IRFP240 Output Curve Characterization

Application

This circuit characterizes the IRFP240 N-channel power MOSFET by sweeping drain-source voltage while stepping gate-source voltage. It is useful when comparing the device threshold region, low-voltage triode behavior, and high-current output characteristics before choosing a gate-drive level or load condition.

Design Context

VDS is the swept drain supply and drives the MOSFET drain through the Id current probe. The source is tied to the common return. VGS is a second DC source from gate to source and is stepped as the secondary sweep, creating a family of drain-current curves from one schematic.

Expected Behavior

Drain current increases as VGS rises above the threshold region. At low VDS, the curves show the low-resistance triode region; as VDS increases, each curve bends toward the model output characteristic for that gate drive.

Key Values

• VDS sweep: 0 V to 12 V in 1 V steps.
• VGS sweep: 4 V to 10 V in 2 V steps.
• Id: drain current measured in the upper drain branch.
• Source return: common ground reference for both sweep sources.

Suggested Experiments

• Narrow the VDS sweep around 0 V to 2 V to inspect the triode-region knee.
• Adjust the VGS step range to compare near-threshold drive against stronger gate drive.
• Add a realistic load after reviewing the raw output curves to see how the load line intersects the MOSFET behavior.

Featured Component

The IRFP240 is the N-channel power MOSFET under test. Its gate-source voltage controls the drain-source channel current, so this output-curve demo focuses on how the device conducts for different gate-drive levels.