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FETs (JFETs and MESFETs) > MESFET, Curtice Model
MESFET, Curtice Model
The .MODEL statement for the Curtice
model MESFET is:
.MODEL modelname NJF LEVEL=3
[SAT=0] [modelparameter=]val] ...
or
.MODEL modelname PJF LEVEL=3
[SAT=0] [modelparameter=]val] ...
LEVEL=3 specifies
a MESFET model. The SAT=0 parameter
specifies the Curtice MESFET model.
The Level 3 MESFET models use all the Level 1 and Level
2 model parameters listed in the module for the JFET
Model, SPICE Model.
Level 3 MESFET Additional
Model Parameters
Model Parameter
|
Description
|
Unit
|
Default
|
LEVEL
|
3 is required to select one of
several MESFET models (see SAT parameter)
|
None
|
1 (default if LEVEL parameter is
omitted)
|
SAT
|
Saturation factor (MESFET model
selector)
0 = Standard Curtice model
1 = Curtice model with tanh coefficient
2 = Statz cubic approximation to Curtice model with gate field degradation
3 = Variable saturation model or Triquint extended
(TOM) model
|
None
|
0
|
A
|
Active layer thickness
Aeff = A ´
SCALM
|
Meter
|
0.5e-6
|
ACM
|
0 = SPICE method
1 = physical basis (required for Triquint TOM features)
|
None
|
0
|
AF
|
Flicker noise exponent
|
None
|
1.0
|
ALIGN
|
Correction for gate misalignment
|
Meter
|
0.0
|
ALPHA (ALFA,
ALPHA1)
|
Saturation factor
|
Volt-1
|
2.0
|
AREA
|
Area factor
|
None
|
1.0
|
BETA
|
Transconductance (gain)
|
Amp/Volt2
|
1.0e-4
|
CAPOP
|
Capacitor model
0 = SPICE depletion capacitor model
1 = Statz charge-conserving symmetric capacitor model
(Level 3 only)
2 = Modified Statz model
|
None
|
0
|
CAPDS (CDS)
|
Drain-source capacitance
|
Farad
|
0.0
|
CGD
|
Zero-bias gate-drain junction capacitance
|
ACM = 0 : Farad
ACM = 1 :
Farad/Meter2
|
0.0
|
CGS
|
Zero-bias gate-source junction
capacitance
|
ACM = 0 : Farad
ACM = 1 :
Farad/Meter2
|
0.0
|
CRAT
|
Source ratio of gate capacitance
|
None
|
0.666
|
D
|
Semiconductor dielectric constant
Silicon: 11.7
Gallium arsenide: 10.9
|
None
|
11.7
|
DCAP
|
Capacitance equation selector
|
None
|
2
|
DGAM
|
Dispersion model feedback coefficient
|
None
|
0.0
|
FC
|
Coefficient for PB in forward-bias
capacitance calculations,
CAPOP = 0 or 2
|
None
|
0.5
|
GAMDS (GAMMA,
GAMA)
|
Lowering coefficient for drain
voltage-induced threshold voltage
|
None
|
0.0
|
GCAP
|
Zero-bias gate capacitance
|
ACM = 0 : Farad
ACM = 1 :
Farad/Meter2
|
Not used if not provided
|
GDSNOI
|
Channel noise coefficient (NLEV
= 3)
|
None
|
1.0
|
HDIF
|
Distance of heavily-doped (low
resistance) region from source or drain contact to lightly-doped region
|
Meter
|
0.0
|
IS
|
Gate junction saturation current.
|
ACM = 0: Amp
ACM = 1:
Amp/Meter2
|
1.0e-14
|
K1
|
Threshold voltage sensitivity to
bulk node
|
Volt½
|
0.0
|
KF
|
Flicker noise coefficient
|
None
|
0.0
|
L
|
FET gate length
|
Meter
|
0.0
|
LAMBDA (LAMB)
|
Channel length modulation factor
Must be 0 for Triquint TOM model compatibility.
|
Volt-1
|
0.0
|
LAM1
|
Channel length modulation gate
voltage parameter
|
Volt-1
|
0.0
|
LDEL
|
Difference between drawn length
and actual or optical device length
|
Meter
|
0.0
|
LDIF
|
Distance of lightly-doped region
from heavily-doped region to transistor edge
|
Meter
|
0.0
|
MJ
|
Grading coefficient for gate-drain
and gate-source diodes
(CAPOP = 0 or 2)
Step junction: 0.50
Linear graded junction: 0.33
|
None
|
0.50
|
N
|
Emission coefficient for gate-drain
and gate-source diodes
|
None
|
1.0
|
NCHAN
|
Effective channel dopant concentration
|
atom/cm3
|
1.552e+22
|
ND
|
Drain subthreshold factor
|
Volt-1
|
0.0
|
NG
|
Gate subthreshold factor
|
Volt-1
|
0.0
|
NLEV
|
Noise equation selector
|
None
|
2
|
PB
|
Gate junction potential
|
Volt
|
0.8
|
RD
|
Drain ohmic resistance
|
Ohm
|
0.0
|
RG (RG2)
|
Gate ohmic resistance
|
Ohm
|
0.0
|
RS
|
Source ohmic resistance
|
Ohm
|
0.0
|
RSH
|
Sheet resistance of heavily-doped
region
|
Ohm/square
|
0.0
|
RSHG
|
Gate sheet resistance
|
Ohm/square
|
0.0
|
SATEXP
|
Drain voltage exponent
|
None
|
3.0
|
TNOM
|
Nominal circuit temperature
|
°C
|
25
|
TT
|
Transit time
|
Second
|
0.0
|
UCRIT
|
Critical field for mobility degradation
Must be 0 for Triquint TOM model compatibility.
|
Volt/cm
|
0.0
|
VBI
|
Gate diode built-in voltage
|
Volt
|
1.0
|
VGEXP (Q)
|
Gate voltage exponent
|
None
|
2.0
|
VP
|
Pinch-off voltage
|
Volt
|
Calculated
|
VTO
|
Threshold voltage. If VTO is nonzero,
it overrides the internal calculation.
Negative VTO denotes a depletion transistor (for
both NJF and PJF), while positive VTO denotes an enhancement transistor.
|
Volt
|
Calculated
|
W
|
FET gate width
|
Meter
|
0.0
|
WDEL
|
Difference between drawn width
and actual or optical device width
|
Meter
|
0.0
|
Curtice MESFET Model Netlist Example
.MODEL mesfet3 NJF LEVEL=3 SAT=0
.model njf NJF level=3 sat=3
+ beta=626e-6 lambda=0 k1=0.02 delta=0
+ vto=-2.33 is=0.5e-9 tt=1.0e-14 capds = 1e-14
+ n=1.2 cgs=1e-15 cgd=1e-15 satexp=3.2
+ gamds=1e-4 ucrit=1e-2 q=2.5 alpha=2.5 rg=10
+ m=0.5 pb=0.7 fc=0.5 capop=1
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