[TangerineSDR] TangerineSDR Board Sizes and Mock-up

[Rick - W2GPS]

John,

I noticed the various layout examples in the SiLabs 53xx documentation but I
did not notice the 6-layer requirement. At present, the board stack is
4-layer, 80mm (0.31") thick to match the M.2 specification.  It is set up to
match the stack-up requirements for standard configuration from low cost
board houses like 4pcb.com. I just checked and it will be easy to change
this to 6-layer, 80mm (0.31") thick board while staying within their low
cost board structure.

I will need to find a low cost TCXO for the base configuration. The OCXO I
show is well over $100 in 50-piece quantity. It can get to twice that if
over specified.  I hope the footprints can be overlaid to save room.

The board size will be a challenge, I'm sure.

Rick
W2GPS


-----Original Message-----
From: TangerineSDR <tangerinesdr-bounces at lists.tapr.org> On Behalf Of John
Ackermann N8UR via TangerineSDR
Sent: September 21, 2019 4:43 PM
To: tangerinesdr at lists.tapr.org
Cc: John Ackermann N8UR <jra at febo.com>
Subject: Re: [TangerineSDR] TangerineSDR Board Sizes and Mock-up

Thanks, Rick.  I've finally started paying attention and have been thinking
about some unique GPSDO ideas.  They may change the physical parts a bit but
we're a long way from having anything finalized.

I think we've concluded that the RF output from the M8F module is not
acceptable for RF use -- it has a very ugly dither pattern so we will likely
need a external (TC)(OC)XO and DAC no matter what architecture we end up
with.

One thing to note: the SiLabs 53xx chip wants a 6 layer board and also has
some fairly funky layout requirements; a bunch of this is due to crosstalk
reduction, and the 48 MHz crystal used as the cleanup oscillator.  The chip
is physically small, but pretty complex to lay out.

73,
John

On 9/21/19 4:24 PM, Rick - W2GPS via TangerineSDR wrote:
> All,
> 
> I have been working on the clock module to see if the proposed size for
the clock module is reasonable. Attached is a 3D top view showing major
components. Not shown is the D/A to drive the OCXO and various minor
components. These may wind up on the bottom of the board.
> 
> Rick
> W2GPS
> 
> -----Original Message-----
> From: TangerineSDR <tangerinesdr-bounces at lists.tapr.org> On Behalf Of 
> Scotty Cowling via TangerineSDR
> Sent: September 17, 2019 11:50 AM
> To: TAPR TangerineSDR Modular Software Defined Radio 
> <tangerinesdr at lists.tapr.org>
> Cc: Scotty Cowling <scotty at tonks.com>
> Subject: [TangerineSDR] TangerineSDR Board Sizes and Mock-up
> 
> Here is a sneak preview of part of the TangerineSDR talk I will be giving
at DCC on Saturday.
> 
> Rick, this should be enough information on the PCB sizes to figure out if
we have enough room or not.
> 
> The CKM can be extended downward and/or to the right (when looking at the
assembly with the RPi I/O connector on top). We may have to make the DE
board larger anyway, if our CAD guy needs more routing room.
> 
> 73,
> Scotty WA2DFI
> 
> 


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