transistor ac analysis
Well, you can consult any electronic circuit book to get a more detailed answer for you question. However, a basic idea is...
Input capacitor, normaly the books introduce bypass capacitor for bias, it is not common in a integrated sense, instead it is use for discrete components.
Output capacitor, you always will have a load at the output, normally it is asumed a capacitive load.
Not all the capacitors can be replaced by shor circuit, in the case you are taking about, the capacitor can be replaced if it is large enough, for example take a look at the impedance expression: Zc=1/sC, if C is large then Zc --> 0.
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