Basic knowledge in Passive Filter Design

[qq8807]

Dear everybody.

Hi..., see u all again.

As mentioned in the title above, I need some technical advises from u all guys about designing a passive filter design.

I need a 'pie filter design', in which an inductor is sandwiched by 2 capacitors to ground.

The purpose is to block any frequency below than 2.5MHz from entering the main communication equipment.

The filter will be located at each end line of my power protection circuit line. There will be 3 sets of this filter.

Hmm... I am not sure about the load resistance... this one, how could I define the load.... I am really unsure...

So, could u all guys give me some advises for designing this pie filter ??



Qq

 

[kchriste]

The purpose is to block any frequency below than 2.5MHz from entering the main communication equipment.

Don't you mean that you want to block frequencies above the 2.5Mhz cutoff point?
Googling found this Lowpass PI filter calculator and this Hipass PI filter calculator.

 

[crutschow]

Is a pie filter for removing the seeds from the apples?

 

[qq8807]

Hmm... I forgot something to add....

The current that flow in the line is 2.6A maximum....

 

[Leftyretro]

Dear everybody.

Hi..., see u all again.

As mentioned in the title above, I need some technical advises from u all guys about designing a passive filter design.

I need a 'pie filter design', in which an inductor is sandwiched by 2 capacitors to ground.

The purpose is to block any frequency below than 2.5MHz from entering the main communication equipment.

The filter will be located at each end line of my power protection circuit line. There will be 3 sets of this filter.

Hmm... I am not sure about the load resistance... this one, how could I define the load.... I am really unsure...

So, could u all guys give me some advises for designing this pie filter ??



Qq

Do a search on filter calculators, there are many free ones available. Input and output impedances is something you have to bring to the formula as well as the 3db cutoff frequency. You don't normally design and build a filter and then measure to determine what it's input and output impedances are, it's something you have to know from the attended application.

There are many different kinds of filter circuits each with different calculation methods. Different filter models offer different optimazations as to output ripple content, slope shape, passband attenuation, etc. If can be a pretty complex topic that is heavy on the math. However modern computer programs have taken a lot of the pain away.

Good luck

 

[qq8807]

Thanks a lot for the helps from kchriste, Leftyretro & crutschow.

By the way, I need to check the impedance of the intended application, right ?? :/

 

[Leftyretro]

Thanks a lot for the helps from kchriste, Leftyretro & crutschow.

By the way, I need to check the impedance of the intended application, right ?? :/

Only if you want to be able to calculate the values of the components needed