Hey guys

Is there a value for the large signal resistance from the Collector to the emitter of a BJT ? like i know for MOSFETs there is a large signal Rds, and a small signal ro , what about BJTs ? and how do you calculate this value

thanks

 

BJTs go by a Vce(sat) parameter, which is a very dynamic. It depends very much on current through the transistor and temperature.

Steve

 

Hey guys

Is there a value for the large signal resistance from the Collector to the emitter of a BJT ? like i know for MOSFETs there is a large signal Rds, and a small signal ro , what about BJTs ? and how do you calculate this value

thanks

BJTs dont have a fixed resistance like FETs , it depends upon your circuit.

You can find it if you devide Vce by Ic for a particular circuit

 

The collector of a transistor is a very high impedance. The circuit's output impedance is just the collector resistor in parallel with the load resistance.

 

Output resistance can be estimated at least for the small signal model by dividing the BJT's "Early voltage" by the collector current. Here is the wikipedia article describing this relationship.

hgmjr