What we call this opamp configuration? [SOLVED]
1- What we call this opamp configuration?
2- What's the advantage and the disadvantage of this circuit?
3- And what's the purpose of the L2 in the feedback?
I have changed gradually the value of L2 from 1 pH to hundreds of H but nothing noticeable, then I replaced it with a resistor and did the same process the result was the same, in the end I replaced them with a wire the result was also the same.
Edit: this circuit was designed in National Aviation University of Kyiv, Ukraine.
The circuit is suposed to exhibits a maximum in-band total harmonic distortion (THD) of 1.7%. And a maximum in-band phase noise of −139.3 dBc/Hz at 100 kHz offset frequency and has an outstanding value of a standard figure of merit (FoM) of −198.6 dBc/Hz.
Edit2:
For question 3 the inductor L1 provides positive shunt–shunt feedback.
Edit3:
For question 1 the opamp configuration is a Negative inductance circuit, a type of negative impedance converter.
This circuit can be configurated in different ways the negative of any impedance can be produced, including negative capacitance and negative inductance.
1 answer
What we call this opamp configuration?
A mess.
What's the advantage and the disadvantage of this circuit?
This can't be judged without the stated objectives. It might be useful for keeping undergrads busy trying to analyze this circuit.
And what's the purpose of the L2 in the feedback?
None the way the circuit is drawn. Ideal opamps have infinite input impedance, meaning no current flows into or out of the inputs. With no current flowing thru it, L2 doesn't "do" anything.
It's hard to guess what went wrong or what was intended, but L2 should be working against some finite impedance, and was probably intended to be in the negative feedback path.
Again, it's impossible to evaluate a circuit without specs for what it's supposed to do. Any inputs and outputs also need to be defined as to what they are supposed to receive or produce.
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