There are two groups of microwave devices.
- Semiconductor Devices
- Tube Devices
Semiconductor Microwave Devices
There are the following microwave semiconductor devices.
It is one of the microwave semiconductor devices which are used as an oscillator and mixer. The backward diode is made of gallium arsenide semiconductor. This diode is used up to the frequencies of 200 GHz.
The abbreviation for the backward diode is BWD. This diode works at low input power and it provides the high output power.
It is the microwave semiconductor diode which is used as an oscillator. In some of the cases Gunn diode can also be used as an amplifier. Its frequency range is from 4 GHz to 100 GHz. The semiconductor material used for Gunn diode is gallium arsenide or indium phosphate mixed with the silicon.
The abbreviation of impatt diode is taken from word impact avalanche transit time. This diode is used for oscillation and amplification of the microwave length of frequency. The higher range of frequency is 200 GHz.
This diode is used for the rectification for microwave length of frequencies. In some of the cases we use the schottky diode for switching and mixing purposes also. The frequency range of this diode is from 3 Mhz to 10 GHz.
The tunnel diode is a microwave semiconductor device which is used for oscillation, amplification, mixing and switching purpose. The frequency range of tunnel diode is up to 100 GHz.
Varactor diode is mostly used in television and F.M receiver circuits. This diode can also be used in F.M transmitter circuits. The frequency range of varactor diode is up to 105 GHz. This type of diode changes its capacitance with the change of the bias applied to it.
The conventional transistor cannot be used for the microwave frequencies because of its low efficiency and high distortion. The field effect transistors (FET) made of gallium arsenide semiconductor material is used for this purpose due to its efficient energy bands for very high frequency. We use these transistors for the purpose of amplification of the high frequencies.
Integrated Circuits (I.C)
As the inductance and capacitance for the very high frequencies is supposed to be very small, therefore, the physical size of inductor and capacitor becomes the smallest possible at very high frequencies. So, the hybrid integrated circuits can be easily manufactured for the purpose of microwave frequencies.