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Does BJT behave like current source in active mode but voltage source in saturation?

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matrixofdynamism

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Behaving like a current source means that change in load does not impact the current. This seems true for a BJT since the current depends on the base current in the active mode.

Behaving like voltage source means that the voltage applied on the load does not change but the current does. This seems true for the BJT in saturation since if we change the load e.g add another equal value resistor in parallel and the transistor gain parameter does not change since it is in saturation and its power dissipation limit is not violated, then in this example the collector current shall double.

Is this correct way of understanding how BJT behaves?
 

Not really.

In saturation you see what looks like a resistive
characteristic but there is still a dependence on
the "forced beta" or relation between Ib and Ic.
Vce(sat) is a spec of interest but always tied to
a specific test condition. An ideal voltage source,
it is not.
 
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    CataM

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Your understanding is basically correct, as long as there is sufficient base current to keep the transistor in saturation (typically as least 1/10th of the maximum collector current).
 

BJT will behave as a current source unless VCE drops not down below VCE(SAT) value.So, the load can be between 0 Ohm and VCC-VCE(SAT)/Ic(constant) value.
You can see that in a typical IC-VCE curves.
 

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