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Decoupling cap for RF PCB (Read 2968 times)

mixed_signal

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Decoupling cap for RF PCB
Aug 01^st, 2014, 9:07am

Hi,

I have designed a receiver with 2.4GHz LO, 2.42GHz RF and 20MHz baseband. The baseband has a seperate VDD and I want to decouple the 20MHZ in VDD. What kind of capacitors shall I use to decouple 20MHz ? Shall I use electrolytic cap with srf=20MHz? Can anyone suggest a good decoupling strategy?

The baseband has both 20MHz and 2.4GHz component. I can use 20nF for 20MHz and 20F for 2.4 GHz but since they are widely spaced I am concerned about antiresonance issues.

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loose-electron Senior Fellow Offline Best Design Tool = Capable Designers Posts: 1638 San Diego California	Re: Decoupling cap for RF PCB Reply #1 - Aug 1^st, 2014, 5:37pm you want a parallel combination of electrolytic for low frequency and ceramic for high frequency. Research self resonance of capacitors a bit. http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=5&cad=rja&uact=8&ve... Above is a good basics document
Back to top	Jerry Twomey www.effectiveelectrons.com Read My Electronic Design Column Here Contract IC-PCB-System Design - Analog, Mixed Signal, RF & Medical IP Logged

Ken Kundert Global Moderator Offline Posts: 2386 Silicon Valley	Re: Decoupling cap for RF PCB Reply #2 - Aug 3^rd, 2014, 5:24pm Here is a description of how to design a bypassing network: http://www.designers-guide.org/Design/bypassing.pdf -Ken
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loose-electron Senior Fellow Offline Best Design Tool = Capable Designers Posts: 1638 San Diego California	Re: Decoupling cap for RF PCB Reply #3 - Aug 4^th, 2014, 2:00pm Understanding the subtle aspects of the different capacitor types, strengths and weaknesses, thermal varinace issues, dielectric issues, ESR, self resonance frequencies of a capacitor, etc, are all useful items to be familiar with.
Back to top	Jerry Twomey www.effectiveelectrons.com Read My Electronic Design Column Here Contract IC-PCB-System Design - Analog, Mixed Signal, RF & Medical IP Logged

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