BJT Punch-Through Voltage Calculator
Compute the total collector-base junction potential required for the depletion region to span a uniformly doped neutral base: Vtotal=q·NB·WB²/(2·εSi). This is not the externally applied reverse bias; subtract the junction built-in potential to estimate that bias.
Description
Compute the total collector-base junction potential required for the depletion region to span a uniformly doped neutral base: Vtotal=q·NB·WB²/(2·εSi). This is not the externally applied reverse bias; subtract the junction built-in potential to estimate that bias.
BJT Punch-Through Voltage Calculator is a focused tool for the following task. Compute the total collector-base junction potential required for the depletion region to span a uniformly doped neutral base: Vtotal=q·NB·WB²/(2·εSi). This is not the externally applied reverse bias; subtract the junction built-in potential to estimate that bias. It reports Punch-through voltage from the values you provide rather than inventing measurements, coefficients, or professional judgment that are not part of the input.
When to use BJT Punch-Through Voltage
Use this semiconductor calculation for first-order device, material, fabrication, interconnect, packaging, or reliability estimates when every coefficient and unit convention is known.
- Base doping (cm^-3)
- Required number in cm^-3. Uniform base doping concentration. Must be greater than 0 cm⁻³.
- Base width (µm)
- Required number in µm. Neutral base width between emitter and collector junctions. Must be greater than 0 µm.
The cited overview of Bipolar junction transistor supplies background for the terminology and domain context used by this tool.1
How BJT Punch-Through Voltage works
Compute the total collector-base junction potential required for the depletion region to span a uniformly doped neutral base: Vtotal=q·NB·WB²/(2·εSi). This is not the externally applied reverse bias; subtract the junction built-in potential to estimate that bias. Inputs are interpreted exactly in the displayed units and the calculation returns the following fields without presentation rounding.
- Punch-through voltage (V)
- Returned number in V. Total depletion-supporting junction potential at punch-through. Subtract built-in potential to estimate external reverse bias.
Limitations and assumptions
- Material composition, geometry, process history, temperature, electric field, bias, interfaces, parasitics, and fitted parameter ranges can invalidate a compact semiconductor model.
- Base doping must be at least 5e-324.
- Base width must be at least 5e-324.
- Use finite inputs in the displayed units, preserve source measurements and assumptions, and independently verify consequential decisions.
Alternative or Complementary approaches
Compare the estimate with measured process data, current device documentation, and a higher-fidelity circuit, field, thermal, quantum, or TCAD model when the decision requires it.
References
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Bipolar junction transistor — Wikipedia contributors
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