Tunnel diode application and operation


Here we know the application of tunnel diode in detail. Here we know tunnel diode application, what is the tunnel diode and how it works?

Before its applications, let me give an overview of What is a tunnel Diode. It will help you understand its working, characteristics, and applications in broad way.

What is a tunnel Diode:

It is also known as Esaki Diode, on the name of the Inventor. “A Tunnel diode is a p-n junction device which exhibits negative resistance.”

And this diode works on tunneling effect. Now the next thing to understand is “Tunnelling effect”

It works on the principle of Tunneling effect. Metal-Insulator-Metal (MIM) diode is another type of Tunnel diode, but its present application appears to be limited to research environments due to inherit sensitivities, its applications considered to be very limited to research environments.

Tunnelling Effect:

Tunnelling is a quantum mechanical effect which would be impossible according to the mechanics. This effect allows the particle to cross the barrier with less energy than the barrier energy. As per equation, the probability increases with a decrease in the barrier energy.

P α exp (-A*Eb *W)


p = probability

Eb = barrier energy (b is in base of E)

W = Barrier width

Some of the applications of tunnel diodes are:

  • Due to a triple valued feature of its current curve, it is used as a logic memory storage device.
  • Due to small capacitance, inductance and negative resistance it is used in relaxation oscillators and microwave oscillators.
  • Due to the tunneling mechanism, it is used as an ultra high speed switch.
  • The switching time is of the order of nanoseconds or even picoseconds.
  • Due to the triple valued feature of its curve from current, it is used as a logic memory storage device.
  • Due to extremely small capacitance, inductance and negative resistance, it is used as a microwave oscillator at a frequency of about 10 GHz.
  • Due to its negative resistance, it is used as a relaxation oscillator circuit.

Tunnel diode operation

Tunnel diode can operate either in a forward direction or reverse direction. Here we are explaining the operation of the tunnel diode in both biasing. Operation with the help of V-I characteristics curve is explained in the next heading below.

  • Forward biasing:
  • In forward bias operation, when the voltage increases electronsat the first tunnel start to flow through the narrow p-n junction barrier and got aligned with empty valence band holes on the p-side of the p-n junction. As voltage increases, this state becomes misaligned and, as a result, the current starts falling. The region into which the current drops is known as negative resistance region. By increasing voltage further, diode begins to operate as a normal diode into which electrons starts moving across the p-n junction through conduction and no longer by tunneling through the p-n junction barrier.
  • Reverse Biasing:
  • In Reverse bias operation, filled state on the p-side of the junction becomes increasingly aligned with empty states at the N-side. When they get properly aligned electrons starts tunnel through the p-n junction barrier in the reverse direction. In the reverse direction, these are also known as back diodes and can act as fast rectifiers with extreme linearity for power signals and zero offset voltage.

Hope now you totally understand about the tunnel diode application. If you have any question related to tunnel diode application than comment below. we will help you soon.

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