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)

Answer 1

CE configuration is the most widely used transistor.

Variation of base current (I_B) with the base-emitter voltage V_BE is called input characteristics.

Variation of collector current I_C with the collector − Emitter voltage V_CE is called output characteristics

Input characteristics

Output characteristics

 

Parameters of Transistors

Input resistance (r_i)

`r_i = ((triangleV_"BE")/(triangleI_B))_(V_"CE")`

ΔV_BE − Base-emitter voltage

ΔI_B − Base current

V_CE − Constant collector-emitter voltage

Output resistance (r₀)

`r_0 = ((triangleV_"CE")/(triangleI_C))_(I_B)`

ΔV_CE − Collector-emitter voltage

ΔI_C − Collector current

I_B − Base current

Current amplification factor (β)

`beta_(ac) = ((triangleI_c)/(triangleI_B))_(V_(CE))`

I_C − Collector current

I_B − Base current

V_CE − Constant collector-emitter voltage.