Designer’s Guide Community

Simon New Member Offline Posts: 1	RF Filter Nov 25^th, 2003, 7:14pm Hello all, I meet some trouble when I design High pass filters. My target is to tune the filter rejection more than 40dB, at cut frequency 450MHz, and want the slope is very sharp, about 30MHz. Is this target viable? What is the best performance at present market? and which compay can provide?
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oscilentinc

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Re: RF Filter
Reply #1 - May 12^th, 2011, 11:30am

Hi Simon, When you try and develop your High Pass Rf Filter you need to make sure that it has the correct impedance level set. check out a list of our RF Filter electronics here http://www.oscilent.com/catalog/Category/rf_saw_filter.htm. also some thing that you might want to check on is the input and output levels too.

pm me if you have any more questions

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rfcooltools.com Senior Member Offline Posts: 159	Re: RF Filter Reply #2 - May 12^th, 2011, 12:31pm Simon, You may be able to do this discretely provided that you can get inductors and capacitors with tight enough tolerances and high enough Q. For example this image is a filter designed with near ideal Q components. http://rfcooltools.com
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loose-electron

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Re: RF Filter
Reply #3 - May 13^th, 2011, 10:58am

time to get a book on filter design. Zeverev is the classic

http://www.amazon.com/Handbook-Filter-Synthesis-Anatol-Zverev/dp/0471986801

but its out of print - there are others written on the topic too.

As for filter done with high Q components - if you can not get it in the real world, whats the point of designing it in the first place?

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Jerry Twomey
www.effectiveelectrons.com
Read My Electronic Design Column Here
Contract IC-PCB-System Design - Analog, Mixed Signal, RF & Medical

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rfcooltools.com

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Re: RF Filter
Reply #4 - May 13^th, 2011, 12:13pm

loose-electron,

Quote:

as for filter done with high Q components - if you can not get it in the real world, whats the point of designing it in the first place?

whats the point? Its a necessary step to understanding the order/ realizability .

You should be saying, "if it does not work with ideal Q components whats the point of designing it with real world components? "

Even Zeverev uses ideal Q to develop the prototype filter prior to scaling. Its a necessary step to make an ideal filter then add the reality of self resonance and Q degradation.

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rfcooltools.com

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Re: RF Filter
Reply #5 - May 13^th, 2011, 12:13pm

loose-electron,

Quote:

as for filter done with high Q components - if you can not get it in the real world, whats the point of designing it in the first place?

whats the point? Its a necessary step to understanding the order/ realizability .

You should be saying, "if it does not work with ideal Q components whats the point of designing it with real world components? "

Even Zeverev uses ideal Q to develop the prototype filter prior to scaling. Its a necessary step to make an ideal filter then add the reality of self resonance and Q degradation.

http://rfcooltools.com

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