lec10 bjt amplifiers

Basic ELECTRONICS

(2+1)ENGR MUHAMMAD SHAKEEL AKRAM

ELECTRONICS ENGINEERING FICT, BUITEMS.

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CHAPTER 6

BJT AMPLIFIERS

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COMMON EMITTER AMPLIFIERS• Most commonly used amplifier• High voltage gain• High current gain • 180˚ out of phase

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COMMON EMITTER AMPLIFIERS• DC analysis

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COMMON EMITTER AMPLIFIERS• AC analysis

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COMMON EMITTER AMPLIFIERS• AC analysis (cont…)

• Voltage at base

• Input resistance at base

• Output resistance

Example

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COMMON EMITTER AMPLIFIERS• AC analysis (cont…)

• Voltage gain

• Current gain

• Power gain

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COMMON COLLECTOR AMPLIFIERS• Also called emitter follower• High input resistance• High current gain • Voltage gain is equal to one• Power gain is nearly equal to current gain• No phase inversion • High input resistance• Low output resistance

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COMMON BASE AMPLIFIERS

• High voltage gain• Current gain equal to one• So power gain becomes nearly equal to

voltage gain• Low input resistance• High output resistance

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COMPARISON OF AMPLIFIERS

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