Difference Between Impatt Diode and Trapatt Diode and Baritt Diode

Ever since the expansion of current semiconductor device theory scientists have wondered about whether it is achievable to make a two terminal negative resistance device. In 1958 WT read revealed the concept of avalanche diode. There are different types of diodes are available in the market which are used in the microwave and RF are classified into various types, namely, Varactor, pin, step recovery, mixer, detector, tunnel and avalanche transit time devices like Impatt diode, Trapatt diode and Baritt diodes. From this, it has been exposed that the diode can generate negative resistance at the microwave frequencies. This is attained by using carrier force ionization & drift in the high field power region of the reverse biased semiconductor region. From this concept, here this article gives an overview of a Difference Between Impatt and Trapatt Diode and Baritt diode.

Difference Between Impatt and Trapatt Diode and Baritt Diode

The Difference Between Impatt and Trapatt Diode and Baritt Diode are discussed below.

IMPATT Diode

An IMPATT diode is a one kind of high power semiconductor electrical component, that is used in high frequency microwave electronic devices. These diodes include negative resistance, which are used as oscillators to produce amplifiers as well as microwaves. IMPATT diodes can operate at frequencies between about 3 GHz & 100 GHz or more. The main advantage of this diode is their high-power capability. The applications of Impact Ionisation Avalanche Transit Time diodes mainly include low-power radar systems, proximity alarms, etc. A major disadvantage of using this diode is phase noise level is high if they generate. These outcomes from the statistical nature of the avalanche process.

Impatt Diode
Impatt Diode

The structure of the IMPATT diode is alike to a normal PIN diode or Schottky diode basic outline but, the operation and theory are very different.The diode uses avalanche breakdown united with the transit times of the charge carriers to facilitate it to offer a negative resistance region and then perform as an oscillator. As avalanche breakdown’s nature is very noisy & signals formed by an IMPATT diode have high levels of phase noise.

TRAPATT Diode

The term TRAPATT stands for “trapped plasma avalanche triggered transit mode”. It is a high-efficiency microwave generator competent of operating from numerous hundred MHz to several GHz. The TRAPATT diode belongs to the similar basic family of the IMPATT diode. However, TRAPATT diode has a number of advantages and also a number of applications. Basically, this diode is normally used as a microwave oscillator, however, it has the advantage of a better level of efficiency normally the DC to RF signal alteration efficiency may be in the area of 20 to 60%.

Trapatt Diode
Trapatt Diode

Normally, the construction of the diode consists of a p+ n n+ which is used for high power levels an n+ p p+ construction is better. For function the Trapped Plasma Avalanche Triggered Transit Or TRAPATT is energized using a current pulse which roots the electric field to enhance to an important value where multiplication of avalanche occurs. At this point the field fails nearby due to the produced plasma.

The partition and flow of the holes and electrons are driven by a very much minor field. It almost shows that they have been ‘trapped’ behind with a velocity lesser than the velocity of saturation. After the plasma increases across the entire active region, the electrons and holes start to drift to the reverse terminals and then the electric field starts to rise again.

Trapatt Diode Structure
Trapatt Diode Structure

The working principle of TRAPATT diode is that the avalanche front advances faster than the saturation velocity of the carriers. In common, it beats the value of saturation by a factor of around three. The mode of the diode doesn’t depend upon the injection phase delay.

Although the diode gives a high level of efficiency than the IMPATT diode. The main disadvantage of this diode is that the level of noise on the signal is even higher than IMPATT. A stability needs to be ended according to the required application.

BARITT Diode

The acronym of the BARITT diode is “Barrier Injection Transit Time diode”, bears numerous comparisons to the more generally used IMPATT diode. This diode is used in the microwave signal generation like the more common IMPATT diode and also this diode is frequently used in burglar alarms and where it can simply create a simple microwave signal with a comparatively low noise level.

This diode is very similar with respect to the IMPATT diode, but the main difference between these two diodes is that the BARITT diode utilizes thermionic emission rather than multiplication of avalanche.

Baritt Diode
Baritt Diode

One of the main advantages of using this kind of emission is that the procedure is less noisy. As a result, the BARITT diode doesn’t experience from the similar noise levels like an IMPATT. Basically the BARITT diode comprises of two diodes, which are placed back to back. Whenever potential is applied across the device, most of the potential drop happens across the reverse biased diode. If the voltage is then enlarged until the ends of the depletion area meet, then a state known as punch through happens.

The Difference Between Impatt and Trapatt Diode and Baritt diode are given in a tabular form

Properties IMPATT Diode TRAPATT Diode BARITT Diode
Full name Impact Ionisation Avalanche Transit Time Trapped Plasma Avalanche Triggered Transit Barrier Injection Transit Time
Developed by RL Johnston in the year 1965 HJ Prager in the year 1967  D J Coleman in the year 1971
Operating Frequency range 4GHz to 200GHz 1 to 3GHz  4GHz to 8GHz
Principle of operation Avalanche multiplication Plasma avalanche Thermionic emission
Output power 1Watt CW and > 400Watt pulsed 250 Watt at 3GHz , 550Watt at 1GHz Just few milliwatts
Efficiency 3% CW and 60% pulsed below 1GHz, more efficient and more powerful than the Gunn diode type
Impatt diode Noise Figure: 30dB (worse than a Gunn diode)
35% at 3GHz and 60% pulsed at 1GHz 5% (low frequency) , 20%(high frequency)
Noise Figure  30dB (worse than Gunn diode)  Very high NF of the order of about 60dB Low NF about 15dB
Advantages ·         This microwave diode has high power capability compare to other diodes.

·         Output is reliable compared to other diodes

·         Higher efficiency than Impatt

·         Very low power dissipation

·         Less noisy than impatt diodes

·         NF of 15dB at C band using Baritt amplifier

Disadvantages ·         High noise figure

·         High operating current

·         High spurious AM/FM noise

·         Not suitable for CW operation due to high power densities

·         High NF of about 60dB

·         Upper frequency is limited to below millimeter band

·         Narrow bandwidth

·         Limited few mWatts of power output

Applications ·         Voltage controlled Impatt oscillators

·         Low power radar system

·         Injection locked amplifiers

·         Cavity stabilized impatt diode oscillators

·         Used in microwave beacons

·         Instrument landing systems •  LO in radar

·         Mixer

·         Oscillator

·         Small signal amplifier

Thus, this is all about the Difference Between Impatt and Trapatt Diode and Baritt diode which includes principles of operation, frequency range, o/p power, efficiency, noise figure, advantages, disadvantages and its applications. Furthermore, any queries regarding this concept or to implement the electrical projects, please give your valuable suggestions by commenting in the comment section below. Here is a question for you, what are the functions of Impatt diode, Trapatt diode and Baritt diode?

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