# P-Channel LDMOS FET

P-Channel laterally diffused metal oxide semiconductor or vertically diffused metal oxide semiconductor transistors suitable for high voltage

**Libraries:**

Simscape /
Electrical /
Semiconductors & Converters

## Description

The P-Channel LDMOS FET block lets you model LDMOS (or VDMOS) transistors suitable for high voltage. The model is based on surface potential and includes effects due to an extended drain (drift) region:

Nonlinear capacitive effects associated with the drift region

Surface scattering and velocity saturation in the drift region

Velocity saturation and channel-length modulation in the channel region

Charge conservation inside the model, so you can use the model for charge sensitive simulations

The intrinsic body diode

Reverse recovery in the body diode model

Temperature scaling of physical parameters

For the option with exposed thermal port (see Thermal Port), dynamic self-heating

For information on physical background and defining equations, see the N-Channel LDMOS FET block reference page. Both the p-type and n-type versions of the LDMOS model use the same underlying code with appropriate voltage transformations, to account for the different device types.

The charge model is similar to that of the surface-potential-based MOSFET model, with additional expressions to account for the charge in the drift region. The block uses the derived equations as described in [1], which include both inversion and accumulation in the drift region.

### Modeling Body Diode

The block models the body diode as an ideal, exponential diode with both junction and diffusion capacitances:

$${I}_{dio}={I}_{s}\left[\mathrm{exp}\left(-\frac{{V}_{BD}}{n{\varphi}_{T}}\right)-1\right]$$

$${C}_{j}=\frac{{C}_{j0}}{\sqrt{1+\frac{{V}_{BD}}{{V}_{bi}}}}$$

$${C}_{diff}=\frac{\tau {I}_{s}}{n{\varphi}_{T}}\mathrm{exp}\left(-\frac{{V}_{BD}}{n{\varphi}_{T}}\right)$$

where:

*I*is the current through the diode._{dio}*I*is the reverse saturation current._{s}*V*is the body-drain voltage._{BD}*n*is the ideality factor.*ϕ*is the thermal voltage._{T}*C*is the junction capacitance of the diode._{j}*C*is the zero-bias junction capacitance._{j0}*V*is the built-in voltage._{bi}*C*is the diffusion capacitance of the diode._{diff}*τ*is the transit time.

The capacitances are defined through an explicit calculation of charges, which are then differentiated to give the capacitive expressions above. The block computes the capacitive diode currents as time derivatives of the relevant charges, similar to the computation in the surface-potential-based MOSFET model.

### Modeling Temperature Dependence

The default behavior is that dependence on temperature is not modeled, and the
device is simulated at the temperature for which you provide block parameters. To
model the dependence on temperature during simulation, select ```
Model
temperature dependence
```

for the
**Parameterization** parameter on the **Temperature
Dependence** tab.

The model includes temperature effects on the capacitance characteristics, as well as modeling the dependence of the transistor static behavior on temperature during simulation.

The **Measurement temperature** parameter on the
**Main** tab specifies temperature
*T _{m1}* at which the other device
parameters have been extracted. The

**Temperature Dependence**tab provides the simulation temperature,

*T*, and the temperature-scaling coefficients for the other device parameters. For more information, see Temperature Dependence.

_{s}### Thermal Port

You can expose the thermal port to model the effects of generated heat and device
temperature. To expose the thermal port, set the **Modeling option**
parameter to either:

`No thermal port`

— The block does not contain a thermal port and does not simulate heat generation in the device.`Show thermal port`

— The block contains a thermal port that allows you to model the heat that conduction losses generate. For numerical efficiency, the thermal state does not affect the electrical behavior of the block.

For more information on using thermal ports and on the **Thermal Port**
parameters, see Simulating Thermal Effects in Semiconductors.

If you expose the thermal port, the block includes dynamic self-heating. This lets you simulate the effect of self-heating on the electrical characteristics of the device.

### Variables

To set the priority and initial target values for the block variables before simulation,
use the **Initial Targets** section in the block dialog box or Property
Inspector. For more information, see Set Priority and Initial Target for Block Variables.

Use nominal values to specify the expected magnitude of a variable in a model. Using
system scaling based on nominal values increases the simulation robustness. Nominal values
can come from different sources. One of these sources is the **Nominal
Values** section in the block dialog box or Property Inspector. For more
information, see System Scaling by Nominal Values.

## Ports

### Conserving

## Parameters

## References

[1] Aarts, A., N. D’Halleweyn, and R. Van Langevelde. “A
Surface-Potential-Based High-Voltage Compact LDMOS Transistor Model.”
*IEEE Transactions on Electron Devices*. 52(5):999 - 1007. June
2005.

[2] Van Langevelde, R., A. J. Scholten, and D. B. M. Klaassen.
"Physical Background of MOS Model 11. Level 1101."* Nat.Lab. Unclassified
Report 2003/00239*. April 2003.

[3] Oh, S-Y., D. E. Ward, and R. W. Dutton. “Transient
analysis of MOS transistors.” *IEEE J. Solid State
Circuits*. SC-15, pp. 636-643, 1980.

## Extended Capabilities

## Version History

**Introduced in R2016b**