diode ac model in reverse bias

Discussion in 'General Electronics Chat' started by sohrab.tapar, Nov 5, 2010.

  1. sohrab.tapar

    Thread Starter New Member

    Nov 5, 2010
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    Hi,
    what ac model PSpice uses for a diode in reverse bias?

    the model comprises of a capacitance and a resistor. i know that much, but what is the values for the R and C.

    I have some formulas for R and C from the book "Semiconductor Device Modeling with SPICE"

    R is equal to the slope of the I-V curve for the diode at its operating point.

    and C is equal to C_junction + C_diffusion
    there are formulas for each C.

    I use those formulas to simulate a simple circuit myself and then I compare my results with SPICE results.

    results are consistent for direct bias and also for breakdown region, but I get strange results in SPICE in reverse bias.

    does anyone know what ac model SPICE uses for a diode in reverse bias?
     
  2. Ron H

    AAC Fanatic!

    Apr 14, 2005
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