; these, like Norton amps are a specialty area few venture into.

Beware of Chapter 10 Op Amp Noise Theory Applications. It has a good presentation of noise in general with errata. (See https://e2e.ti.com/support/amplifiers... for a disquisition with replies by Art Kay and Bruce Carter). Apparently in the 4th edition Bruce Carter has made this an appendix, but the problems remain.

As a 464 page PDF, OpAmps for Everyone is unwieldy.

[Meadowlark · Rating 4 out of 5]

I'm just reading sections until I learn how to test two basic op amp functions for my analog electronics projects.