Calculation results
Interactive analysis charts
Linear current-voltage plot
Logarithmic current-voltage plot
Log-current regression plot
Local ideality factor plot
Regression residuals
Formula used
The calculator converts every entry into coherent SI units. It then applies the selected diode relationship. Reported values remain estimates under model assumptions.
How to use this calculator
- Select a calculation method and temperature unit.
- Enter one point, two points, or an I–V dataset.
- Choose resistance, filtering, regression, and display options.
- Press Calculate and review warnings before using results.
- Export results using CSV, PDF, copy, or print controls.
Example data
| Voltage (V) | Current (mA) | Expected use |
|---|---|---|
| 0.48 | 0.018 | Lower forward region |
| 0.52 | 0.063 | Exponential region |
| 0.56 | 0.230 | Exponential region |
| 0.60 | 0.850 | Exponential region |
| 0.64 | 3.100 | Upper forward region |
| 0.68 | 9.600 | Possible resistance influence |
These values provide a demonstration dataset only. Real devices vary with construction and temperature. Measure carefully before making engineering decisions.
Interpretation and limitations
The Shockley equation simplifies real diode behaviour. Self-heating and parasitic effects can alter results. Confirm important findings with controlled laboratory measurements.
- Keep junction temperature stable during measurement.
- Avoid reverse-bias values in logarithmic fitting.
- Exclude high-current regions dominated by series resistance.
- Use enough current span for dependable regression.
- Treat presets as demonstrations, not guaranteed specifications.
Frequently asked questions
What is a diode ideality factor?
It describes how closely measured current follows the Shockley model. Different mechanisms can change its fitted value. It is not a complete diode diagnosis.
Which calculation method is best?
Regression usually uses measurements more effectively than one point. Differential analysis shows variation across voltage. Full fitting helps when resistance effects matter.
Why must current be positive?
Logarithmic methods require a positive current value. Zero and negative values create invalid logarithms. The calculator can ignore those entries.
How does temperature affect the result?
Thermal voltage changes directly with absolute temperature. Incorrect temperature therefore changes the calculated factor. Use junction temperature whenever it is available.
What does series-resistance correction do?
It estimates voltage across the diode junction itself. Measured terminal voltage includes an resistive drop. Correcting that drop can improve high-current analysis.
What is a good regression R²?
A value closer to one indicates better linear agreement. High R² does not prove model validity. Inspect residuals and the selected voltage range.
Can the calculator analyse LEDs?
Yes, suitable forward-bias measurements can be analysed. LEDs may show stronger resistance and recombination effects. Choose the fitting region carefully.
Why is my ideality factor unusually high?
Leakage, self-heating, resistance, or noisy data may contribute. An unsuitable current range can also distort fitting. Review charts and warnings before interpretation.
Can exported results replace laboratory reports?
Exports provide convenient calculation summaries and datasets. They do not establish measurement traceability. Document equipment, uncertainty, calibration, and test conditions separately.