Microwave Devices: TRAPATT and IMPATT Diodes
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Questions and Answers

What does TRAPATT stand for?

  • Transistor Avalanche Triggered Plasma Propagation Time
  • Transit Avalanche Triggered Plasma Propagation Time
  • Transit Avalanche Plasma Propagation Time
  • Trapped Plasma Avalanche Triggered Transit (correct)

What is the basic operation of the oscillator in TRAPATT diodes?

  • Semiconductor p+-n-n+ junction diode reverse biased
  • Semiconductor n+-p-p+ junction diode forward biased
  • Semiconductor p+-n-n+ junction diode forward biased
  • Semiconductor n+-p-p+ junction diode reverse biased (correct)

What are the typical structures of high-peak-power TRAPATT diodes?

  • Silicon p+-n-n+ or n+-p-p+
  • Silicon n+-p-p+
  • Silicon n+-p-p+ or p+-n-n+ (correct)
  • Silicon p+-n-n+

What happens as a high-field avalanche zone propagates through the diode in TRAPATT operation?

<p>A dense plasma of electrons and holes fills the depletion layer (B)</p> Signup and view all the answers

What type of voltage waveform is typically assumed for the TRAPATT mode of an avalanche p+ -n-n+ diode?

<p>Square wave (D)</p> Signup and view all the answers

What is the purpose of the doping of the depletion region in TRAPATT diodes?

<p>To reduce breakdown voltage (B)</p> Signup and view all the answers

What happens at point B to point C in the TRAPATT diode?

<p>The particle current exceeds the external current and the electric field is depressed throughout the depletion region. (D)</p> Signup and view all the answers

What happens at point D in the TRAPATT diode?

<p>The field is further depressed and 'traps' the remaining plasma. (D)</p> Signup and view all the answers

What occurs at point E in the TRAPATT diode?

<p>A residual charge of electrons remains in one end of the depletion layer and a residual charge of holes in the other end. (A)</p> Signup and view all the answers

What is true about point F in the TRAPATT diode?

<p>All the charge that was generated internally has been removed. (A)</p> Signup and view all the answers

What occurs at point G in the TRAPATT diode?

<p>The diode charges up again like a fixed capacitor. (C)</p> Signup and view all the answers

What is responsible for depressing the electric field throughout the depletion region in a TRAPATT diode?

<p>The generation of a sufficient number of carriers. (C)</p> Signup and view all the answers

Flashcards

TRAPATT

Trapped Plasma Avalanche Triggered Transit, a type of semiconductor oscillator.

TRAPATT diode operation

Reverse-biased semiconductor n+-p-p+ junction diode.

TRAPATT diode structure

Silicon n+-p-p+ or p+-n-n+ structures are typical.

Avalanche zone propagation

A dense plasma of electrons and holes fills the depletion region during operation.

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Voltage waveform in TRAPATT

Typically a square wave.

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Doping purpose

Reduces breakdown voltage in TRAPATT diodes.

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Point B to C

Internal particle current surpasses external current, the depletion field decreases.

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Point D

Field continues to decrease, the plasma is trapped.

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Point E

Residual charges occur at different ends of depletion region.

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Point F

Internally generated charge gets cleared.

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Point G

Diode recharges like a capacitor.

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Field depression cause

Sufficient carrier generation.

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High-peak-power diodes structures

Typically silicon n+-p-p+ or p+-n-n+.

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Plasma

A collection of electrons & holes in a substance.

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Depletion region

Area in the diode without charge carriers.

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Carrier generation

Creation of electrons and holes.

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Study Notes

TRAPATT Overview

  • TRAPATT stands for "TRapped Plasma Avalanche Triggered Transit."
  • The oscillator in TRAPATT diodes operates based on the principle of the avalanche effect combined with electron transit, generating high-frequency oscillations.

Diode Structures

  • High-peak-power TRAPATT diodes typically feature a p+ -n-n+ structure to enhance performance and power handling capabilities.

Avalanche Zone Dynamics

  • As a high-field avalanche zone propagates through the diode during TRAPATT operation, it induces rapid electron multiplication leading to pulse generation.

Voltage Waveform

  • The TRAPATT mode of an avalanche p+ -n-n+ diode typically assumes a specific voltage waveform characterized by steep rise and fall times.

Doping Purpose

  • Doping the depletion region in TRAPATT diodes serves to control the electric field distribution and improve the ionization rates during the avalanche process.

Operational Points in TRAPATT

  • Between points B and C in the TRAPATT diode, there is a transition phase where the charge carriers from the avalanche increase rapidly.
  • At point D, the device experiences a significant increase in current due to the rapid multiplication of charges.
  • Point E represents a peak operational state within the diode where optimal performance is achieved before rapid decline.
  • Point F indicates a transitional phase where the device begins to recover from the peak current operation.
  • At point G, the diode returns to its original state following the discharge of stored charge carriers.

Electric Field Dynamics

  • The depression of the electric field throughout the depletion region in a TRAPATT diode is primarily caused by the high concentration of charge carriers generated during the avalanche process.

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Description

Test your knowledge of TRAPATT and IMPATT diodes with this quiz covering lecture ten of ECO 411 on Microwave Devices by Prof. Dalia Elsheakh. Learn about the operation and characteristics of these high-efficiency microwave generators.

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