I have a proof-of-concept prototype in mind that requires a lossless negative floating inductor. I have researched and found many active circuits that can synthesize them, using conventional op-amps, current-feedback op-amps, OTAs, current conveyors, and many, (MANY) more. Most of these devices are unfamiliar to me. I am willing to learn about them, but am hoping for some helping narrowing down the field. Can people who have experience with these devices suggest what they think are the best approaches and why? I am particular interested in aspects like:
1. Ease of stabilization
2. Commercial availability (for a circuit board prototype)
3. Frequency range
Incidentally, I will need a negative grounded capacitor as well, but the floating inductor seemed trickier, so I thought I would start with that.
Thanks in advance for your help...
At a single frequency, a capacitor can be thought of as a negative inductor, but the capacitor's negative reactance decreases in magnitude with frequency, while a negative inductor's reactance increases in magnitude with frequency.
In other words, the reactance formula for a positive capacitance is:
X_C = -1/(j omega C)
But for a negative inductor is
X_L = -j omega L
I need this frequency dependence in order to make the desired circuit work. I have seen active feedback circuits (e.g. using op-amps) that can do this, but there are so many, I am looking for guidance from anybody who has experience using them.
Thanks for helping me to clarify!
Matt
I'm sorry, I should have said that for the positive capacitor:
X_C = -j/(omega C)
Same issue, though.
https://en.wikipedia.org/wiki/Negative_impedance_converter - especially the chapter "Basic circuit and analysis" - seems to be quite good to start with. Setting R1=R2 would leave you to insert "whatever you like" as R3: an inductor, a capacitor, some complex RLC circuit.
Theoretically speaking, stability shouldn't be a big issue. Reality tells you that it might become an issue, depending on the value of R3. Thus there is no "general solution". Although it should be clear that a "better" opamp usually yields better results.
Hope this helps a bit - or some of my dear followers chime in :)
(If not within 2 days or so: post another "answer" to remind me to recommend this question to some of my contacts.)
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