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- čas přidán 18. 08. 2024
- Back to basics introduction to the differential amplifier, aka the diff-pair, long-tailed pair, emitter coupled pair, etc. The basic operation of the circuit is presented, along with a simple mechanical simulation. Also, how the addition of current sources and mirrors can be used to address some of the performance issues, and begin to form the rudimentary beginnings of an op amp. This is the follow-up video from "teaser" video published earlier.
Teaser video:
• #192: Preview of next ...
Video note pages:
www.qsl.net/w2a...
Could you please live forever? All generations would appreciate your high quality teaching skills. All the best!
I love it when I search for something like this on CZcams and yours' is the first video that comes up. Please don't ever stop making back to basics videos. It's hands down my favourite series from you. Thanks for making these.
I love that too!
Same here
I swear on everything, that you are the best CZcamsr, Teacher or Professor in this World who has explained the Differential Amplifier thank you from my heart forever
I'm a retired electronic engineer, but still find these videos highly interesting. The clarity with which you explain things is fantastic. Sadly, such videos were not around when I studied for my degree, but today's budding electronic engineers have a real advantage with the availability of your videos.
Your videos, especially the back to basics ones, are an invaluable learning resource. I've heard it been said that a great teacher inspires, you certainly do!
It's hard to believe that a single video could be so incredibly enlightening. Hands down, the best to be found anywhere. Deepest thanks!
Tremendous. Thanks for such greatness. Way back, it took me a while to understand how the current mirror applied to the differential amplifier. Taking the single ended output from the collector of only one transistor means throwing away the gain of the other. To add the gain of the other side in, you would need to invert and add. The current mirror is simply a inverting unity gain current amplifier, adding an inverted copy of the other side to the output. I love the neatly drawn notes and the rusty clipboard. Looks like a yellow Sylvania tube box on the left. I look forward to more.
I love the mechanical circuit demonstrator! Great work, Alan. I had never thought about trading double-ended output for higher gain as you showed with the current mirror.
Thanks Ben, the demonstrator came to me when I started to think out how to describe/visualize the operation using a see-saw analogy.
Applied Science i see you everywhere haha
The very best explanation of a difference amplifier. I saw this video and am hooked to this channel. Thanks for taking time to produce videos like this.
I hope you enjoy my other videos as much as you liked this one.
Mechanical model!!! What a nice way of describing the concept! Very creative way, I'm impressed
This is a masterpiece that needs to be used by every single electronics or engineering school in the world and neighboring planets (and have every school donate another half a million dollar piece of equipment to your lab :)). I remember back in the day when I was the best kid in class but still went through a state of messed-up-ism (pardon my advanced technical jargon) till I used some stability theory and calculus math to get the common mode vs differential mode and CMRR stuff. Those videos need to be considered a national (and rural places of the world) treasure. I can't find words to thank you enough for the effort, so I'll try to do more than words.
The best explanation of long-tailed pair ever. Thank you.
W2AEW is an awesome teacher. He has cleared up so many mysteries that I have encountered during my electronics studies.
You gotta LOVE this guy.
This is something I am pretty familiar with, but the way it was explained was just georgeous!
Sir, you are the best when it comes to integrating theoretical knowledge with practical applications. Thanks for all of your videos
Always good to see what I already know explained in an excellent way.
Finally I managed to understand how a differential amplifier works. Thanks. Please if you can, do more "Back to Basics" videos you are making many people happy. You have a gift to spread knowledge. Thanks a lot.
I went to a pretty good school. I gauge this by the technicians and engineers that I have met in the field that attended my school compared to other schools. Also I gauge this by the fact that I always seem to end up as lead technician or lead engineer.
In all honesty though, I think I would have been a much better professional if I had teachers like you, Derek Banas and Dave Jones(The Crazy Aussie). Of course I cannot forget that the great Forrest M, Mins III.
You guys are fantastic. Not only do you cover complex subjects, but you do so in such a way so that a student can instantly see the uses for certain circuits.
I applaud you all.
Thank you very much! I cut my teeth on the Forrest Mims Notebook Series in the 70's - I learned so much from them. It's no accident that my style tends to mimic his - I try to teach/tutor the way that he taught me through his books. I'm honored to know that you put me in the same category.
MrLRankin2 This dude actually explains stuff in a good way; Dave Jones *used* to do that stuff. Today he's a sellout, caring more for cashing in on the viewers than actually do the stuff that brought him where he's now. w2aew any day for me
Another great video. I've been watching your videos for a while now, and find myself waiting for the next. I don't usually comment or have anything to say but I now feel compelled to thank you for the pleasure and understanding you have provided me since you started. You have such clear exposition, no wasted detail, and great delivery. You have a talent for teaching. I don't know how much time you put into these videos but they are all marvels of succinct production. Despite knowing the material already I always enjoy them. Thanks again.
Thank you for the nice comments. The videos do take quite a bit of time to produce, on the order of 10:1 or more in time. In other words, each minute of video represents 10 minutes or more of time.
***** I have made some videos of fumbling and trying to figure things out and failing. Not popular. That is not what people want to see.
Yet you make it look easy. Which is not the full truth.
HaHa - Show Business - is like that.
Thank you so much! This video really helped me put together all the *practical* aspects of differential amplifiers that university somehow completely muddles up behind the math. Couldn't have asked for a better demo, visualization, and explanation. You're an engineering student's miracle.
I love the practical perspective of your explanations and the way you build up the circuit step by step.
Putting visual emphasis on the circuit drawings and measured values rather than the actual breadboard was a good choice as the latter serves no information other than proofing the circuit is real.
I know all this - or rather perhaps I did know at one time - but really your explanations are the best. Last time I learned was from the tektronix training manuals on diff amps which was pretty pure mathematical model derivation and not at an intuitive level. Thank you for doing this and please keep going making more at this circuit building block level. I can wire up anything digital or high speed easily - but "simple" circuits like this I always find a need to refresh on it's basic workings. The next generation of EE's needs to not rely on only arduino's, 555's and such to build things!
Really really really really thank you so much for this video, sometimes im afraid of asking some doubts I have in class because nobody says anything and they seem to get all so easily. Grazie mille.
I'm happy to hear that this video helped you!
What an amazing explanation with physical example. Absolutely love it
Thank you or the video Alan. Your prep is time consuming and very professional and much appreciated. Your explanations are easy to follow. LTP's are the more complex of Phase Inverters used in the analog amplifier world, and I got a lot out of your explanation.
Video has been around for awhile, but still relevant none-the-less... Thanks, nice to review some basic material and have you do the thinking so we don’t have to. Started out 98/2 analog, the last decade has been 98/2 digital for me, so it’s nice to break the rust off...
Oh wow. You've made some good videos but this was something else. I don't think I've ever learned so much from one video before.
Once again, Alan, a nicely demonstrated and explained talk. I could have used this video when I was studying electrons a decade or more ago! You put a lot of work into these demos and I for one really appreciate this. Thanks Alan.
I had to watch this video series few times. But when finally it clicks, the feeling is incredible. Thank you so much. Very grateful for the amazing videos.
One of the best lectures I have come across on differential transistor circuits leading to op-amp design. Excellent work!
Most of the time i don't understand completely because I dont know enough. But i still watch over and over, go back study a little, and re watch. Till i understand some of it at least. I wish i had an opportunity to study all of this.
Thank you!!! I have been trying to read articles and notes ... watched a couple of videos ... and finally found your video .. and finally I understand quite clearly on diff pair amplifiers ... I will definitely start to watch more of you videos and will follow your lessons! Thanks a million!
Never seen a clear explanations of electronics like that.thanks a million of times Alan.
Excellent explanation, thank you very much for taking the time to do this. A great refresher after not looking at long tailed pairs for many years.
There are two unique points I love about this video.
1) the variation of diode operation due to increase in temperature.
2) Your mechanical simulator !
Thanks for the crazy video !!
Wish I could work with you.. Thanks again, much appreciated !
+Deb Mullick Thank you, I'm glad you enjoyed it.
+w2aew So we have current source at top and current mirror too? Don't both force a certain current quantity? Also, how does the voltage at the ouput when using the current mirror sit "between" the voltage at the two emitters?
In that last example, the gain is very, very high. Output voltage is mid-swing only when current exactly match.
You do very good work..... and plenty of it.....I taught electronics for about 4 years and it's one thing to know a subject and quite another to be able to present and teach it effectively....you obviously like to teach.....I admire and appreciate your efforts.....rgds, AK5XX La Grange Texas
What a fantastic video...one of my favourites (and I'm a big fan !). I love that you led us step-by-step to an explanation (and, of course, a demonstration) of how an op amp works: that was an unexpected surprise. Thank you - I enjoyed every second of it.
I really enjoy designing circuits with discreet transistors, to get to understand electronics at a deeper level. Your explanations on the steps taken to form the basis of an opamp, is superb. Thankyou for the work you do to present very imformative lectures on circuit design.
Hi! I just wanted to say I love your videos and that I really would like to have more of these back to basics videos. I find it much easier to understand a concept if I have a lot of videos on the same concept, but from different creators - everyone churns out some unique features. Although, you are simply the best! What I'm trying to say is that: don't get out off by the fact that others have done videos on the exact same subject, like really simple stuff, cause it's useful anyways and you'll still be better than them! Thanks again!
Thank you for your nice comments! I will continue to provide a mix of "basics" and advanced topics for my videos...
w2aew Great, and thank you once again!
Yes, stay motivated. You are a great tutor. From your vids, and some others, and some independent fiddling I am starting to recognize some of the building-block circuits: here and there.
Cheers,
Mark
******************
Incredible videos with such great demonstrations! Thank you
God bless ya! You know that old phase "use it or loose it". Haven't done this level of theroy since college. Great review of diff amps and I really appreciate all your videos. Keep up the good work!
73s
KB8NIV
The subtle point is in the basic diff amp the shared resistor current will change with increasing differential voltage at the input. This will affect the differential output. With the current source replacing the Emitter resistor the current in effect can't change. It is fixed with the high impedance to ground . The output resulting from the differential input is then wholly down to the change in Vce.
Great explanation of the diff amplifier with very helpful test setup for demonstration. Thank you so much fpor your work!
Beautiful explanation of why current sources / sinks are used in differential amplifiers.
Thank you for preparing and posting this video.
Your mechanical simulator of a diff amp was brilliant. As someone who tends to "learn visually", that gave me quite the thrill.
Ryan Jensen I tend to visualize how circuits work by picturing voltage as "elevation", just as they're viewed on an oscilloscope - so this mechanical analog seemed to fit.
beautiful job on an important circuit concept!! the mechanical device is very useful. and the gentle merge into the op amp concept. thank you. this one is worth a couple of watches.
I've been blowing through your videos but I must say this video blew me away!!! Watching your videos just seem to click
I loved the mechanical circuit demonstrator!
I did too.
🙋🙋🙋
Yea, it was great!
I love your style Alan, I think back to 1984 and study at electronics voc tech. I am always great full for your videos.
Wow! This is great. You are so good at this and know so much!
Everything just clicked together, very well explained, thank you.
Yet another example of why oh why weren't my teachers like you? Great video, as always it's a pleasure to watch!
Salute for mechanical demonstrator. Respect. Hats off.
You can demonstrate identicality with dual transistors in one package like 2SC1583.
Cheers from Indonesia
Really enjoyed the video and it's progression through alternative circuits to get better performance.Keep up the great work! Explained very well.
Thank you for the valuable contribution ! Even the mechanical simulator alone is something that will be very useful in understanding differential amplifiers. I am happy I came across this video.
Excellent explanation, visual aides, and demos. Thank you!
I not only enjoyed the video, I loved it! Thank you so much, I am a constant follower of your videos and they are all great. Very good insight from them. Please keep going on!
Thank you!
Excellent, excellent insight into the inner working of the differential amplifier.
Excellent explanation. Simple and to the point!
Thanks for taking the time to go over this in detail. I found it very helpful.
Great instructional video. I've been around a long time but I actually never have seen a mechanical diff amp ! Thank you making these videos.
This helps me a lot understand the diff pair.
i should have had such teachers like you at my technical schooling - Thank you very much and 73
Great job as always. Clear as mud. You make the material easy to understand. Keep making great video. Thank you for your time and effort...
Thanks for taking the time to explain this. I can appreciate the amount of effort that went into this.
Excellent instructional videos! Thanks for taking the time to do them. I have turned many young hams on to your clips. Very well done!
Thank you so much for explaining this matter in such a clear way. Big fan of your videos!
Fantastic. I like the "mechanical" display, neat idea. Thanks for the videos.
Love the AlanSpice simulator.
Great stuff Alan,
Your ability to draw good clear schematics and explain circuit function is amazing.
You should definitely keep all your drawings and consider publishing a book someday.
I would love to see a back to basics that covers "capacitors" and how and when and why to choose a given "type". ex. poly, ceramic, tantalum, silver mica. and what are each of their favorable and unfavorable characteristics for a given application. Digital electronics, RF, analog, audio, high frequency, etc.
thanks and keep up the good work.
Dwight
N7KBC
Great idea, Dwight, on a capacitor video. I'll definitely add that to my list of future video topics.
Another deluxe video. I tried searching your videos while trying to replace an opamp to drive the pass transistors in a PSU ( discrete components had higher voltage ratings than most opamps ). It cleared some things up, thanks :)
Keep it analog, w2aew! :)
Alan, excellent video! It is great to revisit old knowledge stored in the back of my brain a long time ago... :)
I can't really understand one thing: how can someone gives thumbs down to your back to basics videos?!? The information is there, your english is very clear and the circuits and examples are spot on. Perhaps people were thinking this covered some other subject, despite the title and description? Oh, well...
Maybe someone wanted a 2 minute video - who knows. If someone has a legitimate complaint, I would hope that they'd leave a comment so that I can learn from that. Anyway, thank you for your nice comments!
@@w2aew My observation is that on most good CZcams videos, I see somewhere around 1% thumbs down, regardless. At the moment (four years on!) this one is currently at 8/2200, which is 0.275% -- tiny!
All your vids are great, and so helpful, but this one was definitely on the Top Ten list. Bless you and yours.
on daily basis you are solving my years long confusions. Thank a lot. -/\-, from India.
Surely one thumbs down frm someone will because either he doesn't understand English or the subject itself.
Amazing explanation. Can't ask more than this. Keep doing the good work and thanks, I have a viva today and genuinely, the concept is crystal clear now.
Really surprised by the mechanical demo and by the voltage change by touching the transistor!!! Excellent video!!!!!
Very good presentation. Direct and to the point. I am trying to debug/improve a vertical amplifier circuit for a oscilloscope project from Radio Electronics April, May 1980 (Daniel Metzger & Dennis Perry). I have matched the the transistors as close as I can, but seems to be very difficult to calibrate, and difficult to set the DC balance. The vertical output looks distorted and unstable. I have the article.
Great demonstration. I'm looking forward to watching more of your videos.
Another excellent video, thanks for sharing.
Awesome explanation.
Another belter Alan, thanks, wish you had been teaching at my college! Time to hit the breadboard and play!
Nice explanation and neat demonstrator too.
Thanks. Your channel provides much valuable information. Thumbs up.
Watch the two videos part 1 and part 2 listed below which begin with descriptions of differential-mode and common-mode currents with animations. A basic scheme of a differential amplifier is introduced with the description of the analogous operation of a U-tube manometer. This is followed with a description of enhancements to the basic scheme of the amplifier to make it suppress common-mode output voltages more efficiently.
The Basic action of a Differential Amplifier- the heart of the Opamp.
Part 1 of 2
czcams.com/video/uggOykLShMU/video.html
Part 2 of 2
czcams.com/video/jLJAYyap5WA/video.html
I always feel like thanking you after every video i watch. Thankyou! Amazing as usual!
+Adil Malim I thank *you* for watching and appreciating my videos!
+w2aew Don't we have emitter degeneration due to Re at the emitter in the tail?
+Yueeiuyoo depends how you look at it. if u look at the LPT as 2 CE amps then yes.
+Yueeiuyoo Only for common mode signals. For differential signals, the low impedance of the coupled emitters effectively negates the degenerative feedback.
@@w2aewDo the diff signals only see the re from the transistors? doesn't the common mode degeneration affect the signal swing available at the output?
This a a great video!!
Really enjoyed it!
I loved that mechanical simulator!!
The "Back to basics" series is GREAT!
Kind regards!!
Generally I tend to watch the video's even if I don't really understand what's going on and this video was no exception... I found myself watching till the end wondering why I would need to know about this??? Then at the very end I'm told that this circuit is basically the beginning to a discreet op amp... Wow... This is the first time that I have ever watched an episode of electronics who done it LoL... Had me trying to guess all the way till I was like oh ok that's what it's for Hahahahahaha.... I think that now I have to re watch the video now that I have an idea of what this circuit could be used for.... Actually I kinda like the idea of a discreet op amp... Might have to look around for a video on that topic...
Anyway... Great video by an awesome teacher..
Interesting, gotta check back on this one!
Very helpful video. Thank you!
teachers like you make me want to be a teacher.
Thank you so much for this video. I understood so much better from your video than a book.
Can you make a video on darlington pairs and sziklai pair? I have recently started experimenting with the obscure sziklai pair and it performs REALLY well when used as a voltage follower. The turn on voltage in common collector mode is ~0.6V higher that the drop across the load, and used in common emitter mode, just 0.6V from ground. I have made a really simple voltage regulator with it in LTspice, and it seems to have really good load and line regulation.
trying to make a watt meter out of a long tailed pair here, very helpful vid, thanks
Wow this video has been so enlightening. thank you. How can you take the output from a differential amp? How can you take a single ended output rather than dual output.
Yes, you can take a single-ended output (from either side) - this is actually what is typically done inside an op amp.
Very interesting to see that a simple single transistor current source to make such a dramatic difference/improvement.
You are a great teacher.. Please keep them coming
It cannot be better!! Keep doing these great videos!
Awesome tutorial !...cheers.
What a superb tutorial, Alan, you rock! Thank you!
Hey Alan,
This is a great tutorial on differential amplifiers. I've always found that most profs simply throw the math at you and expect you to understand how it all works based on the equations. While the mathematical analysis is accurate, I find it does nothing for intuitive understanding (which I find is key). That is why I love you videos. They explain how the circuits work rather than just throwing math at you. Thank-you!
For fun, I am in the midst of designing my own function generator and building a wideband amplifier to try to get a decent 20Mhz square wave using discrete components. I am currently designing it with a 2 stage cascode design, but am finding that I am losing too much headroom and was wondering about the frequency response of a differential amplifier and the pros and cons of using a diff amp as opposed to a cascode?
For bandwidth, you're going to be better off with the cascode I think. It alleviates the most significant BW limiting factor of the CE amp and diff amp - the Miller Effect.