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PNDCAP models a PN junction depletion and diffusion capacitance. It is identical to the model used in SPICE for diodes and the capacitance components of BJTs.
| Name | Description | Unit Type | Default |
|---|---|---|---|
| ID | Device ID | Text | PD1 |
| *CJ0 | Zero-voltage junction capacitance | Capacitance | 0 pF |
| *VJ | Junction potential | Voltage | 1 V |
| *M | Grading parameter | 0.5 | |
| *FC | Depletion capacitance linearization parameter | 0.5 | |
| *TT | Storage time | Time | 0 ns |
| *IS | Reverse saturation current | Current | 1e-11 mA |
| *N | Ideality factor | 1 | |
| *T | Temperature | Temperature | 27 DegC |
| AFAC | Area scaling factor | 1 |
* indicates a secondary parameter
NOTE: Although junction current parameters must be entered to calculate diffusion capacitance, this model does not include junction current.
The depletion charge expression is identical to that of PNCAP. Additionally, PNDCAP includes a diffusion charge component, given by the following:
where
In the above equations, q is electron charge, K is Boltzmann's constant, and T is temperature in Kelvins. The total charge is the sum of the depletion and diffusion components.
This element does not have an assigned layout cell. You can assign artwork cells to any element. See “Assigning Artwork Cells to Layout of Schematic Elements” for details.