60. Op Amp Basics Part 4; Impedance, Bandwidth, and Gain

This time around we look at the relationship between amplification and bandwidth, the amount of input and output impedance in inverting and non-inverting configurations, the special case of the voltage follower (buffer), and the phase relationship between input and output. The bandwidth and gain relationship are explored in bench test.

[@jeevankumard1069]

Such a great video.. precise explanation ... Thumbs up 👍

[@ohmedarick1]

Thanks again for another great video...

[@TheOffsetVolt]

Thank s for all of the comments. I'm glad the videos were useful and am grateful you watch them.

[@electronicssciencebysherry5050]

It's incredible

[@joparkcat]

thanks

[@alibehrouz9833]

nice job man such a nuce music you used for introducing topic

[@yestersound7090]

Hello, another great video! One of the best electronics tutorials here on YT! I'm working hard on my first ever project - phono stage based around a vintage discrete op amp from a 70's console. What about making a video on basic design principles of small signal audio related circuits? Something that could give a guideline on how to even approach a small basic design of a complete amp. Greetings from Scotland!!

[@TheOffsetVolt]

Thank you. If it's an op amp from the 70's, there are a few improved devices that should work. The 741 predates your system. I will look into doing something like this in the future. And greetings from Texas!

[@user-lj3oz5wk1f]

I truly enjoy your videos & it helps me to learn a lot. while calculating the phase difference using scope division method demonstrated , measurement is perfect for Inverting/Non-inverting amplifier when I have the gain in place . But the phase measurement using scope division doesn't reflect the true phase shift in DEGREE when I am measuring at 3dB point for BUFFER . Kindly help me know what could have gone wrong in my measurement. I am using uA741.

[@fernandohood5542]

I want to design a two stage amplifier operating at 1mhz with a gain of 40db. Any ideas?

[@w9fgh]

How can the Voltage Follower possibly work? The output is grounded.

[@poincareelcartografo5406]

Thank you so much for posting these videos!! I have a question: In an Inverting op amp, which is the feedback parameter B? According to this source ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-071j-introduction-to-electronics-signals-and-measurement-spring-2006/lecture-notes/22_op_amps1.pdf (p. 10), is Ri/Rf (which I think is the right answer). But according to other sources, it seems to be Ri/(Ri+Rf), like in the Non-inverting topology. Which is the right answer?

[@Jnglfvr]

At 19:19 it's not clear to me how you are extrapolating the change in open loop gain with frequency with the change in closed loop bandwidth. The two are not directly related. The change of open loop gain with frequency follows -20 dB per decade loss. The change in closed loop bandwidth is unrelated to frequency but is linearly related to attenuation factor (Ri/(Ri + Rf)). You seem to be implying that the closed loop bandwidth at some level of gain is the same is the same as the open loop bandwidth at that same level of gain.