SPICE-compatible diode
Simscape / Electrical / Additional Components / SPICE Semiconductors
The SPICE Diode block represents a SPICE-compatible diode.
SPICE, or Simulation Program with Integrated Circuit Emphasis,
is a simulation tool for electronic circuits. You can convert some SPICE subcircuits into
equivalent Simscape™
Electrical™ models using the Environment Parameters block and
SPICE-compatible blocks from the Additional Components library. For more
information, see subcircuit2ssc
.
Variables for the SPICE Diode block equations include:
Variables that you define by specifying parameters for the SPICE Diode block. The visibility of some of the parameters depends on the value that you set for other parameters. For more information, see Parameters.
Geometry-adjusted variables, which depend on several values that you specify using parameters for the SPICE Diode block. For more information, see Geometry-Adjusted Variables.
Temperature, T, which is 300.15
K
by default. You can use a different value
by specifying parameters for the SPICE
Diode block or by specifying parameters for both the
SPICE Diode block and an
Environment
Parameters block. For more information, see Diode Temperature.
Temperature-dependent variables. For more information, see Temperature Dependence.
Minimal conductance, GMIN, which is
1e–12
1/Ohm
by default. You can use a different
value by specifying a parameter for an Environment
Parameters block. For more information, see Minimal Conduction.
Thermal voltage, Vt. For more information, see Thermal Voltage.
Several variables in the equations for the SPICE diode model consider the geometry of the device that the block represents. These geometry-adjusted variables depend on variables that you define by specifying SPICE Diode block parameters. The geometry-adjusted variables depend on these variables:
AREA — Area of the device
SCALE — Number of parallel connected devices
The associated unadjusted variable
The table includes the geometry-adjusted variables and the defining equations.
Variable | Description | Equation |
---|---|---|
CJOd | Geometry-adjusted zero-bias junction capacitance |
|
IBVd | Geometry-adjusted reverse breakdown current |
|
ISd | Geometry-adjusted saturation current |
|
RSd | Geometry-adjusted series resistance |
|
You can use these options to define diode temperature, T:
Fixed temperature — The block uses a temperature that is
independent from the circuit temperature when the Model
temperature dependence using parameter in the
Temperature settings of the
Spice Diode block is set to
Fixed temperature
. For this model,
the block sets T equal to
TFIXED.
Device temperature — The block uses a temperature that
depends on circuit temperature when the Model temperature
dependence using parameter in the
Temperature settings of the
Spice Diode block is set to
Device temperature
. For this model,
the block defines temperature as
Where:
TC is the circuit temperature.
If there is no Environment Parameters block in the circuit, TC is equal to 300.15 K.
If there is an Environment
Parameters block in the circuit,
TC is
equal to the value that you specify for the
Temperature parameter in the
Spice settings of the
Environment
Parameters block. The default value
for the Temperature parameter is
300.15
K
.
TOFFSET is the offset local circuit temperature.
Minimal conductance, GMIN, has a default value of
1e–12
1/Ohm
. To specify a different value:
If there is not an Environment Parameters block in the diode circuit, add one.
In the Spice settings of the Environment Parameters block, specify the desired GMIN value for the GMIN parameter.
Thermal voltage, Vt, is defined by the equation
Where:
N is the emission coefficient.
T is the diode temperature. For more information, see Diode Temperature.
k is the Boltzmann constant.
q is the elementary charge on an electron.
This table shows the equations that define the relationship between the diode current, Id, and the diode voltage, Vd. As applicable, the model parameters are first adjusted for temperature. For more information, see Temperature Dependence.
Vd Range | Id Equation |
---|---|
|
Where:
ISd is the geometry-adjusted saturation current. For more information, see Geometry-Adjusted Variables.
Vt is thermal voltage. For more information, see Thermal Voltage.
N is the emission coefficient.
q is the elementary charge on an electron.
k is the Boltzmann constant.
T is the diode temperature. For more information, see Diode Temperature.
GMIN is the diode minimum conductance. For more information, see Minimal Conduction.
BV is the reverse breakdown voltage.
The table shows the equations that define the relationship between the diode charge Qd, and the diode voltage, Vd. As applicable, the model parameters are first adjusted for temperature. For more information, see Temperature Dependence.
Vd Range | Qd Equation |
---|---|
Where:
FC is the forward bias depletion capacitance coefficient.
VJ is the junction potential.
TT is the transit time.
CJOd is the geometry-adjusted zero-bias junction capacitance. For more information, see Geometry-Adjusted Variables.
M is the grading coefficient.
The relationship between the geometry-adjusted saturation current and the diode temperature is
Where:
ISd is the geometry-adjusted saturation current. For more information, see Geometry-Adjusted Variables.
T is the diode temperature. For more information, see Diode Temperature.
TMEAS is the parameter extraction temperature.
XTI is the saturation current temperature exponent.
N is the emission coefficient.
EG is the activation energy.
Vt is thermal voltage. For more information, see Thermal Voltage.
The relationship between the junction potential and the diode temperature is
Where:
VJ is the junction potential.
EGTMEAS is the activation energy for the temperature at which the diode parameters were measured. The defining equation is .
EGT is the activation energy for the diode temperature. The defining equation is .
The relationship between the geometry-adjusted diode zero-bias junction capacitance and the diode temperature is
Where:
CJOd is the geometry-adjusted zero-bias junction capacitance. For more information, see Geometry-Adjusted Variables.
M is the grading coefficient.
The block does not support noise analysis.
The block applies initial conditions across junction capacitors and not across the block ports.