P-Channel MOSFET
P-Channel metal oxide semiconductor field-effect transistor using either
Shichman-Hodges equation or surface-potential-based model
Description
The P-Channel MOSFET block provides two main modeling
variants:
Based on threshold voltage — Uses the Shichman-Hodges equation to represent the
device. This modeling approach, based on threshold voltage, has the benefits of simple
parameterization and simple current-voltage expressions. However, these models have difficulty
in accurately capturing transitions across the threshold voltage and lack some important
effects, such as velocity saturation. For details, see Threshold-Based Model.
Based on surface potential — Uses the surface-potential equation to represent the
device. This modeling approach provides a greater level of model fidelity than the simple
square-law (threshold-voltage-based) models can provide. The trade-off is that there are more
parameters that require extraction. For details, see Surface-Potential-Based Model.
Together with the thermal port variants (see Thermal Port),
the block therefore provides you with four choices. To select the desired variant, right-click
the block in your model. From the context menu, select >
, and then one of the following options:
— Basic model, which represents the
device using the Shichman-Hodges equation (based on threshold voltage) and does not simulate
thermal effects. This is the default.
— Model based on threshold
voltage and with exposed thermal port.
— Model based on surface
potential. This model does not simulate thermal effects.
— Thermal variant
of the model based on surface potential.
Threshold-Based Model
The threshold-based variant of the block uses the Shichman and Hodges equations [1] for an insulated-gate field-effect transistor to represent a P-Channel MOSFET.
The drain-source current, IDS, depends on the
region of operation:
In the off region (–VGS <
–Vth) the drain-source current is:
In the linear region (0 < –VDS <
–VGS
+Vth) the drain-source current is:
In the saturated region (0 < –VGS
+Vth <
–VDS) the drain-source current is:
In the preceding equations:
K is the transistor gain.
VDS is the negative drain-source
voltage.
VGS is the gate-source voltage.
Vth is the threshold voltage. For the
four terminal parameterization, Vth is
obtained using these equations:
VBS
Range | Vth
Equation |
---|
| |
| |
| |
λ is the channel modulation.
Charge Model for Threshold-Based Variant
The block models junction capacitances either by fixed capacitance values, or by tabulated
values as a function of the drain-source voltage. In either case, you can either directly
specify the gate-source and gate-drain junction capacitance values, or let the block derive them
from the input and reverse transfer capacitance values. Therefore, the
Parameterization options for charge model on the Junction
Capacitance tab are:
Specify fixed input, reverse transfer and output capacitance
— Provide fixed parameter values from datasheet and let the block convert the input and
reverse transfer capacitance values to junction capacitance values, as described below. This
is the default method.
Specify fixed gate-source, gate-drain and drain-source
capacitance
— Provide fixed values for junction capacitance parameters
directly.
Specify tabulated input, reverse transfer and output
capacitance
— Provide tabulated capacitance and drain-source voltage
values based on datasheet plots. The block converts the input and reverse transfer capacitance
values to junction capacitance values, as described below.
Specify tabulated gate-source, gate-drain and drain-source
capacitance
— Provide tabulated values for junction capacitances and
drain-source voltage.
Use one of the tabulated capacitance options (Specify tabulated input, reverse
transfer and output capacitance
or Specify tabulated gate-source,
gate-drain and drain-source capacitance
) when the datasheet provides a plot of
junction capacitances as a function of drain-source voltage. Using tabulated capacitance values
gives more accurate dynamic characteristics and avoids the need for iterative tuning of
parameters to fit the dynamics.
If you use the Specify fixed gate-source, gate-drain and drain-source
capacitance
or Specify tabulated gate-source, gate-drain and
drain-source capacitance
option, the Junction Capacitance
tab lets you specify the Gate-drain junction capacitance,
Gate-source junction capacitance, and Drain-source junction
capacitance parameter values (fixed or tabulated) directly. Otherwise, the block
derives them from the Input capacitance, Ciss, Reverse transfer
capacitance, Crss, and Output capacitance, Coss parameter
values. These two parameterization methods are related as follows:
CGD = Crss
CGS = Ciss –
Crss
CDS = Coss –
Crss
For the four terminals parameterization, the Input capacitance,
Ciss, Reverse transfer capacitance, Crss, and
Output capacitance, Coss are obtained using these equations:
CGD = Crss
CGS +
CGB = Ciss –
Crss
CDB = Coss –
Crss
A simplified Meyer's capacitance model is used to describe the gate-source capacitance,
CGS, the gate-bulk capacitance,
CGB, and the gate-drain capacitance,
CGD. These figures show how the gate-bulk and
gate-source capacitances change instantaneously, while the
Gate-bulk and gate-source capacitance change instantaneously.
The two fixed capacitance options (Specify fixed input, reverse transfer and
output capacitance
or Specify fixed gate-source, gate-drain and
drain-source capacitance
) let you model gate junction capacitance as a fixed
gate-source capacitance CGS and either a fixed or
a nonlinear gate-drain capacitance CGD. If you
select the Gate-drain charge function is nonlinear
option for the
Gate-drain charge-voltage linearity parameter, then the gate-drain
charge relationship is defined by the piecewise-linear function shown in the following
figure.
For instructions on how to map a time response to device capacitance values, see the
N-Channel IGBT block reference page. However, this mapping is only approximate
because the Miller voltage typically varies more from the threshold voltage than in the case for
the IGBT.
Note
Because this block implementation includes a charge model, you must model the impedance of
the circuit driving the gate to obtain representative turn-on and turn-off dynamics. Therefore,
if you are simplifying the gate drive circuit by representing it as a controlled voltage
source, you must include a suitable series resistor between the voltage source and the
gate.
Surface-Potential-Based Model
The surface-potential-based variant of the block provides a greater level of model fidelity
than the simple square-law (threshold-voltage-based) model. The surface-potential-based block
variant includes the following effects:
Fully nonlinear capacitance model (including the nonlinear Miller capacitance)
Charge conservation inside the model, so you can use the model for charge sensitive
simulations
Velocity saturation and channel-length modulation
The intrinsic body diode
Reverse recovery in the body diode model
Temperature scaling of physical parameters
For the thermal variant, dynamic self-heating (that is, you can simulate the effect of
self-heating on the electrical characteristics of the device)
This model is a minimal version of the world-standard PSP model (see https://briefs.techconnect.org/papers/introduction-to-psp-mosfet-model/),
including only certain effects from the PSP model to strike a balance between model fidelity and
complexity. For details of the physical background to the phenomena included in this model, see
[2].
The surface-potential equation is derived similar to the way described on the
N-Channel MOSFET block reference page, with all voltages, charges, and
currents multiplied by -1.
The overall model consists of an intrinsic MOSFET defined by the surface-potential
formulation, a body diode, series resistances, and fixed overlap capacitances, as shown in the
schematic.
Modeling Body Diode
The block models the body diode as an ideal, exponential diode with both junction and
diffusion capacitances:
where:
Idio is the current through the diode.
Is is the reverse saturation current.
VBD is the body-drain voltage.
n is the ideality factor.
ϕT is the thermal voltage.
Cj is the junction capacitance of the
diode.
Cj0 is the zero-bias junction
capacitance.
Vbi is the built-in voltage.
Cdiff is the diffusion capacitance of the
diode.
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.
Threshold-Based Model
For threshold-based variant, you can include modeling the dependence of the transistor
static behavior on temperature during simulation. Temperature dependence of the junction
capacitances is not modeled, this being a much smaller effect.
When including temperature dependence, the transistor defining equations remain the same.
The gain, K, and the threshold voltage,
Vth, become a function of temperature according to
the following equations:
Vths =
Vth1 + α (
Ts – Tm1)
where:
Tm1 is the temperature at which the transistor
parameters are specified, as defined by the Measurement temperature
parameter value.
Ts is the simulation temperature.
KTm1 is the transistor gain at the measurement
temperature.
KTs is the transistor gain at the simulation
temperature. This is the transistor gain value used in the MOSFET equations when temperature
dependence is modeled.
Vth1 is the threshold voltage at the
measurement temperature.
Vths is the threshold voltage at the
simulation temperature. This is the threshold voltage value used in the MOSFET equations when
temperature dependence is modeled.
BEX is the mobility temperature exponent. A typical value of
BEX is -1.5.
α is the gate threshold voltage temperature coefficient,
dVth/dT.
For the four terminals parameterization, Vth
is obtained using these equations:
VBS Range | Vth Equation |
---|
| |
| |
| |
Where:
is the surface potential and .
Eg(0) is the extrapolated zero degree
band-gap, which is equal to 1.16
eV
for silicon.
VBS is the bulk-source voltage.
For most MOSFETS, you can use the default value of -1.5
for
BEX. Some datasheets quote the value for α, but most
typically they provide the temperature dependence for drain-source on resistance,
RDS(on). Depending on the block parameterization
method, you have two ways of specifying α:
If you parameterize the block from a datasheet, you have to provide
RDS(on) at a second measurement temperature. The
block then calculates the value for α based on this data.
If you parameterize by specifying equation parameters, you have to provide the value for
α directly.
If you have more data comprising drain current as a function of gate-source voltage for
more than one temperature, then you can also use Simulink®
Design Optimization™ software to help tune the values for α and
BEX.
Surface-Potential-Based Model
The surface-potential-based 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 Tm1 at which the other
device parameters have been extracted. The Temperature Dependence tab
provides the simulation temperature, Ts, and the
temperature-scaling coefficients for the other device parameters. For more information, see
Temperature Dependence (Surface-Potential-Based Variant).
Thermal Port
The block has an optional thermal port, hidden by default. To
expose the thermal port, right-click the block in your model, and
select the appropriate block variant:
For a model based on threshold voltage and with exposed
thermal port, select > > .
For a thermal variant of the model based on surface
potential, select > > .
This action displays the thermal port H on the block icon, and exposes
the Thermal Port parameters.
Use the thermal port to simulate the effects of generated heat and device temperature. For
more information on using thermal ports and on the Thermal Port
parameters, see Simulating Thermal Effects in Semiconductors.
Assumptions and Limitations
When modeling temperature dependence for threshold-based block variant, consider the
following:
The block does not account for temperature-dependent effects on the junction
capacitances.
When you specify RDS(on) at a second measurement
temperature, it must be quoted for the same working point (that is, the same drain current and
gate-source voltage) as for the other RDS(on) value.
Inconsistent values for RDS(on) at the higher
temperature will result in unphysical values for α and unrepresentative
simulation results. Typically RDS(on) increases by a
factor of about 1.5 for a hundred degree increase in temperature.
You may need to tune the values of BEX and threshold voltage,
Vth, to replicate the
IDS–VGS
relationship (if available) for a given device. Increasing
Vth moves the
IDS–VGS
plots to the right. The value of BEX affects whether the
IDS–VGS
curves for different temperatures cross each other, or not, for the ranges of
VDS and
VGS considered. Therefore, an inappropriate value
can result in the different temperature curves appearing to be reordered. Quoting
RDS(on) values for higher currents, preferably
close to the current at which it will operate in your circuit, will reduce sensitivity to the
precise value of BEX.
Ports
Conserving
expand all
G
— Gate terminal
electrical
Electrical conserving port associated with the transistor gate terminal
D
— Drain terminal
electrical
Electrical conserving port associated with the transistor drain terminal
S
— Source terminal
electrical
Electrical conserving port associated with the transistor source terminal
B
— Body terminal
electrical
Electrical conserving port associated with the transistor body terminal
Dependencies
To enable this port, set Number of terminals to
Four
.
Parameters
expand all
Main (Threshold-Based Variant)
This configuration of the Main tab corresponds to the threshold-based
block variant, which is the default. If you are using the surface-potential-based variant of the
block, see Main (Surface-Potential-Based Variant).
Number of terminals
— Terminal parameterization
Three
(default) | Four
Number of terminals of the block.
Parameterization
— Block parameterization
Specify from a datasheet
(default) | Specify using equation parameters directly
Select one of the following methods for block parameterization:
Specify from a datasheet
— Provide the
drain-source on resistance and the corresponding drain current and gate-source
voltage. The block calculates the transistor gain for the Shichman and Hodges
equations from this information. This is the default method.
Specify using equation parameters directly
— Provide the transistor gain.
Drain-source on resistance, R_DS(on)
— Drain-source on resistance
0.167
Ohm
(default)
The ratio of the drain-source voltage to the drain current for specified values of drain
current and gate-source voltage. RDS(on) should
have a positive value.
Dependencies
This parameter is visible only when you select Specify from a
datasheet
for the Parameterization
parameter.
Drain current, Ids, for R_DS(on)
— Drain current, Ids, for R_DS(on)
-2.5
A
(default)
The drain current the block uses to calculate the value of the drain-source resistance.
IDS should have a negative value.
Dependencies
This parameter is visible only when you select Specify from a
datasheet
for the Parameterization
parameter.
Gate-source voltage, Vgs, for R_DS(on)
— Gate-source voltage, Vgs, for R_DS(on)
-4.5
V
(default)
The gate-source voltage the block uses to calculate the value of the drain-source
resistance. VGS should have a negative
value.
Dependencies
This parameter is visible only when you select Specify from a
datasheet
for the Parameterization
parameter.
Gain, K
— Gain, K
2
A/V2
(default)
Positive constant gain coefficient for the Shichman and Hodges equations.
Dependencies
To enable this parameter, set Parameterization to
Specify using equation parameters directly
.
Gate-source threshold voltage, Vth
— Gate-source threshold voltage
-1.4
V
(default)
Gate-source threshold voltage Vth in the
Shichman and Hodges equations. For an enhancement device,
Vth should be negative. For a depletion mode
device, Vth should be positive.
Dependencies
To enable this parameter, set Terminals to
Three
.
Gate-source threshold voltage at zero bulk-source voltage, Vth0
— Gate-source threshold voltage at zero bulk-source voltage
-1.4
V
(default)
Gate-source threshold voltage at zero bulk-source voltage
Vth0 in the Shichman and Hodges
equations.
Dependencies
To enable this parameter, set Terminals to
Four
.
Channel modulation, L
— Channel modulation
0
1/V
(default)
The channel-length modulation, usually denoted by the mathematical symbol λ. When in the
saturated region, it is minus the rate of change of drain current with drain-source voltage.
The effect on drain current is typically small, and the effect is neglected if calculating
transistor gain K from drain-source on-resistance,
RDS(on). A typical value is 0.02, but the effect
can be ignored in most circuit simulations. However, in some circuits a small nonzero value
may help numerical convergence.
Gate-source threshold voltage at first non-zero bulk-source voltage, Vth1
— Gate-source threshold voltage at first non-zero bulk-source voltage
-1.6071
V
(default)
Gate-source threshold voltage at first non-zero bulk-source voltage
Vth1 in the Shichman and Hodges
equations.
Dependencies
To enable this parameter, set:
First bulk-source voltage, Vbs1
— First bulk-source voltage
1
V
(default)
First bulk-source voltage, Vbs1
Dependencies
To enable this parameter, set:
Gate-source threshold voltage at second non-zero bulk-source voltage, Vth2
— Gate-source threshold voltage at second non-zero bulk-source voltage
-1.7660
V
(default)
Gate-source threshold voltage at second non-zero bulk-source voltage
Vth2 in the Shichman and Hodges
equations.
Dependencies
To enable this parameter, set:
Second bulk-source voltage, Vbs2
— Second bulk-source voltage
2
V
(default)
Second bulk-source voltage, Vbs2
Dependencies
To enable this parameter, set:
Body factor
— Body factor
0.5
V^0.50000
(default)
Body factor, γ.
Dependencies
To enable this parameter, set:
Surface potential
— Surface potential
0.5
V
(default)
Surface potential
Dependencies
To enable this parameter, set:
Measurement temperature
— Measurement temperature
25
degC
(default)
Temperature Tm1 at which
Drain-source on resistance, R_DS(on) is measured.
Main (Surface-Potential-Based Variant)
This configuration of the Main tab corresponds to the
surface-potential-based block variant. If you are using the threshold-based variant of the
block, based on the Shichman and Hodges equations, see Main (Threshold-Based Variant).
Number of terminals
— Terminal parameterization
Three
(default) | Four
Number of terminals of the block.
Gain
— Gain
18
A/V2
(default)
The MOSFET gain, β. This parameter primarily defines the linear
region of operation on an
ID–VDS
characteristic.
Flatband voltage
— Flatband voltage
-1.1
V
(default)
The flatband voltage, VFB, defines the gate
bias that must be applied in order to achieve the flatband condition at the surface of the
silicon. You can also use this parameter to arbitrarily shift the threshold voltage due to
material work function differences, and to trapped interface or oxide charges. In practice,
however, it is usually recommended to modify the threshold voltage by using the
Body factor and Surface potential at strong
inversion parameters first, and only use this parameter for fine-tuning.
Body factor
— Body factor
3.5
V1/2
(default)
Body factor, γ, in the surface-potential equation. This parameter
primarily impacts the threshold voltage.
Surface potential at strong inversion
— Surface potential at strong inversion
1
V
(default)
The 2ϕB term in the surface-potential
equation. This parameter also primarily impacts the threshold voltage.
Velocity saturation factor
— Velocity saturation factor
0.4
1/V
(default)
Velocity saturation, θsat, in the
drain-current equation. Use this parameter in cases where a good fit to linear operation
leads to a saturation current that is too high. By increasing this parameter value, you
reduce the saturation current. For high-voltage devices, it is often the case that a good fit
to linear operation leads to a saturation current that is too low. In such a case, either
increase both the gain and the drain ohmic resistance or use a P-Channel
LDMOS FET block instead.
Channel-length modulation factor
— Channel-length modulation factor
0
(default)
The factor, α, multiplying the logarithmic term in the
GΔL equation. This parameter describes the onset
of channel-length modulation. For device characteristics that exhibit a positive conductance
in saturation, increase the parameter value to fit this behavior. The default value is
0
, which means that channel-length modulation is off by default.
Channel-length modulation voltage
— Channel-length modulation voltage
5e-2
V
(default)
The voltage Vp in the
GΔL equation. This parameter controls the
drain-voltage at which channel-length modulation starts to become active.
Surface roughness scattering factor
— Surface roughness scattering factor
0
1/V
(default)
Indicates the strength of the mobility reduction. The mobility is μ =
μ/Gmob, where μ0 is the low-field
mobility without the effect of surface scattering. The mobility reduction factor,
Gmob, is given by 0, where
θsr is the surface roughness scattering factor and
Veff is a voltage that is indicative of the
effective vertical electric field strength in the channel,
Eeff. For high vertical electric fields, the
mobility is roughly proportional to Eeff for
holes.
Linear-to-saturation transition coefficient
— Linear-to-saturation transition coefficient
8
(default)
This parameter controls how smoothly the MOSFET transitions from linear into saturation,
particularly when velocity saturation is enabled. This parameter can usually be left at its
default value, but you can use it to fine-tune the knee of the
ID–VDS
characteristic. The expected range for this parameter value is between 2 and 8.
Measurement temperature
— Measurement temperature
25
degC
(default)
Temperature Tm1 at which the block parameters
are measured. If the Device simulation temperature parameter on the
Temperature Dependence tab differs from this value, then device
parameters will be scaled from their defined values according to the simulation and reference
temperatures. For more information, see Temperature Dependence (Surface-Potential-Based Variant).
Ohmic Resistance
Source ohmic resistance
— Source ohmic resistance
1e-4
Ohm
(default) | nonnegative scalar
The transistor source resistance, that is, the series resistance associated with the
source contact. The value must be greater than or equal to 0
. The default
value for threshold-based variants is 1e-4
Ohm. The default value for
surface-potential-based variants is 2e-3
Ohm.
Drain ohmic resistance
— Drain ohmic resistance
0.01
Ohm
(default) | nonnegative scalar
The transistor drain resistance, that is, the series resistance associated with the
drain contact. The value must be greater than or equal to 0
. The default
value for threshold-based variants is 0.01
Ohm. The default value for
surface-potential-based variants is 0.17
Ohm.
Gate ohmic resistance
— Gate ohmic resistance
8.4
Ohm
(default) | nonnegative scalar
The transistor gate resistance, that is, the series resistance associated with the gate
contact. The value must be greater than or equal to 0
.
Dependencies
This parameter is visible only for the surface-potential-based block variants.
Body ohmic resistance
— Transistor body resistance
0.001
Ohm
(default) | nonnegative scalar
The transistor body resistance, that is, the series resistance associated with the
body contact.
Dependencies
To enable this parameter, set:
Bulk ohmic resistance
— Transistor bulk resistance
2e-3
Ohm
(default) | nonnegative scalar
The transistor body resistance, that is, the series resistance associated with the
bulk contact.
Dependencies
To enable this parameter, set:
Junction Capacitance
This tab is visible only for the threshold-based variant of the block.
Parameterization
— Junction capacitance parameterization
Specify fixed input, reverse transfer and output
capacitance
(default) | Specify fixed gate-source, gate-drain and drain-source
capacitance
| Specify tabulated input, reverse transfer and output
capacitance
| Specify tabulated gate-source, gate-drain and drain-source
capacitance
Select one of the following methods for capacitance parameterization:
Specify fixed input, reverse transfer and output
capacitance
— Provide fixed parameter values from datasheet and let
the block convert the input, output, and reverse transfer capacitance values to junction
capacitance values, as described in Charge Model for Threshold-Based Variant. This is the default method.
Specify fixed gate-source, gate-drain and drain-source
capacitance
— Provide fixed values for junction capacitance
parameters directly.
Specify tabulated input, reverse transfer and output
capacitance
— Provide tabulated capacitance and source-drain voltage
values based on datasheet plots. The block converts the input, output, and reverse
transfer capacitance values to junction capacitance values, as described in Charge Model for Threshold-Based Variant.
Specify tabulated gate-source, gate-drain and drain-source
capacitance
— Provide tabulated values for junction capacitances and
source-drain voltage.
Input capacitance, Ciss
— Input capacitance
182
pF
(default) | [225 210 200 185 175 170]
The gate-source capacitance with the drain shorted to the source.
Dependencies
This parameter is visible only when you select one of these options for the parameter
in the Junction Capacitance settings:
Specify fixed input, reverse transfer and output
capacitance
- If you select this setting for the parameter, specify the
input capacitance as a scalar. The default value is 182
pF
.
Specify tabulated input, reverse transfer and output
capacitance
- If you select this setting for the Parameterization parameter, specify the input capacitance as a vector. The
default value is [225 210 200 185 175 170]
pF
Reverse transfer capacitance, Crss
— Reverse transfer capacitance
24
pF
(default) | [75 60 50 35 25 20]
pF
The drain-gate capacitance with the source connected to ground.
Dependencies
This parameter is visible only when you select one of these options for the parameter
in the Junction Capacitance settings:
Specify fixed input, reverse transfer and output
capacitance
- If you select this setting for the parameter, specify the
input capacitance as a scalar. The default value is 24
pF
.
Specify tabulated input, reverse transfer and output
capacitance
- If you select this setting for the Parameterization parameter, specify the input capacitance as a vector. The
default value is [75 60 50 35 25 20]
pF
Output capacitance, Coss
— Output capacitance
0
pF
(default) | [180 160 125 80 60 45]
pF
The drain-source capacitance with the gate and source shorted.
Dependencies
This parameter is visible only when you select one of these options for the parameter
in the Junction Capacitance settings:
Specify fixed input, reverse transfer and output
capacitance
- If you select this setting for the parameter, specify the
input capacitance as a scalar. The default value is 0
pF
.
Specify tabulated input, reverse transfer and output
capacitance
- If you select this setting for the Parameterization parameter, specify the input capacitance as a vector. The
default value is [180 160 125 80 60 45]
pF
Gate-source junction capacitance
— Gate-source junction capacitance
158
pF
(default) | [150 150 150 150 150 150]
pF
The value of the capacitance placed between the gate and the source.
Dependencies
This parameter is visible only when you select one of these options for the parameter
in the Junction Capacitance settings:
Specify fixed gate-source, gate-drain and drain-source
capacitance
- If you select this setting for the parameter, specify the
input capacitance as a scalar. The default value is 158
pF
.
Specify tabulated gate-source, gate-drain and drain-source
capacitance
- If you select this setting for the Parameterization parameter, specify the input capacitance as a vector. The
default value is [150 150 150 150 150 150]
pF
Gate-drain junction capacitance
— Gate-drain junction capacitance
24
pF
(default) | [75 60 50 35 25 20]
pF
The value of the capacitance placed between the gate and the drain.
Dependencies
This parameter is visible only when you select one of these options for the parameter
in the Junction Capacitance settings:
Specify fixed gate-source, gate-drain and drain-source
capacitance
- If you select this setting for the parameter, specify the
input capacitance as a scalar. The default value is 24
pF
.
Specify tabulated gate-source, gate-drain and drain-source
capacitance
- If you select this setting for the Parameterization parameter, specify the input capacitance as a vector. The
default value is [75 60 50 35 25 20]
pF
Drain-source junction capacitance
— Drain-source junction capacitance
0
pF
(default) | [105 100 75 45 35 25]
pF
The value of the capacitance placed between the drain and the source.
Dependencies
This parameter is visible only when you select one of these options for the parameter
in the Junction Capacitance settings:
Specify fixed gate-source, gate-drain and drain-source
capacitance
- If you select this setting for the parameter, specify the
input capacitance as a scalar. The default value is 0
pF
.
Specify tabulated gate-source, gate-drain and drain-source
capacitance
- If you select this setting for the Parameterization parameter, specify the input capacitance as a vector. The
default value is [105 100 75 45 35 25]
pF
Corresponding source-drain voltages
— Corresponding source-drain voltages
[0.1 0.3 1 3 10 30]
V
(default)
The source-drain voltages corresponding to the tabulated capacitance values.
Dependencies
This parameter is visible only when the Parameterization
parameter, in the Junction capacitance tab, is set to
Specify tabulated input, reverse transfer and output capacitance
or to Specify tabulated gate-source, gate-drain and output
capacitance
.
Gate-source voltage, Vgs, for tabulated capacitances
— Gate-source voltage, Vgs, for tabulated capacitances
0
V
(default)
For tabulated capacitance models, this parameter controls the voltage dependence of the
Reverse transfer capacitance, Crss or the Gate-drain junction
capacitance parameter (depending on the selected parameterization option). These
capacitances are a function of the drain-gate voltage. The block calculates drain-gate
voltages by subtracting this gate-source voltage value from the negative of the values
specified for the Corresponding source-drain voltages parameter (Vdg = –Vsd –
Vgs).
Dependencies
This parameter is visible only when the Parameterization
parameter, in the Junction capacitance tab, is set to
Specify tabulated input, reverse transfer and output capacitance
or to Specify tabulated gate-source, gate-drain and output
capacitance
.
Gate-drain charge-voltage linearity
— Gate-drain charge-voltage linearity
Gate-drain capacitance is constant
(default) | Gate-drain charge function is nonlinear
The two fixed capacitance options let you model gate junction capacitance as a
fixed gate-source capacitance CGS and either
a fixed or a nonlinear gate-drain capacitance
CGD. Select whether the gate-drain
capacitance is fixed or nonlinear:
Gate-drain capacitance is constant
— The
capacitance value is constant and defined according to the selected
parameterization option, either directly or derived from a datasheet. This is
the default method.
Gate-drain charge function is nonlinear
—
The gate-drain charge relationship is defined according to the
piecewise-nonlinear function described in Charge Model for Threshold-Based Variant. Two additional parameters appear to let you define the
gate-drain charge function.
Dependencies
This parameter is visible only when the Parameterization
parameter, in the Junction capacitance tab, is set to
Specify fixed input, reverse transfer and output
capacitance
or to Specify fixed gate-source, gate-drain
and drain-source capacitance
.
Gate-drain oxide capacitance
— Gate-drain oxide capacitance
200
pF
(default)
The gate-drain capacitance when the drain-gate voltage is less than the
Drain-gate voltage at which oxide capacitance becomes active parameter
value.
Dependencies
This parameter is visible only when the Gate-drain charge-voltage
linearity parameter is set to Gate-drain charge function
is nonlinear
.
Drain-gate voltage at which oxide capacitance becomes active
— Drain-gate voltage at which oxide capacitance becomes active
0.5
V
(default)
The drain-gate voltage at which the drain-gate capacitance switches between off-state
(CGD) and on-state
(Cox) capacitance values.
Dependencies
This parameter is visible only when the Gate-drain charge-voltage
linearity parameter is set to Gate-drain charge function
is nonlinear
.
Gate-bulk and gate-source charge-voltage linearity
— Gate-bulk and gate-source charge-voltage linearity
Gate-bulk and gate-source capacitance change
instantly
(default) | Gate-bulk and gate-source capacitance change
gradually
Gate-bulk and gate-source charge-voltage linearity.
Dependencies
This parameter is visible only when the Number of terminals
parameter, in the Main tab, is set to
Four
.
Channel Capacitances
This tab is visible only for the surface-potential-based variant of the block.
Oxide capacitance
— Oxide capacitance
1500
pF
(default)
The parallel plate gate-channel capacitance.
Gate-source overlap capacitance
— Gate-source overlap capacitance
100
pF
(default)
The fixed, linear capacitance associated with the overlap of the gate electrode with the
source well.
Gate-drain overlap capacitance
— Gate-drain overlap capacitance
14
pF
(default)
The fixed, linear capacitance associated with the overlap of the gate electrode with the
drain well.
Body Diode
Reverse saturation current
— Reverse saturation current
0
A
(default) | 5.2e-13
A
The current designated by the Is symbol in the
body-diode equations.
To enable conduction through the body diode, for applications where the MOSFET
current changes sign during the simulation, such as when the MOSFET is driving an
inductive load, set this parameter to a non-zero value.
For applications where the MOSFET current never changes sign, such as in a
small-signal amplifier, set this parameter to 0 to improve simulation speed.
Dependencies
The default value for this parameter depends on the chosen variant for this block:
Threshold-Based Variant - If you select this variant, the default value is
0
A
.
Surface-Potential-Based Variant - If you select this variant, the default value is
5.2e-13
A
.
Built-in voltage
— Built-in voltage
0.6
V
(default)
The built-in voltage of the diode, designated by the
Vbi symbol in the body-diode equations. Built-in
voltage has an impact only on the junction capacitance equation. It does not affect the
conduction current.
Ideality factor
— Ideality factor
1
(default)
The factor designated by the n symbol in the body-diode
equations.
Zero-bias junction capacitance
— Zero-bias junction capacitance
0
pF
(default) | 480
pF
The capacitance between the drain and bulk contacts at zero-bias due to the body diode
alone. It is designated by the Cj0 symbol in the
body-diode equations.
Dependencies
The default value for this parameter depends on the chosen variant for this block:
Threshold-Based Variant - If you select this variant, the default value is
0
pF
.
Surface-Potential-Based Variant - If you select this variant, the default value is
480
pF
.
Transit time
— Transit time
50e-9
s
(default)
The time designated by the τ symbol in the body-diode
equations
When the Reverse saturation current and Transit
time parameters are both non-zero, this block includes the reverse
recovery inside the body diode model.
Temperature Dependence (Threshold-Based Variant)
This configuration of the Temperature Dependence tab corresponds to
the threshold-based block variant, which is the default. If you are using the
surface-potential-based variant of the block, see Temperature Dependence (Surface-Potential-Based Variant)
Parameterization
— Temperature dependence parameterization
None — Simulate at parameter measurement
temperature
(default) | Model temperature dependence
Select one of the following methods for temperature dependence parameterization:
None — Simulate at parameter measurement
temperature
— Temperature dependence is not modeled. This is the
default method.
Model temperature dependence
— Model
temperature-dependent effects. Provide a value for simulation temperature,
Ts, a value for BEX, and a
value for the measurement temperature Tm1 (using
the Measurement temperature parameter on the
Main tab). You also have to provide a value for α
using one of two methods, depending on the value of the
Parameterization parameter on the Main tab. If
you parameterize the block from a datasheet, you have to provide
RDS(on) at a second measurement temperature,
and the block will calculate α based on that. If you parameterize by
specifying equation parameters, you have to provide the value for α
directly.
Drain-source on resistance, R_DS(on), at second measurement temperature
— Drain-source on resistance, R_DS(on), at second measurement temperature
0.25
Ohm
(default)
The ratio of the drain-source voltage to the drain current for specified values of drain
current and gate-source voltage at second measurement temperature. It must be quoted for the
same working point (drain current and gate-source voltage) as the Drain-source on
resistance, R_DS(on) parameter on the Main tab.
Dependencies
This parameter is visible only when you select Specify from a
datasheet
for the Parameterization parameter on the
Main tab.
Second measurement temperature
— Second measurement temperature
125
degC
(default)
Second temperature Tm2 at which
Drain-source on resistance, R_DS(on), at second measurement temperature
is measured.
Dependencies
This parameter is visible only when you select Specify from a
datasheet
for the Parameterization parameter on the
Main tab.
Gate threshold voltage temperature coefficient, dVth/dT
— Gate threshold voltage temperature coefficient, dVth/dT
2
mV/K
(default)
The rate of change of gate threshold voltage with temperature.
Dependencies
This parameter is visible only when you select Specify using equation
parameters directly
for the Parameterization parameter
on the Main tab.
Mobility temperature exponent, BEX
— Mobility temperature exponent
-1.5
(default)
Mobility temperature coefficient value. You can use the default value for most MOSFETs.
See the Assumptions and Limitations section for additional considerations.
Body diode reverse saturation current temperature exponent
— Body diode reverse saturation current temperature exponent
3
(default)
The reverse saturation current for the body diode is assumed to be proportional to the
square of the intrinsic carrier concentration, ni =
NC
exp(–EG/2kBT). NC is the temperature-dependent
effective density of states and EG is the
temperature-dependent bandgap for the semiconductor material. To avoid introducing another
temperature-scaling parameter, the block neglects the temperature dependence of the bandgap
and uses the bandgap of silicon at 300K (1.12eV) for all device types. Therefore, the
temperature-scaled reverse saturation current is given by
Is,m1 is the value of the Reverse
saturation current parameter from the Body Diode
tab, kB is Boltzmann’s constant
(8.617x10-5eV/K), and
ηIs is the Body diode reverse
saturation current temperature exponent. The default value is
3
, because NC for
silicon is roughly proportional to T3/2. You can remedy the
effect of neglecting the temperature-dependence of the bandgap by a pragmatic choice
of ηIs.
Device simulation temperature
— Device simulation temperature
25
degC
(default)
Temperature Ts at which the device is
simulated.
Temperature Dependence (Surface-Potential-Based Variant)
This configuration of the Temperature Dependence tab corresponds to
the surface-potential-based block variant. If you are using the threshold-based variant of the
block, see Temperature Dependence (Threshold-Based Variant)
Parameterization
— Temperature dependence parameterization
None — Simulate at parameter measurement
temperature
(default) | Model temperature dependence
Select one of the following methods for temperature dependence parameterization:
None — Simulate at parameter measurement
temperature
— Temperature dependence is not modeled. This is the
default method.
Model temperature dependence
— Model
temperature-dependent effects. Provide a value for the device simulation temperature,
Ts, and the temperature-scaling coefficients
for other block parameters.
Gain temperature exponent
— Gain temperature exponent
1.3
(default)
The MOSFET gain, β, is assumed to scale exponentially with
temperature, β = βm1
(Tm1/Ts)^ηβ. βm1 is the value of the
Gain parameter from the Main tab and
ηβ is the Gain temperature
exponent.
Dependencies
This parameter is visible only when you select Model temperature
dependence
for the Parameterization parameter.
Flatband voltage temperature coefficient
— Flatband voltage temperature coefficient
5e-4
V/K
(default)
The flatband voltage, VFB, is assumed to scale
linearly with temperature, VFB =
VFBm1 +
(Ts –
Tm1)ST,VFB. VFBm1 is the value of the
Flatband voltage parameter from the Main tab and
ST,VFB is the
Flatband voltage temperature coefficient.
Dependencies
This parameter is visible only when you select Model temperature
dependence
for the Parameterization parameter.
Surface potential at strong inversion temperature coefficient
— Surface potential at strong inversion temperature coefficient
-8.5e-4
V/K
(default)
The surface potential at strong inversion,
2ϕB, is assumed to scale linearly with temperature, 2ϕB =
2ϕBm1 +
(Ts –
Tm1)ST,ϕB. 2ϕBm1 is the value of the
Surface potential at strong inversion parameter from the
Main tab and
ST,ϕB is the
Surface potential at strong inversion temperature coefficient.
Dependencies
This parameter is visible only when you select Model temperature
dependence
for the Parameterization parameter.
Velocity saturation temperature exponent
— Velocity saturation temperature exponent
1.04
(default)
The velocity saturation, θsat, is assumed to
scale exponentially with temperature, θsat =
θsat,m1
(Tm1/Ts)^ηθ. θsat,m1 is the value of the
Velocity saturation factor parameter from the Main
tab and ηθ is the Velocity saturation
temperature exponent.
Dependencies
This parameter is visible only when you select Model temperature
dependence
for the Parameterization parameter.
Surface roughness scattering temperature exponent
— Surface roughness scattering temperature exponent
0.65
(default)
This parameter leads to a temperature-dependent reduction in the MOSFET transconductance
at high gate voltage. The surface roughness scattering,
θsr, is assumed to scale exponentially with
temperature, θsr =
θsr,m1
(Tm1/Ts)^ηsr. θsr,m1 is the value of the
Surface roughness scattering factor parameter from the
Main tab and ηsr is the
Surface roughness scattering temperature exponent.
Dependencies
This parameter is visible only when you select Model temperature
dependence
for the Parameterization parameter.
Resistance temperature exponent
— Resistance temperature exponent
0.95
(default)
The series resistances are assumed to correspond to semiconductor resistances.
Therefore, they decrease exponentially with increasing temperature. Ri =
Ri,m1
(Tm1/Ts)^ηR, where i is S, D, or G, for the source, drain, or gate
series resistance, respectively. Ri,m1 is the value
of the corresponding series resistance parameter from the Ohmic
Resistance tab and ηR is the
Resistance temperature exponent.
Dependencies
This parameter is visible only when you select Model temperature
dependence
for the Parameterization parameter.
Body diode reverse saturation current temperature exponent
— Body diode reverse saturation current temperature exponent
3
(default)
The reverse saturation current for the body diode is assumed to be proportional to the
square of the intrinsic carrier concentration, ni =
NC
exp(–EG/2kBT). NC is the temperature-dependent
effective density of states and EG is the
temperature-dependent bandgap for the semiconductor material. To avoid introducing another
temperature-scaling parameter, the block neglects the temperature dependence of the bandgap
and uses the bandgap of silicon at 300K (1.12eV) for all device types. Therefore, the
temperature-scaled reverse saturation current is given by
Is,m1 is the value of the Reverse
saturation current parameter from the Body Diode
tab, kB is Boltzmann’s constant
(8.617x10-5eV/K), and
ηIs is the Body diode reverse
saturation current temperature exponent. The default value is
3
, because NC for
silicon is roughly proportional to T3/2. You can remedy the
effect of neglecting the temperature-dependence of the bandgap by a pragmatic choice
of ηIs.
Dependencies
This parameter is visible only when you select Model temperature
dependence
for the Parameterization parameter.
Device simulation temperature
— Device simulation temperature
25
degC
(default)
Temperature Ts at which the device is
simulated.
Dependencies
This parameter is visible only when you select Model temperature
dependence
for the Parameterization parameter.
References
[1] Shichman, H. and D. A. Hodges. “Modeling and simulation of
insulated-gate field-effect transistor switching circuits.” IEEE J. Solid State
Circuits. SC-3, 1968.
[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
C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.
Introduced in R2008a