Negative capacitance

125

01:10:46

Within a given voltage/current range the circuit on the right acts exactly like a capacitor with a negative value. The value can be adjusted by changing the 1k resistor.
The opamps with a gain of 1V/V are differential amplifiers http://everycircuit.com/circuit/5474894897479680

Note: the capacitor can be replaced by any component you want a negative equivalent of such as a resistor, inductor or diode.

published 6 years ago

hurz

6 years ago

forgive me, but what you mean is "positive inductivity"? http://everycircuit.com/circuit/5186865297358848

redy906

6 years ago

@hurz negative capacitance is only the same as inductance for sinusoidal waves, try using the squarewave to see what i mean.

hurz

6 years ago

as i demonstrated, its only for a single spectral componente, while rectangular wave shapes are build of infinite odd harmonics.

redy906

6 years ago

@hurz i think you missed my point. Negative capacitance cant be replaced inductance because if you match there impedances for one frequency they will be different for every other frequency. Therefore they can never be equivalent for signals composed of multiple sinusoids or signals of changing frequency.

hurz

6 years ago

you missed the point in my circuit i have just used a single frequency as it will work for only a fixed frequency. If you apply a rectangular as you said it can not work as i explain for you. Again, rectangular wave shapes are a base frequency plus a sum of odd harmonics, which will have a different impedance. For sin wave it can be seen as inductivity replacment, nothing else said. You can calcutate for any given frequency the equivalent inductivity! Just use L=1/(omega^2*C), but this is for a later time for you.

redy906

6 years ago

@hurz the point of this circuit is not to find inductance of equivalent impedance to a capacitor for a single sine wave of fixed frequency, it is to create negative capacitance (which it does).

hurz

6 years ago

forgive me, or 'positive inductivity' at a given frequency.

redy906

6 years ago

@hurz sure i guess, i dont really care about specific wording.

hurz

6 years ago

@redy906, sure you guess.

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