Hmm. I think i
I think you are very right.
I didnt consider the zero resistance path which is parallel with ro.
Now this makes very much sense.
Thank you.
I disagree because gain is not zero.
r0 = VA/ Ic
Va not equal to zero.
Ic is the dc bias current, which is also not zero.
Hence r0 is not zero.
For the resistance ro, which is connected from collector to ground( as emitter is grounded), the current passing through resistor is ( -gm Vπ).
So...
ofcourse, that is my doubt. The output is tied to Vcc.
But the presence of ro in the model, accounts for the "Intrinsic Gain" in BJT.
Gain becomes -gm*ro.
Where does this gain (Intrinsic Gain) show up? As output is tied to Vcc, the output cannot change. So where does this gain go?
yes,
if there is no change in VCE (ΔVCE = 0) it has no influence at all.but in a case where emitter is collected to the ground, and in the absence of a load resistance at the collector,
the small signal output taken from collector junction will be equal to ( -gm * Vπ * r0 ).
Is this correct...
hi in my case VCE is not zero.
VCC is maintained between collector and ground . And Emitter is grounded.
This means VCE is equal to VCC ( dc battery)
VCE =VCC, but ΔVCE = 0 ( since we are not applying any small signal at VCE, ΔVCE= 0)
please assume BJT is biased in the forward active region...
In BJT hybrid pi small signal model, we have a resistor "ro" between Collector and Emitter.
This resistor is to include the change in collector current when there is a small signal voltage change between collector and emitter. (due to early effect)
I am finding that all BJT hybrid small...