BCM20736S layout instructions?

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Anonymous
Not applicable

Hi,

I'm trying to understand how to layout this IC so that I get the best range possible but the instructions on the technical manual are nor very clear to me.MWSnap 2017-03-21, 12_45_26.jpg

Are side A and D on the edge of the board or is the GND Plane on the edge of the board? If the GND plane is not the edge of the board then what should I do after that? Can I just extend this GND plane for the entire board?

Where there is the L indication for the GND plane the same does nor reach the edge of the keepout area. Why is that? What should be placed above this area?

Would someone have an example that has a good range with this IC (no external antenna)?

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1 Solution
BoonT_56
Employee
Employee
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Firstly, the above picture is the layout recommendation of the 20737S SiP module. This module has packaged the IC, filter, crystal, EEPROM and antenna altogether under one roof.

Side A can be near to the edge of the motherboard.

The purpose of the L-shaped ground plane is to maximize the antenna efficiency (up to 40% with a maximum usable range of 50m) of the embedded antenna. Deviations will result in the reduction of range, but it may be acceptable to some as they need probably only 10m. It can sit on the top layer or underneath. Below is a picture of a top-only layout and do take note there are no component on the ground plane.

20732S.jpg

Otherwise, you may lay the ground in a two-layer arrangement as shown below. The picture were extracted from an actual layout and I think it offered a better view.

(1) Top layer (in blue)

top.jpg

(2) Second layer (in purple)

bottom.jpg

More details at here:

Sample BCM20732S PCB Layout

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3 Replies
BoonT_56
Employee
Employee
500 likes received 250 likes received 100 likes received

Firstly, the above picture is the layout recommendation of the 20737S SiP module. This module has packaged the IC, filter, crystal, EEPROM and antenna altogether under one roof.

Side A can be near to the edge of the motherboard.

The purpose of the L-shaped ground plane is to maximize the antenna efficiency (up to 40% with a maximum usable range of 50m) of the embedded antenna. Deviations will result in the reduction of range, but it may be acceptable to some as they need probably only 10m. It can sit on the top layer or underneath. Below is a picture of a top-only layout and do take note there are no component on the ground plane.

20732S.jpg

Otherwise, you may lay the ground in a two-layer arrangement as shown below. The picture were extracted from an actual layout and I think it offered a better view.

(1) Top layer (in blue)

top.jpg

(2) Second layer (in purple)

bottom.jpg

More details at here:

Sample BCM20732S PCB Layout

Anonymous
Not applicable

On the top layer in blue there is a trace coming out from the corner (it is a GND trace) but the datasheet clearly states

  • Connect to system ground from side D of the module (pins 13–22).
  • Route signal traces out of the module from side C (between pins 27 and 30) or side D (between pins 16 and 19) of the module. Traces can be overlapped to avoid routing through the keep-out area.

In our previous designs we implemented the layout exactly as descried by you plus we respected the above two points but we never get more than 10m. Is there a more detailed description on how to do the layout? The information given on the documentation is not clear for such an important aspect of the design witch is the RF requirements.

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WICED Sense 1 and 2 use the SiP module.

Here's the WICED Sense 2 PCB Files

These may be useful to extract exact layout requirements.

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