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PMOS - Model SPICE-compatible P-Channel MOSFET

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SPICE-Compatible Semiconductors

Description

The PMOS block represents a SPICE-compatible P-channel MOSFET.

The PMOS block model includes the following components:

Resistance Calculations

The following table shows how the PMOS block calculates the transistor drain resistance. The abbreviations in the table represent the values of the following block parameters:

Drain resistance, RD ParameterSheet resistance, RSH ParameterDrain Resistance
NaNNaN0
RDNaN or RSHRD
NaNRSHRSH*NRD

The following table shows how the PMOS block calculates the transistor source resistance. The abbreviations in the table represent the values of the following block parameters:

Source resistance, RS ParameterSheet resistance, RSH ParameterSource Resistance
NaNNaN0
RSNaN or RSHRS
NaNRSHRSH*NRS

Bulk-Source Diode Model

The block provides the following relationship between the bulk-source current Isb and the bulk-source voltage Vsb after adjusting the applicable model parameters for temperature.

Applicable Range of Vsb ValuesCorresponding Igs Equation

Where:

Bulk-Drain Diode Model

The block provides the following relationship between the bulk-drain current Idb and the bulk-drain voltage Vdb after adjusting the applicable model parameters for temperature.

Applicable Range of Vdb ValuesCorresponding Igs Equation

Where:

Level 1 Drain Current Model

The block provides the following relationship between the drain current Isd and the drain-source voltage Vsd in normal mode ( ) after adjusting the applicable model parameters for temperature.

Normal Mode

Applicable Range of Vsg and Vsd ValuesCorresponding Isd Equation

Where:

The block provides the following relationship between the drain current Isd and the drain-source voltage Vsd in inverse mode ( ) after adjusting the applicable model parameters for temperature.

Inverse Mode

Applicable Range of Vdg and Vsd ValuesCorresponding Isd Equation

Where:

Level 3 Drain Current Model

The block provides the following model for drain current Isd in normal mode ( ) after adjusting the applicable model parameters for temperature.

Where:

The blocks uses the same model for drain current in inverse mode ( ), with the following substitutions:

Basic Drain Current Model

The block provides the following relationship between the drain current Isd and the drain-source voltage Vds:

Velocity Saturation Scaling

If you specify a positive value for the Max carrier drift velocity, VMAX parameter, the block calculates ScaleVMAX using the following equation:

Otherwise, ScaleVMAX = 1.

Channel Length Modulation Scaling

The block scales the drain current to account for channel length modulation if the block meets all of the following criteria:

The block scales the drain current using the following equation:

The block uses the following procedure to calculate Δl:

  1. The block first calculates the intermediate value Δl0.

    • If you specify a positive value for the Max carrier drift velocity, VMAX parameter, the block computes the intermediate value gdsat as the greater of 1e-12 and the result of the following equation:

      where:

      Then, the block uses the following equation to calculate the intermediate value Δl0:

      where KA is the product of the Mobility modulation, KAPPA parameter value and α.

    • Otherwise, the block uses the following equation to calculate the intermediate value Δl0:

  2. The block checks for punch through and calculates Δl.

    • If Δl0 is greater than (LENGTH-2*LD)/2, the block calculates Δl using the following equation:

    • Otherwise, Δl = Δl0.

Weak Inversion Scaling

If VSG is less than Von, the block calculates ScaleINV using the following equation:

Otherwise, ScaleINV = 1.

Junction Charge Model

The block models the following junction charges:

Junction Overlap Charges

The block calculates the following junction overlap charges:

Bulk Junction Charges

The block provides the following relationship between the bulk-drain bottom junction charge Qbottom and the junction voltage Vdb after adjusting the applicable model parameters for temperature.

Applicable Range of Vdb ValuesCorresponding Qbottom Equation

if CBD > 0.

otherwise.

if CBD > 0.

otherwise.

Where:

The block uses the equations in the preceding table to calculate the bulk-source bottom junction charge, with the following substitutions:

The block provides the following relationship between the bulk-drain sidewall junction charge Qsidewall and the junction voltage Vdb after adjusting the applicable model parameters for temperature.

Applicable Range of Vdb ValuesCorresponding Qsidewall Equation

Where:

The block uses the equations in the preceding table to calculate the bulk-source sidewall junction charge and the sidewall junction voltage, with the following substitutions:

Temperature Dependence

Several transistor parameters depend on temperature. There are two ways to specify the transistor temperature:

The block provides the following relationship between the transconductance KP and the transistor temperature T:

where:

The block provides the following relationship between the surface potential PHI and the transistor temperature T:

where:

The block provides the following relationship between the built-in voltage VBI and the transistor temperature T:

where:

The block provides the following relationship between the bulk saturation current IS and the transistor temperature T:

where:

The block provides the following relationship between the bulk junction saturation current density JS and the transistor temperature T:

where:

The block provides the following relationship between the bulk junction potential PB and the transistor temperature T:

where:

The block provides the following relationship between the bulk-drain junction capacitance CBD and the transistor temperature T:

where:

The block uses the CBD(T) equation to calculate:

The block provides the following relationship between the sidewall junction capacitance CJSW and the transistor temperature T:

where:

Basic Assumptions and Limitations

The model is based on the following assumptions:

Dialog Box and Parameters

Model Selection Tab

MOS model

Select one of the following MOSFET model options:

Dimensions Tab

Device area factor, AREA

The transistor area. This value multiplies the following parameter values:

  • Transconductance, KP

  • Bulk saturation current, IS

  • Bulk jct sat current density, JS

  • Zero-bias BD capacitance, CBD

  • Zero-bias BS capacitance, CBS

  • G-S overlap capacitance, CGSO

  • G-D overlap capacitance, CGDO

  • G-B overlap capacitance, CGBO

  • Bottom junction cap per area CJ

  • Side jct cap/area of jct perimeter CJSW

It divides the following parameter values:

  • Drain resistance, RD

  • Source resistance, RS

  • Sheet resistance, RSH

The default value is 1. The value must be greater than 0.

Number of parallel devices, SCALE

The number of parallel MOS instances for this device. This parameter multiplies the output current and device charge. The default value is 1. The value must be greater than 0.

Length of channel, LENGTH

Length of the channel between the source and drain. The default value is 1e-04 m.

Width of channel, WIDTH

Width of the channel between the source and drain. The default value is 1e-04 m.

Area of drain, AD

Area of the transistor drain diffusion. The default value is 0 m2. The value must be greater than or equal to 0.

Area of source, AS

Area of the transistor source diffusion. The default value is 0 m2. The value must be greater than or equal to 0.

Perimeter of drain, PD

Perimeter of the transistor drain diffusion. The default value is 0 m.

Perimeter of source, PS

Perimeter of the transistor source diffusion. The default value is 0 m.

Resistors Tab

Drain resistance, RD

The transistor drain ohmic resistance. The default value is Nan Ω. This value means the parameter is unspecified, so the block calculates the drain resistance as described in Resistance Calculations. The value must be equal to 0 or greater than or equal to Rmin. Rmin is a built-in model constant whose value is 1e-12.

Source resistance, RS

The transistor source ohmic resistance. The default value is Nan Ω. This value means the parameter is unspecified, so the block calculates the drain resistance as described in Resistance Calculations. The value must be equal to 0 or greater than or equal to Rmin. Rmin is a built-in model constant whose value is 1e-12.

Sheet resistance, RSH

Resistance per square of the transistor source and drain. The default value is Nan Ω. This value means the parameter is unspecified. The block only uses this parameter value if you do not specify one or both of the Drain resistance, RD and Source resistance, RS parameter values, as described in Resistance Calculations. The value must be greater than or equal to 0.

Number of drain squares, NRD

Number of squares of resistance that make up the transistor drain diffusion. The default value is 1 . The value must be greater than or equal to 0. The block only uses this parameter value if you do not specify one or both of the Drain resistance, RD and Source resistance, RS parameter values, as described in Resistance Calculations.

Number of source squares, NRS

Number of squares of resistance that make up the transistor source diffusion. The default value is 1 . The value must be greater than or equal to 0. The block only uses this parameter value if you do not specify one or both of the Drain resistance, RD and Source resistance, RS parameter values, as described in Resistance Calculations.

DC Currents Tab

Threshold voltage, VTO

The gate-source voltage above which the transistor produces a nonzero drain current. The default value is 0 V. If you assign this parameter a value of NaN, the block calculates the value from the specified values of the Oxide thickness, TOX and Substrate doping, NSUB parameters. For more information about this calculation, see Temperature Dependence.

Transconductance, KP

The derivative of drain current with respect to gate voltage. The default value is 2e-05 A/V2. The value must be greater than or equal to 0. If you assign this parameter a value of NaN, the block calculates the value from the specified values of the Oxide thickness, TOX and Substrate doping, NSUB parameters. For more information about this calculation, see Level 1 Drain Current Model or Level 3 Drain Current Model as appropriate for the selected value of the MOS model parameter.

Bulk threshold, GAMMA

Body effect parameter, which relates the threshold voltage, VTH, to the body bias, VBS, as described in Level 1 Drain Current Model. The default value is 0 . The value must be greater than or equal to 0. If you assign this parameter a value of NaN, the block calculates the value from the specified values of the Oxide thickness, TOX and Substrate doping, NSUB parameters. For more information about this calculation, see Level 1 Drain Current Model or Level 3 Drain Current Model as appropriate for the selected value of the MOS model parameter.

Surface potential, PHI

Twice the voltage at which the surface electron concentration becomes equal to the intrinsic concentration and the device transitions between depletion and inversion conditions. The default value is 0.6 V. The value must be greater than or equal to 0. If you assign this parameter a value of NaN, the block calculates the value from the specified values of the Oxide thickness, TOX and Substrate doping, NSUB parameters. For more information about this calculation, see Level 1 Drain Current Model or Level 3 Drain Current Model as appropriate for the selected value of the MOS model parameter.

Channel modulation, LAMBDA

The channel-length modulation. This parameter is only visible when you select Level 1 MOS for the MOS model parameter. The default value is 0 1/V.

Bulk saturation current, IS

The magnitude of the current that the junction approaches asymptotically for very large reverse bias levels. The default value is 1e-14 A. The value must be greater than or equal to 0.

Bulk jct sat current density, JS

The magnitude of the current per unit area that the junction approaches asymptotically for very large reverse bias levels. The default value is 0 A/m2. The value must be greater than or equal to 0.

Emission coefficient, ND

The transistor emission coefficient or ideality factor. The default value is 1. The value must be greater than 0.

Width effect on threshold, DELTA

The factor that controls the effect of transistor width on threshold voltage. This parameter is only visible when you select Level 3 MOS for the MOS model parameter. The default value is 0.

Max carrier drift velocity, VMAX

The maximum drift velocity of the carriers. This parameter is only visible when you select Level 3 MOS for the MOS model parameter. The default value is 0 m/s.

Fast surface state density, NFS

The fast surface state density adjusts the drain current for the mobility reduction caused by the gate voltage. This parameter is only visible when you select Level 3 MOS for the MOS model parameter. The default value is 0 1/cm2.

Vds dependence threshold volt, ETA

The coefficient that controls how the threshold voltage depends on the drain-source voltage in the drain current calculation. This parameter is only visible when you select Level 3 MOS for the MOS model parameter. The default value is 0.

Vgs dependence on mobility, THETA

The coefficient that controls how the mobility affects the gate voltage in the drain current calculation. This parameter is only visible when you select Level 3 MOS for the MOS model parameter. The default value is 0 1/V.

Mobility modulation, KAPPA

The coefficient that controls how the mobility affects the channel length in the drain current calculation. This parameter is only visible when you select Level 3 MOS for the MOS model parameter. The default value is 0.2.

C-V Tab

Model junction capacitance

Select one of the following options for modeling the junction capacitance:

  • No — Do not include junction capacitance in the model. This is the default option.

  • Yes — Specify zero-bias junction capacitance, junction potential, grading coefficient, forward-bias depletion and capacitance coefficient.

G-S overlap capacitance, CGSO

Gate-source capacitance due to the diffusion that occurs when the device operates in depletion mode. This parameter is only visible when you select Yes for the Model junction capacitance parameter. The default value is 0 F/m. The value must be equal to 0 or greater than or equal to Cmin. Cmin is a built-in model constant whose value is 1e-18.

G-D overlap capacitance, CGDO

Gate-drain capacitance due to the diffusion that occurs when the device operates in depletion mode. This parameter is only visible when you select Yes for the Model junction capacitance parameter. The default value is 0 F/m. The value must be equal to 0 or greater than or equal to Cmin. Cmin is a built-in model constant whose value is 1e-18.

G-B overlap capacitance, CGBO

Gate-base capacitance due to the diffusion that occurs when the device operates in depletion mode. This parameter is only visible when you select Yes for the Model junction capacitance parameter. The default value is 0 F/m. The value must be equal to 0 or greater than or equal to Cmin. Cmin is a built-in model constant whose value is 1e-18.

Zero-bias BD capacitance, CBD

The value of the capacitance placed between the base and the drain. This parameter is only visible when you select Yes for the Model junction capacitance parameter. The default value is 0 F. The value must be equal to 0 or greater than or equal to Cmin. Cmin is a built-in model constant whose value is 1e-18.

Zero-bias BS capacitance, CBS

The value of the capacitance placed between the base and the source. This parameter is only visible when you select Yes for the Model junction capacitance parameter. The default value is 0 F. The value must be equal to 0 or greater than or equal to Cmin. Cmin is a built-in model constant whose value is 1e-18.

Bottom junction cap per area CJ

Zero-bias bulk junction bottom capacitance per junction area. This parameter is only visible when you select Yes for the Model junction capacitance parameter. The default value is 0 F/m2. The value must be equal to 0 or greater than or equal to Cmin. Cmin is a built-in model constant whose value is 1e-18.

Bottom grading coefficient, MJ

The transistor bottom grading coefficient. This parameter is only visible when you select Yes for the Model junction capacitance parameter. The default value is 0.5. The value must be equal to 0 or less than MGmax. MGmax is a built-in model constant whose value is 0.9.

Side jct cap/area of jct perimeter CJSW

Zero-bias bulk junction sidewall capacitance per junction perimeter. This parameter is only visible when you select Yes for the Model junction capacitance parameter. The default value is 0 F/m. The value must be equal to 0 or greater than or equal to Cmin. Cmin is a built-in model constant whose value is 1e-18.

Side grading coefficient, MJSW

The transistor sidewall grading coefficient. This parameter is only visible when you select Yes for the Model junction capacitance parameter. The default value is 0.5. The value must be equal to 0 or less than MGmax. MGmax is a built-in model constant whose value is 0.9.

Bulk junction potential, PB

The potential across the bulk junction. This parameter is only visible when you select Yes for the Model junction capacitance parameter. The default value is 0.8 V. The value must be equal to 0 or greater than or equal to VJmin. VJmin is a built-in model constant whose value is 0.01.

Capacitance coefficient FC

The fitting coefficient that quantifies the decrease of the depletion capacitance with applied voltage. This parameter is only visible when you select Yes for the Model junction capacitance parameter. The default value is 0.5. The value must be equal to 0 or less than or equal to FCmax. FCmax is a built-in model constant whose value is 0.95.

Specify initial condition

Select one of the following options for specifying an initial condition:

  • No — Do not specify an initial condition for the model. This is the default option.

  • Yes — Specify the initial diode voltage.

      Note   The PMOS block applies the initial diode voltage across the junction capacitors and not across the ports.

Initial condition voltage ICVDS

Drain-source voltage at the start of the simulation. This parameter is only visible when you select Yes for the Model junction capacitance and Yes for the Specify initial condition parameter. The default value is 0 V.

Initial condition voltage ICVGS

Gate-source voltage at the start of the simulation. This parameter is only visible when you select Yes for the Model junction capacitance and Yes for the Specify initial condition parameter. The default value is 0 V.

Initial condition voltage ICVBS

Bulk-source voltage at the start of the simulation. This parameter is only visible when you select Yes for the Model junction capacitance and Yes for the Specify initial condition parameter. The default value is 0 V.

Process Tab

Oxide thickness, TOX

Thickness of the gate oxide. The default value is NaN m. The value must be greater than or equal to 0.

    Note   When you select Level 3 MOS for the MOS model parameter, the block uses a value of 1e-7 rather than NaN by default.

Lateral diffusion, LD

Length of lateral diffusion. The default value is 0 m.

Substrate doping, NSUB

Substrate doping. The default value is NaN 1/cm3. The value must be greater than or equal to 1.45e10 (the carrier concentration of intrinsic silicon).

Surface state density, NSS

Substrate doping. The default value is 0 1/cm2.

Surface mobility, U0

Zero-bias surface mobility coefficient. The default value is 600 cm2/V/s.

Junction depth, XJ

Junction depth. This parameter is only visible when you select Level 3 MOS for the MOS model parameter. The default value is 0 m.

Gate type?,TPG

Select one of the following MOSFET gate materials (as compared to the substrate):

  • Opposite of substrate — The gate material is the opposite of the substrate. This means that TPG = 1 in the device equations. This is the default option.

  • Same as substrate — The gate material is the same as the substrate. This means that TPG = –1 in the device equations.

  • Aluminum — The gate material is aluminum. This means that TPG = 0 in the device equations.

Temperature Tab

Model temperature dependence using

Select one of the following options for modeling the diode temperature dependence:

  • Device temperature — Use the device temperature, which is the Circuit temperature value plus the Offset local circuit temperature, TOFFSET value. The Circuit temperature value comes from the SPICE Environment Parameters block, if one exists in the circuit. Otherwise, it comes from the default value for this block.

  • Fixed temperature — Use a temperature that is independent of the circuit temperature to model temperature dependence.

Offset local circuit temperature, TOFFSET

The amount by which the transistor temperature differs from the circuit temperature. This parameter is only visible when you select Device temperature for the Model temperature dependence using parameter. The default value is 0 K.

Fixed circuit temperature, TFIXED

The temperature at which to simulate the transistor. This parameter is only visible when you select Fixed temperature for the Model temperature dependence using parameter. The default value is 300.15 K. The value must be greater than 0.

Parameter extraction temperature, TMEAS

The temperature at which the transistor parameters were measured. The default value is 300.15 K. The value must be greater than 0.

Ports

The block has the following ports:

G

Electrical conserving port associated with the transistor gate terminal.

D

Electrical conserving port associated with the transistor drain terminal.

S

Electrical conserving port associated with the transistor source terminal.

B

Electrical conserving port associated with the transistor bulk terminal.

References

[1] G. Massobrio and P. Antognetti. Semiconductor Device Modeling with SPICE. 2nd Edition, McGraw-Hill, 1993. Chapter 3.

See Also

NMOS

  

PJFETPJFET PNPPNP

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