what happen when removing C from high pass filter

[davors]

when the high pass heppen

hmmm... I have a question...
:roll:
what would happen to the signal at the output of the filter in term of freq and amplitude if the CAPACITOR in the high-pass filter is shorted?

hmmm.... 8O

 

[echo47]

Sounds like you are reading from a homework assignment.
Show us the schematic, and tell us what *you* think would happen, and someone here may help you!

 

[gzif]

Hint for your HW :

At High frequency Capacitor acts as Short Circuit ;-)

 

[davors]

Hint for your HW :

At High frequency Capacitor acts as Short Circuit ;-)

hmmm... as i know for a Low Pass filter when C as short circuit, Vo will become zero....
So is it high pass filter will act the opposite way? i.e Vo = Vi ?

 

[vfone]

You can try to do this experiment using any RF simulator.
If you eliminate (or shorted) the output cap in a HPF (assuming that you are talking about a 3 pole high-pass filter, using 2 caps and one inductor) the circuit will became a 2 pole HPF.
The difference between 3 pole and 2 pole is:
-the cut-off frequency will remain almost the same.
-with 2 pole HPF you will get less rejection of the signal, in rejection band of the filter.

Regards

 

[davors]

You can try to do this experiment using any RF simulator.
If you eliminate (or shorted) the output cap in a HPF (assuming that you are talking about a 3 pole high-pass filter, using 2 caps and one inductor) the circuit will became a 2 pole HPF.
The difference between 3 pole and 2 pole is:
-the cut-off frequency will remain almost the same.
-with 2 pole HPF you will get less rejection of the signal, in rejection band of the filter.

Regards

What is a RF simulator? a software? i dun think i have it...

i accidently post my reply of this topic some where else... i m reposting it here..

[
hmmm...
as what i know. for a LOW PASS filter, when the capacitor is an open cct, no current flows via any of the elements since they rall in series with the capacitor... the current through the resistances is zero, the voltage across them is zero... so Vi = Vo right? when the capacitor is shorted then, frequency is arbitrarily big, so the Vo = 0...

for high pass case... is it just the reverse thing? hmmm... any idea?
]

hmm... please assist... report due tomorrow~~~~
thanks for all the reply...

by the way... what is the uses of a fourth order active filter? just to construct band pass or band reject filter? anything more practical? books just tell theory... didn't mentioned about this...

 

[davors]

doing passive filter networkexperiment next week...

any nice website or books recommend?

 

[ertug]

I can recommend you this book:

Introductory Circuits for Electrical and Computer Engineering: James Nilsson-Susan Riedel (Prentice Hall)

Networks, passive filters, active filters...

 

[drasta]

You can do some simulations on filters in mathlab, and see what happends if the topology is complicated.

 

[djalli]

Simulations are done better in EDA software. They will confirm the theory.

 

[afonso]

by the way... what is the uses of a fourth order active filter? just to construct band pass or band reject filter? anything more practical? books just tell theory... didn't mentioned about this...

It can be any filter... the order means how much "selective" the filter will be.

 

[a_aziz]

hi.
if your circuit is involving of just a C and a R you can not remowe C. However you should give details about your circuit.