A nonlinear impedance converter
Václav Doležal, R.W. Newcomb · IEEE Transactions on Circuits and Systems · 1981
It is shown that under reasonable assumptions a common op amp circuit operating under nonlinear conditions possesses a nonlinear input admittance operatorY(.). By an appropriate choice of parameters a negative admittance may be obtained in the vicinity of the origin. Bounds on the behavior ofY(.)and Its inverse are given.