Low-pass filter in a minibooster?

[Davelectro]

Hi folks.

We know that in a minibooster/mu amp/srpp the feedback capacitor can be tweaked to increase or decrease the low frequency response. I was wondering if it is also possible to control the amount of HF right from the upper part of the minibooster module (instead of just placing a filter before or after).

Thanks in advance.

[artifus]

i maybe wrong, as i often am, but i was under the impression that feedback caps attenuated hf and that it was input and output caps that cut the lo

[Davelectro]

i maybe wrong, as i often am, but i was under the impression that feedback caps attenuated hf and that it was input and output caps that cut the lo

Well, that's true for a common source/emitter stage where the cap connects drain and gate of the same transistor. But in this particular case (i mean the MB) the cap goes between the drain of the bottom transistor and the gate of the upper one.

[PRR]

> the feedback capacitor ... the low frequency response.

Bootstrap cap. (Yes it is "feedback" but not "negative feedback" which is what we most often imply.)

> amount of HF right

Cap from output to ground. Try 1nFd.

[Davelectro]

> the feedback capacitor ... the low frequency response.

Bootstrap cap. (Yes it is "feedback" but not "negative feedback" which is what we most often imply.)

> amount of HF right

Cap from output to ground. Try 1nFd.

"Bootstrap"! That's right.

So this LP filter would be cap to ground + output resistance of the stage. Makes perfect sense.

Thank you very much PRR.