What is transferred electron diode? Gunn Diode Tutorial


The Transferred Electron Diode (TED) is a two terminal passive semiconductor electronic component. The diode is used in high-frequency electronics. The Gunn diode is based on the Gun effect discovered in 1962 by Physicist J. B. Gunn. There are three regions in the diode. Two regions are heavily N-doped on the terminal and there will be a thin layer of n-doped material between them.

gunn diode
Source: https://www.indiamart.com

The TED which is also called as Gunn diode is used in electronic oscillators. The diode will contribute towards the generation of microwaves. The technology can be implemented in automatic door openers. The diode comprises of N-doped semiconductor material. Most of the diodes contain both P and N-doped regions. When you apply the voltage to the device, you will notice highest electrical gradient at the thin middle layer.

Applications of Gunn Diode

The diode manages a region of negative differential resistance in the current-voltage characteristic curve. If there is an increase in voltage, there will be a decrease in current. The radio frequency functioning can be amplified with the help of the diode.

Gunn Diodes have high-frequency capability and they are used at microwave frequencies. Some diodes are used above the microwave frequency as well. Oscillators are the most common applications of gunn diodes. The diode can be used in microwave amplifiers to increase the signal strength.

gunn diode
Gunn Diode oscillator Source: http://www.emarket-usa.com

Microwave power for airborne collision avoidance radar, sensors and anti-lock brakes will be done with Gunn diode. The expected frequency with the diode is in between one and hundred GHz. You can use diodes very easily. Microwave RF signals can be generated at a very low cost with the help of Gunn diodes.

Tuning the Gunn diode

The frequency of the signal generated by the diode is based on thickness of the active region. However, it can be altered as per your needs. The diodes are mounted in a waveguide and a resonant circuit is formed with the whole assembly. The resonant frequency can be altered in various ways. If an adjustment screw is placed in the waveguide cavity, you can go for mechanical adjustments. You should have electrical tuning as well in addition to the mechanical adjustment.

Varactor diode can be coupled to the Gunn oscillator circuit and the voltage on the varactor can be changed as per your needs. You can change the capacitance and frequency of the Gunn assembly so that the trimming will take place.

gunn diode
Gunn diode oscillator circuit, Source: http://www.qsl.net

YIG is the most effective tuning scheme which can be implemented with the diode. The YIG name is obtained through the presence of ferromagnetic material, Yttrium Iron Garnet. The diode will be placed along with the YIG which will reduce the effective size of the cavity in a very efficient manner. You can place a coil outside the waveguide. The magnetic volume of the YIG will increase when the current passes through the coil. In this process, the electrical size of the cavity will be reduced. Thus, the frequency of operation will increase. There will be a lower level of phase noise when you go for YIG. It is possible to change the frequency as per your needs.

Source: http://911electronic.com/gunn-diode/


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