Q: Bipolar Junction Transistor

Syntax

Qxxxxxxx nc nb ne ns mname {area} {args}
.BJT label nc nb ne ns mname {area} {args}

Purpose

Bipolar junction transistor,

Comments

Nc, nb, ne, and ns are the collector, base, emitter, and substrate nodes, respectively. Mname is the model name.

Area is a unit-less multiplier for the area.

The options rstray and norstray determines whether or not series resistances are included. rstray is the default. Norstray is the equivalent of setting the model parameters rc, re, and rb all to zero.

Entering a parameter value of 0 is not the same as not specifying it. This behavior is not compatible with SPICE. In SPICE, a value of 0 is often interpreted as not specified, with the result being to calculate it some other way. If you want it to be calculated, don't specify it.

Another subtle difference from SPICE is that Gnucap may omit some unnecessary parts of the model, which may affect some reported values. It should not affect any voltages or currents. For example, if the gate and drain are tied, Cgs will be omitted from the model, so the printed value for Cgdovl and Cgd will be 0, which will disagree with SPICE. It doesn't matter because a shorted capacitor can store no charge.

Element Parameters

Basic Spice compatible parameters

Area = x

Junction area. (Default = 1) This is a scaling parameter, with no relevant actual units.

OFF

(Default = not specified) If this word is specified, the initial guess will assume the device is off.

TEMP = x

Junction temperature. (Default = the global temperature.)

ICVBE = x

Initial condition, Vbe. (Default = NA) Use this as the initial condition, when the UIC option is specified. The syntax is different from Spice, but the function is the same.

ICVCE = x

Initial condition, Vce. (Default = NA) Use this as the initial condition, when the UIC option is specified. The syntax is different from Spice, but the function is the same.

Model Parameters

IS = x

Transport saturation Current per area. (Default = 1e-16)

BF = x

Ideal maximum forward beta. (Default = 100)

NF = x

Forward current emission coefficient. (Default = 1)

VAF = x

Forward Early voltage. (Default = Infinite) Alternate name is VA.

IKF = x

Forward beta roll-off corner current. (Default = Infinite)

ISE = x

B-E leakage saturation current. (Default = c2 * is)

C2 = x

B-E leakage scale factor. (Default = 0)

NE = x

B-E leakage emission coefficient. (Default = 1.5)

BR = x

Ideal maximum reverse beta. (Default = 1)

NR = x

Reverse current emission coefficient. (Default = 1)

VAR = x

Reverse Early voltage. (Default = Infinite) Alternate name is VB.

IKR = x

Reverse beta roll-off corner current. (Default = Infinite)

ISC = x

B-C leakage saturation current. (Default = c4 * is)

C4 = x

B-C leakage scale factor. (Default = 0)

NC = x

B-C leakage emission coefficient. (Default = 2)

RB = x

Zero bias base resistance. (Default = 0)

IRB = x

Current for base resistance=(rb+rbm)/2". (Default = Infinite) Current where base resistance falls halfway to its minimum value.

RBM = x

Minimum base resistance at high current. (Default = rb)

RE = x

Emitter resistance. (Default = 0)

RC = x

Collector resistance. (Default = 0)

CJE = x

Zero bias B-E depletion capacitance. (Default = 0)

VJE = x

B-E built in potential. (Default = .75) Alternate name is PE.

MJE = x

B-E junction grading coefficient. (Default = .33) Alternate name is ME.

TF = x

Ideal forward transit time. (Default = 0)

XTF = x

Coefficient for bias dependence of TF. (Default = 0)

VTF = x

Voltage giving VBC dependence of TF. (Default = Infinite)

ITF = x

High current dependence of TF. (Default = 0)

PTF = x

Excess phase at freq=1.0/(TF*2PI) Hz. (Default = 0)

CJC = x

Zero bias B-C depletion capacitance. (Default = 0)

VJC = x

B-C built in potential. (Default = .75) Alternate name is PC.

MJC = x

B-C junction grading coefficient. (Default = .33) Alternate name is MJ.

XCJC = x

Fraction of B-C capacitance connected to internal base node. (Default = 1)

TR = x

Ideal reverse transit time. (Default = 0)

CJS = x

Zero bias C-S capacitance. (Default = 0) Alternate name is CCS.

VJS = x

Substrate junction built in potential. (Default = .75) Alternate name is PS.

MJS = x

Substrate junction grading coefficient. (Default = 0) Alternate name is MS.

XTB = x

Forward and reverse beta temperature exponent. (Default = 0)

EG = x

Energy gap for IS temperature dependency. (Default = 1.11)

XTI = x

Temperature exponent for effect on IS. (Default = 3)

FC = x

Coefficient for forward-bias depletion capacitance formula. (Default = .5)

TNOM = x

Parameter measurement temperature, Celsius. (Default = 27)

Probes

VBEInt

Base-emitter internal voltage.

VBCInt

Base-collector internal voltage.

VBXInt

External base to internal base voltage.

VCSInt

Collector-substrate internal voltage.

VBS

Base-substrate voltage.

VBE

Base-emitter voltage.

VBC

Base-collector voltage.

VCS

Collector-substrate voltage.

VCB

Collector-base voltage.

VCE

Collector-emitter voltage.

VES

Emitter-substrate voltage.

VEB

Emitter-base voltage.

VEC

Emitter-collector voltage.

VB

Base-ground voltage.

VC

Collector-ground voltage.

VE

Emitter-ground voltage.

VS

Substrate-ground voltage.

VBI

Internal Base-ground voltage.

VCI

Internal Collector-ground voltage.

VEI

Internal Emitter-ground voltage.

ICE

Collector-emitter current.

ICEOffset

Offset part of ICE.

GO

Output (collector-emitter) conductance.

GM

Transconductance.

IPI

Base-emitter current.

IPIOffset

Offset part of IPI.

GPI

Base-emitter conductance.

IMU

Base-collector current.

IMUOffset

Offset part of IMU.

GMU

Base-collector conductance.

IB

Base current.

GX

Conductance of base spreading resistance.

RX

Base spreading resistance.

IC

Collector current.

IE

Emitter current.

QBX

External Base-collector charge.

CQBX

External Base-collector capacitance.

CBX

External Base-collector capacitance (CQBX).

QBC

Internal Base-collector charge.

CQBC

Internal Base-collector capacitance.

CBC

Internal Base-collector capacitance (CQBC).

CMU

Internal Base-collector capacitance (CQBC).

QCS

Collector-substrate charge.

CQCS

Collector-substrate capacitance.

CCS

Collector-substrate capacitance (CQCS).

QBE

Base-emitter charge.

CQBE

Base-emitter capacitance.

CBE

Base-emitter capacitance. (CQBE).

CPI

Base-emitter capacitance. (CQBE).

P

Power.

PD

Power dissipated. The power dissipated as heat. It is always positive and does not include power sourced. It should be the same as P because transistors cannot generate energy.

PS

Power sourced. The power sourced by the part. It is always positive and does not consider its own dissipation. It should be 0 because transistors cannot generate energy.

All parameters of the internal elements (Ice, Ipi, Imu, Rc, Re, Yb, Cbx, Cbc, Ccs, Cbe) are available. To access them, concatenate the labels for the internal element with this device, separated by a dot. Cbe.Q6 is the base to emitter capacitance of Q6.

In this release, there are no probes available in AC analysis except for the internal elements.