NPN BJT Common-Emitter Output Curve Tracer

Application

This circuit shows NPN BJT in a common-emitter curve-tracer setup. It is useful when comparing collector-current capability, saturation behavior, and the effect of base drive before choosing bias or load values.

Design Context

The collector-emitter voltage source sweeps VCE from 0 V to 10 V. A secondary DC sweep steps the base-bias source from 1 V to 4 V through RB, creating a family of collector-current curves from one schematic. Pin behavior should be reviewed in the component editor.

Expected Behavior

Collector current increases as base drive increases. At low VCE the curves show the saturation knee; at higher VCE they flatten into the active region where the transistor behaves more like a controlled current device.

Key Values

• VCE sweep: 0 V to 10 V in 0.1 V steps.
• VB sweep: 1 V to 4 V in 1 V steps through RB.
• RB: 220 kOhm, providing modest base-drive current for small-signal characterization.

Suggested Experiments

• Reduce RB to increase base drive and compare the collector-current curves.
• Narrow the VCE sweep around 0 V to 1 V to inspect saturation behavior more closely.
• Change the VB step range to focus on lower-current or higher-current operation.

Featured Component

NPN BJT is the NPN transistor under test. Its collector, base, and emitter terminals are arranged in the standard common-emitter characterization setup so the chart emphasizes output-current behavior versus collector-emitter voltage.