Transistor Miller Effect Neutralization

[@AllElectronicsChannel]

Support the channel becoming a Patron patreon.com/allelectronics

[@azimyth1542]

This is the best explination of the miller effect on youtube

[@AllElectronicsChannel]

Thank you!!

[@fabiotrevisan8922]

That's an outstanding explanation of the Miller effect, its nasty detrimental effect on common emitter amplifier voltage gain stages, and a very interesting and rather obscure method of counteracting its effects without resorting to the usual method of cascoding. This technique, as you implemented, was used in the tubes era as you mentioned, but didn't find much adoption in the transistor era due to the effect of CB capacitance modulation (by the changing collector voltage), which doesn't happen on valves. Tektronix found a way to model that modulation and create a similar inductor arrangement they called T-coil. It was introduced in vast amounts in the Tek454A 150MHz fully transistorized oscilloscope (The fastest ever achieved without use of ICs). There's a chapter of the book "The Art and Science of Analog Circuit Design", edited by the analog designer guru Jim Williams (R.I.P.) that covers that particular trickery). I'm very impressed by the video and if I may comment your speech resembles a Brazilian. Not that your English is not good, but me, being a Brazilian myself, recognize some of the Brazilian accent. Congratulations!

[@AllElectronicsChannel]

Thank you so much for your comment! I have the book!! Probably we need to make a video about the T coil, amazing technique and pretty obscure. Welcome to the channel!

[@enriquevarela8616]

Precioso video , podrías explicar los diferentes tipos de realimentación ,serie , paralelo etc

[@canadian_spaceman]

Great video, great explanation!

[@_wave64_]

I wonder - can you implement the phase inversion needed for the neutralization, by a 1/2 wave transmission line between the collector and the base?

[@AllElectronicsChannel]

Only for a single frequency..

[@johnaweiss]

That's amazing! Could we state a general rule for many circuits? (not just for this BJT circuit). "Capacitively-coupled negative feedback can neutralize capacitively-coupled positive feedback, including parasitic or intrinsic capacitance, restoring upper bandwidth."

[@AllElectronicsChannel]

Yep!

[@kostiaspongo]

Good video, great job. Greetings from Spain.

[@AllElectronicsChannel]

Thanks!! 😁😁

[@buffplums]

Excellent tutorial mate.

[@AllElectronicsChannel]

Thank you!

[@juanalfaro8784]

What is this setup or technique called? I need to know more about this, it works for me but for some strange reason it only goes up to 130MHz, I already tried with other ferrites, more or less turns on the ferrite, transistors up to 6GHz, but I still can't exceed 130MHz.

[@sersheva]

Could you please explain the dot notation in the feedback circuit? You said that B is inverted but the dot is in phase with the A primary coil. I understand that if the input signal goes up, A dot goes down so B dot goes down and it wouldn't be contributing to the input signal, that is confusing me a lot. Thank you in advance!

[@AllElectronicsChannel]

It was drawed wrong!!

[@sersheva]

@@AllElectronicsChannel hahaha thank you, I feel relieved now

[@like_cabezon3810]

¿This could be the reason why my lc colpitts oscillator stops working at a freq around 6 or 8 Mhz? I think that also could be of the parasitic capacitances of the breadboard or the design of the amplifier because I read that if your amplifier has a lot of gain it will cost you lost in bandwith but i´m not sure of that last thing. For the amplifier i´m using a 2n2222 with 1mA collector-emiter current 12V VCC and 5 volt drop in collector- emmiter and I am taking the output from the collector. What you suggest to me to go to greater frequencies with this lc? Thanks for your videos I learn a lot.

[@AllElectronicsChannel]

Hello! It can be, but for higher frequencies, like 100MHz. At these higher frequencies, I recommend you to use common-base topologies, that don't suffer from miller effect. For at 2n2222 in a protoboard I have made 40MHz colpitts without any problem. Did you bypass the DC supply with good polyester capacitors near the oscillator? It's really important to have good supply bypass. Follow me on Instagram @allelectronicsgr and send me a picture and the schematic, so I can help you better!

[@fredflintstone8048]

Just subbed to the channel.. Good explanation. Thanks for sharing this.

[@AllElectronicsChannel]

Welcome!

[@researchandbuild1751]

Wouldn't this essentially be increasing the input impedance of the amplifier? It seems like the reason the signal drops in the non neutralized is because the impedance drops because the input capacitance drains off some of the gain. The feedback bootstrap raises the input impedance to be more flat...

[@AllElectronicsChannel]

Exactly!

[@researchandbuild1751]

@@AllElectronicsChannel Really enjoy your videos! You make smith chart easy to understand, thank you!

[@AllElectronicsChannel]

Welcome!

[@andrewandrosow4797]

Hello!It`s a good video vith explainations! I want to design a wideband RF push-pull mosfer power amp. Can I use this approach in a mosfet wideband power amplifier? For examle from 1 to 30MHz. Is this amplifier stable enough? I mean poor stability like in an old regen tube AM reciever - there any change of temperature/voltage led to autogeneration)))

[@AllElectronicsChannel]

Hello, thank you! You can use it, but as you said, you need to test much more for stability... I think that for the bandwidth you are interested, this technique is not needed. 1 to30MHz seems better to only use negative feedback to stabilize the gain!

[@SureshKumar-nk2ok]

sir coil winding details of B dot and A dots ,thank u for video regards

[@AllElectronicsChannel]

Thanks, I don't remember exactly. Probably three of four loops in a small toroidal core.

[@lucasangonesi8485]

show de bola, brigadão

[@AllElectronicsChannel]

👍👍👍

[@kabandajamir9844]

So nice

[@AllElectronicsChannel]

Thank you!

[@rubenhidalgocarrillo]

Good video.

[@AllElectronicsChannel]

Thank you, man!

[@garydion]

This is a fantastic explanation of the Miller effect and a way to neutralize it! I'm trying to follow the dot convention on the transformer in the drawing though. Shouldn't the dot on the left be on the bottom, so it inverts? Wait... okay, just now I noticed you linked to your article with images showing the dot moved to the lower side. I want my five minutes back! (Just kidding!)

[@AllElectronicsChannel]

You got me 🙃🙃 !! Hahaha Thank you for watching