Engee documentation

SPICE Diode

SPICE diode.

spice diode

Description

The SPICE Diode unit is a diode compatible with the SPICE model.

SPICE is a simulation tool for electronic circuits. You can convert some SPICE subcircuits into equivalent models using the block Environment Parameters and blocks from the SPICE library.

Equations

Variables for the SPICE Diode block equations include:

  • Variables that you define when you set parameters for the SPICE Diode block. The visibility of some parameters depends on the value you set for other parameters. See Parameters for more information.

  • Geometry-corrected variables that depend on several values you have set using the parameters in the SPICE Diode block. For more information, see Geometry-corrected variables.

  • Temperature, , which by default is 300.15 K . 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 the Environment Parameters. For more information, refer to Diode Temperature.

  • Temperature dependent variables. See Temperature Dependent for more information.

  • Internal conductivity, , which by default is 1e-12 1/Ohm . You can use a different value by specifying the parameters for the block, Environment Parameters. For more information, see Internal Conductivity.

  • Thermal Voltage, . For more information, see Thermal Voltage.

Geometry-corrected variables

Several variables in the equations for the SPICE diode model take into account the geometry of the device that the block represents. These geometry-corrected variables depend on the variables you define when you set the parameters for the SPICE Diode block. The geometry-corrected variables depend on these variables:

  • - device area;

  • - the number of devices connected in parallel;

  • The corresponding unadjusted variable.

The table shows the geometry-adjusted variables and their defining equations.

Variable

Description

Equation

Geometry-corrected zero bias junction capacitance

Geometry-corrected reverse breakdown current

Geometry-corrected saturation current

Geometry-corrected series resistance

Diode temperature

You can use these options to determine the diode temperature, :

  • Fixed temperature - the block uses a temperature that is independent of the circuit temperature when the Model temperature dependence using parameters of the SPICE Diode block are set to Fixed temperature. For this model, the block sets equal to .

  • Device temperature - The block uses a temperature that depends on the circuit temperature when the Model temperature dependence using parameter of the SPICE Diode block is set to Device temperature. For this model, the block defines the temperature as

where

  • - is the temperature of the circuit;

  • If there is no Environment Parameters block in the circuit, is 300.15 K.

  • If the circuit has an Environment Parameters block, is equal to the value you set for the Temperature parameter in the Environment Parameters block settings. By default, the value of the Temperature parameter is 300.15 K.

  • - local loop temperature offset.

Internal Conductivity

The internal conductivity, , has a value of 1e-12 1/Ohm by default. To specify a different value:

  1. If there is no Environment Parameters block in the diode schematic, add one.

  2. In the Environment Parameters block settings, specify the desired value for the GMIN parameter.

Thermal voltage

The thermal voltage, , is determined by the equation

where

  • - emission coefficient.

  • - is the diode temperature. See Diode temperature for more information;

  • - Boltzmann constant;

  • - the elementary charge of an electron.

Current-voltage equations

These equations define the relationship between the diode current, , and the diode voltage, . Depending on the situation, the model parameters are first adjusted for temperature. For more information, see Diode Temperature.

























where

  • - forward current;

  • - reverse current;

  • - normal current;

  • - recombination current;

  • - high injection coefficient;

  • - generation factor;

  • - high breakdown current;

  • - low level breakdown current;

  • - thermal voltage. For more information, see thermal voltage;

  • - saturation current;

  • - recombination current;

  • - straight knee current;

  • - junction potential;

  • - emission coefficient;

  • - reverse emission coefficient;

  • - reverse breakdown emission coefficient;

  • - low level reverse breakdown idealisation factor;

  • - gradation factor;

  • - reverse breakdown voltage

  • - reverse breakdown current;

  • - low-level reverse breakdown knee current.

Diode charge

The table shows the equations defining the relationship between the diode charge, , and the diode voltage, . Depending on the situation, the parameters of the model are first adjusted for temperature. For more information, see Temperature Dependence.

Voltage range

Equation

where

  • - is the depleted capacitance coefficient at forward bias;

  • - junction potential;

  • - transit time;

  • - geometrically corrected zero bias junction capacitance. For more information, see Geometry-corrected variables.

  • - grading factor;

  • ;

  • ;

  • .

Temperature dependence

Relationship between geometry-corrected saturation current and diode temperature:

where

  • - is the geometry-corrected saturation current. See Geometry-corrected variables for more information;

  • - diode temperature. For more information, see Diode temperature;

  • - parameters extraction temperature;

  • - temperature exponent of saturation current;

  • - emission coefficient;

  • - activation energy;

  • - thermal voltage. For more information, see Thermal Voltage.

Relationship between recombination current and diode temperature:

where

  • - recombination current;

  • - is the back emission coefficient.

Dependence between the forward knee current and diode temperature:

where

  • - direct elbow current;

  • - IKF linear temperature coefficient.

Dependence between breakdown voltage and diode temperature:

where

  • - breakdown voltage;

  • - linear temperature coefficient BV;

  • - quadratic temperature coefficient BV.

Relationship between ohmic resistance and diode temperature:

where

  • - active resistance;

  • - linear temperature coefficient RS;

  • - RS quadratic temperature coefficient.

Dependence between junction potential and diode temperature:

where

  • - junction potential;

  • - activation energy for the temperature at which the diode parameters were measured. The defining equation: .

  • - Activation energy for the temperature of the diode. Defining equation: .

The relationship between the geometrically corrected junction capacitance of a zero junction diode and the diode temperature:

where

  • - is the geometrically corrected zero-switching junction capacitance. See Geometry-corrected variables for more information;

  • - is the grading factor.

Assumptions and limitations

  • The block does not support noise analysis.

  • The block applies initial conditions to the transition capacitors, not the block ports.

Ports

Conserving

# - — negative contact (cathode)
electricity

Details

An electrical port associated with a cathode.

Program usage name

n

# + — positive contact (anode)
electricity

Details

The electrical port associated with the anode.

Program usage name

p

Parameters

Main

# Device area, AREA — seating
m^2 | cm^2 | ft^2 | in^2 | km^2 | mi^2 | mm^2 | um^2 | yd^2

Details

The area of the diode. The value should be .

Values

m^2 | cm^2 | ft^2 | in^2 | km^2 | mi^2 | mm^2 | um^2 | yd^2
Default value

1.0 m^2
Program usage name

AREA
Evaluatable

Yes

# Number of parallel devices, SCALE — number of parallel devices

Details

The number of parallel diodes this unit represents. The value must be .

Default value

1.0
Program usage name

SCALE
Evaluatable

Yes

# Saturation current, IS — saturation current
A/m^2

Details

The magnitude of current to which the ideal diode equation approaches asymptotically for very large reverse bias levels. The value should be .

Values

A/m^2
Default value

1e-14 A/m^2
Program usage name

IS
Evaluatable

Yes

# High-injection knee current, IKF — high injection knee current
A/m^2

Details

The value of the current at which the high current in the forward beta range decays. The value should be .

Values

A/m^2
Default value

Inf A/m^2
Program usage name

IKF
Evaluatable

Yes

# Recombination current parameter, ISR — recombination current
A/m^2

Details

The amount of current resulting from the recombination of electrons and holes within a junction.

Values

A/m^2
Default value

0.0 A/m^2
Program usage name

ISR
Evaluatable

Yes

# Emission coefficient, N — emission factor

Details

The emission factor of a diode, or ideality factor. The value should be .

Default value

1.0
Program usage name

N
Evaluatable

Yes

# Emission coefficient for ISR, NR — emission coefficient for recombination current (ISR)

Details

The emission coefficient of the diode for the recombination current. The value should be .

Default value

2.0
Program usage name

NR
Evaluatable

Yes

# Grading coefficient, M — grading factor

Details

Gradation factor, . The value should be in the range .

Dependencies

To use this parameter, select the Model junction capacitance parameters check box.

Default value

0.5
Program usage name

M
Evaluatable

Yes

# Junction potential, VJ — joint potential
V | MV | kV | mV

Details

Junction potential, . The value should be .

Dependencies

To use this parameter, select the Model junction capacitance parameters check box.

Values

V | MV | kV | mV
Default value

1.0 V
Program usage name

VJ
Evaluatable

Yes

# Ohmic resistance, RS — series resistance
Ohm*m^2

Details

The resistance of a series connection of diodes. The value should be .

Values

Ohm*m^2
Default value

0.01 Ohm*m^2
Program usage name

RS
Evaluatable

Yes

Junction Capacitance

# Model junction capacitance — junction capacitance switching

Details

Select this check box to enable transition capacitance.

Default value

false (switched off)
Program usage name

model_junction_capacitance
Evaluatable

No

# Zero-bias junction capacitance, CJO — zero bias junction capacitance
F/m^2

Details

The value of the capacitance parallel to the exponential diode. The value must be .

Dependencies

To use this parameter, check the Model junction capacitance parameters checkbox.

Values

F/m^2
Default value

0.0 F/m^2
Program usage name

CJO
Evaluatable

Yes

# Capacitance coefficient, FC — capacitance factor

Details

A compliance factor, , that quantifies the reduction in barrier capacitance when a voltage is applied. The value should be .

Dependencies

To use this parameter, select the Model junction capacitance parameters check box.

Default value

0.5
Program usage name

FC
Evaluatable

Yes

# Transit time, TT — charge transfer time
d | s | hr | ms | ns | us | min

Details

The charge transfer time, , associated with the diffusion capacitance. The value should be .

Dependencies

To use this parameter, select the Model junction capacitance parameters check box.

Values

d | s | hr | ms | ns | us | min
Default value

0.0 s
Program usage name

TT
Evaluatable

Yes

# Specify initial condition — switching on the initial state

Details

Select this check box to enable the parameters for setting the initial state.

The SPICE Diode block applies the diode’s initial voltage through the transition capacitors, not the ports.

Dependencies

To use this parameter, select the Model junction capacitance parameters check box.

Default value

false (switched off)
Program usage name

capacitance_initial_condition
Evaluatable

No

# Initial condition voltage, V0 — initial stress
V | MV | kV | mV

Details

The diode voltage at the beginning of the simulation.

The block applies the initial state to the diode junction, so the initial state is only effective if charge storage is enabled, i.e. when one or both of the parameters Zero-bias junction capacitance, CJO and Transit time, TT are greater than zero.

Dependencies

To use this parameter, check the Model junction capacitance and Specify initial condition parameters.

Values

V | MV | kV | mV
Default value

0.0 V
Program usage name

V0
Evaluatable

Yes

Reverse Breakdown

# Model reverse breakdown — reversing the breakdown

Details

Select this check box to enable breakdown in the reverse direction.

Default value

false (switched off)
Program usage name

model_reverse_breakdown
Evaluatable

No

# Reverse breakdown voltage, BV — reverse breakdown threshold voltage
V | MV | kV | mV

Details

If the voltage falls below this value, the block simulates the rapid increase in conductivity that occurs when the diode breaks down. The value must be .

Dependencies

To use this parameter, check the Model reverse breakdown parameters checkbox.

Values

V | MV | kV | mV
Default value

Inf V
Program usage name

BV
Evaluatable

Yes

# Reverse breakdown current, IBV — reverse breakdown current
A/m^2

Details

The diode current corresponding to the voltage specified for the Reverse breakdown voltage, BV parameters. The value must be .

Dependencies

To use this parameter, check the Model reverse breakdown parameters.

Values

A/m^2
Default value

1e-10 A/m^2
Program usage name

IBV
Evaluatable

Yes

# Low-level reverse breakdown knee current, IBVL — low-level reverse breakdown knee current
A/m^2

Details

Low-level reverse breakdown knee current.

Dependencies

To use this parameter, select the Model reverse breakdown parameters check box.

Values

A/m^2
Default value

0.0 A/m^2
Program usage name

IBVL
Evaluatable

Yes

# Reverse breakdown ideality factor, NBV — perfect reverse breakdown coefficient

Details

Ideality factor for the parameters Reverse breakdown voltage, BV.

Dependencies

To use this parameter, select the Model reverse breakdown parameters checkbox.

Default value

1.0
Program usage name

NBV
Evaluatable

Yes

# Low-level reverse breakdown ideality factor, NBVL — low-level back breakdown ideality factor

Details

Ideality factor for the parameter Low-level reverse breakdown knee current, IBVL.

Dependencies

To use this parameter, select the Model reverse breakdown parameters checkbox.

Default value

1.0
Program usage name

NBVL
Evaluatable

Yes

Temperature

# Model temperature dependence using — temperature inclusion
Device temperature | Fixed temperature

Details

Select one of these options to simulate the temperature dependence of the diode:

  • Device temperature - usage of the device temperature to model the temperature dependence.

  • Fixed temperature - usage of a temperature that is independent of the circuit temperature to model the temperature dependence.

For more information, refer to Diode Temperature.

Values

Device temperature | Fixed temperature
Default value

Device temperature
Program usage name

T_parameterization
Evaluatable

No

# Saturation current temperature exponent, XTI — saturation current temperature exponent

Details

The order of exponential increase in saturation current as temperature increases. The value should be .

Default value

3.0
Program usage name

XTI
Evaluatable

Yes

# Activation energy, EG — activation energy
Btu_IT | J | MJ | MWh | Wh | eV | kJ | kWh | mJ | mWh

Details

Activation energy of the diode. The value should be .

Values

Btu_IT | J | MJ | MWh | Wh | eV | kJ | kWh | mJ | mWh
Default value

1.11 eV
Program usage name

EG
Evaluatable

Yes

# IKF temperature coefficient (linear), TIKF — temperature coefficient
1/K | 1/degR | 1/deltaK | 1/deltadegC | 1/deltadegF | 1/deltadegR

Details

Linear temperature coefficient for the parameter High-injection knee current, IKF.

Values

1/K | 1/degR | 1/deltaK | 1/deltadegC | 1/deltadegF | 1/deltadegR
Default value

0.0 1/K
Program usage name

TIKF
Evaluatable

Yes

# RS temperature coefficient (linear), TRS1 — linear temperature coefficient for active resistance (RS)
1/K | 1/degR | 1/deltaK | 1/deltadegC | 1/deltadegF | 1/deltadegR

Details

Linear temperature coefficient for the parameter Ohmic resistance, RS.

Values

1/K | 1/degR | 1/deltaK | 1/deltadegC | 1/deltadegF | 1/deltadegR
Default value

0.0 1/K
Program usage name

TRS1
Evaluatable

Yes

# RS temperature coefficient (quadratic), TRS2 — quadratic temperature coefficient for active resistance (RS)
1/K^2 | 1/degR^2 | 1/deltaK^2 | 1/deltadegC^2 | 1/deltadegF^2 | 1/deltadegR^2

Details

Quadratic temperature coefficient for Ohmic resistance, RS.

Values

1/K^2 | 1/degR^2 | 1/deltaK^2 | 1/deltadegC^2 | 1/deltadegF^2 | 1/deltadegR^2
Default value

0.0 1/K^2
Program usage name

TRS2
Evaluatable

Yes

# BV temperature coefficient (linear), TBV1 — linear temperature coefficient for breakdown voltage (BV)
1/K | 1/degR | 1/deltaK | 1/deltadegC | 1/deltadegF | 1/deltadegR

Details

Linear temperature coefficient for the parameter Breakdown voltage, BV.

Values

1/K | 1/degR | 1/deltaK | 1/deltadegC | 1/deltadegF | 1/deltadegR
Default value

0.0 1/K
Program usage name

TBV1
Evaluatable

Yes

# BV temperature coefficient (quadratic), TBV2 — quadratic temperature coefficient for breakdown voltage (BV)
1/K^2 | 1/degR^2 | 1/deltaK^2 | 1/deltadegC^2 | 1/deltadegF^2 | 1/deltadegR^2

Details

Quadratic temperature coefficient for the parameter Breakdown voltage, BV.

Values

1/K^2 | 1/degR^2 | 1/deltaK^2 | 1/deltadegC^2 | 1/deltadegF^2 | 1/deltadegR^2
Default value

0.0 1/K^2
Program usage name

TBV2
Evaluatable

Yes

# Fixed circuit temperature, TFIXED — constant circuit temperature
K | degC | degF | degR | deltaK | deltadegC | deltadegF | deltadegR

Details

The simulation temperature of the diode. The value should be .

Dependencies

To use this parameter, set the Model temperature dependence using parameters to Fixed temperature.

Values

K | degC | degF | degR | deltaK | deltadegC | deltadegF | deltadegR
Default value

300.15 K
Program usage name

TFIXED
Evaluatable

Yes

# Parameter extraction temperature, TMEAS — diode parameters measurement temperature
K | degC | degF | degR | deltaK | deltadegC | deltadegF | deltadegR

Details

The temperature at which the diode parameters are measured. The value should be .

Values

K | degC | degF | degR | deltaK | deltadegC | deltadegF | deltadegR
Default value

300.15 K
Program usage name

TMEAS
Evaluatable

Yes

# Offset local circuit temperature, TOFFSET — local circuit temperature offset
K | degC | degF | degR | deltaK | deltadegC | deltadegF | deltadegR

Details

The amount by which the diode temperature differs from the circuit temperature.

Dependencies

To use this parameter, set the Model temperature dependence using parameters to Device temperature.

Values

K | degC | degF | degR | deltaK | deltadegC | deltadegF | deltadegR
Default value

0.0 K
Program usage name

TOFFSET
Evaluatable

Yes

See also

  1. Environment Parameters

  2. Diode (Advanced)