Current Source in BJT Model from HSPICE

Discussion in 'General Electronics Chat' started by miezko, Nov 18, 2013.

  1. miezko

    Thread Starter New Member

    Nov 18, 2013
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    0
    Hello,

    (Title should be: "Current Source in BJT Model from HSPICE")

    I'm trying to implement the BJT model from the HSPICE Manual (see page 146 at http://www.ece.rochester.edu/courses/ECE222/hspice/hspice_devmod.pdf) in another circuit simulator. This model includes the collector emitter current source but no explicite base current source. When I check the DC model equations however (page 156), they give two formulas, one for the collector current ic and one for the base current ib.

    Is this an error in the manual? Where should I place the ib current source in the schematic?

    Thanks in advance and best regards,
    Miezko
     
    Last edited by a moderator: Nov 18, 2013
  2. LvW

    Active Member

    Jun 13, 2013
    674
    100
    No - it is certainly not an error.
    May I ask you why do you expect a current source for Ib?
    Ib is just a result of an applied voltage Vbe - and as such it is modelled in any SPICE simulator.
    Note that the bipolar transistor in fact is a voltage controlled (non-ideal) current source. And all the models are built correspondingly.
     
  3. miezko

    Thread Starter New Member

    Nov 18, 2013
    3
    0
    Hi,

    Thank you for your answer! I was confused since this formula is not used for any other calculation.

    Gives the formula for ic (page 152) the current value for the current source "ice" or is this the terminal current (directly flowing in the collector node)?
     
  4. miezko

    Thread Starter New Member

    Nov 18, 2013
    3
    0
    Hey, I just wanted to ask again about the current source ice. There is one formula for ic on page 152 but there is no formula for ice. In the manual it is written:

    ic = External collector terminal current
    ice = DC current collector to emitter


    So what is the correct formula for ice in the schematic (page 146)?


    Thanks in advance for any help
     
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