- For a transistor to work as an amplifier, it must operate in the active region.
- In this region, the emitter-base junction is forward biased to allow current injection of charge carriers from emitter to base.
- The base-collector junction is reverse biased so that the charge carriers injected into the base are swept into the collector, resulting in current amplification.
- Other biasing configurations result in cutoff or saturation, not amplification.