I know it is possible to replace large-ish floating inductors (~ 5mH) with a gyrator, typically using two opamps:


What I've unsuccessfully tried to solve is : can we build something equivalent to the circuit above, but using only caps, resistors and BJT's ?

I guess it is theoretically possible, given that an OpAmp can in practice be built out of caps, resistors and BJT's, but I guess the question becomes: is there a simple circuit, made only of BJTs caps and resistors that can properly simulate a floating 5mH inductor ?

  • \$\begingroup\$ In what way do you mean "floating" - the picture you show is a grounded impedance and not floating. \$\endgroup\$
    – Andy aka
    Aug 19, 2014 at 8:03
  • 1
    \$\begingroup\$ You do know op-amps are made of transistors, right? \$\endgroup\$ Aug 19, 2014 at 8:35
  • 1
    \$\begingroup\$ @ConnorWolf : you read the last three lines of my question, right ? \$\endgroup\$ Aug 19, 2014 at 9:50
  • \$\begingroup\$ @Andyaka : yes, the picture I am showing is grounded, but IIUC this specific gyrator implementation will actually work even when not grounded, as opposed to other gyrator types that can only replace a grounded inductor. \$\endgroup\$ Aug 19, 2014 at 9:52
  • \$\begingroup\$ Where will Vout be? \$\endgroup\$
    – Andy aka
    Aug 19, 2014 at 9:55


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Browse other questions tagged or ask your own question.