Electronic Devices and Circuits Engineering Sciences 154

Consider the following circuit:

where NLD is a nonlinear device (e.g., a diode) which has a known IV characteristic.  Since V_D must satisfy both the known IV characteristic and the equation

both may be plotted on the same graph as in the following diode example:

Forward biased

Reverse biased

 

Another interesting example of a NLD is the (Esaki) tunnel diode which has a region of "negative" resistance in its characteristic.

Characteristic of an Esaki (tunnel) diode	Monostable operation of an Esaki (tunnel) diode
Bistable operation of an Esaki (tunnel) diode	Astable operation of an Esaki (tunnel) diode

 
Tunnel Diode Oscillator

The excess small forward current flow in a tunnel or Esaki diode is a manifestation of quantum mechanical tunneling.  Consider the following pictures:

(source)