MAT01 / MAT02 hfe rise with current ?

[Bernhard]

MAT01 datasheet shows hfe rising to 6mA maximum, MAT02 is only specified to 1mA, above it will remain constant over a certain current range or be down at 6mA ?
MAT01 seems to be faster, recommendation ?

 

[Mark Tillotson]

Current gain always falls off eventually at higher currents, due to basic BJT physics, namely high level injection effects in the base at higher current. Its typical that gain is already drooping by the maximum operating current of the device, probably because the gain drooping is the reason for limiting the operating current - as the base is starting to overload with carriers, the device becomes less transistor-like.

As emitter doping levels are typically 100 times those in the base, there will definitely be a point the base starts to overload with injected carriers.

 

[Bernhard]

Its typical that gain is already drooping by the maximum operating current of the device, probably because the gain drooping is the reason for limiting the operating current - as the base is starting to overload with carriers, the device becomes less transistor-like.

Ok, max emitter current is 20mA for the MAT02 but hfe only specified to 1mA, above that unclear.

LM394 does not seem to have a sweet spot, maybe that is why it has a certain reputation of "bad sound" ?

 

[EUVL]

Bernhard,

You have PM.


Patrick