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CC2530 DEVELOPMENT KIT

vpmedina
Prodigy 10 points

Other Parts Discussed in Thread: CC2530EM

Hi all,

I am using CC2530DK and I am trying to recreate the CC2530EM.

I tried using the gerber of the EM but it is just too small for me to create manually. I still can't have it fabricated. I still need to do some tests.

So what I did was modify the layout of the EM a little. Just enough for me to create it on my own. I separated the tracks and increased the diameter of the vias. Though I was careful not to touch the RFports and the crystal.

When I tried it out, I got a very significant decrease in RF power. Range was dismal and so was directivity.

With the EM, i could get a 1% PER for about 30m. But with my own module, range was a dismal 3m.

The tracks that I changed were those only on the GPIOs.

Here are pictures of the original and modified layout.

But here's the thing, not only is the layout modified, I am not sure about the dielectric I am using. Yes, it is fr4 - same as the EM - but I just learned recently that not all fr4s are made equal. Its characteristics are dependent on the manufacturer. For one thing, my fr4 thickness is 1.6mm, and the EM is 0.8mm. I am still waiting to here from our supplier about the characteristics of the fr4.

Does anyone know the characteristics of the EM's fr4.

  • 0
    Expert 1835 points

    Hi vpmedina,

    Did you respect design rules for your 50 Ohm RF line. What kind of antenna do you use?

    Launix.

  • 0
    TI__Expert 3595 points

    Okay, for the upper right corner of the chip, how are you doing the vias to ground for the pins over there?  I see a really scary path from the ground on the decoupling on pin 24, that is almost useless as a ground at 2.4 GH, I would rotate that cap 90 degrees and have it to the vertical ground plane.  That top plane needs a lot of vias to ground, all those sections should have grounding going on, don't see it though.

  • 0 in reply to Chris M
    Mastermind 8170 points

    Overall it looks pretty good except, to be redundant, as shown the ground situation does not support operation. The ground under the device and near the bypass caps and matching elements is critical.  

    You write the thickness of the board increased and there is uncertainty in the Er of the FR-4.  Since the bulk of the matching net work is LC and the transmission line is short and ultimately terminated in a nice load (the antenna) these parameters are not real critical.  The Er of FR-4 is nominally 4.3 and ranges from 4.1 to 4.5 and when you consider some circuits are actually on pre-preg (Er 3.7 or so) and not directly on the FR-4 core and still work fine. 

    A fine drill bit and a little thru wire between the top and ground plane in about 10 places you should recover much of the loss.