A bipolar junction transistor is a three-terminal semiconductor device that can amplify current or switch signals. It consists of two PN junctions forming either an NPN or PNP structure.
base - Control terminalcollector - High-current terminalemitter - Low-current terminal (reference)substrate - Substrate/bulk connection
| Parameter | Type | Default | Description |
|---|
name | String | required | Component identifier |
Type | String | "npn" | Transistor type: "npn" or "pnp" |
Is | Real | 1e-15 | Transport saturation current (A) |
Bf | Real | 100 | Ideal maximum forward beta |
Nf | Real | 1.0 | Forward emission coefficient |
Nr | Real | 1.0 | Reverse emission coefficient |
Br | Real | 1.0 | Ideal maximum reverse beta |
| Parameter | Type | Default | Description |
|---|
Ikf | Real | 0 | Forward beta high current roll-off knee current (A) |
Ikr | Real | 0 | Reverse beta high current roll-off knee current (A) |
Vaf | Real | 0 | Forward Early voltage (V) |
Var | Real | 0 | Reverse Early voltage (V) |
Ise | Real | 0 | Base-emitter leakage saturation current (A) |
Ne | Real | 1.5 | Base-emitter leakage emission coefficient |
Isc | Real | 0 | Base-collector leakage saturation current (A) |
Nc | Real | 2.0 | Base-collector leakage emission coefficient |
| Parameter | Type | Default | Description |
|---|
Rb | Real | 0 | Zero bias base resistance (Ω) |
Rbm | Real | 0 | Minimum base resistance (Ω) |
Irb | Real | 0 | Current at which Rb falls to half of Rbm (A) |
Rc | Real | 0 | Collector ohmic resistance (Ω) |
Re | Real | 0 | Emitter ohmic resistance (Ω) |
| Parameter | Type | Default | Description |
|---|
Cje | Real | 0 | Base-emitter zero-bias depletion capacitance (F) |
Vje | Real | 0.75 | Base-emitter built-in potential (V) |
Mje | Real | 0.33 | Base-emitter junction grading coefficient |
Cjc | Real | 0 | Base-collector zero-bias depletion capacitance (F) |
Vjc | Real | 0.75 | Base-collector built-in potential (V) |
Mjc | Real | 0.33 | Base-collector junction grading coefficient |
Xcjc | Real | 1.0 | Fraction of Cjc connected internal to Rb |
Cjs | Real | 0 | Substrate zero-bias depletion capacitance (F) |
Vjs | Real | 0.75 | Substrate built-in potential (V) |
Mjs | Real | 0.0 | Substrate junction grading coefficient |
Fc | Real | 0.5 | Forward bias depletion capacitance coefficient |
| Parameter | Type | Default | Description |
|---|
Tf | Real | 0 | Ideal forward transit time (s) |
Xtf | Real | 0 | Coefficient for bias dependence of Tf |
Vtf | Real | 0 | Voltage describing Vbc dependence of Tf (V) |
Itf | Real | 0 | High current parameter for Tf (A) |
Tr | Real | 0 | Ideal reverse transit time (s) |
Ptf | Real | 0 | Excess phase at 1/(2π·Tf) Hz (deg) |
| Parameter | Type | Default | Description |
|---|
Kf | Real | 0 | Flicker noise coefficient |
Af | Real | 1.0 | Flicker noise exponent |
Ffe | Real | 1.0 | Flicker noise frequency exponent |
Kb | Real | 0 | Burst noise coefficient |
Ab | Real | 1.0 | Burst noise exponent |
Fb | Real | 1.0 | Burst noise frequency exponent |
| Parameter | Type | Default | Description |
|---|
Temp | Real | 26.85 | Device temperature (°C) |
Tnom | Real | 26.85 | Nominal temperature (°C) |
Xtb | Real | 0 | Forward/reverse beta temperature coefficient |
Xti | Real | 3.0 | Is temperature effect exponent |
Eg | Real | 1.11 | Energy gap (eV) |
| Parameter | Type | Default | Description |
|---|
Area | Real | 1.0 | Area scaling factor |
using CircuitSim
circ = Circuit()
q1 = BJT("q1", Type="npn", Bf=100, Is=1e-15)
vcc = DCVoltageSource("vcc", voltage=12.0)
vb = DCVoltageSource("vb", voltage=0.7)
rc = Resistor("rc", resistance=1000.0)
rb = Resistor("rb", resistance=10000.0)
gnd = Ground("gnd")
add_component!(circ, q1)
add_component!(circ, vcc)
add_component!(circ, vb)
add_component!(circ, rc)
add_component!(circ, rb)
add_component!(circ, gnd)
@connect circ vcc.nplus rc.n1
@connect circ rc.n2 q1.collector
@connect circ q1.emitter gnd.n
@connect circ q1.substrate gnd.n
@connect circ vb.nplus rb.n1
@connect circ rb.n2 q1.base
@connect circ vb.nminus gnd.n
@connect circ vcc.nminus gnd.n
println("Circuit netlist:")
println(netlist_qucs(circ))
Circuit netlist:
# Qucs netlist generated by CircuitSim.jl
BJT:q1 3 4 0 0 Type="npn" Is="1.0e-15" Nf="1.0" Nr="1.0" Ikf="0" Ikr="0" Vaf="0" Var="0" Ise="0" Ne="1.5" Isc="0" Nc="2.0" Bf="100" Br="1.0" Rbm="0" Irb="0" Rc="0" Re="0" Rb="0" Cje="0" Vje="0.75" Mje="0.33" Cjc="0" Vjc="0.75" Mjc="0.33" Xcjc="1.0" Cjs="0" Vjs="0.75" Mjs="0.0" Fc="0.5" Vtf="0" Tf="0" Xtf="0" Itf="0" Tr="0" Temp="26.85" Kf="0" Af="1.0" Ffe="1.0" Kb="0" Ab="1.0" Fb="1.0" Ptf="0" Xtb="0" Xti="3.0" Eg="1.11" Tnom="26.85" Area="1.0"
Vdc:vcc _net2 gnd U="12.0"
Vdc:vb _net1 gnd U="0.7"
R:rc _net2 _net4 R="1000.0"
R:rb _net1 _net3 R="10000.0"
This common-emitter configuration demonstrates basic BJT amplification. With VBE ≈ 0.7V, the transistor should be in active mode with collector current IC = β·IB flowing through RC.