In order to make analog calculation (for analog regulator simulation), what would be the means to make an squaring amplifier ?

  • There is an obvious solution with a multiplier circuit as pointed here;
  • I also imagined using a mosfet like in the following drawing and in this case I would need another similar circuit for the negative part of the signal;

but before trying to effectively design it, I wondered if there would be other well known simple solution.

Edit : Some people seem to dislike the application of analog computing. Just think of it as an educational application.

Edit2 : To make things more precise, let's say that to avoid saturation problems, the identity element would be 10v, So for a 1v input we get a 0.1v output and for a 0.1v input, we get 1mV output, and it would be even better if we had a circuit which would give the same positive output for the same negative inputs.

enter image description here

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    \$\begingroup\$ This question and answer may be of some interest as it also uses a technique similar to that mentioned by Neil above. \$\endgroup\$
    – Andy aka
    Aug 6, 2019 at 13:47
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    \$\begingroup\$ This is too broad as you have failed to state any specifics of the application requirement as it impacts the performance required of the solution and failed to give any actual justification for why an analog solution is required. There are many ways to solve problems but you give no basis for picking the appropriate one, thus failing the SE requirement for specific answerability. All of this was pointed out when you tried to reopen a similarly flawed question. It was explained then what you would need to have a valid question, essentially none of which you have provided. \$\endgroup\$ Aug 6, 2019 at 14:23
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    \$\begingroup\$ Analog computers existed, but are largely extinct as they have many implementation problems. You've failed to state specifics of your requirement ruling out a digital solution or even allowing a selection to be made between analog techniques. THIS IS A BAD QUESTION showing that you learned nothing from your meta question about why the other bad question was closed. \$\endgroup\$ Aug 6, 2019 at 14:43
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    \$\begingroup\$ This is not a discussion forum, it is a site reserved only for specific questions which can have specific answers. You do not have an answerably specific question, if you want to have an open ended discussion about various techniques, you need to take it to a discussion forum, which is not what an SE site is. \$\endgroup\$ Aug 6, 2019 at 15:22
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    \$\begingroup\$ It's an overly broad question without a specific answer. Nevermind that you haven't actually asked a question anywhere in your 'question'. \$\endgroup\$
    – brhans
    Aug 6, 2019 at 16:51

1 Answer 1


This circuit will do squaring. I leave calibration, and temperature compensation, to you.

What is the bandwidth? at 1mA input, the 2N3904 will have about 40pF Cbe (computed from Ftau). With 100 ohm resistors, thus 4nanosecond Tau on nodes, BW is about 40MHz.


simulate this circuit – Schematic created using CircuitLab

  • \$\begingroup\$ Is this some "shared" information or this this something you designed ? \$\endgroup\$
    – Camion
    Aug 7, 2019 at 8:30

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