[hpsdr] Phoenix again

[Rob Frohne]

Hi Richard, et. al.,

Your links below don't work for me.  I'd like to read them before giving 
many comments.

I'm wondering if you can possibly carve up your present board in some 
way and see if there are any improvements.  Board layout is really 
important and you really need an eye that can see the coupling, etc. as 
you design them.

Rob

richardh at iinet.net.au wrote:
> ***** High Performance Software Defined Radio Discussion List *****
>
>
> In fact doing a quick bit of reading it seems that I have made a number of
> mistakes with the original design. (grr why didnt I do the reading before :))
>
> Some of the mixer clock traces cross several sections of ground plane which are
> digital and then analog. This is probably the source of the spurs that I have
> had. It will probably be impossible to do this on a 2 layer board.
>
> I think I also have to separate the quadrature generation from the FPGA = the
> clock here should be treated as an "analog" signal = maybe the old Johnson
> counter implemented in tinyLogic , with chip select for transmit and receive.
>  
> It seems more important (according to the articles = see
> www.e2v.com/assets/media/files/documents/...data.../doc0999A.pdf and
> www.einfochips.com/.../designers.../Grounding%20in%20Mixed%20Signal%20PCB.pdf) to
> isolate both power and ground planes into digital and analog sections and run
> traces that connect between them over a "bridge" between them than worry about a
> connection at a single point.
>  
> I would be interested in comments 
>
> Richard
>
> On Sun Nov  1 14:10 , "richardh at iinet.net.au"  sent:
>
>   
>> ***** High Performance Software Defined Radio Discussion List *****
>>
>> Anthony
>>
>> Thanks for the comments
>>
>> OK on the H mode mixer = this is somewhat more complex than the current
>> arrangement = what performance gain am I likely to see?
>>
>> I cant quite see the connection on the pdf files 
>> I presume you make a connection between the two at the GND point on the Atlas
>> connector = close to the +5V pins = is that correct?
>>
>> I tried to separate the Analog and digital planes on the original Phoenix 
>> I wonder if the problem lies with the fact that the DDS has an analog section =>
>> FPGA for quadrature generator section (this has a digital ground plane)  => back
>> to the analog plane fore the mixers. Maybe all these sections should be separated
>> and tied together at one point.
>> Alternatively, should I have a layer for digital and another layer for analog?
>>
>> Also = what is the name of the PCB manufacturer you are using?
>> I dont want to go through a process of finding one who I can work with if you
>> guys have already done so.
>> I take it they would want all layers in Gerber format.
>>
>> What sort of cost am I looking for if I have say 
>>
>> Top
>> Power Plane
>> signal plane 
>> Analog Ground plane 
>> Bottom/Digital ground plane 
>>
>> for prototypes?
>>
>> Does the order matter?
>>
>> Thanks for any feedback = I am a novice at this stuff
>>
>> Richard VK6BRO
>>
>>
>> On Wed Oct 28  7:53 , Anthony Taylor  sent:
>>
>>     
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-- 
Rob Frohne, Ph.D., P.E.
E.F. Cross School of Engineering
Walla Walla University
100 SW 4th Street
College Place, WA 99324
(509) 527-2075			 http://people.wallawalla.edu/~rob.frohne

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