Well I dont know how would it be complicated for the reader but for me it is quite hard. The schematic is attached.
I've apporixemately I think draw the equivalent high frequency circuit model. Firstly Rin is asked. What I dont understand is that at both bjts a capaciter Cpi will be in parallel with the resistance rpi. So how would this effect Rin? I dont think that one can neglect Cpi in such case. A hint would be great.
Also inorder to find the midband gain where can I start from exactly? The equivalent high freq circuit model gets huge and complicated. I just could not relate the vsig with the second bjt circuit.
Thanx for any help.
I've apporixemately I think draw the equivalent high frequency circuit model. Firstly Rin is asked. What I dont understand is that at both bjts a capaciter Cpi will be in parallel with the resistance rpi. So how would this effect Rin? I dont think that one can neglect Cpi in such case. A hint would be great.
Also inorder to find the midband gain where can I start from exactly? The equivalent high freq circuit model gets huge and complicated. I just could not relate the vsig with the second bjt circuit.
Thanx for any help.
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