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
    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