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CC1101 Reference Design with EAGLE

Peyman Siyari
Prodigy 105 points
Other Parts Discussed in Thread: CC1101

Hi

I'm Working with CC1101 and I designed the application circuit's PCB with EAGLE 5.0. Now to montage this circuit i use 0603 capacitors and inductors.

Here's the Project files:

http://www.4shared.com/file/Ne7OabXf/-_Workspace_-_-_Copy__RC___SMA.html

1. Could anyone please check the design and reply anything wrong with the design such as CC1101 dimensions or capacitors and inductors' dimensions according to 0603 package or routing or using SMA connector?

2. How could I determine the board's thickness in EAGLE? should it be 0.8 mm?

  • 0
    TI__Expert 4435 points

    Siyari,

    Several customers have tried to use 603 components for balun and filter.    The results showed they could get a couple to work but the yield when building more units was very poor.  This is primarily because the self reasonance of the 603 package is lower in frequency and the inductors go non-linear or even capacitive.    I would not suggest using general purpose 603.    We taken customer's Gerber files and simulated the board layotu and components which also indicates you cannot use 603 and expect a solid RF design.    Of course this is also related to the radio's operation frequency.  If you plan to use the radio at 868 to 915 then this is definitely true.    At lower frequencies it might be possible if the values are not too large.   Self resonance also goes lower with higher component values. 

    Johnanson has component values in 603 which tend to have lower parasitic which translates into higher package self resonance.  No one that I no of has explore using them,  because they cost more than switching to 401 packages. 

    I'm not familiar with Eagle layout tool.   Most layout tools allow you to define the board thickness in this definition of substrate section. 

    From the radios RF output pins to the antenna the layout is very critical for the chip to deliver maximum power to the antenna.   If you change this layout or board thickness from the reference you will need to recalculate the traces impedance.  This is done by using a PCB board trace calculator.      Change the lengths of these lines also changes the amount of RF power delivered to the antenna and can cause higher harmonics thus prevent radio certification.   TI recommends copy the layout exactly for the balun/filter.  If you need longer length to attach to the antenna then design a 50 ohm transmission line but include pads between the antenna and traces for tuning. 

    In summary you have physical limits of the discrete components that is relate to package size. 

    Rgds,       

  • 0 in reply to RRS
    Prodigy 105 points

    Thank You for your complete answer

    I didn't know that these packages are this much different

    I guess it's better to use reference designs themselves

  • 0 in reply to Peyman Siyari
    TI__Expert 4435 points

    Siyari,

    If you are skilled in RF and have the RF equipment,  making these changes for lower frequencies < 868MHz is not dependent upon package size.    The solutions TI provides are optimzed with 401 packages.  This saves the customer considerable time and money and is a good reason to copy the designs as close as possible, epsecially in the RF path.    Using another package would entail considerable more work for you to validate your design.     Meeting the distortion specs is generally the biggest challenge so depending upon your frequency you plan to use and the volume of your product will determine how these changes in packages and layout effect you.   Since it is hard to predict the harmonics without building the board you must way this in your decision. 

    The biggest reason for using 603 packages are their are more pick and place machines available.  This has changed over the past few years, so numerous assemble houses have pick and place capability at no extra cost.

    Rgds,

  • 0 in reply to RRS
    Prodigy 10 points

    Hello, I just ran across these posts and have a question regarding the use of the cc1101. I also used Eagle (6.3) to layout a cc1101 along with other components and we also are having trouble running the radio (cc1101 433MHz). I see mentioned layout files and would like to know if Eagle files are available for this radio chip?

    Bob Moreno

    fireflyRFID

  • 0 in reply to Bob Moreno
    TI__Guru** 106705 points

    Hi Bob,

    We do not have any reference designs in Eagle format. I would recommend you download the CC1101 reference design and simply follow the layout from the gerber files.

    /Fredrik

  • 0 in reply to Fredrik K
    TI__Guru**** 317180 points

    Bob, it you need some help with your CC1101 design please post a new post on the forum with a full description of the problem and we will do our best to help you out.