Common-emitter bias Calculator

Collector voltage	9.17 V
Emitter voltage	1.3 V
Collector–emitter voltage	7.87 V

Collector voltage

9.17 V

Emitter voltage

1.3 V

Collector–emitter voltage

7.87 V

Approximate peak voltage swing	2.83 V
Base current	12.86 µA
Transistor power	10.12 mW

Approximate peak voltage swing

2.83 V

Base current

12.86 µA

Transistor power

10.12 mW

How common-emitter bias works

R1 and R2 set the base bias, R3 is the collector resistor and R4 provides emitter feedback. The calculation includes divider loading by base current. The schematic measures collector and emitter voltage; the usable swing is limited by cutoff and saturation.

I_B\approx\frac{V_{TH}-0.7\,\mathrm V}{R_{TH}+(\beta+1)R_4}

Uses VBE ≈ 0.7 V and VCE(sat) ≈ 0.2 V. The generic transistor simulation uses a nonlinear junction model; bias and headroom are estimates. Inputs must keep the transistor in its active region.

Change the form inputs or click a component value on the schematic. Choose Try in CircuitSim to simulate the configured circuit.

Do the math

Selected input values
V1	12 V
R1	47 kΩ
R2	10 kΩ
R3	2.2 kΩ
R4	1 kΩ
Q1	100

Divider equivalent voltage: $V_{TH}=V_1R_2/(R_1+R_2)$
$12\,\mathrm{V}\times0.18$
≈ 2.11 V
Divider equivalent resistance: $R_{TH}=R_1\parallel R_2$
$\frac{47\,\mathrm{k\Omega}\times10\,\mathrm{k\Omega}}{57\,\mathrm{k\Omega}}$
≈ 8.25 kΩ
Loaded base current: $I_B\approx\frac{V_{TH}-0.7\,\mathrm V}{R_{TH}+(\beta+1)R_4}$
$\frac{1.41\,\mathrm{V}}{109.25\,\mathrm{k\Omega}}$
≈ 12.86 µA
Collector current: $I_C=\beta I_B$
$100\times12.86\,\mathrm{\mu A}$
≈ 1.29 mA
Collector voltage: $V_C=V_1-I_CR_3$
$12\,\mathrm{V}-2.83\,\mathrm{V}$
≈ 9.17 V

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Schematic

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How common-emitter bias works

Common-emitter bias calculator

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Schematic

Results

How common-emitter bias works

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