How do we convert imperfect passive circuits into op-amp inverting circuits with negative feedback? What does the op-amp really do in these circuits?

08 August 2013 13 3K Report

Once we made various virtual “elements” as follows:

* ammeter with zero internal resistance

https://www.researchgate.net/post/How_do_we_improve_the_real_ammeter_How_do_we_create_an_almost_ideal_ammeter_What_does_the_op-amp_really_do_in_the_circuit_of_an_op-amp_ammeter2

* “resistor” with zero resistance

https://www.researchgate.net/post/Is_there_any_connection_between_the_humble_resistor_and_the_transimpedance_amplifier_What_does_the_op-amp_really_do_in_this_electronic_circuit?

* “capacitor” with infinite capacitance (as regards the time behavior)

https://www.researchgate.net/post/Can_we_virtually_increase_the_capacitance_up_to_infinity_How_do_we_make_such_virtual_capacitors_Have_they_the_same_properties_as_real_capacitors?

* “diode” with zero voltage threshold, etc.,

https://www.researchgate.net/post/Can_we_virtually_decrease_the_forward_voltage_drop_across_a_diode_up_to_zero_How_do_we_make_such_virtual_ideal_diodes_with_zero_voltage_threshold?

and we guess that maybe, we can make many other virtual elements... we begin realizing that all they are based on the same general idea – “voltage compensation”

http://en.wikibooks.org/wiki/Circuit_Idea/Voltage_Compensation

The idea is extremely simple and intuitive and although it is realized by Miller in electronics

http://en.wikipedia.org/wiki/Talk:Miller_effect#How_to_modify_impedance

http://en.wikipedia.org/wiki/Miller_theorem

we can see it all around us... As for me, I realized this great circuit idea in the early 90's

http://en.wikipedia.org/wiki/Talk:Miller_theorem

https://www.researchgate.net/publication/254864969_How_I_Revealed_the_Secret_of_Parallel_Negative_Feedback_Circuits_(a_circuit_story)

It is wonderful to see the same common idea behind many seemingly different circuit solutions, “to see the forest for the trees”! And it is so funny to see how others explore and remember hundreds of particular circuits but you – only one general... since for you they all look like the same... because you know the general idea on which all they are built... you have the key...

Well, if it is such a great idea, let us express it in one sentence: “We can modify the IV properties of elements by adding an additional proportional voltage in series to the elements.”

I have implemented this concept in a more attractive manner in the animated Flash movie below:

http://www.circuit-fantasia.com/collections/tools/pnfb-builder.html

That is all! Cyril

Data How I Revealed the Secret of Parallel Negative Feedback Circ...

Cyril Mechkov

I just can not believe that there is no interest (no answers, only 77 views) in the most powerful idea in circuitry, especially in circuits with operational amplifiers! In my opinion, more than 80% of them are circuits with negative feedback, and most of them are inverting circuits that are based on this powerful... brilliant circuit idea!

Just write "op-amp inverting amplifier" in the Google window and it will show more than 320,000 pages

https://www.google.com/#q=op-amp+inverting+amplifier&safe=off

or "op-amp inverting integrator" and you will see more than 70,000 pages

https://www.google.com/#q=op-amp+inverting+integrator&safe=off

I wonder if there are people here in ResearchGate regarding the practical circuits or only scientists theorists?

Cyril Mechkov

To awaken your interest (respectively of your students:), here are some of the most popular op-amp circuits based on this great circuit idea:

Cyril Mechkov

Prof. Subramanyam, thanks for the encouragement! All we need it to continue these so interesting discussions about circuit secrets... It would be great if each of us add at least one circuit to this collection that is based on this great idea...

Cyril Mechkov

Oh my God, I forgot to show the most "elegant simplicity" based on this idea - how to convert the humble resistor into a transimpedance amplifier (a piece of wire:)

Cyril Mechkov

Finally, I have asked the extremely interesting question about how to create virtual electrical elements in electronics:

https://www.researchgate.net/post/How_do_we_create_virtual_electrical_elements_in_electronics_Are_they_really_elements_or_circuits

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