BJT Large Signal

Thread Starter

Mazaag

Joined Oct 23, 2004
255
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
 

scubasteve_911

Joined Dec 27, 2007
1,202
BJTs go by a Vce(sat) parameter, which is a very dynamic. It depends very much on current through the transistor and temperature.

Steve
 

mik3

Joined Feb 4, 2008
4,846
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
 

Audioguru

Joined Dec 20, 2007
11,251
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.
 

hgmjr

Joined Jan 28, 2005
9,029
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
 
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