Question about CC2520 reference design

So I suggest you to stick with the updated reference design from TI website.

Somehow I was unable to attach the screenshot in my previous post, so here it is:

Hi,Igor,

Thanks for your reply.The key is that in the reference design this area is all covered with GND.But the area in the picture is not covered with GND.I think it is important.Because that PCB line has impedance.

I think they are competely different.

Regards,

             stones.

Hi Stones,

What is the version (revision) of the reference design you are viewing?

It seems to me that the version you are viewing and the version

I was linked you to are different.

Can you please download the reference design I've linked you to.

Br,

Igor

Hi Igor Sherer,

             I have download the reference design that is the same as mine.I open the "Cadstar_files.zip" in the "swrr054" with Altium design winter9.Below is the PCB.

Hi Igor Sherer,

             I have download the reference design that is the same as mine.I open the "Cadstar_files.zip" in the "swrr054" with Altium design winter9.Below is the PCB.

Regards,

stones

Hi Stones,

Ok, now I see where the confusion comes from... :)

Inside the "swrr054.zip" locate "CC2520EM_PCB_2_1_RF.zip", extract the folder from this zip,

download viewMate viewer, and import all the *.spl files to it (Altium doesn't support this type of file).

You will notice that the PCB looks like that one in your photo.

Since you have a working design (from TI), I suggest you to stick with that one found in 

"CC2520EM_PCB_2_1_RF.zip".

However, it is odd indeed why the same zip includes two different designs denoted with the same

version number.

Br,

Igor

Hi Stones,

I don't know exactly.

But i think it may related to signal isolating.

If you want to copy its design,I suggest you to copy the CC2520EMK_800.

Hope this may help you a little.

Hi Igor,

            Thanks for your reply.I want to ask a question that where does the *.spl come from.which software can i edit the PCB?

Regards,

stones.

Hi Stones,

I think that .spl used by cadstar, I'm not sure though.

You can view it by viewMate viewer. It is a free of charge SW,

you can download it here.

Install and open it, then go to File tab->import->gerbers...

go to a folder with .spl files, select'em all and open.

Br,

Igor

Hi Igor,

            I want to use the PCB in the "CC2520EM_PCB_2_1_RF.zip".How can I edit it?

Regards,

stones

Hi Stones,

You can download CADSTAR express and export the .spl files to some other format supported by altium.

I'm not familiar with .spl converters, nor I have the time to look for such SW.

It may be not the easiest way, but it works.

Br,

Igor

Dear stones

In Cadstar there are functions that can automatically fill templates. (Here copper gnd)

If there is similar functions in Altium try switching it to manual.

Reading this case, I suspect a badly defined gnd template in the particular area.

Tor-Inge

Dear Tor-Inge

     Thanks for your reply.So it is a software problem.Is it right? Shall I  refer the PCB in "CC2520EM_PCB_2_1_RF.zip",not "Cadstar_files.zip"?Why does TI put two types of PCB in the same version?

Regards,

stones

Hi Stones

Well, Believe there is only one version however, if I am right this version is changed when loaded into Altium due to this automatic feature and a poorly defined template in the design file.    

Please try and reverse the design in Altium (turn off automatic poor if such a function exists in the tool). Alternatively try importing the gerberfiles that and to start you’re own using these as design starting point.

Tor-Inge

Hi Tor-Inge,

Thanks very much.Now another question appears.It is that there are pads on the interface of Inverted F antenna.,so when PCB manufacturer make the PCB,there is not top solder on the pad.copper foil expose.

Regards,

stones

Hi Stones

The pads on the inverted F-antenna are an unfortunate consequence that we initially implemented the Inverted F antenna as a discrete component in our CAD solution.  The inverted F antenna is a copper structure and not a part that should be soldered onto the board.

In some of our new designs the antenna is represented by a graphic drawing in schematic and a ground template in layout omitting this issue. If a similar solution is possible in Altium this should resolve the thermal relief problem reported. An alternative strategy might to remove thermal relief on the pads.

I hope this answers the question.

Tor-Inge

Hi Tor-Inge,

Thanks for your reply.But copper foil will expose because there is no  top solder layer when PCB manufacturer make PCB.My PCB happens to this event.How can I deal with problem?If I must remove the pad from PCB anttenna.

Below is the  circuit diagram that uses CADSTAR.

Regards,

stones

This is an another question related to the reference design.

In the reference design the  width of line connecting matching nw and sma connector is 55mils But width of line connecting matching nw and  inverted F antenna is 40.Is it necessary to maintain 50 ohm impedance for both(inverted F ant /sma connector) the cases