GUI Plot Specific
The Plot Specific tab houses tests that each produce a specific, well-defined plot — the kind of curve you would find in a component datasheet or characterisation report. Unlike the generic Automation tests (which produce configurable data tables), each test here has a fixed, opinionated output: known axis meanings, a live canvas, and a result you can read directly without post-processing.
The intent is that any time a characterisation task has a canonical plot shape — transistor output curves, gain vs frequency, dropout voltage vs load, efficiency map — it gets its own card here rather than being approximated through the general automation framework.
Currently implemented: Static Characteristic (IV Curve) and Transfer Characteristic for BJT and FET devices.
Select FET or BJT with the toggle in the top-right corner. The labels, axis names, and default parameter values update accordingly.
Sweeps the collector/drain voltage (V_CE or V_DS) across a range while holding base/gate drive at a series of fixed levels. Plots a family of I_C / I_D curves — one per base/gate step.
Drain / Collector (inner, swept):
| Field | Description |
|---|---|
| Source | PSU to use for the collector/drain |
| Channel | PSU channel |
| V Start / Stop / Step | Collector/drain voltage sweep range |
| I Limit | Current limit (A) — also sets the Y-axis ceiling on the plot |
| Settle | Time to wait after each voltage step before measuring |
Gate / Base (outer, stepped):
| Field | Description |
|---|---|
| Source | PSU to use for the gate/base |
| Channel | PSU channel |
| CC / CV toggle (BJT only) | Constant-current (base current steps) or constant-voltage (V_BE steps) |
| Start / Stop / Step | Gate/base sweep range — in mA when CC mode is active for BJT |
| I Limit / V Compliance | Current limit for CV mode; compliance voltage for CC mode |
| Settle | Time to wait after each gate/base step before the inner sweep begins |
Current Measurement:
By default the collector/drain current is read from the PSU's internal ammeter. Set I Meter to an external DMM for better accuracy.
The Y-axis is fixed to 0 – I_limit during the sweep for a stable display. After the sweep finishes:
- ⊡ Auto — fits the Y-axis to the actual data range
- ↺ Reset — returns to the fixed 0 – I_limit range
- Scroll to zoom, drag to pan, double-click to reset
Sweeps the gate/base voltage (V_BE or V_GS) at a single fixed collector/drain bias voltage. Plots I_C / I_D vs gate/base voltage — the transistor's transconductance curve.
Drain / Collector (fixed bias):
| Field | Description |
|---|---|
| Source / Channel | PSU for the drain/collector |
| I Limit | Drain/collector current limit |
| V_CE / V_DS | Fixed bias voltage to hold during the sweep |
| Settle | Settle time after the bias is applied |
Gate / Base (inner, swept):
| Field | Description |
|---|---|
| Source / Channel | PSU for the gate/base |
| I Limit | Gate/base current limit |
| V Start / Stop / Step | Gate/base voltage sweep range |
| Settle | Settle time after each step |
-
⬇ PNG — saves the current canvas as a PNG to
./results/ -
⬇ CSV — saves all plotted data points as a CSV to
./results/
The footer shows the number of curves and total points once a sweep is complete.
- For BJT base current (CC mode), a step value of 0 mA correctly leaves the base output off — true zero base current, not a PSU minimum.
- Use a calibrated SMU for gate/base current if you need accurate I_B readback; bench PSUs have significant current measurement error at low currents.
- The FET / BJT toggle also updates the Transfer Characteristic parameters (e.g. wider default sweep range for FET gate voltage).