Understanding the BJT Model Statement
Syntax
.MODEL mname NPN <(> <pname1 = val1> ... <)>
or
.MODEL mname PNP <pname1 = val1> ...
|
mname
|
Model name. Elements refer to the model by this name.
|
|
NPN
|
Identifies an NPN transistor model
|
|
pname1
|
Each BJT model can include several model parameters.
|
|
PNP
|
Identifies a PNP transistor model
|
Example
.MODEL t2n2222a NPN
+ ISS= 0. XTF= 1. NS = 1.00000
+ CJS= 0. VJS= 0.50000 PTF= 0.
+ MJS= 0. EG = 1.10000 AF = 1.
+ ITF= 0.50000 VTF= 1.00000
+ BR = 40.00000 IS = 1.6339e-14 VAF= 103.40529
+ VAR= 17.77498 IKF= 1.00000
+ NE = 1.31919 IKR= 1.00000 ISC= 3.6856e-13
+ NC = 1.10024 IRB= 4.3646e-05 NF = 1.00531
+ NR = 1.00688 RBM= 1.0000e-02 RB = 71.82988
+ RC = 0.42753 RE = 3.0503e-03 MJE= 0.32339
+ MJC= 0.34700 VJE= 0.67373 VJC= 0.47372
+ TF = 9.693e-10 TR = 380.00e-9 CJE= 2.6734e-11
+ CJC= 1.4040e-11 FC = 0.95000 XCJC= 0.94518
Using BJT Basic Model Parameters
To permit the use of model parameters from earlier versions of Star-Hspice, many of the model parameters have aliases, which are included in the model parameter list in Using BJT Basic DC Model Parameters. The new name is always used on printouts, even if an alias is used in the model statement.
BJT model parameters are divided into several groups. The first group of DC model parameters includes the most basic Ebers-Moll parameters. This model is effective for modeling low-frequency large-signal characteristics.
Low-current Beta degradation effect parameters ISC, ISE, NC, and NE aid in modeling the drop in the observed Beta, caused by the following mechanisms:
-
Recombination of carriers in the emitter-base space charge layer
-
Recombination of carriers at the surface
-
Formation of emitter-base channels
Low base and emitter dopant concentrations, found in some BIMOS type technologies, use the high-current Beta degradation parameters, IKF and IKR.
Use the base-width modulation parameters, that is, early effect parameters VAF and VAR, to model high-gain, narrow-base devices. The model calculates the slope of the I-V curve for the model in the active region with VAF and VAR. If VAF and VAR are not specified, the slope in the active region is zero.
The parasitic resistor parameters RE, RB, and RC are the most frequently used second-order parameters since they replace external resistors. This simplifies the input netlist file. All of the resistances are functions of the BJT multiplier M value. The resistances are divided by M to simulate parallel resistances. The base resistance is also a function of base current, as is often the case in narrow-base technologies.
Transient model parameters for BJTs are composed of two groups: junction capacitor parameters and transit time parameters. The base-emitter junction is modeled by CJE, VJE, and MJE. The base-collector junction capacitance is modeled by CJC, VJC, and MJC. The collector-substrate junction capacitance is modeled by CJS, VJS, and MJS.
TF is the forward transit time for base charge storage. TF can be modified to account for bias, current, and phase, by XTF, VTF, ITF, and PTF. The base charge storage reverse transit time is set by TR. There are several sets of temperature equations for the BJT model parameters that you can select by setting TLEV and TLEVC.
Table 16-1: BJT Model Parameters
|
DC
|
BF, BR, IBC, IBE, IS, ISS, NF, NR, NS, VAF, VAR
|
|
beta degradation
|
ISC, ISE, NC, NE, IKF, IKR
|
|
geometric
|
SUBS, BULK
|
|
resistor
|
RB, RBM, RE, RC, IRB
|
|
junction capacitor
|
CJC, CJE, CJS, FC, MJC, MJE, MJS, VJC, VJE, VJS, XCJC
|
|
parasitic capacitance
|
CBCP, CBEP, CCSP
|
|
transit time
|
ITF, PTF, TF, VT, VTF, XTF
|
|
noise
|
KF, AF
|
Using BJT Basic DC Model Parameters
|
Name (Alias)
|
Unit
|
Default
|
Description
|
|
BF (BFM)
|
|
100.0
|
Ideal maximum forward Beta
|
|
BR (BRM)
|
|
1.0
|
Ideal maximum reverse Beta
|
|
BULK (NSUB)
|
|
0.0
|
Sets the bulk node to a global node name. A substrate terminal node name (ns) in the element statement overrides BULK.
|
|
IBC
|
amp
|
0.0
|
Reverse saturation current between base and collector. If both IBE and IBC are specified, Star-Hspice uses them in place of IS to calculate DC current and conductance; otherwise it uses IS.
IBCeff = IBC · AREAB · M
AREAC replaces AREAB, depending on vertical or lateral geometry.
|
|
EXPLI
|
amp
|
1e15
|
Current explosion model parameter. The PN junction characteristics above the explosion current area linear, with the slope at the explosion point. This speeds up simulation and improves convergence.
EXPLIeff = EXPLI · AREAeff
|
|
IBE
|
amp
|
0.0
|
Reverse saturation current between base and emitter. If both IBE and IBC are specified, Star-Hspice uses them in place of IS to calculate DC current and conductance; otherwise it uses IS.
IBEeff = IBE · AREA · M
|
|
IS
|
amp
|
1.0e-16
|
Transport saturation current. If both IBE and IBC are specified, Star-Hspice uses them in place of IS to calculate DC current and conductance; otherwise it uses IS.
ISeff = IS · AREA · M
|
|
ISS
|
amp
|
0.0
|
Reverse saturation current bulk-to-collector or bulk-to-base, depending on vertical or lateral geometry selection
SSeff = ISS · AREA · M
|
|
LEVEL
|
|
1.0
|
Model selector
|
|
NF
|
|
1.0
|
Forward current emission coefficient
|
|
NR
|
|
1.0
|
Reverse current emission coefficient
|
|
NS
|
|
1.0
|
Substrate current emission coefficient
|
|
SUBS
|
|
|
Substrate connection selector:
+1 for vertical geometry, -1 for lateral geometry
default=1 for NPN, default=-1 for PNP
|
|
UPDATE
|
|
0
|
UPDATE = 1 selects alternate base charge equation
|
Using Low-Current Beta Degradation Effect Parameters
|
Name (Alias)
|
Unit
|
Default
|
Description
|
|
ISC (C4, JLC)
|
amp
|
0.0
|
Base-collector leakage saturation current. If ISC is greater than 1e-4, then:
ISC = IS · ISC
otherwise:
ISCeff = ISC · AREAB · M
AREAC replaces AREAB, depending on vertical or lateral geometry.
|
|
ISE (C2, JLE)
|
amp
|
0.0
|
Base-emitter leakage saturation current. If ISE is greater than
1e-4, then:
ISE = IS · ISE
otherwise:
ISEeff = ISE · AREA · M
|
|
NC (NLC)
|
|
2.0
|
Base-collector leakage emission coefficient
|
|
NE (NLE)
|
|
1.5
|
Base-emitter leakage emission coefficient
|
Using Base Width Modulation Parameters
|
Name (Alias)
|
Unit
|
Default
|
Description
|
|
VAF (VA, VBF)
|
V
|
0.0
|
Forward early voltage. Use zero to indicate an infinite value.
|
|
VAR (VB, VRB, BV)
|
V
|
0.0
|
Reverse early voltage. Use zero to indicate an infinite value.
|
Using High-Current Beta Degradation Effect Parameters
|
Name (Alias)
|
Unit
|
Default
|
Description
|
|
IKF (IK, JBF)
|
amp
|
0.0
|
Corner for forward Beta high-current roll-off. Use zero to indicate an infinite value.
IKFeff = IKF · AREA · M
|
|
IKR (JBR)
|
amp
|
0.0
|
Corner for reverse Beta high-current roll-off. Use zero to indicate an infinite value
IKReff = IKR · AREA · M
|
|
NKF
|
|
0.5
|
Exponent for high-current Beta roll-off
|
Using Parasitic Resistance Parameters
|
Name (Alias)
|
Unit
|
Default
|
Description
|
|
IRB (JRB, IOB)
|
amp
|
0.0
|
Base current, where base resistance falls half-way to RBM. Use zero to indicate an infinite value.
IRBeff = IRB · AREA · M
|
|
RB
|
ohm
|
0.0
|
Base resistance
RBeff = RB / (AREA · M)
|
|
RBM
|
ohm
|
RB
|
Minimum high-current base resistance
RBMeff = RBM / (AREA · M)
|
|
RE
|
ohm
|
0.0
|
Emitter resistance
REeff = RE / (AREA · M)
|
|
RC
|
ohm
|
0.0
|
Collector resistance
RCeff = RC / (AREA · M)
|
Using Junction Capacitor Parameters
|
Name (Alias)
|
Unit
|
Default
|
Description
|
|
CJC
|
F
|
0.0
|
Base-collector zero-bias depletion capacitance
Vertical: CJCeff = CJC · AREAB · M
Lateral: CJCeff = CJC · AREAC · M
|
|
CJE
|
F
|
0.0
|
Base-emitter zero-bias depletion capacitance (vertical and lateral):
CJEeff = CJE · AREA · M
|
|
CJS (CCS, CSUB)
|
F
|
0.0
|
Zero-bias collector substrate capacitance
Vertical: CJSeff = CJS · AREAC · M
Lateral: CJSeff = CJS · AREAB · M
|
|
FC
|
|
0.5
|
Coefficient for forward bias depletion capacitance formula for DCAP=1
DCAP Default=2 and FC is ignored
|
|
MJC (MC)
|
|
0.33
|
Base-collector junction exponent (grading factor)
|
|
MJE (ME)
|
|
0.33
|
Base-emitter junction exponent (grading factor)
|
|
MJS(ESUB)
|
|
0.5
|
Substrate junction exponent (grading factor)
|
|
VJC (PC)
|
V
|
0.75
|
Base-collector built-in potential
|
|
VJE (PE)
|
V
|
0.75
|
Base-emitter built-in potential
|
|
VJS (PSUB)
|
V
|
0.75
|
Substrate junction built in potential
|
|
XCJC (CDIS)
|
|
1.0
|
Internal base fraction of base-collector depletion capacitance
|
Using Parasitic Capacitances Parameters
|
Name
|
Unit
|
Default
|
Description
|
|
CBCP
|
F
|
0.0
|
External base-collector constant capacitance
CBCPeff = CBCP · AREA · M
|
|
CBEP
|
F
|
0.0
|
External base-emitter constant capacitance
CBEPeff = CBEP · AREA · M
|
|
CCSP
|
F
|
0.0
|
External collector substrate constant capacitance (vertical) or base substrate (lateral)
CCSPeff = CCSP · AREA · M
|
Using Transit Time Parameters
|
Name (Alias)
|
Unit
|
Default
|
Description
|
|
ITF (JTF)
|
amp
|
0.0
|
TF high-current parameter
ITFeff = ITF · AREA · M
|
|
PTF
|
x
|
0.0
|
Frequency multiplier to determine excess phase
|
|
TF
|
s
|
0.0
|
Base forward transit time
|
|
TR
|
s
|
0.0
|
Base reverse transit time
|
|
VTF
|
V
|
0.0
|
TF base-collector voltage dependence coefficient. Zero indicates an infinite value.
|
|
XTF
|
|
0.0
|
TF bias dependence coefficient
|
Using Noise Parameters
|
Name
|
Unit
|
Default
|
Description
|
|
AF
|
|
1.0
|
Flicker-noise exponent
|
|
KF
|
|
0.0
|
Flicker-noise coefficient
|
Using BJT LEVEL=2 Model Parameters
|
Name
|
Unit
|
Default
|
Description
|
|
BRS
|
|
1.0
|
Reverse beta for substrate BJT.
|
|
GAMMA
|
|
0.0
|
Epitaxial doping factor,
GAMMA = (2 · ni / n)
2
where n is epitaxial impurity concentration
|
|
NEPI
|
|
1.0
|
Emission coefficient
|
|
QCO
|
Coul
|
0.0
|
Epitaxial charge factor
Vertical: QCOeff=QCO · AREAB · M
Lateral: QCOeff=QCO · AREAC · M
|
|
RC
|
ohm
|
0.0
|
Resistance of the epitaxial region under equilibrium conditions
RCeff=RC/(AREA · M)
|
|
VO
|
V
|
0.0
|
Carrier velocity saturation voltage. Use zero to indicate an infinite value.
|
Handling BJT Model Temperature Effects
Several temperature parameters control derating of the BJT model parameters. They include temperature parameters for junction capacitance, Beta degradation (DC), and base modulation (Early effect) among others.
Table 16-2: BJT Temperature Parameters
|
Function
|
Parameter
|
|
base modulation
|
TVAF1, TVAF2, TVAR1, TVAR2
|
|
capacitor
|
CTC, CTE, CTS
|
|
capacitor potentials
|
TVJC, TVJE, TVJS
|
|
DC
|
TBF1, TBF2, TBR1, TBR2, TIKF1, TIKF2, TIKR1, TIKR2, TIRB1, TIRB2, TISC1, TISC2, TIS1, TIS2, TISE1, TISE2, TISS1, TISS2, XTB, XTI
|
|
emission coefficients
|
TNC1, TNC2, TNE1, TNE2, TNF1, TNF2, TNR1, TNR2, TNS1, TNS2
|
|
energy gap
|
EG, GAP1, GAP2
|
|
equation selectors
|
TLEV, TLEVC
|
|
grading
|
MJC, MJE, MJS, TMJC1, TMJC2, TMJE1, TMJE2, TMJS1, TMJS2
|
|
resistors
|
TRB1, TRB2, TRC1, TRC2, TRE1, TRE2, TRM1, TRM2
|
|
transit time
|
TTF1, TTF2, TTR1, TTR2
|
Using Temperature Effect Parameters
|
Name (Alias)
|
Unit
|
Default
|
Description
|
|
BEX
|
|
2.42
|
VO temperature exponent (LEVEL 2 only)
|
|
BEXV
|
|
1.90
|
RC temperature exponent (LEVEL 2 only)
|
|
CTC
|
1/°
|
0.0
|
Temperature coefficient for zero-bias base collector capacitance. TLEVC=1 enables CTC to override the default Star-Hspice temperature compensation.
|
|
CTE
|
1/°
|
0.0
|
Temperature coefficient for zero-bias base emitter capacitance. TLEVC=1 enables CTE to override the default Star-Hspice temperature compensation.
|
|
CTS
|
1/°
|
0.0
|
Temperature coefficient for zero-bias substrate capacitance. TLEVC=1 enables CTS to override the default Star-Hspice temperature compensation.
|
|
EG
|
eV
|
|
Energy gap for pn junction
for TLEV=0 or 1, default=1.11;
for TLEV=2, default=1.16
1.17 - silicon
0.69 - Schottky barrier diode
0.67 - germanium
1.52 - gallium arsenide
|
|
GAP1
|
eV/°
|
7.02e-4
|
First bandgap correction factor (from Sze, alpha term)
7.02e-4 - silicon
4.73e-4 - silicon
4.56e-4 - germanium
5.41e-4 - gallium arsenide
|
|
GAP2
|
x
|
1108
|
Second bandgap correction factor (from Sze, beta term)
1108 - silicon
636 - silicon
210 - germanium
204 - gallium arsenide
|
|
MJC (MC)
|
|
0.33
|
Base-collector junction exponent (grading factor)
|
|
MJE (ME)
|
|
0.33
|
Base-emitter junction exponent (grading factor)
|
|
MJS (ESUB)
|
|
0.5
|
Substrate junction exponent (grading factor)
|
|
TBF1
|
1/°
|
0.0
|
First-order temperature coefficient for BF
|
|
TBF2
|
1/°2
|
0.0
|
Second-order temperature coefficient for BF
|
|
TBR1
|
1/°
|
0.0
|
First-order temperature coefficient for BR
|
|
TBR2
|
1/°2
|
0.0
|
Second-order temperature coefficient for BR
|
|
TIKF1
|
1/°
|
0.0
|
First-order temperature coefficient for IKF
|
|
TIKF2
|
1/°2
|
0.0
|
Second-order temperature coefficient for IKF
|
|
TIKR1
|
1/°
|
0.0
|
First-order temperature coefficient for IKR
|
|
TIKR2
|
1/°2
|
|
Second-order temperature coefficient for IKR
|
|
TIRB1
|
1/°
|
0.0
|
First-order temperature coefficient for IRB
|
|
TIRB2
|
1/°2
|
0.0
|
Second-order temperature coefficient for IRB
|
|
TISC1
|
1/°
|
0.0
|
First-order temperature coefficient for ISC
TLEV=3 enables TISC1.
|
|
TISC2
|
1/°2
|
0.0
|
Second-order temperature coefficient for ISC
TLEV=3 enables TISC2.
|
|
TIS1
|
1/°
|
0.0
|
First-order temperature coefficient for IS or IBE and IBC TLEV=3 enables TIS1.
|
|
TIS2
|
1/°2
|
0.0
|
Second-order temperature coefficient for IS or IBE and IBC TLEV=3 enables TIS2.
|
|
TISE1
|
1/°
|
0.0
|
First-order temperature coefficient for ISE
TLEV=3 enables TISE1.
|
|
TISE2
|
1/°2
|
0.0
|
Second-order temperature coefficient for ISE.
TLEV=3 enables TISE2.
|
|
TISS1
|
1/°
|
0.0
|
First-order temperature coefficient for ISS
TLEV=3 enables TISS1.
|
|
TISS2
|
1/°2
|
0.0
|
Second-order temperature coefficient for ISS
TLEV=3 enables TISS2.
|
|
TITF1
|
|
|
First-order temperature coefficient for ITF
|
|
TITF2
|
|
|
Second-order temperature coefficient for ITF
|
|
TLEV
|
|
1
|
Temperature equation level selector for BJTs (interacts with TLEVC)
|
|
TLEVC
|
|
1
|
Temperature equation level selector for BJTs, junction capacitances and potentials (interacts with TLEV)
|
|
TMJC1
|
1/°
|
0.0
|
First-order temperature coefficient for MJC
|
|
TMJC2
|
1/°2
|
0.0
|
Second-order temperature coefficient for MJC
|
|
TMJE1
|
1/°
|
0.0
|
First order temperature coefficient for MJE
|
|
TMJE2
|
1/°2
|
0.0
|
Second-order temperature coefficient for MJE
|
|
TMJS1
|
1/°
|
0.0
|
First-order temperature coefficient for MJS
|
|
TMJS2
|
1/°2
|
0.0
|
Second-order temperature coefficient for MJS
|
|
TNC1
|
1/°
|
0.0
|
First-order temperature coefficient for NC
|
|
TNC2
|
|
0.0
|
Second-order temperature coefficient for NC
|
|
TNE1
|
1/°
|
0.0
|
First-order temperature coefficient for NE
|
|
TNE2
|
1/°2
|
0.0
|
Second-order temperature coefficient for NE
|
|
TNF1
|
1/°
|
0.0
|
First-order temperature coefficient for NF
|
|
TNF2
|
1/°2
|
0.0
|
Second-order temperature coefficient for NF
|
|
TNR1
|
1/°
|
0.0
|
First-order temperature coefficient for NR
|
|
TNR2
|
1/°2
|
0.0
|
Second-order temperature coefficient for NR
|
|
TNS1
|
1/°
|
0.0
|
First-order temperature coefficient for NS
|
|
TNS2
|
1/°2
|
0.0
|
Second-order temperature coefficient for NS
|
|
TRB1 (TRB)
|
1/°
|
0.0
|
First-order temperature coefficient for RB
|
|
TRB2
|
1/°2
|
0.0
|
Second-order temperature coefficient for RB
|
|
TRC1 (TRC)
|
1/°
|
0.0
|
First-order temperature coefficient for RC
|
|
TRC2
|
1/°2
|
0.0
|
Second-order temperature coefficient for RC
|
|
TRE1 (TRE)
|
1/°
|
0.0
|
First-order temperature coefficient for RE
|
|
TRE2
|
1/°2
|
0.0
|
Second-order temperature coefficient for RE
|
|
TRM1
|
1/°
|
TRB1
|
Firs-order temperature coefficient for RBM
|
|
TRM2
|
1/°2
|
TRB2
|
Second-order temperature coefficient for RBM
|
|
TTF1
|
1/°
|
0.0
|
First-order temperature coefficient for TF
|
|
TTF2
|
1/°
2
|
0.0
|
Second-order temperature coefficient for TF
|
|
TTR1
|
1/°
|
0.0
|
First-order temperature coefficient for TR
|
|
TTR2
|
1/°
2
|
0.0
|
Second-order temperature coefficient for TR
|
|
TVAF1
|
1/°
|
0.0
|
First-order temperature coefficient for VAF
|
|
TVAF2
|
1/°
2
|
0.0
|
Second-order temperature coefficient for VAF
|
|
TVAR1
|
1/°
|
0.0
|
First-order temperature coefficient for VAR
|
|
TVAR2
|
1/°
2
|
0.0
|
Second-order temperature coefficient for VAR
|
|
TVJC
|
V/°
|
0.0
|
Temperature coefficient for VJC. TLEVC=1 or 2 enables TVJC to override the default Star Hspice temperature compensation.
|
|
TVJE
|
V/°
|
0.0
|
Temperature coefficient for VJE. TLEVC=1 or 2 enables TVJE to override the default Star Hspice temperature compensation.
|
|
TVJS
|
V/°
|
0.0
|
Temperature coefficient for VJS. TLEVC=1 or 2 enables TVJS to override the default Star Hspice temperature compensation.
|
|
XTB (TB, TCB)
|
|
0.0
|
Forward and reverse Beta temperature exponent (used with TLEV=0, 1 or 2)
|
|
XTI
|
|
3.0
|
Saturation current temperature exponent. Use XTI = 3.0 for silicon diffused junction. Set XTI = 2.0 for Schottky barrier diode.
|
Star-Hspice Manual - Release 2001.2 - June 2001
