DC Load Line and Operating Point

>>  For Common Emitter configuration, output characteristic are :

bjt12

>>  DC Load line is plotted on output characteristic, graphically to calculate the DC values of VCE and IC.

>>  DC Load line obtained through KVL in output loop.

bjt20

VCC – IC RC – VCE = 0

IC = – ( VCE / R) + VCC / RC

 

>>  For a given value of Base current, the point of intersection of output characteristic and DC load line is called as operating point or Quienscent point.

>>  Operating point gives the DC values of IC and VCE. [ This method is applied in industry to calculate the accurate value of VCE and IC ]

bjt19

>>  For a given value of Rand VCC. Thus it represents all collector current levels and corresponding collector emitter voltages that can exist in the circuit.

SELECTION OF OPERATING POINT

Case 1 : Operating point near Saturation region

bjt21

Case 2 : Operating point near cutoff region 

bjt22

Case 3 : Operating point at the centre of Load line / Active region

bjt23

>>  Output signal is perfect sinusoidal means no distortions are present in output.

 

Advertisements

Leave a Reply

Please log in using one of these methods to post your comment:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s