Lec7 Bipolar Junction Transistor
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Transcript of Lec7 Bipolar Junction Transistor
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Structure
• Three terminals • Base (lightly doped)• Emitter (heavily doped)• Collector (Moderately doped)
• Tow PN junctions • Base emitter • Base collector
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Basic Transistor Operation
• Active region • BE forward bias • BC reverse bias
• Saturation region • BE forward bias • BC forward bias
• Active region • BE reverse bias • BC reverse bias
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Transistor Characteristics and Parameters
• DC beta• DC current gain in Common Emitter • Less than 20 to greater than 200
• DC alpha • DC current gain in common base • 0.95 to 0.99
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BJT as an Amplifier
• Linearly increasing the Amplitude• Current gain β = • As IB is very small Ic ≈ IE
VcE = Vcc – Ic Rc
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