modelCgd
Spice-style gate capacitance between gate and drain of MOSFETs
Extends from Interfaces.SpiceTwoPort (Special twoPort element used by Spice models).
Information
The Spice-style gate capacitances for MOSFETs are non-linear capacitors that use different formulae to compute the capacitance value in the four different regions: accumulation, depletion, saturation, and the linear region. Different Spice dialects vary in the formulae they use for this purpose. Many Spice dialects actually don't use a formula for the gate capacitances at all, but rather compute the electric charges stored in these regions directly, which is conceptually cleaner. However, that approach is computationally cumbersome, as it leads to an awkward algebraic loop [1]. Thus, we chose to compute the gate capacitances directly, and use a (physically incorrect) approximate non-linear capacitor model. The numerical error should remain small, as the time constants associated with temperature variation are much larger than those associated with electrical phenomena.This particular model uses the space charge formula advocated in [2].
Parameters:
Level: MOSFET modeling level (default value = 3)
Level=0: Static injection model
Level=1: Shichman-Hodges model
Level=2: Grove-Frohman model
Level=3: Empirical model
Level=4: Simplified Grove-Frohman model
Type: Type of MOSFET (default value = 1)
Type = +1: NMOS
Type = -1: PMOS
Tnom: Reference temperature (default value = 300.15 K)
VFB: Flat band voltage at reference temperature (default value = 0 Volt)
KP: Transconductance parameter at reference temperature (default value = 0 Amp/Volt2)
GAMMA: Body-effect parameter (default value = Volt0.5)
PHI: Surface inversion potential at reference temperature (default value = 0 Volt)
COX: Specific capacitance of SiO2 (default value = 0 F/m2)
NFS: Surface fast state density (default value = 0 1/m2)
XJ: Metallurgical junction depth (default value = 0 m)
L: Channel length (default value = 1e-4 m)
W: Channel width (default value = 1e-4 m)
LD: Lateral diffusion (default value = 0 m)
XD: Depletion factor (default value = 0 m/Volt0.5)
XQC: Coefficient of channel charge share (default value = 0)
XQC <= 0.5: Ward-Dutton model of gate capacitance computation
XQC > 0.5: Meyer model of gate capacitance computation
DELTA: Width effect on threshold voltage (default value = 0)
ETA: Static feedback on threshold voltage (default value = 1)
CGD0: Gate-drain overlap capacitance per meter (default value = 1e-12 F/m)
EG: Energy gap for temperature effect on saturation current (default value = 1.11 Volt)
References:
- Cellier, F.E. (1991), Continuous System Modeling, Springer-Verlag, New York, pp. 224-225.
- Massobrio, G. and P. Antognetti (1993), Semiconductor Device Modeling with Spice, 2nd edition, McGraw Hill, New York, pp.196-197.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Modelica.SIunits.Temperature | Tnom (from SpiceTwoPort) | 300.15 | Reference temperature |
| Real | pi | Modelica.Constants.pi | |
| Modelica.SIunits.Entropy | k | Modelica.Constants.k | Boltzmann's constant |
| Modelica.SIunits.Permittivity | e0 | Modelica.Constants.epsilon_0 | Permittivity of free space |
| Modelica.SIunits.ElectricCharge | q | 1.6021892e-19 | Electron charge |
| Modelica.SIunits.ElectronNumberDensity | ni | 1.45e16 | Intrinsic carrier concentration |
| Real | ks | 11.8 | Dielectric constant of Si |
| Real | GapC1 | 7.02E-4 | First bandgap correction factor Silicon |
| Modelica.SIunits.Temperature | GapC2 | 1108.0 | Second bandgap correction factor Silicon |
| Real | c0 | 0.0631353 | |
| Real | c1 | 0.8013292 | |
| Real | c2 | -0.01110777 | |
| Integer | Level | 3 | Level of MOS model (check documentation window for details) |
| Integer | Type | 1 | Type=1 for NMOS; Type=-1 for PMOS |
| Modelica.SIunits.Voltage | VFB | 0 | Flat band voltage at reference temperature |
| Modelica.SIunits.Transconductance | KP | 0 | Transconductance parameter at reference temperature |
| Real | GAMMA | 0 | Body-effect parameter |
| Modelica.SIunits.Voltage | PHI | 0 | Surface inversion potential at reference temperature |
| Real | COX | 0 | Specific capacitance of SiO2 |
| Real | NFS | 0 | Surface fast state density |
| Modelica.SIunits.Length | XJ | 0 | Metallurgical junction depth |
| Modelica.SIunits.Length | L | 1e-4 | Channel length |
| Modelica.SIunits.Length | W | 1e-4 | Channel width |
| Modelica.SIunits.Length | LD | 0 | Lateral diffusion |
| Real | XD | 0 | Depletion factor |
| Real | XQC | 0 | Coefficient of channel charge share |
| Real | DELTA | 0 | Width effect on threshold voltage |
| Real | ETA | 0 | Static feedback on threshold voltage |
| Real | CGD0 | 1e-12 | Gate-drain overlap capacitance per meter |
| Modelica.SIunits.Voltage | EG | 1.11 | Energy gap for temperature effect on saturation current at 0 K |
Connectors
| Type | Name | Default | Description |
|---|---|---|---|
| BondLib.Interfaces.BondCon | BondCon1 (from TwoPort) | Left bond graph connector | |
| BondLib.Interfaces.BondCon | BondCon2 (from TwoPort) | Right bond graph connector | |
| Modelica.Blocks.Interfaces.RealInput | u1 | Connector of Real input signal 1 | |
| Modelica.Blocks.Interfaces.RealInput | u2 | Connector of Real input signal 2 | |
| Modelica.Blocks.Interfaces.RealInput[5] | u | Connector of Real input signals |
Components
| Type | Name | Default | Description |
|---|---|---|---|
| Real | e1 (from TwoPort) | Bondgraphic primary effort | |
| Real | f1 (from TwoPort) | Bondgraphic primary flow | |
| Real | e2 (from TwoPort) | Bondgraphic secondary effort | |
| Real | f2 (from TwoPort) | Bondgraphic secondary flow | |
| Modelica.SIunits.Temperature | DTemp (from SpiceTwoPort) | Difference between circuit temperature and reference temperature | |
| Real | DTempSq (from SpiceTwoPort) | Square of DTemp | |
| Modelica.SIunits.Voltage | vds | Drain-source voltage | |
| Modelica.SIunits.Voltage | vgs | Gate-source voltage | |
| Modelica.SIunits.Voltage | vbs | Bulk-source voltage | |
| Modelica.SIunits.Voltage | Vt | Thermal voltage | |
| Modelica.SIunits.Voltage | EGref | Energy gap at reference temperature | |
| Modelica.SIunits.Voltage | EGval | Energy gap at device temperature | |
| Modelica.SIunits.Voltage | PHIval | Surface inversion potential at device temperature | |
| Modelica.SIunits.Voltage | Vfb | Flat band voltage at device temperature | |
| Modelica.SIunits.Voltage | Vth | Threshold voltage | |
| Modelica.SIunits.Voltage | Von | Adjusted threshold voltage | |
| Modelica.SIunits.Capacitance | Cval | Gate capacitance between gate and bulk |