The Class A amplifier - basics and simulation (1/2)
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- เผยแพร่เมื่อ 4 มี.ค. 2022
- #152 In this video I am looking at some of the main aspects regarding the Class A operation of amplifiers. I will check out how the gain of a transistor is not really fixed so to see why you need some way to stabilize the gain and then look at the various ways in which loads can be connected to the amplifier, and how this has an impact on efficiency.
Related videos:
Class A amplifier part 1 - • The Class A amplifier ...
Class A amplifier part 2 - • The Class A amplifier ...
Class B amplifier part 1 - • The Class B amplifier ...
Class B amplifier part 2a - • The Class B amplifier ...
Class B amplifier part 2b - • The Class B amplifier ...
Class C amplifier part 1 - • The RF Class C amplifi...
Class C amplifier part 2 - • The RF Class C amplifi...
Class D audio amplifier part 1 - • The Class D audio ampl...
Class D audio amplifier part 2 - • The Class D audio ampl...
Class D audio amplifier part 3 - • The Class D audio ampl...
Class D RF amplifier part 1 - • The Class D RF amplif...
Class D RF amplifier part 2 - • The Class D RF amplifi...
Used datasheets and further reading:
www.onsemi.com/pdf/datasheet/...
www.onsemi.com/pdf/datasheet/...
rfic.eecs.berkeley.edu/ee242/p...
www.qsl.net/va3iul/RF%20Power...
Special Thanks to all my supporters on Patreon! Especially @afiskon, Ralf B., Paul Pr. Richard and Jonathan Alvarado!
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![Gain block RF Amplifiers - Theory and Design [1/2]](http://i.ytimg.com/vi/8myFI-tmowo/mqdefault.jpg)
So good to listen to somebody who really knows electronics!
Excellent! You're opening new ways of thoughts to me... I didn't think of the possibilities of coils / transformers in the transistor collector line before.😊
Great work ...
I wonder why I didn't get the knowledge of your channel in my college days...
One of the best videos teaching about a certain topic I have ever seen, thanks alot!
Brilliant presentation, to the point, very clear language, no repetitions.
I know that it is not really necessary, but it would be interesting if those who cover transistor amplifiers would mention that if one goes into deeper details of the input and output impedance of the transistor amplifier, one finds that for a positive going signal there is a slight difference from the impedance for a negative going signals. This is due to the " diode " characteristics of emitter base junction,
Again well done in making this video.
👌👍would love 2 see this in a ''physical'' cense!! there's nothing better than having ''physical work'' experience!! I hope U examine ''MATLAB'/simulink''....good luck...
Excellent video. Can't wait for the next video...
A well designed class A amplifier has a smooth soft sweet sound especially when paired with a good quality well designed class A preamplifier good well designed speakers the sound can’t be beat for something so easy to build yourself.
Who cares if it may be bigger, heavier, generates a lot of heat, or only 20% to 40% efficient.
They are so easy and cheap to build yourself and sound better then anything you can buy in a big box store like Best Buy or other store.
"a good quality well designed class A preamplifier" hi this is exactly what i am looking for A good line preamp with gain of 2-3 max Do you have any sugestion ? i would need only a schematic
My feeling is that the preamp makes most of the sound
Just take a same power amp and listen to it when driven by a solid state preamp and a tube preamp ... a sea of difference And usually the tube preamp sounds more musical
Regards, gino
nonsense
Great video. You covered so many different configurations in a logical order, improving each time from the last.
If you don’t mind, where do you learn all the intricate details and different topologies? Especially for RF applications. Certain books?
Yeah, I'd like to know this as well...
Experimental Methods in Rf design, best book 100%
What do you think of EveryCircuit? How precise is it for real circuit prototyping? I mean the preciseness of the calculations made by it. I am talking about the ergonomics and design related preferences.
Honesty I never tried it. In general the "preciseness" of a simulation will have to do with how well the components are modeled...
Can it be made so the resistor on the collector side is inversely proportional to the input voltage resulting in an automatic gain control? And what structures need to be added so the input can be current instead of voltage?
Hello, and welcome back!
this is good :)
Great Video. My Suggestion on something New and Fresh in TH-cam; How about future videos on microcontrollers EMI susceptibility comparison / Challenge for example STM32 versus formal Atmel versus 6502 versus 8051 versus [option] automobile grade vs [option] military grade etc. in hostile environment with both Conducted and radiated interference whether it can run codes without hiccups? And then next next video on Shielding to improve.
Thank you so much for your Videos about RF! Im from Germany and the german community doesn´t upload a single video about RF-Amps. I have one question to ask, is there no calculation for the RF-Choke?
Greetings from Germany ! ✌
I like the video very helpful thank you for making it and as a thank you I suggest that you start taking a good mineral supplement especially one high in iron because you have a iron deficiency 🙈🙉🙊
❤️👍
I understand the first diagram on negative feedback (top left), and the maths of how (with high local gain) actual gain is determined by the negative feedback. I understand the low left circuit, setting negative feedback by a voltage divider built of 2 resistors.
But the leap to the lower right diagram is beyond me.
R(L) and R(E) do not seem to implement the same voltage divider as the previous circuit.
I'm happy that you're right, and the simulations back you up, but I don't understand *why* you're right.
The example was not supposed to derive one from the other, it was just similar circuits, sort of..
For the single transistor - common emitter amplifier one way of looking at it is as follows:
The voltage variation (input signal) on the base will be the same as in the voltage variation in the emitter ->emitter voltage follows the base voltage. So the voltage drop on the emitter resistor is the same as the input signal.
Now, maximum collector voltage swing + maximum emitter voltage swing is a constant (the supply voltage); since the same(approximately) current passes trough both emitter resistor and collector resistor, the ratio of collector voltage to emitter voltage is equal to resistors rations.
So now, input signal ratio to collector voltage (output signal) is equal to the 2 resistor ratio. Let me know if this makes sense.
class A amplifier series is great 👍.
but idk why some people say collector feedback biasing is superior compared to
voltage divider biasing?
I guess that is a different topics to cover - various bias methods. In general depending on the use case there is one method better than others - I still need to do a bit of digging on this though.
@@FesZElectronics hmm 👍
In a common emitter amplifier stage, the output voltage at the collector is an amplified and inverted copy of the input signal. Put simply, if you feed back some of that voltage to the base, you add in a small signal that opposes the input signal. The result will be that any tendency for the collector voltage to change will be opposed by the feedback voltage. That increases the stability of the collector bias point. It also tends to reduce the voltage gain and both the input and output impedances. Depending on what is most important to you, the effect of the negative feedback from collector to base will either be an overall advantage or disadvantage, but with good design, it can be superior to the straight voltage divider biasing.
Hi thank you very much indeed
After discovering your excellent channel i watched the tutorial video on LTSpice
I would like to carry out distortion analysis with LTSpice of some schematics of really basic audio preamps i have found around
But i get really strange distortion spectra ... maybe i am setting the parameters wrongly
Could you please make a specific video abouy how to perform the distortion analysis of this class A amplifier with LTSpice ?
Thank you very much indeed Kind regards, gino
I tried covering some of the aspects that affect the FFT analysis a while ago - like some parameters that can be set to get a cleaner result, maybe you will find this helpful - th-cam.com/video/rVAvW1Jh2AE/w-d-xo.html
@@FesZElectronics Hi thank you for the very kind and helpful advice
I am very ignorant in electronics but I am fascinated by this simulation sw
I would like to see the effects of changing parts in very simple line preamp schematics
i have one using only 2 bjts said to sound great Thanks a lot again kind regards gino
Great video but I can't seem to make sense of your efficiency calculations 10:41
you first calculate "case1voltage" and in the output equation you subtract case1voltage from itself?
Hi, please could you explain to me more in details why voltage output is 2*Vdd? Thanks
Hi,
I also had trouble with that statement. After some tedious calculation I discovered by chance the simple solution:
First, think about the DC analysis. Your collector will be (with an ideal inductor) at vdd. Thats one vdd.
Second, think about AC analysis. You are basically imposing a sine voltage over the inductor, that means (considering a sine wave) the voltage created by the coil will be at a max vdd.
You can of course get higher voltages for other scenarios, for example if you charge a large coil for a while (DC) and then apply a sine in a circuit with a ridiculous amount of gain.
Hope you find that helpful
Hello
Thank you
I went file class a to LTspice
I've copied your first circuit in ltspice. From what I can tell, its exact in all the details as timestamp 9:25 except for the measurement lines. When I run the simulation, my output waveform has a flat spot around 9.9995V for about .05us. The peaks in both directions also do not look as smooth as your waveform. What am I doing wrong that is causing this?
It might be related to the transistor model that you are using; maybe you can try a default model that is present in LTspice to see if the same thing occurs. I think the model I used was from the onsemi website.
@@FesZElectronics Thanks very much for responding. I did some more research, watched a few more of your videos. I came back to this and used a 2n3904 and was able to get a functioning circuit. Grasping the details has been a challenge. Going back through some of your videos definitely helped. I look forward to watching more. Thank you very very much!
can use for gnss LNA operation?
Hi ! For that purpose, you need to consider at least two main issues: 1/ the frequency of operation, for GPS it's about 1500 Mhz... and 2/ a low noise factor device (NoiseFactor
Why do we use inductor instead of resistor in collector terminal in this ?
An inductor is a reactive component - it stores and releases energy; in contrast a resistor only dissipates energy. Using inductors is far more energy efficient, if you can practically use a large enough value.
@@FesZElectronics Thank you
where the iconic, the builders backsound mr. Fesz?
Amplification is a misnomer. What's going on is that a large constant voltage source's current is regulated by a small fluctuating voltage. The ratio between these two is considered to be the amplification. The input signal itself is not amplified, it only regulates a larger signal.
Wow, what's next? Transistors don't have actual gates in them that let the electrons pass through like bouncers at a club?
@@AuxiliaryPanther My explanation of controlling a larger source with a smaller source makes it easier to understand exactly what's going on. My professors never made this clear. They professed instead of taught. So I thought I could possibly help somebody who had the same shitty lessons.
I'd be interested though to hear your bouncer analogy. It never hurts to hear another explanation.
@@TheAnimeist oh, that was the whole analogy. My whole reply was also a joke. I'm sorry you didn't have a good textbook to read in support of your education.
@@AuxiliaryPanther LOL, sometimes things get lost in an internet conversation. Especially good sarcasm. Have a good day!
Mansplaining.
You would never have 100u coupling capacitor for and unknown input frequency. You would never have an input impedance of 1M for a driver signal. Just a bad demonstration.
😃😄😁😆😅 5 Smiles and power regulations sweet induction 🤣. No seriously way better to volt regulator set up?????.
Dude you need to get some sleep.
Slow down 👎
The's amplifier class (C) not (A)
@Google user yes, because the A-class amplifier doesn't have an inductor, it has a resistance connected to pin collector
@Google userWell, I don't know what to say. This science has nothing fixed and it's constantly evolving. Strange things always strike me.
@Google user Definitely
@Google user Can we communicate on Facebook?
@Google user hahaha You spend your time wisely my friend, Facebook is a waste of time