GUI Plot Specific

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.

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Static Characteristic (IV Curve)

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.

Y-axis scaling

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

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Transfer Characteristic

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

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Export

• ⬇ 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.

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Tips

• 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).