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I am studying the construction of some touch sensors, and I need inductances of 10mH, I know I can easily do it, and also purchase them without much difficulty, however I know that it is possible to simulate such inductances using a circuit called Gyrator.

What would be the pros and cons of replacing a passive inductor by a simulated inductor with Gyrator.

Delfino
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The major disadvantage of a gyrator is that it needs DC power and a DC bias to set the circuit up correctly. The advantage of an inductor of course is that this is not needed.

Another disadvantage of a gyrator is that they are all (from what I've seen of the simple transistor/op-amp type) all ground referenced at one end of the inductor i.e. if you wanted an inductor that was ungrounded on both pins then it becomes a lot more complex.

Many inductors are used in power applications (such as switch mode power supplies). In simple words, gyrators are useless in these applications.

The main area that I see a lot of gyrators used is in audio graphic equalizers where a low power and low to medium Q factor is needed. Also frequencies are moderately low i.e. limited to no-more than 20kHz.

Andy aka
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  • I did not know this limitation, performance, up to *20khz*, which impacts a lot on my choice. Regarding the _interference_ as _10 subcircuits_ using the gyrator, there is much interference as may occur with conventional inductors? – Delfino May 26 '15 at 20:46
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    Gyrators can work very much higher than 20kHz - I was giving an example where they are used a lot. – Andy aka May 26 '15 at 21:18
  • @Andyaka Are SMPS out because they require the use of the magnetic feild or is it the switching speed that is why they are out ? – efox29 May 26 '15 at 22:48
  • @efox29 lack of magnetic field effects. An SMPS can (in theory) be designed to operated at low-ish frequencies by using a massive inductor. – helloworld922 May 26 '15 at 23:17
  • @helloworld922 it was what I suspected. Appreciated. – efox29 May 26 '15 at 23:25
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    @efox29: Technically, SMPS's don't require magnetic fields. What they require is *kinetic energy storage*. They work by converting potential energy to kinetic, and back to potential. Gyrators, unfortunately, don't store any energy -- neither potential nor kinetic. – Zulu May 27 '15 at 02:07
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    @Zulu if they don't require magnetic feilds, then a capacitor could be used in some sort of topology as well in SMPS - do they have a topology like that ? – efox29 May 27 '15 at 02:12
  • @efox29: No, capacitors store energy as potential (not kinetic) energy, so they are not useful in buck, boost, etc. converters. However, they *are* useful in a different class of converters called *charge pumps*. – Zulu May 27 '15 at 02:14
  • @efox29 To convert a switching waveform to a "smooth" and power efficient dc waveform requires a low pas filter formed by an L and a C. Gyrators need power and therefore are pointless to use. – Andy aka May 27 '15 at 07:13
  • @efox29 - The topology which does use a capacitor as the storage element is the Cuk converter. The Cuk converter also has low ripple on both the input and the output. – MicroservicesOnDDD Jul 19 '20 at 03:25