High Freq. response of CE amplifier

Thread Starter


Joined Oct 25, 2008
I am designing a two stage CE amplifier followed by a common collector/emitter follower.

The bandwidth spec is 10hz to 10khz.

I know all the coupling caps, Emitter caps and input caps all act as high pass filters and thus set the low frequency cut off.

Where do a put a Low pass filter in this circuit and how do I calculate the highfrequency cutoff for it?.

The emitter follower is directly coupled to the output of the second CE stage. I am thinking a capacitor from this output (or the input of the CC) to ground would do the trick - but what resistance do i use to set the time constant?

Any help would be appreciated. Thank you.


Joined Dec 20, 2007
Modern little transistors have a frequency response up to 300MHz when the gain becomes zero.
Depending on how much negative feedback you use then if the stray wiring capacitance of your circuit is low then a flat response up to 1MHz is reasonable.