QB_PH_SEC8_026: Semiconductor Devices & Diodes

In a common-emitter BJT biasing circuit, the DC collector supply voltage is $V_{\text{CC}} = 12\text{ V}$ and the collector resistor is $R_C = 2\text{ k}\Omega$. If the transistor is driven into complete saturation, what is the saturation collector current $I_{C,\text{sat}}$ in mA? (Assume saturation voltage $V_{\text{CE,sat}} = 0.2\text{ V}$. Give your answer to one decimal place)

Correct Answer

### Step-by-Step Derivation & Verification: 1. **Collector Loop Kirchhoff's Voltage Law**: $V_{\text{CC}} - I_C R_C - V_{\text{CE}} = 0$ 2. **Saturation Condition**: In saturation, $V_{\text{CE}}$ reaches its minimum saturation value $V_{\text{CE,sat}} = 0.2\text{ V}$: $I_{C,\text{sat}} = \frac{V_{\text{CC}} - V_{\text{CE,sat}}}{R_C}$ 3. **Evaluation**: $I_{C,\text{sat}} = \frac{12\text{ V} - 0.2\text{ V}}{2000\,\Omega} = \frac{11.8\text{ V}}{2000\,\Omega} = 5.9 \times 10^{-3}\text{ A} = 5.9\text{ mA}$ 4. **Official Answer**: 5.9 mA.