Making a filter that remains the same when loaded

[LvW]

To put it another way, maximum gain is dependent on the ß of the transistor. But since each transistor has a different ß it is hard to know just what that maximum gain will be.

However, I must state - for the sake of accuracy - that two gain stages with different ß values and the same dc quiescent current Ic have the same signal gain.
This gain does NOT depend on ß but on the transconductance gm only (that is the slope of the Ic=f(Vbe) curve).
What differs is the signal input resistance at the base node only (smaller base current for higher ß values).
(It is a common misconception that higher current gain would give also higher voltage gain; perhaps, this false conclusion is caused by the - false - assumption that the BJT would be a current-controlled device).

 

[Ry122]

hopefully there's some other benefit in addition to it making the gain stage's gain being less dependent on the inherent beta value of each transistor, because hand selecting a couple of transistors so they have the same beta value is extremely doable for me.

 

[LvW]

hopefully there's some other benefit in addition to it making the gain stage's gain being less dependent on the inherent beta value of each transistor, because hand selecting a couple of transistors so they have the same beta value is extremely doable for me.

Ry122 - in my post#25 I have listed all the benefits in case of ac feedback.

 

[Ry122]

only 1 of those is applicable though right, since all the others can be obtained by only having an Re for DC

 

[Baluncore]

@ Ry122. What is the application for this amplifier ?

 

[Ry122]

microphone amplifier

 

[LvW]

only 1 of those is applicable though right, since all the others can be obtained by only having an Re for DC

Sorry - but that`s not true. If Re is bypassed using a capacitor you only have one single effect: Stabilization of the dc opereating point.
All other benefits connected with ac feedback are lost.