CC2530 with PCB Antenna

Wonderland,

Yes you can use the CC2530 + JTI Balun ref design and replace the SMA antenna with the inverted F antenna. Please follow both designs as closely as possible. This will ensure the best possible results. Please use a series and shunt component at the PCB antenna feed point in order to tune the mismatch that may occur.

It is recommended that you use a 4 layer board with a dedicated solid ground layer right under the component layer (top layer). A solid ground plane ensures shortest return paths for the RF signals, which reduces spurious emissions and allows you to pass specifications. So, it is critical to have ground plane.

However, there should not be any ground plane under the antenna. There should be a copper exclusion layer that does not allow any ground around the PCB antenna.

Again, please follow the reference designs as closely as possible.

Chatto,

Please guide me how to pick the series and shunt component at the PCB antenna feed point for tuning the mismatch? Any application notes to discuss this? 

Now the CC2530 + JTI Balun ref design has only 2-layers with ground traces.  Since you recommended a 4-layer board, my questions are:

1)     Should I keep the top and bottom layers the same and just add a GND layer under the top layer? 

2)     Also what will be the third layer, VDD or signals? 

3)     Should I keep all the ground traces?

Please advise.  Thanks.

Hi Wonderland,

To tune the antenna you need a network analyzer. You solder a semi rigid coaxial cable to the feed point of the antenna matcing components (you have to remove the balun so the chip is disconnected) and you measure the impedance of the antenna. By using the smith chart you can calculate values for your matching components.

You can stick to 2 layers and simply copy the CC2530+JTI reference design, but a 4 layer design will often have better performance. If you go for 4 layers, the second layer would be ground and the third can be used for a VDD plane and also some signal routing. You should fill all empty space on both the top and bottom layer with ground as well.

/Fredrik

Thanks Fredrik,

I have 2 more questions:

1)     Will the matching components be difference for each PCB we build?  Or once we find the matching sets, we will be using the same sets for all PCBs we build?

2)     Should I use the same matching set as CC2430 DB design at the feed point of the antenna, where L341 = L_1N8_0402_S and
C341 = C_5P6_0402_NP0_J_50 as a starting point?

Thanks again.