Chapter 4 BJT2

# 3212 28 j p c h e n the equivalent circuit in a

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3/2/12 28 J. P C h e n The equivalent circuit in (a) represents the BJT as a voltage-controlled current source (a transconductance amplifier), The equivalent circuit in (b) represents the BJT as a current-controlled current source (a current amplifier). The Hybrid- Model

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3/2/12 29 J. P C h e n These models explicitly show the emitter resistance re rather than the base resistance r π featured in the hybrid- π model. The T Model
3/2/12 30 J. P C h e n Expression Physical meaning gm is the slope of the iC v BE curve a t the bias point Q . At room temperature, Transconductance (@ I c=1 mA) T CQ m V I g = m g 40ms

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3/2/12 31 J. P C h e n Input resistance at base Input resistance at emitter Relationship between these two resistances Input Resistance at Base and Emitter m BQ T b be g I V i v r β π = = m EQ T e be e g I V i v r α = = e r r ) 1 ( β π + =
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• Fall '10
• ChengJianping
• Transistor, Bipolar junction transistor, Electronic amplifier, Input Resistance, Early effect

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