What is negative capacitance, how to make , how to simulate

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negative capacitance!

Hi Alls,

does anyone have experience about negative capacitance.

I searched through internet but I still can not catch the idea

What is negative capacitance.
How to make a negative capacitance
How to simulate the negative capacitance.

Help me please,

BRs,

Test_out
 

Re: negative capacitance!

test_out said:
Hi Alls,
does anyone have experience about negative capacitance.
I searched through internet but I still can not catch the idea
What is negative capacitance.
How to make a negative capacitance
How to simulate the negative capacitance.
Help me please,
Click to expand...

Hi test_out,

A neg. cap is a capacitance with an additional phase shift of 180 deg. (phase between voltage and current like an inductance).
It can be used to compensate, for example, the unwanted influence of pos. capacitances, or in oscillating circuits for tuning purposes.
A neg. cap can be technically realized only with an active circuit.
Normally, a Negative Impedance Converter (NIC) is used for this purpose.
It consists of one opamp which has neg. feedback consisting of an Rn-C-path (C grounded). In addition there is a resistor Rp between output and pos. input.
Then, the input impedance at the pos. input is equivalent to a neg. capacitance.
C=-C*Rn/Rp.
Try to perform an ac analysis to confirm the behaviour.
 

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