# Doing the math: The inside story of the Analog Engineer’s Pocket Reference

As an analog applications engineer, much of my problem-solving involves recommending application circuits for customers to use as subcircuits in their overall product design. Thus, I understand the need for standard values, formulas, printed circuit board (PCB) characteristics and shortcuts for predicting performance.

A colleague of mine, Tim Green, has about 32 years of experience, of which 16 are in board-/system-level design. When I asked him how he handled these common design aids, he opened his file cabinet and pulled out a folder stuffed full of dog-eared and well-worn papers he’d collected over the years of his favorite design collateral. One of the things that fell out was a small 25-page booklet called “The Burr-Brown Electronic Engineers Pocket Reference,” published in 1994.

That booklet was the motivation for Tim and I to modernize, simplify, organize and electronically publicize the new Texas Instruments Analog Engineer’s Pocket Reference (Figure 1).

Figure 1: TI’s new Analog Engineer’s Pocket Reference inspired by a 1994 Burr-Brown booklet

One general problem with pocket references is that you have to be really familiar with them. In other words, when confronted with a difficult problem, you might resort to a Web search before using the pocket reference if you don’t know that the answer is in the pocket reference.

So in order to help familiarize you with the new TI pocket reference, I have put together some questions. Try to answer the questions using the pocket reference and you will gain a much deeper understanding of the book’s powerful content.

Question 1 (hint: Analog section):

Referring to the circuit below, what is the phase shift at 100kHz?

Question 2 (hint: Amplifier section):

Referring to the circuit below, what is the rise time for the 20mVpp step wave input? Note that this is a small signal step and the OPA209 has a gain bandwidth product (GBW) of 18MHz (data sheet SBOS426).

Question 3 (hint: Amplifier section):

What is the noise spectral density of a 10kΩ resistor?

Question 4 (hint: Amplifier section):

Given the transient closed-loop waveform shown below, what is the loop gain phase margin?

Question 5 (hint: PCB and Wire section):

Referring to the figure below, what type of package is this?

Question 6 (hint: Sensor section):

What is the resistance for a PT100 resistance temperature detectors (RTD) at 100℃? Assume that the RTD adheres to the ITS-90 standard.

Question 7 (hint: A/D Converter section):

Calculate the effective number of bits (ENOB) for an analog-to-digital (A/D) converter assuming signal-to-noise and distortion (SINAD) (dB) of 75dB.

For the benefit of those who are still working through the problems, please do not post answers in the comments. I will post the answers next week. Good luck!

Download the Analog Engineer’s Pocket Reference to get often-used A/D conversion formulas in one place.

• This is indeed a very valuable quick reference guide. Thanks a lot, and kudos  for the effort put forward by the authors. I would like to point out one small error that I noticed though - on page 26 equation ( 23 )  RMS voltage of trapezoidal wave should have the term τ/T inside the square root - if I am not mistaken.

• Binish,

You are correct.  Thanks for finding this issue; we will correct the equation on the next edition.   We also plan on adding additional material in future releases, so let us know if there is something you would like to see.

Art

• Great reference. Is it possible to get a printed version?

I found a small error: the dimensions of the SOT23 and the SC70 packages are not entirely correct. The width values are interchanged.

• Lukas,  Thanks for the feedback.  We will be editing the pocket reference and re-post the edited version.

• I need this as a print version!

• I have a few suggestions: Active filter topologies and current feedback amplifier (when to use them and pitfalls) would be useful.

And I think that a lot of designers in other parts of the world (including me and my colleagues) are not used to imperial units. An additional indication of the corresponding values in mm / mm² / µm  could really help.  AWG, mills, square mils, oz, etc. are not common here.

BTW: The front page design is a real piece of art.

• Thank you for doing this book and allowing us to use it free of charge. I did find one small error/typo on page 9 in the conversion example's answer. 10mm X 39.4 (mm/mil) = 384, I believe should equal 394.

I'll be taking this to work and using it quite often. I have been an electronics technician for about 20 years now.

Rick

• This is a great resource, thanks!  One niggling criticism from me:Figure 6: LED forward voltage drop by color

• Kudos to you, Art and to Tim for creating this useful tool. Keep up the Burr- Brown ethic!

• This looks really handy. One thing I see is that on page 25, on equations 19 and 20, it look like T and t need swapped.

• I've downloaded this and it seems very useful.  I guess I'm old-school, but is this available as a hard-copy spiral-bound volume as shown in the picture?  Did a little searching and didn't find anything...  I think folks (including me) wouldn't mind paying a nominal fee for a hard copy.

• Thanks for all of the feedback.  As an op amp stability guy I am only stable with negative feedback! But seriously, we do appreciate your finding and reporting errors.  We are making corrections and will also post an errata for the Third Edition in case you have a printed copy.  We are also working on making printed copies available for printing plus shipping cost only.  We are investigating some copyright permissions so stay tuned.

• I too would be willing to purchase printed color copies.  If so, please add several  extra notes pages at the end of the book, graph paper (won't ask for green ;).  Great work, thanks!

• Great reference, it really covers much of what I've learned Sophomore and Junior year studying Electrical Engineering, from coaxial cable physics to Bode plots, to THD, to ADCs. Amazing.

Would it be possible to include a definition for 'dBc'?  I discovered it means dB relative to a carrier signal.

For many young people like myself, much explanation of shorthand taken for granted by older engineers is entirely necessary.

One thing I would like to see is a guide to typical analog applications - as if someone compiled a bunch of example circuits from the bottom of TI datasheets and generalized them so that construction of almost any analog configuration was almost effortless.  It's impossible to take the grunt work out of building circuits, and there will never be an engineer who didn't spend hours frustrated because of a problem that was staring them in the face.

I think this guide's logical next step is expansion into practical usefulness for someone trying to design complete analog systems.

• Magnus,

Thanks for the feedback!  We recently did an update on the pocket reference, so make sure you have the fourth edition (see link below).  Unfortunately, we didn’t add the definition of dBc to the fourth edition.  We plan on continuing to update this, so we will get it in the next edition.  Also, another resource to look at is precision labs.  Precision labs is a series of training videos on amplifier topics (see link below).

Thanks, Art Kay

www.ti.com/.../precision-amplifier-pocket-reference-e-book.page

www.ti.com/.../precision-amplifier-precision-labs.page