Negative Impedance Converter:

Negative-impedance converter (NIC) is an significant building block that is useful in realising negative impedances. A negative resistance is necessary an active device which may be used advantageously in realizing oscillators and enhancing the quality factor of resonators. The circuit realisation of the NIC is illustrated in Figure.

Figure: Op-amp Realisation of the NIC

Routine analysis of the circuit gives

i₁  = V₁ - V₀ /R₁             

i ₂ = V₂  - V₀ /R₂

Because of the property of the ideal op-amp

V₁ = V₂

From the above

i₁/ i₂  = R₂ /R₁

 Therefore, the transmission matrix of the circuit is given by

From the above transmission matrix, this is seen that the circuit is a NIC since upon terminating port 2 into a load impedance Z_L, the impedance looking at the input and port is given by

Z _in       =- (R₁/R₂  )Z _L