Q. A Silicon Transistor Whose Common Emitter Output Characteristics Are Shown  In Dig Is Used In The Circuit With

V_cc=22.5v, R_c=5.6k, R_e=1k, R₂=10k, And R₁=90k.

For This Transistor b=55.Find The Q Point.

In many cases transistor characteristics are not available but b is known .Then the calculation of Q point is carried out as shown.

We know that

I_c=bI_b.

V=10*22.5/100

R_b=(10*90)/100

Kirchoffs voltage law applied to the collector and base circuits respectively yields

-22.5 + 6.6I_c + I_b+ V_ce=0.

0.65-2.25+Ic+10.0Ib=0

Therefore

-1.60 + I_c+ 10 / 55I_c=0.

I_c = 1.36mA

I_b = 24.8mA

Also we know that

-22.5 + 6.6*1.36 + 0.025 + V_ce=0.

Hence

V_ce=13.5V.