BJT Models (both NPN and PNP)

**Type Names:** `npn`, `pnp`

The bipolar junction transistor model in * WRspice* is an adaptation of
the integral charge control model of Gummel and Poon. This modified
Gummel-Poon model extends the original model to include several
effects at high bias levels. The model will automatically simplify to
the simpler Ebers-Moll model when certain parameters are not
specified. The parameter names used in the modified Gummel-Poon model
have been chosen to be more easily understood by the program user, and
to reflect better both physical and circuit design thinking.

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 B-E junction, `cjc`, `vjc`, and
`mjc` for the B-C junction, and `cjs`, `vjs`, and `mjs` for the C-S (Collector-Substrate) junction. The temperature
dependence of the saturation current, `is`, is determined by the
energy gap, `eg`, and the saturation current 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`
line or overridden by a specification on the `.model` line.

The BJT parameters used in the modified Gummel-Poon model are listed
below. The parameter names used in earlier versions of SPICE2 are
still accepted. The parameters marked with an asterisk in the **area** column scale with the `area` parameter given in the device
line.

There is also a level=4 BJT model which uses the VBIC equation set, as used in the NGspice-17 simulator. This model is documented elsewhere.

BJT Model Parametersnameareaparameterunitsdefaultexampleis* transport saturation current A1.0e-16 1.0e-15 bfideal maximum forward beta - 100 100 nfforward current emission coefficient - 1.0 1 vafforward Early voltage Vinfinite 200 ikf* corner for forward beta high current roll-off Ainfinite 0.01 ise* B-E leakage saturation current A0 1.0e-13 neB-E leakage emission coefficient - 1.5 2 brideal maximum reverse beta - 1 0.1 nrreverse current emission coefficient - 1 1 varreverse Early voltage Vinfinite 200 ikr* corner for reverse beta high current roll-off Ainfinite 0.01 isc* B-C leakage saturation current A0 1.0e-13 ncB-C leakage emission coefficient - 2 1.5 rb* zero bias base resistance 0 100 ikb* current where base resistance falls halfway to its min value Ainfinite 0.1 rbm* minimum base resistance at high currents rb10 re* emitter resistance 0 1 rc* collector resistance 0 10 cje* B-E zero-bias depletion capacitance F0 2pf vjeB-E built-in potential V0.75 0.6 mjeB-E junction exponential factor - 0.33 0.33 tfideal forward transit time S0 0.1ns xtfcoefficient for bias dependence of tf- 0 - vtfvoltage describing VBC dependence of tfVinfinite - itf* high-current parameter for effect on tfA0 - ptfexcess phase at freq=1.0/( tf^{ . }2 ) Hzdeg0 - cjc* B-C zero-bias depletion capacitance F0 2pf vjcB-C built-in potential V0.75 0.5 mjcB-C junction exponential factor - 0.33 0.5 xcjcfraction of B-C depletion capacitance connected to internal base node - 1 - trideal reverse transit time S0 10ns cjs* zero-bias collector-substrate capacitance F0 2pf vjssubstrate junction built-in potential V0.75 - mjssubstrate junction exponential factor - 0 0.5 xtbforward and reverse beta temperature exponent - 0 - egenergy gap for temperature effect on iseV1.11 - xtitemperature exponent for effect on is- 3 - kfflicker-noise coefficient - 0 - afflicker-noise exponent - 1 - fccoefficient for forward-bias depletion capacitance formula - 0.5 - tnomparameter measurement temperature C25 50