#273: Common Emitter Amplifier Design Tips & Shortcuts

This video provides some basic design tips and shortcuts for the Common Emitter, Class A, Amplifier. The considerations for selection of the DC Bias point are presented, as well as some tips on how to set/compute the gain for both degenerated and high-gain configurations. Below you will find links for related videos and for a PDF copy of the notes used in this video:

A much more detailed treatment of a single BJT amplifier is presented by TheSignalPath here:

Video Notes:

[tomsmith]

I went to school with a guy who could explain a weeks worth of classroom lecture in math in 10 minutes over a beer. Clear, concise, and simple. You're like that guy. Great video!

[micomrkaic]

The best explainer of electronics on YouTube. Bar none.

[jacobfaseler]

Just about every other tutorial gets lost in the math. I appreciate your approach from the angle of design philosophy : especially in how you clarify the decision tree of a typical design. Chef’s kiss.

[KCLIBURN-mjqx]

I'd like to thank you W2EAW for demonstrating that those who truly know their stuff can be so comfortable with sharing their knowledge and professional insight with those who like to watch and learn. I am a retired technician who got his initial training in electronics in the US Navy and worked in the field of avionics for several years before getting civilian jobs in the field of test and electrical service and test/calibration for a muni. in electric substations. I am impressed because usually EE's wherever I've worked at are usually very tight lipped about sharing anything professional and you differ with your easy to understand tutorials. I'd like to give a huge thank you for that and keep them coming. Thank you for sharing with us. Oh btw, I have several pieces of t.e. including scopes (dig. and analog) sig. gens., imp. meters and other various peices but your test bench makes me want to buy a whole lot more!

[cetola]

I regularly recommend your videos as high quality electronics tutorials. Those videos you mentioned really helped me through my post-bac work in microelectronics. Thanks for all your hard work and attention to detail. Much appreciated.

[Daklon]

I've been 3 days trying to understand how the different values for the resistors are choosen and how can I calculate them to have a defined gain. You explained it very clearly in this video, and with the other videos that you pointed I think I finally fully understand it. So thank you very much

[TheRadioShop]

A lot of times  I read similar notes like this in a book and find myself having to go back and read again and again.  Your tutorials and demonstration process makes this so much better to understand.  Very well thought out video approach. Thanks for sharing. Your knowledge is amazing.

[moshe]

i have watched 1000 videos on youtube, i know this video is old, but you are explaining the best by far from all others, so i had to say somthing, amazing teacher...

[johnnicolaou]

It is nice to finally find someone who explains electronics in a way I understand. Thanks for your hard work. Please keep it up.

[amanuelnigatu]

That what we call teaching!!! 4 or 5 classes with just 20 minutes.thank you sir

[ColossusEternum]

Bravo sir, I have been driving myself crazy with math, Ive been attempting to learn the hybrid and R(pi) models. But all these videos leave out simpler insights like the bias string to base current ratio. You are doing a great service to humanity with these videos, and I hope you keep making them

[troutrou]

Hi Alan,

I discovered your channel recently, 3 months or so. I watched each and every one of your old videos one by one, I am up to date now.
I have never commented before (I do give a thumb up to every one of them, though, obviously), but I thought I would this time, for a change ! ;-) I mean, as you said it took you quite some time to come up with this video, but the result is excellent and I do, like many others it seems, appreciate it immensely. So I hope that the recognition you get and deserve, will keep you motivated and that you will keep doing great stuff like this whenever you find the time.
Every second of your videos is pleasing to look at and listen to. I love every aspect of your videos. The technical content, the way you present it, your lovely hand drawn notes and schematics, your experiments, quick calculations to demonstrate the point... you act and talk like a proper engineer that you are, as well as a man of passion, a pleasing and efficient blend. I think that's why many electronics teachers here in France just aren't good... most of the time they actually don' t have ANY experience in professional electronics design (and not much passion in them either). They just study EE then go straight to teaching, zero "real world" professional experience ! :-/
I also studied EE in the UK as well, at Uni for 3 years (did a B.Eng there, 20 years ago), and the teachers also looked clueless and uninspiring, couldn't sense any trace of passion in them either. Was pretty depressing...

Anyway, enough rambling. Just wanted to comment at least once, to express my true appreciation for your contribution to EE education. Keep up the excellent work ! :-) The number of subscribers, 75K to date, is a good metric I think. This alone should convince you that your are doing something good and valuable here. Sure, EEVBlog is much bigger, nearly 500K subscribers, but I think this is largely due to, as I remember him confessing once, the fact that he is more (overall I mean) of an entertainer and show man, than a teacher. Your videos however target more those interested in the educational value that an experienced design engineer can bring. This obviously is a narrower audience. In this respect, I think 75K is a really strong number which I hope you appreciate as well.

Thanks again for the time and effort you put in all your videos :-)

Vincent Trouilliez, from across the pond.

[williamogilvie]

Very thorough presentation on CE amplifiers. Definitely the best on utube, and probably better than most university lectures on the subject.

[johndczerwinski]

Another great video! I've been researching information on BJT common-emitter amplifiers for over 2 weeks using several books. This is, by far, the most comprehensive series of videos on the subject. Thanks for taking the time to put this together

[carldavis]

I must really thank you. You are one of the few who bothers with the math in a demonstration. I have re-watched almost every one of your videos, most more than 3 times. However, I want you to understand, the math portion of your tutorials is what makes them great for me.

[microdrone]

I'm getting back to basics for an ongoing project, destined for modularity and miniaturization, the potentially tiny bipolar transistor circuitry is really important for these applications. W2AEW is by far one of the most useful and enjoyable sources for this really important subject matter, thanks dude!!
I'm a long time fan, and I am really thankful for your sense of detail and nice way of explaining things. Thanks to you I am a proud owner of 2 Tek 4 channel scopes, an old crt from ebay :) and a TBS1064. For what I'm doing they are more than sufficient, the latter being my basis for accurate measurements, and quick and easy to look at comparisons, thanks to the trace colors. Especially coupled with your expert advice and great quality video productions, I have lots of 'fill in the gaps' for my general knowledge in relevant areas. Cheers!!

[JamesAnderson-bzcg]

There are good teachers and bad teachers. You are one of the very best. I've been watching several of your videos. The knowledge that you hold and then make relatively easy to understand (certainly easier than other tutors) is first rate. I actually find myself understanding what you are saying because you teach it in such a great way. Theory and practical to show your workings is especially great instead of pure theory which can be mind boggling. I'm a visual learner predominantly and with you showing the electrons wobbling around on a scope is brilliant.
With excellent short cut methods that only a real engineer can pass onto a student is invaluable as a way of referencing quickly and easily to verify that the build or design is going in the right way without over complicating things too much. Its bite sized snippets of information like that, that make it more manageable to remember. As others have said and especially at my age (50) I find myself going back to reference books several time to read the theoretical text, which is very important, but very time consuming. Your time and huge efforts are very much appreciated. Your other videos pick up on much more theoretical detail which is also superb.
Please keep up the excellent work and thank you.

[parleyk]

Hi Allan I just wanted to say thank you for all the thought that goes into these videos. They are by far the most simple and informative videos on this subject. Im 15 and I’m learning electronics purely for the fun of it but even at such a young age I am still able to clearly understand these videos because of your simple and straight forward way of teaching. Thanks again.

[danielstimpson]

You are such a good teacher Alan. I just love the videos like this, they make the subject so understandable and enjoyable. If I had the time I could immerse myself in transistors. Many thanks for all your hard work putting these video together.

[davidmaruska]

Its been early 80's since I worked with these formulas, Great brush up!