[hpsdr] bypass caps

[Steven Bible]

Are there some diagrams to illustrate these principles?  

Thanks,

- Steve N7HPR


-----Original Message-----
>From: Ray Anderson <ray.anderson at xilinx.com>
>Sent: Jul 6, 2006 7:57 AM
>To: hpsdr at hpsdr.org
>Cc: FRANCIS CARCIA <carcia at sbcglobal.net>
>Subject: Re: [hpsdr] bypass caps
>
>***** High Performance Software Defined Radio Discussion List *****
>
>
>
>>-----Original Message-----
>>From: hpsdr-bounces at hpsdr.org [mailto:hpsdr-bounces at hpsdr.org] On
>Behalf Of >FRANCIS CARCIA
>>Sent: Thursday, July 06, 2006 6:12 AM
>>To: hpsdr at hpsdr.org
>>Subject: [hpsdr] bypass caps
>
>>***** High Performance Software Defined Radio Discussion List *****
>>hi All,
>>Trace terminations to bypass caps can have a big effect on RF
>performance.
>>A simple trace to one side of a chip cap adds a lot of inductance in
>series >with the cap. The best termination is to use 2 traces to the cap
>contact in >and out. The ground side usually goes to a plane but the
>high side >termination can degrade the performance of the bypass. frank
>wa1gfz
>
>
>Actually, the preferred method to achieve low mounting inductance for
>decaps is to attach the decaps directly to power planes on both the GND
>and VCC side. The spreading inductance contributed by the planes is many
>times lower than you can ever achieve utilizing traces. The closer the
>spacing of the GND and VCC plane pair the lower the inductance. 
>
>For really low mounting inductance you can go to a via-in-pad design or
>vias between the pads to connect to the planes. The bottom line is you
>want to minimize the current loop area. 
>
>-Ray	WB6TPU
>
>
>
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\r\n- Steve\r\n  (n7hpr at tapr.org)\r\n

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