What is a gunn diode a gunn diode is a microwave semiconductor diode designed to work in devices having microwave frequencies. The tunnel diode is used as a very fast switching device in computers. Mar 02, 2020 a gunn diode is a passive semiconductor device with two terminals, which composes of only an ndoped semiconductor material, unlike other diodes which consist of a pn junction. Dec 16, 2017 a tunnel diode is a special type of pn junction diode that shows the negative resistance between two values of forward voltage ie, between peak point voltage and valley point voltage. This page covers gunn diode basics and its applications. Explain the significance of rwh model and two valley model in. A new model is developed to study the microwavemm wave characteristics of twoterminal ganbased transfer electron devices teds, namely a gunn diode and an impact avalanche transit time impatt. Because of the way this element was built, gunn diode is more often called ted transferred electron device. It is based on the gunn effect discovered in 1962 by physicist j. The gunn effect can occur only in selected types of semiconductors from groups as a3b5 and a2b6. That is why gunn diodes cannot be used for rectifying alternating current. New techniques for the study of gunn diode contacts. To evaluate the gunn oscillation theoretically, it is necessary to incorporate their highfield transport characteristics in analytical models, or the use of some sort of simulations like monte carlo. The most common materials used in their manufacturing.
Rs8960 308017 rs metal detector using 555 timer diagram of gunn diode gunn diode at power supply circuit 747 opamp gunn diode radar module gunn diode x band amplifier gunn diode radar text. Gunn diode is one of the many microwave semiconductor devices in use today. The depletion region of two ntype materials is very thin. The gunn diode operation depends on the fact that it has a voltage controlled negative resistance this being dependent upon the fact that when a voltage is placed across the device, most of the voltage appears across the inner active region. These characteristics are similar to the characteristics of the tunnel diode. Explain the significance of rwh model and two valley model in gunn diode. Finally, we will use the gunn diode as an rf source to study the basic operation of a microwave.
Experiment5 study of iv characteristics of gunn diodes. The present work specifies the design and construction of a gunn diode oscillator at x band 8. A gunn diode, also known as a transferred electron device ted, is a form of diode, a twoterminal semiconductor electronic component, with negative resistance, used in highfrequency electronics. Gunn diode or ted transferredelectron device type of the semiconductor or vacuum form of diode, which is designed to operate in the range of microwave frequencies from single ghz to single thz. Gunn diode with notch doping modified version of 1. The gunn device will be damaged if the supply is reversed. As shown in the above graph, initially the current starts increasing in this diode, but after reaching a certain voltage level at a. Under a forward bias condition, this should be about.
A diode is the one way sign for electrical circuits. Microwave lab report final microwave lab report on study of. The gunn diode operating principle is based on the socalled gunn effect from the name of its inventor. Microwave frequencies are electromagnetic radiation of tremendously high frequencies thf, maximum working frequency up to 3 thz, this depends on the material used in its structure. A voltage variable capacitance of a reverse biased junction can be termed as a varactor diode. It is used to generate rf and microwave frequencies. Gunndiode is mainly used as a local oscillator covering the microwave frequency range of 1 to 100ghz by means of the transferred electron mechanism, the negative resistance. Diode characteristics diode and diode circuits diodes and. Block diagram gunn oscillator xg 11 matched termination xl 400 xll isolator xi 621 pin. Equipments gunn oscillator, gunn power supply, pin modulator, isolator, frequency meter, variable attenuator, detector mount, waveguide stands, swr meter, cables and.
A gunn diode is a passive semiconductor device with two terminals, which composes of only an ndoped semiconductor material, unlike other diodes which consist of a pn junction. Tunnel diode basics, operation, vi characteristics. The gunn diode or transferred electron device can be termed a diode because it has two electrodes. Gunn diodes jordan university of science and technology.
We will study the characteristics of a gunn diode oscillator and make power and frequency measurements. In the reverse, when we reverse bias the diode the depletion. Although mdt gunn diodes are designed with longterm reliability in mind with an mttf in excess of 10 6 hours at an active region temperature of 260c with rugged. A gunn diode is considered as a type of diode even though it does not contain any typical pn diode junction like the other diodes, but it consists of two electrodes. Rwh proposed this theory to explain the phenomenon of ve differential resistance ndr in certain bulk materials. The diodes are classified into different types based on their working principles and characteristics. The layers are processed using proprietary techniques resulting in ultralow phase noise and 1f noise. A diodes iv characteristic is shown in figure 6 below. As shown in the above graph, initially the current starts increasing in this diode. The zener diode is a diode designed to operate in the breakdown region and have a specific negative voltage called the zener voltage. Voltagecurrent characteristics turn the meter switch of gunn power supply to voltage position. The lead connected to the ptype material is called the anode and the lead connected to the ntype material is the cathode. Tunnel diode definition, symbol, and working diode. These include generic diode, schotty diode, shockley diode, constantcurrent diode, zener diode, light emitting diode, photodiode, tunnel diode, varactor, vacuum tube, laser diode, pin diode, peltier diode, gunn diode, and so on.
It is our interest to evaluate the transittime and current density of a gunn diode operating in the transittime mode. After certain level of voltage the current will exponentially decrease thus this exhibits the negative differential resistance. A diode is simply a pn junction, but its applications are extensive in electronic circuits. Gunn diode works as an oscillator f 0 1t d gunn diode operates in the limited space charge accumulation lsa mode no domains are formed. It can be observed the structure designed demonstrate the diameter is become wider when the diameter used is added up to 1micron to the left side and right side.
It is also used in highfrequency oscillators and amplifiers. Matched termination xl400 ii description of equipment. Introduction to gunn diode oscillators pasternack blog. Gunn as a first person has observed that in the wafers of gallium arsenide with a very small. Gunn diode free download as powerpoint presentation. The result of damaging metal contacted diodes was in all cases to change the characteristics towards typea see table 4. Gunn diodes can be made from the materials which consist of multiple, initiallyempty, closelyspaced energy valleys in their conduction band like gallium arsenide.
Block diagram matched termination xl 400 gunn power supply gunn oscillator xg 11. To achieve this capacitance and shunt load resistance need to be tuned but not greater than negative resistance. Varactor diode is a semiconductor device in which the junction capacitance can be varied as a function of the reverse bias of the diode. In this article you will get to know about the working, characteristic curvce, advantages, disadvantages and applications of gunn diode. The cv characteristics of a typical varactor diode and its symbols are shown in the following figure. The current is allowed to move through the diode in one direction only. It has negative resistance property by which gunn diode act as oscillator. Piv is the peakinversevoltage of the diode forward bias occurs when the ptype block is connected to the positive terminal of the battery and the ntype is connected to the negative terminal of the battery, as shown below. Gunn diode is fabricated with ntype semiconductor material only. Palankovski advanced material and device analysis group inst. A gunn diode, though very unlike other common semiconductor diodes, is a transferred electron device ted that presents a negative resistance after its threshold voltage is adequately exceeded. Studies on the characteristics of ganbased gunn diode for.
Pin diode acts as modulator and is used alongwith gunn for square wave modulation. Microwave lab report final microwave lab report on. Ntype and utilizes the negative resistance characteristics to generate current at high frequencies. Recent listings manufacturer directory get instant insight into any electronic component. Output power and frequency as a function of voltage. The currentvoltage relationship characteristics of a gunn diode are shown in the above graph with its negative resistance region. Gunn diode acts as oscillator and has negative differential region which helps it to act as microwave source.
When voltage increases in the circuit the current also increases. In certain semiconductors, notably gaas, electrons can exist in a highmass low velocity state as well as their normal lowmass highvelocity state and they can be forced into the highmass state by a steady electric field of sufficient strength. The effect of gross damage caused by heating diode pv148a1 is illustrated in fig. Comparative study and investigation of least mse of v. V i gaas sample iv characteristic in gunn experiments ntype gaas metal metal 5v. Each diode has a positive end, the anode, and a negative end, the. Their main feature is the specific arrangement of energy bands. A tunnel diode is a heavily doped pn junction diode in which the electric current decreases as the voltage increases. It is also termed as a transferred electron device. Gunn diode transistor diode free 30day trial scribd. To study the characteristics of gunn diode and to determine the threshold voltage.
Study of iv characteristics of gunn diodes objectives 1. The diode is a device formed from a junction of ntype and ptype semiconductor material. This diode is a negative differential resistance device, which is frequently used as a lowpowe. This diode is also called as a transferred electronic device. Its characteristics are completely different from the pn junction diode. Measure the gunn diode current corresponding to the various voltage controlled by gunn bias knob through the panel meter and meter switch.
The controllable negative resistance properties of a gunn diode allows it to be used as a microwave oscillator, and these devices are often used in microwave communications. A tunnel diode is a special type of pn junction diode that shows the negative resistance between two values of forward voltage ie, between peak point voltage and valley point voltage. Gunn diode basics gunn diode applications,advantages. Equipments gunn oscillator, gunn power supply, pin modulator, isolator, frequency meter, variable attenuator, detector mount, waveguide stands, swr meter, cables and accessories. Gunn diodes can be made from the materials which consist of multiple, initiallyempty, closelyspaced energy valleys in. A gunn diode is a semiconductor device formed by only ntype material.
The tunnel diode was first introduced by leo esaki in 1958. We will measure the vi characteristics of the diode and its output power using a power meter and a spectrum analyzer. Three important characteristics of a diode are, first of all, the forward voltage drop. Gunn oscilator, gunn power supply, pin modulator, isolator, frequency meter, variable attenuator, detector mount.
Pdf studies on the characteristics of ganbased gunn diode. In general, the cathode of a diode is marked by a solid line on the diode. Gunn diode mounting precautions the gunn diode is a powergenerating device with a relatively low efficiency about 25%. I characteristics of gunn diode using neuro solution mr. Gunn diode mode of operation parameter map 0 s o d v nl q. This is the only case new techniques for the study of gunn diode contacts table 4. Overview microsemis gaas gunn diodes are fabricated from epitaxial layers grown at microsemi by the vapor phase epitaxy technique. Explain the significance of rwh model and two valley model. Gunn diode is a transferred electronic device, which is composed of only one type of semiconductor i. In tunnel diode, electric current is caused by tunneling. View test prep microwave lab report final from general kn 238 at university of washington. Gunn diode tips definition, characteristic and applications. The gunn diode in certain semiconductors, notably gaas, electrons can exist in a highmass low velocity state as well.
1494 1649 940 1068 481 777 155 372 1569 1635 1099 1371 715 561 1027 1279 26 952 1148 399 1056 512 876 1573 859 1036 1409 9 531 682 871 717 44 1387 1501 319 1576 1512 1186 1245 58 666 1129 880 606 1072