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Question
Draw a typical input and output characteristics of an n-p-n transistor in CE configuration. Show how these characteristics can be used to determine (a) the input resistance (r1), and (b) current amplification factor (β)
Solution
CE configuration is the most widely used transistor.
Variation of base current (IB) with the base-emitter voltage VBE is called input characteristics.
Variation of collector current IC with the collector − Emitter voltage VCE is called output characteristics
Input characteristics
Output characteristics
Parameters of Transistors
Input resistance (ri)
`r_i = ((triangleV_"BE")/(triangleI_B))_(V_"CE")`
ΔVBE − Base-emitter voltage
ΔIB − Base current
VCE − Constant collector-emitter voltage
Output resistance (r0)
`r_0 = ((triangleV_"CE")/(triangleI_C))_(I_B)`
ΔVCE − Collector-emitter voltage
ΔIC − Collector current
IB − Base current
Current amplification factor (β)
`beta_(ac) = ((triangleI_c)/(triangleI_B))_(V_(CE))`
IC − Collector current
IB − Base current
VCE − Constant collector-emitter voltage.
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