Tunnel diodes are heavily doped P-N diodes in which electron tunneling ... This negative-resistance region is the most important area of operation. As the voltage is increased, the current decreases.

During the first half of the 20th century radio technology was booming, albeit restricted by the vacuum tube technology of the time which made radios cumbersome in size and power needs. The ...

This is essentially the same thing as the tunnel diode, only the doping is a little lighter. It is called a backward diode because everything is the other way round. It has low impedance in the ...