Gunn diode Application note | Gunn diode Oscillator
This Gunn diode application note covers basic description on Gunn diode Oscillator. The circuit diagram is mentioned.
This type of diode is widely used at high frequency electronic circuits. It is also known as transferred electron device or TED. Unlike other diodes which usually will have both N and P doped regions, Gunn diode has only N-type of semiconductor doping material.
As shown in the figure-1 below, Gunn diode is made of 3 regions out of which two are heavily doped(N+) and one is lightly doped(N-). Upon application of voltage across the Gunn diode, large electrical gradient will develop acoss middle layer (N-) of the device. But at high potential, middle layer conductive properties can be altered and hence will reduce the gradient across the device. This will prevent the conduction slowly after current will get reduced. Refer GUNN diode basics and applications.
Figure depicts Gunn diode layers, transfer characteristics and Gunn diode oscillator circuit. Gunn diode has negative resistance region as shown.
This negative resistance along with lead inductance and some stray capacitance result into oscillations. This relaxation type of oscillation in most of the cases will have large amplitude which will burn out the diode. Large capacitor is connected across the Gunn diode which will help avoid and minimize this failure.
This feature is used to build oscillators at higher frequencies in GHz and THz bands. Here resonator is added in order to control the frequency.
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