Symbol Names: NPN, PNP, NPN2, PNP2
Syntax: Qxxx Collector Base Emitter [Substrate Node]
+ model [area] [off] [IC=<Vbe, Vce>] [temp=<T>]
Example:
Q1 C B E MyNPNmodel
.model MyNPNmodel NPN(Bf=75)
Bipolar transistors require a model card to specify its characteristics. The model card keywords NPN and PNP indicate the polarity of the transistor.
The bipolar junction transistor model is an adaptation of the integral charge control model of Gummel and Poon. This modified GummelPoon model extends the original model to include several effects at high bias levels, quasisaturation, and substrate conductivity. The model automatically simplifies to the EbersMoll model when certain parameters are not specified. The DC model is defined by the parameters Is, Bf, Nf, Ise, Ikf, and Ne which determine the forward current gain characteristics, Is, Br, Nr, Isc, Ikr, and Nc which determine the reverse current gain characteristics, and Vaf and Var which determine the output conductance for forward and reverse regions. Three ohmic resistances Rb, Rc and Re, are included, where Rb can be high current dependent. Base charge storage is modeled by forward and reverse transit times, Tf and Tr, the forward transit time Tf being bias dependent if desired; and nonlinear depletion layer capacitances, which are determined by Cje, Vje and Mje, for the BE junction, Cjc, Vjc, and MJC for the BC junction and Cjs, Vjs, and Mjs for the Collector Substrate junction. The temperature dependence of the saturation current, Is, is determined by the energy gap, Eg, and the saturationcurrent temperature exponent, XTI. Additionally base current temperature dependence is modeled by the beta temperature exponent XTB in the new model. The values specified are assumed to have been measured at the temperature TNOM, which can be specified on the .OPTIONS control line or overridden by a specification on the .model line.
The BJT parameters used in the modified GummelPoon model are listed below.
Modified GummelPoon BJT Parameters
Name 
Description 
Units 
Default 
Is 
Transport saturation current 
A 
1e16 
Bf 
Ideal maximum forward beta 
 
100 
Nf 
Forward current emission coefficient 
 
1. 
Vaf 
Forward Early voltage 
V 
Infin. 
Ikf 
Corner for forward beta high current rolloff 
A 
Infin. 
Ise 
BE leakage saturation current 
A 
0. 
Ne 
BE leakage emission coefficient 
 
1.5 
Br 
Ideal maximum reverse beta 
 
1. 
Nr 
Reverse current emission coefficient 
 
1. 
Var 
Reverse Early voltage 
V 
Infin. 
Ikr 
Corner for reverse beta high current rolloff 
A 
Infin. 
Isc 
BC leakage saturation current 
A 
0 
Nc 
BC leakage emission coefficient 
 
2 
Rb 
Zerobias base resistance 
W 
0 
Irb 
Current where base resistance falls halfway to its min value 
A 
Infin. 
Rbm 
Minimum base resistance at high currents 
W 
Rb 
Re 
Emitter resistance 
W 
0. 
Rc 
Collector resistance 
W 
0. 
Cje 
BE zerobias depletion capacitance 
F 
0. 
Vje 
BE builtin potential 
V 
0.75 
Mje 
BE junction exponential factor 
 
0.33 
Tf 
Ideal forward transit time 
sec 
0. 
Xtf 
Coefficient for bias dependence of Tf 
 
0. 
Vtf 
Voltage describing Vbc dependence of Tf 
V 
Infin. 
Itf 
Highcurrent parameter for effect on Tf 
A 
0. 
Ptf 
Excess phase at freq=1/(Tf*2*PI)Hz 
º 
0. 
Cjc 
BC zerobias depletion capacitance 
F 
0. 
Vjc 
BC builtin potential 
V 
0.75 
Mjc 
BC junction exponential factor 
 
0.33 
Xcjc 
Fraction of BC depletion capacitance connected to internal base node 
 
1. 
Tr 
Ideal reverse transit time 
sec 
0. 
Cjs 
Zerobias collectorsubstrate capacitance 
F 
0. 
Vjs 
Substrate junction builtin potential 
V 
0.75 
Mjs 
Substrate junction exponential factor 
 
0. 
Xtb 
Forward and reverse beta temperature exponent 
 
0. 
Eg 
Energy gap for temperature effect on Is 
eV 
1.11 
Xti 
Temperature exponent for effect on Is 
 
3. 
Kf 
Flickernoise coefficient 
 
0. 
Af 
Flickernoise exponent 
 
1. 
Fc 
Coefficient for forwardbias depletion capacitance formula 
 
0.5 
Tnom 
Parameter measurement temperature 
ºC 
27 
Cn 
Quasisaturation temperature coefficient for hole mobility 
2.42 NPN 2.2 PNP  
D 
Quasisaturation temperature coefficient for scatteringlimited hole carrier velocity 
.87 NPN .52 PNP  
Gamma 
Epitaxial region doping factor 

1e11 
Qco 
Epitaxial region charge factor 
Coul 
0. 
Quasimod 
Quasisaturation flag for temperature dependence 
 
(not set) 
Rco 
Epitaxial region resistance 
W 
0. 
Vg 
Quasisaturation extrapolated bandgap voltage at 0ºK 
V 
1.206 
Vo 
Carrier mobility knee voltage 
V 
10. 
Tre1 
Re linear temperature coefficient 
1/ºC 
0. 
Tre2 
Re quadratic temperature coefficient 
1/ºC² 
0. 
Trb1 
Rb linear temperature coefficient 
1/ºC 
0. 
Trb2 
Rb quadratic temperature coefficient 
1/ºC² 
0. 
Trc1 
Rc linear temperature coefficient 
1/ºC 
0. 
Trc2 
Rc quadratic temperature coefficient 
1/ºC² 
0. 
Trm1 
Rmb linear temperature coefficient 
1/ºC 
0. 
Trm2 
Rmb quadratic temperature coefficient 
1/ºC² 
0. 
Iss 
Substrate junction saturation current 
A 
0. 
Ns 
Substrate junction emission Coefficient 
 
1. 
The model parameter "level" can be used to specify another type of BJT in LTspice. Due to a generous contribution of source code from Dr.Ing. Dietmar Warning of DAnalyse GmbH, Berlin, Germany; LTspice includes a version of VBIC. Set
Level=9 to use the alternate device. Level 4 is a synonym for level 9. The following documentation has been supplied by Dr. Warning:
VBIC  Vertical Bipolar Inter Company model
The VBIC model is a extended development of the Standard GummelPoon (SGP) model with the focus of integrated bipolar transistors in today's modern semiconductor technologies. With the implemented modified QuasiSaturation model from Kull and Nagel it is also possible to model the special output characteristic of switching transistors. It is a widely used alternative to the SGP model for silicon, SiGe and IIIV HBT devices.
VBIC Capabilities compared to Standard GummelPoon Model
o Integrated Substrate transistor for parasitic devices in integrated processes
o Weak avalanche and Baseemitter breakdown model
o Improved Early Effect modeling
o Physical separation of Ic and Ib
o Improved Depletion capacitance model
o Improved temperature modeling
o Selfheating modeling (not in this version)
Model Structure
Because the VBIC model is based on SGP model it is possible to start with SGP parameters, carry out some transformations. Following parameters are from VBIC version 1.2, which is implemented in LTSpice in the 4terminal version without excess phase network and selfheating effect. To switch from SGP to VBIC you should set the extra parameter level to 9.
Name 
Parameter meaning 
Unit 
Default 
tnom 
Parameter measurement temperature 
ºC 
27. 
rcx 
Extrinsic coll resistance 
W 
0.1 
rci 
Intrinsic coll resistance 
W 
0.1 
vo 
Epi drift saturation voltage 
V 
Infin. 
gamm 
Epi doping parameter 

0.0 
hrcf 
High current RC factor 

Infin. 
rbx 
Extrinsic base resistance 
W 
0.1 
rbi 
Intrinsic base resistance 
W 
0.1 
re 
Intrinsic emitter resistance 
W 
0.1 
rs 
Intrinsic substrate resistance 
W 
0.1 
rbp 
Parasitic base resistance 
W 
0.1 
is 
Transport saturation current 
A 
1e16 
nf 
Forward emission coefficient 

1. 
nr 
Reverse emission coefficient 

1. 
fc 
Fwd bias depletion capacitance limit 

0.9 
cbeo 
Extrinsic BE overlap capacitance 
F 
0.0 
cje 
Zero bias BE depletion capacitance 
F 
0.0 
pe 
BE built in potential 
V 
0.75 
me 
BE junction grading coefficient 

0.33 
aje 
BE capacitance smoothing factor 

0.5 
cbco 
Extrinsic BC overlap capacitance 
F 
0. 
cjc 
Zero bias BC depletion capacitance 
F 
0. 
qco 
Epi charge parameter 
C 
0. 
cjep 
BC extrinsic zero bias capacitance 
F 
0. 
pc 
BC built in potential 
V 
0.75 
mc 
BC junction grading coefficient 

0.33 
ajc 
BC capacitance smoothing factor 

0.5 
cjcp 
Zero bias SC capacitance 
F 
0. 
ps 
SC junction built in potential 
V 
0.75 
ms 
SC junction grading coefficient 

0.33 
ajs 
SC capacitance smoothing factor 

0.5 
ibei 
Ideal BE saturation current 
A 
1e18 
wbe 
Portion of IBEI from Vbei 1WBE from Vbex 

1. 
nei 
Ideal BE emission coefficient 

1. 
iben 
Nonideal BE saturation current 
A 
0. 
nen 
Nonideal BE emission coefficient 

2. 
ibci 
Ideal BC saturation current 
A 
1e16 
nci 
Ideal BC emission coefficient 

1. 
ibcn 
Nonideal BC saturation current 
A 
0. 
ncn 
Nonideal BC emission coefficient 

1. 
avc1 
BC weak avalanche parameter 1 
1/V 
0. 
avc2 
BC weak avalanche parameter 2 
1/V 
0. 
isp 
Parasitic transport saturation current 
A 
0. 
wsp 
Portion of ICCP 

1. 
nfp 
Parasitic fwd emission coefficient 

1. 
ibeip 
Ideal parasitic BE saturation current 
A 
0. 
ibenp 
Nonideal parasitic BE saturation current 
A 
0. 
ibcip 
Ideal parasitic BC saturation current 
A 
0. 
ncip 
Ideal parasitic BC emission coefficient 

1. 
ibcnp 
Nonideal parasitic BC saturation current 
A 
0. 
ncnp 
Nonideal parasitic BC emission coefficient 

2. 
vef 
Forward Early voltage 

Infin. 
ver 
Reverse Early voltage 

Infin. 
ikf 
Forward knee current 
A 
Infin. 
ikr 
Reverse knee current 
A 
Infin. 
ikp 
Parasitic knee current 
A 
Infin. 
tf 
Ideal forward transit time 
s 
0. 
qtf 
Variation of TF with basewidth modulation 

0. 
xtf 
Coefficient for bias dependence of TF 

0. 
vtf 
Voltage giving VBC dependence of TF 
V 
Infin. 
itf 
High current dependence of TF 
A 
Infin. 
tr 
Ideal reverse transit time 
sec 
0. 
td 
Forward excessphase delay time 
Sec 
0. 
kfn 
BE Flicker Noise Coefficient 

0. 
afn 
BE Flicker Noise Exponent 

1. 
bfn 
BE Flicker Noise 1/f dependence 

1.0 
xre 
Temperature exponent of RE 

0. 
xrbi 
Temperature exponent of RBI 

0. 
xrci 
Temperature exponent of RCI 

0. 
xrs 
Temperature exponent of RS 

0. 
xvo 
Temperature exponent of VO 

0. 
ea 
Activation energy for IS 
V 
1.12 
eaie 
Activation energy for IBEI 
V 
1.12 
eaic 
Activation energy for IBCI/IBEIP 
V 
1.12 
eais 
Activation energy for IBCIP 
V 
1.12 
eane 
Activation energy for IBEN 
V 
1.12 
eanc 
Activation energy for IBCN/IBENP 
V 
1.12 
eans 
Activation energy for IBCNP 
V 
1.12 
xis 
Temperature exponent of IS 

3. 
xii 
Temperature exponent of IBEI,IBCI,IBEIP,IBCIP 

3. 
xin 
Temperature exponent of IBEN,IBCN,IBENP,IBCNP 

3. 
tnf 
Temperature exponent of NF 

0. 
tavc 
Temperature exponent of AVC2 

0. 
rth 
Thermal resistance 
K/W 
0. 
cth 
Thermal capacitance 
Ws/K 
0. 
vrt 
Punchthrough voltage of internal BC junction 
V 
0. 
art 
Smoothing parameter for reachthrough 

0.1 
ccso 
Fixed CS capacitance 
F 
0. 
qbm 
Select SGP qb formulation 

0. 
nkf 
High current beta rolloff 

0.5 
xikf 
Temperature exponent of IKF 

0. 
xrcx 
Temperature exponent of RCX 

0. 
xrbx 
Temperature exponent of RBX 

0. 
xrbp 
Temperature exponent of RBP 

0. 
isrr 
Separate IS for fwd and rev 

1. 
xisr 
Temperature exponent of ISR 

0. 
dear 
Delta activation energy for ISRR 

0. 
eap 
Excitation energy for ISP 

1.12 
vbbe 
BE breakdown voltage 
V 
0. 
nbbe 
BE breakdown emission coefficient 

1. 
ibbe 
BE breakdown current 

1e06 
tvbbe1 
Linear temperature coefficient of VBBE 

0. 
tvbbe2 
Quadratic temperature coefficient of VBBE 

0. 
tnbbe 
Temperature coefficient of NBBE 

0. 
ebbe 
exp(VBBE/(NBBE*Vtv)) 

0. 
dtemp 
Locale Temperature difference 
º 
0. 
vers 
Revision Version 

1.2 
vref 
Reference Version 

0. 
C. C. McAndrew et al., "Vertical Bipolar Inter Company 1995: An Improved Vertical, IC Bipolar Transistor Model", Proceedings of the IEEE Bipolar Circuits and Technology Meeting, pp. 170 − 177, 1995
C. C. McAndrew et.al., VBIC95, "The Vertical Bipolar InterCompany Model", IEEE Journal of Solid State Circuits, vol. 31, No. 10, October 1996
C. C. McAndrew, VBIC Model Definition, Release 1.2, 18. Sep. 1999