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    Special Diode

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    Santosh Kumar
    The document discusses different types of diodes including Gunn diodes, PIN diodes, varactor diodes, and TRAPATT diodes. Gunn diodes operate based on the Gunn effect and have negative resistance characteristics, allowing them to be used for microwave applications. PIN diodes have three layers and can operate as a variable resistor or capacitor depending on bias. Varactor diodes use reverse bias to vary capacitance. TRAPATT diodes operate at frequencies of 1-3GHz using plasma avalanche triggering.

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    Special Diode

    Uploaded by

    Santosh Kumar
    7 views15 pages
    The document discusses different types of diodes including Gunn diodes, PIN diodes, varactor diodes, and TRAPATT diodes. Gunn diodes operate based on the Gunn effect and have negative resistance characteristics, allowing them to be used for microwave applications. PIN diodes have three layers and can operate as a variable resistor or capacitor depending on bias. Varactor diodes use reverse bias to vary capacitance. TRAPATT diodes operate at frequencies of 1-3GHz using plasma avalanche triggering.

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    Special diode

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    The document discusses different types of diodes including Gunn diodes, PIN diodes, varactor diodes, and TRAPATT diodes. Gunn diodes operate based on the Gunn effect and have negative resistance characteristics, allowing them to be used for microwave applications. PIN diodes have three layers and can operate as a variable resistor or capacitor depending on bias. Varactor diodes use reverse bias to vary capacitance. TRAPATT diodes operate at frequencies of 1-3GHz using plasma avalanche triggering.

    Copyright:

    © All Rights Reserved
    Download as PPTX, PDF, TXT or read online from Scribd
    Download as pptx, pdf, or txt
    7 views15 pages

    Special Diode

    Uploaded by

    Santosh Kumar
    The document discusses different types of diodes including Gunn diodes, PIN diodes, varactor diodes, and TRAPATT diodes. Gunn diodes operate based on the Gunn effect and have negative resistance characteristics, allowing them to be used for microwave applications. PIN diodes have three layers and can operate as a variable resistor or capacitor depending on bias. Varactor diodes use reverse bias to vary capacitance. TRAPATT diodes operate at frequencies of 1-3GHz using plasma avalanche triggering.

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    © All Rights Reserved
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    Gunn Diode

    Gun Diode-(Transferred Electron Device)


     It is working based on “Gunn-Effect”
     It is discovered by J.B.Gunn in 1962
     It offers negative resistance characteristics. Hence, it is used in microwave applications.
     The Gunn Effect can be defined as generation of microwave power (power with microwave
    frequencies of around a few GHz) whenever the voltage applied to a semiconductor device
    exceeds the critical voltage value or threshold voltage value.
     It is not based on PN junction
     Slab of N-type GaAs (gallium arsenide), due to this electron as a majority carrier.
     Sometimes called Gunn diode but has no junctions
     Has a negative-resistance region where drift velocity decreases with increased voltage
     This causes a concentration of free electrons called a domain
    V-I Characteristics-
    V-I Characteristics-
     The current-voltage relationship characteristics of a Gunn diode are shown in
    the above graph with its negative resistance region. These characteristics are
    similar to the characteristics of the tunnel diode.
     As shown in the above graph, initially the current starts increasing in this
    diode, but after reaching a certain voltage level (at a specified voltage value
    called as threshold voltage value), the current decreases if we increase the
    voltage.
     The region where the current falls is termed as a negative resistance region,
    and due to this it oscillates.
     In this negative resistance region, this diode acts as both oscillator and
    amplifier, as in this region, the diode is enabled to amplify signals.
    Applications-
     Used as Gunn oscillators to generate frequencies ranging from 100mW 5GHz to 1W
    35GHz outputs. These Gunn oscillators are used for radio communications, military and
    commercial radar sources.
     Used as sensors for detecting trespassers, to avoid derailment of trains.
     Used as efficient microwave generators with a frequency range of up to hundreds of
    GHz.
     Used for remote vibration detectors and rotational speed measuring tachometers.
     Used as a microwave current generator (Pulsed Gunn diode generator).
     Used in microwave transmitters to generate microwave radio waves at very low powers.
     Used as fast controlling components in microelectronics such as for the modulation of
    semiconductor injection lasers.
     Used as sub-millimeter wave applications by multiplying Gunn oscillator frequency
    with diode frequency.
    PIN Diode-
     Three layer diode
     It offers high resistance.
     It has lower capacitance due to intrinsic layer between P and N-type layers.

     It has high reverse bias voltage( PIV).


    PIN Diode Characteristics-
     It has low capacitance.
     High PIV.
     Sensitive to photo detection.
     Carrier storage.
    PIN Diode Baising

    In forward bias PIN diode


    work as a variable resistor.

    In reverse bias PIN diode work as


    a variable capacitor.
    Low Frequency Model and High Frequency model
     In reverse bias PIN diode work as a variable capacitor.

    Application-
     High voltage rectifier
     RF Switch
     Photo detector
     Variable attenuator
    Varactor Diode/Varicap diode

     It is developed in 1961 by pacific semiconductor.


     It works in reverse bias.
     Based on voltage capacitance it is changing in reverse bias.
     The capacitance change results from a widening of the depletion layer as the reverse-bias
    voltage is increased.
    Application

     Voltage controlled oscillator


     Parametric amplifier
     Frequency multiplier
     Tuning circuit
     Phase lock loops (FM)
     Frequency synthesizers
    TRAPATT Diode (Trapped Plasma
    Avalanche Triggered Transit Mode)
     Frequency of operation 1-3GHz
     Noise Figure 60dB
     It works with low power dissipation
     It works based on plasma Avalanche trigger
     It has DC to RF efficiency between 0.2 to 60%
     It is available with p+-n-n+ or n+-p-p+
     It provides higher efficiency than IMPATT diode but it has higher level noise
    figure
    Characteristics-

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