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Which of the following is true for a BJT operating in the active region?
Emitter junction is forward biased, collector junction is reverse biased
Both junctions are forward biased
Both junctions are reverse biased
Emitter junction is reverse biased, collector junction is forward biased
Emitter junction is forward biased, collector junction is reverse biased
A Bipolar Junction Transistor (BJT) operates in the active region when the Emitter-Base (EB) junction is forward-biased and the Collector-Base (CB) junction is reverse-biased. This configuration allows the transistor to function as an amplifier, where the collector current is controlled by the emitter injection current.
A Bipolar Junction Transistor (BJT) operates in the active region when the Emitter-Base (EB) junction is forward-biased and the Collector-Base (CB) junction is reverse-biased. This configuration allows the transistor to function as an amplifier, where the collector current is controlled by the emitter injection current.
ICтАЛ=╬▓IBтАЛ+(1+╬▓)ICEOтАЛ тАФ Collector current relationship in common emitter configuration
╬▒=IEтАЛICтАЛтАЛ тАФ Common base current gain
╬▓=IBтАЛICтАЛтАЛ тАФ Common emitter current gain
In the active region, the forward-biased EB junction injects majority carriers into the base. Due to the thin base width and reverse bias at the CB junction, these carriers are swept across the base-collector depletion region into the collector, resulting in a collector current ICтАЛтЙИ╬▒IEтАЛ. The reverse bias at the CB junction creates a strong electric field that collects the carriers.
Active region is the primary mode of operation for linear amplification.
The EB junction acts as a low resistance path due to forward biasing.
The CB junction acts as a high resistance path due to reverse biasing.
Transistor acts as a voltage-controlled current source in this region.
Provides high linear gain.
Minimal signal distortion compared to saturation region.
High power dissipation if not biased correctly.
Sensitive to thermal runaway if VCEтАЛ is large.
Small signal amplifiers.
Linear voltage regulators.
Analog signal processing.
Saturation Region: Both EB and CB junctions are forward biased.
Cut-off Region: Both EB and CB junctions are reverse biased.
Reverse Active Region: EB junction is reverse biased, CB junction is forward biased.
A is correct тАФ For a BJT to function as an amplifier in the active region, the emitter junction must be forward-biased and the collector junction must be reverse-biased.
Remember the mnemonic: Active = Forward/Reverse (FR), Saturation = Forward/Forward (FF), Cut-off = Reverse/Reverse (RR). This sequence helps recall the bias conditions for all four regions.