This post is older than 2 years and might not be relevant anymore
More Info: Consider searching for newer posts

nrf52 Layout Questions

I have been designing a four layer stack up PCB for nrf52832 SoC with chip antenna (2450AT18B100 Johanson Technology). This is the first time I have been designing a PCB with an antenna. I am using kicad EDA Software. The stackup of my design is:

  1. Signal and RF traces with ground copper fill (Green Colour in Picture below)
  2. Ground Plane
  3. 3.3V Plane
  4. Bottom Plane (Basically Solid Ground Plane) (Red colour in Picture below)

I am going to add many vias (at 1/12 of RF frequency which will be 2.45 GHz). The antenna part is not completed yet because I am yet to receive some specification from my PCB fabrication house. I will change the width and shape of antenna feed considering the distance between signal plane and ground plane. I have one question regarding the calculation of width of antenna feed line. Since, I have four layers, Can I use formula of coplanar waveguide with bottom ground plane? Won't power plane and bottom layer will effect the impedance of coplanar waveguide? Do I need to take into account presence of power layer and bottom layer (actually solid ground plane).

NOTE: The other sensor in the left part of my layout is a CCD (TCD1304) which is basically a linear image sensor.

What I want from the community is suggestion on the pcb and review my design for RF. Since, this is the first time I have designed such a board, I don't want to design a PCB which won't work or work with very short range. The pictures of my PCB are given below:

Picture 1: image description

Picture 2: image description

Picture3: image description

After reviewing the datasheet of my chip antenna and suggestions from Johanson Technology, I can see they have suggested a large ground plane for which I don't have space.You can check pictures of my layout above as I have marked area for antenna (7mm X 23mm).

The picture below are taken from Johanson Technology's layout suggestion: chip antenna

chip antenna 2

Related