Calculateur de Gain d'AOP Non-Inverseur
Calculez le gain d'un amplificateur opérationnel non-inverseur.
Base Resistor
113,000 Ω
Base Resistor vs Supply Voltage (Vcc)
Formule
## BJT Transistor Biasing In common-emitter configuration a base resistor sets the operating point. ### Formula **I_B = I_C / hFE** **R_B = (Vcc - V_BE) / I_B** Where hFE is DC current gain and V_BE is typically 0.7 V for silicon. This simple bias is beta-dependent; voltage divider bias provides better stability.
Exemple Résolu
Bias a transistor with hFE=100 for 10 mA collector current from 12 V.
- 01I_B = 10 mA / 100 = 0.1 mA = 100 uA
- 02R_B = (12 - 0.7) / 0.0001 = 113,000 ohms (113k)
- 03Power = 12 x 10 = 120 mW
Questions Fréquentes
Why is fixed bias unstable?
Collector current depends on hFE which varies widely between transistors and with temperature. Voltage divider bias is more stable.
What is saturation?
When Vce drops below about 0.2 V the transistor is saturated and acts like a closed switch regardless of further base current increase.
How do I pick hFE?
Use the minimum hFE from the datasheet for worst-case design. Typical values range from 50 to 500.
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