Q-Point · Bias Calculator

NPN · Common-emitter · DC

Voltage-divider bias · DC analysis

Find the transistor's operating point.

Set the six circuit values and the two device parameters. The Q-point solves in real time with the Thévenin method, and the plot shows where it lands on the DC load line. Assumes an NPN BJT in common-emitter with a fixed VBE drop.

CircuitCE-VDB · 001
+VCC 12.0 V R1 47 kΩ RC 2.2 kΩ R2 10 kΩ B C E VC 7.34 V RE 1 kΩ VE 2.11 V VB 2.81 V
Parameters
Operating pointQ
VCE — collector–emitter
6.23V
IC — collector current
2.11mA
IB — base current
14.1µA
VB — base voltage
2.11V
VE — emitter voltage
1.41V
VC — collector voltage
7.36V
PD — power dissipated
13.1mW
Active Forward-active region — suitable for linear amplification.
DC load lineI_C vs V_CE
— 0 0 — V_CE (V) I_C (mA) Q
Formulas
Thévenin voltage
VTH = VCC · R2 / (R1 + R2)
Thévenin resistance
RTH = R1 ∥ R2
Base current
IB = (VTH − VBE) / (RTH + (β+1)·RE)
Q-point
VCE = VCC − IC·(RC + RE)
Model · NPN BJT · DC · β constant · V_BE fixed Approximate — ignores Early effect & thermal drift