The negative impedance converter is an example of such a circuit.

This is usually synthesized using a negative impedance converter circuit.

One standard design is realized by connecting two negative impedance converters in parallel.

The negative impedance converter originated from work by Marius Latour around 1920.

Once active components are permitted, however, a negative element can easily be implemented with a negative impedance converter.

For example, it is possible to create negative capacitance and inductance with negative impedance converter circuits.

A common example of an "active resistance" circuit is the negative impedance converter (NIC) shown in the diagram.

A typical application is a negative impedance converter with voltage inversion (VNIC).

Negative impedance converter (NIC)

A negative impedance converter (NIC) is a simple op amp circuit that has negative resistance.

Another implementation uses one negative impedance converter to create the negative resistance characteristic, and a diode-resistor network to create the nonlinear characteristic.

At the far right is a negative impedance converter made from three linear resistors and an operational amplifier, which implements the locally active resistance (negative resistance).

Similarly, applying a voltage to the negative impedance converter below greater than its power supply voltage V will cause the amplifier to saturate, also making its resistance positive.

The negative of any impedance can be produced by a negative impedance converter (INIC in the examples below), including negative capacitance and negative inductance.

The negative impedance converter (NIC) is a one-port op-amp circuit acting as a negative load which injects energy into circuits in contrast to an ordinary load that consumes energy from them.

The two versions obtained are accordingly a negative impedance converter with voltage inversion (VNIC) and a negative impedance converter with current inversion (INIC).

Some circuits and elements exhibiting negative resistance can also act in a similar way: negative impedance converters (NIC), neon lamps, tunnel diodes (e.g., a diode with an "N"-shaped current-voltage characteristic in the first quadrant), etc.

These arrangements explain important circuit phenomena about modifying impedance (Miller effect, virtual ground, bootstrapping, negative impedance, etc.) and help in designing and understanding various commonplace circuits (feedback amplifiers, resistive and time-dependent converters, negative impedance converters, etc.).