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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.

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    \$\begingroup\$ Gyrators are not susceptible to alternating magnetic fields. \$\endgroup\$
    – Al Bundy
    Commented May 26, 2015 at 20:37

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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.

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  • \$\begingroup\$ 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? \$\endgroup\$
    – Delfino
    Commented May 26, 2015 at 20:46
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    \$\begingroup\$ Gyrators can work very much higher than 20kHz - I was giving an example where they are used a lot. \$\endgroup\$
    – Andy aka
    Commented May 26, 2015 at 21:18
  • \$\begingroup\$ @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 ? \$\endgroup\$
    – efox29
    Commented May 26, 2015 at 22:48
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    \$\begingroup\$ @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. \$\endgroup\$
    – Zulu
    Commented May 27, 2015 at 2:07
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    \$\begingroup\$ @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 ? \$\endgroup\$
    – efox29
    Commented May 27, 2015 at 2:12

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