55. Differential Amplifiers

This video presents the basics of differential amplifiers and acts as a stepping stone to op amps. We cover single ended operation, double ended operation, common mode rejection, differential gain, and input resistance. A circuit will be analyzed and then tested.

[@aerofart]

Mr Offset Volt, I enjoy (and benefit from) your videos tremendously. So much so on fact, that I’m on round two (sometimes round three) of watching them. Your methodical and disciplined approach to analyzing and describing circuit behavior and making a subject that is undoubtedly far more complex accessible to those of us who don’t have a degree in EE is by far the most comprehensive and enjoyable way of covering the subject that I’ve seen on TH-cam. THANK YOU for taking the time and making the effort to do so. Every time I watch your videos I come away from the experience with a sense of confidence that I now understand the material.
Your channel is a treasure and your efforts are laudable. I hope you will continue to be an asset to the community and look forward to many more of your EXCELLENT videos. Thanks again.

[@electronicsexplained287]

Saying just amazing is just not enough! Really well explained thanks a million

[@BrainBlister]

I’m interested in the current source you added. Could you make a video about current sources and mirrors. I see them used in circuits in place of resistors. Its not clear to me how to calculate what current to set to mimic a high value resistor. to get a specific resistance out of the current source.

[@BrainBlister]

How would you set the impedance of the constant current source? do you just need to rely on the transistors characteristics? Thay seems a bit of a gamble when building many devices that need the higher impedance. Would you need to just test a bunch of transistors and pick the desired ones?
Thank you for the great videos.

[@Iosens]

Coming in late.. just discovered and subscribed.
At 52.51, shouldn't RE1 be in the equation, too? It will not make a big difference but since you are calculating everything else exactly... Or is there something I miss?

[@TheOffsetVolt]

Since it's a constant current source, RE1 is common to both sides - it's the little variations on pot that from one side to the other that we have to account for. Hope that helps. Thanks for subscribing!

[@ricomajestic]

Why is the current through the collector, Ic, the same as the current through the emitter, Ie? Also what determines the current through Re - is it just the value of Re, and Vee -0.7V? Anything else?

[@TheOffsetVolt]

Ie and Ic are pretty much identical when Beta is equal to or greater than 100 which these transistors have in spades. Go to about the 20 minute mark and you can see how the current was calculated. Thanks for watching.

[@world52]

where do we see output of differential amplifier output ???

[@bigbread9000000]

I would have liked to have seen you take it a step further and put in a active load

[@andreaskonomis3]

47:40 "Well, there's no such animal as a 4.81k resistor" hahahhahahhah

[@anishbangar1934]

The starting 😂👍👍😍😍

[@rezatayebi4731]

Good

[@POLMAZURKA]

freq===?