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## Theory OF OPERATION :

Fig.1 Tunnel Diode Voltage Divider

Another interesting application of dynamic resistance is the tunnel diode or Esaki diode because of its V-I curve. In the negative resistance portion the voltage divider made with a resistor and a tunnel diode can actually be an amplifier.

For a wiggly voltage
v_{i}
the voltage divider equation can be written as :
\large v_{out} = \frac{R}{R+r_{t}}*v_{i}
(1)
Where
r_{t}
is the incremental resistance of the tunnel diode at the operation current, and the lower case symbol vi stands for small signal variation or
\Delta v_{i}
.
The tunnel diode has
r_{t(incr)}
< 0 in the negative resistance portion :
\large r_{t(incr)} = \frac{\Delta V}{\Delta I} < 0
(2)
As you can see from the formula (1) in the negative resistance portion of the tunnel diode the
r_{t}
is negative and the output voltage is amplified.

## PRACTICAL EXAMPLE :

If you don’t see the example below than you should follow this steps:

- In your browser allow Java SE 7.

- Lower you java security settings (Go to Control Panel >> Java >> Security and set the security level to medium) .

- Edit Site List (Go to Control Panel >> Java >> Security and click on Edit Site List... and add eagerlearning.org in the list).

Let’s take a look a simple voltage divider but instead will use a tunnel diode and check the outputted voltage.

Sorry, you need a Java-enabled browser to see the simulation.

If you want to change resistor or AC voltage value than you should double click on the element and insert the desired value. First Diagram is showing Tunnel Diode V-I characteristic, you can play with the resistance value and see how the V-I characteristic is changing. The second diagram shows the I and V that is flowing through the Tunnel Diode.

Last updated on Mon , 03 2014