Maker Pro
Maker Pro

Analog Homework

vick5821

Jan 22, 2012
700
Joined
Jan 22, 2012
Messages
700
Dear friends,

IMG_20121227_002559_zpsd04a0653.jpg


I want to ask, what is the use of the capacitors there ? Can I just ignore it ? How will be the DC equivalent circuit and AC equivalent circuit ? what is the effect to the capacitors ?

How do I determine which one is bypass capacitorrs or coupling capacitors ?

Thank you
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
25,505
Joined
Jan 21, 2010
Messages
25,505
What do capacitors block?

What effect would a DC offset on vi have on Vg if the capacitor C1 is present? What about if it is absent?

At the operating point, what is Vs? Is this zero? What is vo with C2 present? What about if it is absent?
 

vick5821

Jan 22, 2012
700
Joined
Jan 22, 2012
Messages
700
Capacitors block DC is what I know so far.

Others I do not know. Hope to get some guide :)
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
25,505
Joined
Jan 21, 2010
Messages
25,505
Think about it.

If there is a DC voltage at the input, what effect does C1 have?
 

vick5821

Jan 22, 2012
700
Joined
Jan 22, 2012
Messages
700
C1 will be open circuit and there is no input voltage .

Correct me if I am wrong :)
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
25,505
Joined
Jan 21, 2010
Messages
25,505
OK, so does that affect the bias on the JFet?
 

vick5821

Jan 22, 2012
700
Joined
Jan 22, 2012
Messages
700
Yea, definitely cause there is no voltage supply to the gate of the FET
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
25,505
Joined
Jan 21, 2010
Messages
25,505
True, but the AC analysis presumes a certain operating point. What would happen to your operating point if the input had a DC offset and the capacitor was not present?
 

vick5821

Jan 22, 2012
700
Joined
Jan 22, 2012
Messages
700
Another question, for this below circuit :
100_9037_zps03b0c1ec.jpg


Why is said that the test current i(t) flows in the parallel combination of r(pi) and R(E) ??

I understand both r(pi) and R(E) are parallel, but I cant see that the test current i(t) flows there ?

Or I missed out something ?

Please help.

Thanks :D
 
Top