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Inventing Circuits on the Whiteboard...

Negative Impedance Converter with Voltage Inversion (VNIC)

 

Basic electrical circuit

Graphical representation

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"Ordinary" versus "over-helping" negative resistance

In order to present graphically the circuit operation, we have to superimpose the IV curves of the two real voltage sources - VR1 and VR2, on the same coordinate system. In this arrangement, the intersection point A (working or quiescent point here) represents the current (local) magnitudes of the voltage VA and the current IA. Click to view full-size picture.

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How to make a negative impedance converter (VNIC)

On the graphical representation, when you vary the voltage VIN of the input voltage source, its (your) IV curve moves horizontally. As a result, the working point A slides over the IV curve of the second real voltage source VREF-R2. Click to view full-size picture.

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Op-amp NIC with voltage inversion (VNIC)

On the graphical representation, when you increase the input voltage VIN, its IV curve moves horizontally from left to right. But now, as I decrease the voltage Vs at the same time, its IV curve moves from right to left. As a result, the working point A slides from left to right over a new more horizontal IV curve, which represents the new dynamic resistance Rd > R2. Click to view full-size picture.

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Last updated July 8, 2006