PPolySim OS

BJT Common-Emitter Amplifier

A transistor turns a tiny base current into a big collector current. Set the bias, place the Q-point on the load line, and read the voltage gain.

BJT Common-Emitter AmplifierLive

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Presets

A transistor amplifies because a tiny base current controls a much larger collector current (Ic = β·Ib). The Q-point on the DC load line sets how much undistorted swing you get; too far and the transistor saturates or cuts off. Educational tool.

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Data Inspector

Collector current3.00 mA
V_CE (bias)3.99 V
Voltage gain-4.7 ×
Regionactive ✓

Governing equation

Reading this result: Sitting in the active region with about 4.0 V of V_CE headroom; the gain ≈ -Rc/Re ≈ -4.7×, so shrinking Re trades bias stability for more voltage gain.

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How it works

In a common-emitter amplifier the collector current is Ic = β·Ib, and the operating (Q) point sits on the DC load line Vce = Vcc − Ic(Rc+Re). Centering the Q-point maximizes undistorted swing; pushing it too far drives the transistor into saturation or cutoff. Educational tool.

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Frequently asked questions

Is this common emitter amplifier calculator tool really free?
Yes. BJT Common-Emitter Amplifier runs entirely in your browser using your device's own compute, so local use is free forever. You only pay Compute Tokens if you scale a job to the cloud.
Do I need to install anything?
No. Everything runs client-side in a modern browser — no downloads, no license, no account required to start.
Can I save or share my simulation?
Create a free account to save projects, and use a shareable embed or minted DOI to publish a live, interactive version anywhere.
How accurate are the results?
The solver uses established numerical methods, but results are for research and educational purposes and should be validated against experiment or professional review before you rely on them.