NPN Transistor Normal Operation Conditions
For an NPN transistor to operate normally, typically in the active region (used for amplification), specific biasing conditions must be applied to its junctions:
- Emitter-Base (EB) Junction: This junction must be forward biased. This allows current to flow from the emitter into the base. For an NPN transistor, this means the base voltage must be higher than the emitter voltage (VBE > 0).
- Collector-Base (CB) Junction: This junction must be reverse biased. This creates a region that attracts charge carriers from the emitter region and allows them to be collected. For an NPN transistor, this means the collector voltage must be significantly higher than the base voltage (VCB > 0, or VC > VB).
These biasing conditions enable the transistor to function as an amplifier, where a small change in the base current causes a larger change in the collector current.
Analysis of Options
- Option 1: Emitter-Base Junction forward biased and Base-collector junction reverse biased. This is the condition for normal active region operation.
- Option 2: Both junctions forward biased. This condition leads to the saturation region.
- Option 3: Both junctions reverse biased. This is the condition for the cutoff region.
- Option 4: Emitter-Base Junction reverse biased and Base-collector junction forward biased. This describes the inverse active region, not the normal operation mode.
Therefore, the correct biasing for normal operation is forward-biased Emitter-Base junction and reverse-biased Base-Collector junction.
Important Questions from Bipolar Junction Transistors
Additional heat is dissipated from power transistor by using
When emitter-base junction of a transistor is reverse-biased, the collector current
Emitter follower is used for:
In the common-base configuration, the collector current is given by:
The circuit which produces the best stabilisation of an operating point is _______.
