Re: [SI-LIST] : RF & Digital

Shayle Hirschman (shayle@mho.net)
Wed, 11 Aug 1999 12:19:24 +0000

An excellent suggestion, Mitch.

Any benefit to switching L6 with L9?

Shayle

At 07:59 AM 8/11/99 -0700, you wrote:
>Hi Lum,
>
>As Shayle states this is a rather odd stackup, and I would certainly not
recommend it unless I was under duress to comply. This will not get you the
impedance control you're after unless you take some severe steps to control it
>layer by layer (i.e. differential pairings). I'd suggest the following
stackup design:
>
>L1 : signal
>L2 : GND
>L3: signal
>L4: signal
>L5: +5V
>L6: GND
>L7: signal
>L8: signal
>L9: +2.5V
>L10 : signal
>
>Good luck,
>
>Mitch Morey
>Sr PCB Designer
>San Diego, CA, USA
>
>Shayle Hirschman wrote:
>
>> Why a stack-up of 4 signal layers in a row (L4 to L7)?
>>
>> This seems a bit unusual.
>>
>> Shayle
>>
>> At 08:09 AM 8/11/99 +0800, you wrote:
>> >If I have a design that have digital circuit and a small portion of RF.
>> >There will be some signals going from digital into the RF and out from
>> >the RF to the digital portion. If the digital portion has to be
>> >impedance control at 50ohms, how should I go about doing such design to
>> >ensure that both RF and Digital requirements are taken care of, without
>> >causing any interference between these two circuits? What about the
>> >ground? This design will be a 10-layer with the following stack-up :
>> >L1 : signal
>> >L2 : GND
>> >L3 : +5V
>> >L4 : signal
>> >L5 : signal
>> >L6 : signal
>> >L7 : signal
>> >L8 : +2.5V
>> >L9 : GND
>> >L10 : signal
>> >
>> >I would appreciate any advise from you experts out there.
>> >Thanks and regards.
>> >
>> >
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