In the Nonlinear Diode model in Keysight Genesys there is no forward bias voltage parameter. There is a "junction potential" (Vj) parameter, however. I've never seen or heard anyone use the term junction potential to describe a diode property though. Is it the same thing as forward bias voltage?


The VJ parameter is used by many SPICE-derived simulators for their diode models. It doesn't affect the I-V characteristics of the diode, but rather the capacitance characteristic.

The junction capacitance characteristic is given by



The total capacitance of the diode is


with \$C_j\$ being dominant when the diode is reverse biased, and the diffusion capacitance \$C_d\$ being dominant when the diode is forward biased.

If you want to set the forward voltage of the diode, you need to look at the Shockley diode equation

$$I(V) = I_s \exp\left(\frac{V}{nV_T}-1\right)$$

and set the corresponding SPICE parameters IS and N (and possibly the series resistance RS) to achieve the forward voltage (and reverse leakage) to match your physical diode.

| improve this answer | |

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.