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  • gate discussions for electronics and communications

    nenuadwani

    Member

    Updated: Oct 26, 2024
    Views: 1.2K
    this is the place to discuss about our preparations. lets start from the very basics of electronics i.e. the semiconductors. starting with the diodes i think we should know all the basic current, voltage equations, relations and characteristics. what do you all say CE'ans.
    please continue providing your views and details to help all the CE'ans.
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  • nenuadwani

    Member • Oct 30, 2010

    is there no one here to discuss??
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  • shiwa436

    Member • Nov 1, 2010

    can anyone post some possible questions on Diodes....
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  • nenuadwani

    Member • Nov 1, 2010

    some questions from previous years papers are-
    1. Compared to a p-n junction with NA=ND=1014/cm3, which one of the following
    statements is TRUE for a p-n junction with NA=ND=1020/cm3?
    (A) Reverse breakdown voltage is lower and depletion capacitance is lower
    (B) Reverse breakdown voltage is higher and depletion capacitance is lower
    (C) Reverse breakdown voltage is lower and depletion capacitance is higher
    (D) Reverse breakdown voltage is higher and depletion capacitance is higher

    2. Which of the following is NOT associated with a p-n junction?
    (A) Junction capacitance (B) Charge Storage Capacitance
    (C) Depletion Capacitance (D) Channel Length Modulation

    3. Which of the following is true?
    (A) A silicon wafer heavily doped with boron is a p+ substrate
    (B) A silicon wafer lightly doped with boron is a p+ substrate
    (C) A silicon wafer heavily doped with arsenic is a p+ substrate
    (D) A silicon wafer lightly doped with arsenic is a p+ substrate

    4. Consider the following assertions
    S1: For Zener effect to occur, a very abrupt junction is required
    S2: For quantum tunneling to occur, a very narrow energy barrier is required
    Which of the following is correct?
    (A) Only S2 is true
    (B) S1 and S2 are both true but S2 is not a reason for S1
    (C) S1 and S2 are both true and S2 is a reason for S1
    (D) Both S1 and S2 are false

    these are few questions. but i think from electronics point of view the paper sways around bjt, fet's and mosfets rather than diodes.
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  • nenuadwani

    Member • Nov 8, 2010

    hi friends,
    here in india now we have another benefit. its the issue of using the GATE score card as an entry tool for the PSU's. recently the recruitment advertisement of oil corporation of india has mentioned to use the score card for entry in jobs. so a person giving gate can now opt for a job or entrance in post graduation programmes. so lets go for it.
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  • shiwa436

    Member • Nov 25, 2010

    I miss somewhere in understanding the concept of "energy bands", help me with the following. Valence band is that which holds the valence electrons and is responsible for electrical conduction, then what is need of classifying another band named conduction band..?
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  • nenuadwani

    Member • Nov 27, 2010

    Energy bands are of following types

    Valence band:The energy band formed by a series of energy levels containing valence electrons is known as valence band. At 0 K, the electrons fills the energy levels in valence band starting from lowest one.
    (i) This band is always filled by electrons.
    (ii) This is the band of maximum energy.
    (iii) Electrons are not capable of gaining energy from external electric field.
    (iv) No flow of current due to such electrons.
    (v) The highest energy level which can be occupied by an electron in valence band at 0 K is called Fermi level.

    Conduction band:The higher energy level band is called the conduction band.
    (i) It is also called empty band of minimum energy.
    (ii) This band is partially filled by the electrons.
    (iii) In this band the electrons can gain energy from external electric field.
    (iv) The electrons in the conduction band are called the free electrons. They are able to move anywhere within the volume of the solid.
    (v) Current flows due to such electrons.

    Forbidden energy gap (DEg):Energy gap between conduction band and valence band
    (i) No free electron present in forbidden energy gap.
    (ii) Width of forbidden energy gap upon the nature of substance.
    (iii) As temperature increases ( ), forbidden energy gap decreases (¯) very slightly.
    It is also called band energy gap.
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  • shiwa436

    Member • Dec 29, 2010

    Dear friends, I have a doubt on Diode Clamping circuits...
    If output is taken across the diode, it should equals to the diode voltage, but it is 2E-Vf, why?
    Help me if i was in a mis concept....
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  • shiwa436

    Member • Jan 11, 2011

    Hey no one is responding........... what happend to all the crazy ones........
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  • shiwa436

    Member • Jan 26, 2011

    Every one keep saying me that "BE THOROUGH WITH THE BASICS", what do you mean by basics.......

    Tell me what topics to cover in EDC as basics......... Help me please......
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