Schematic and pcb review

[DavidAbreu99]

Hello,

Is it possible to receive a review for a board i'm developing??

This board is to be used as a Raspberry Pi Hat to be able to communicate using UART between RPi and nRF5340. I've followed the schematic example present on the documentation.

Requirements for the board:

- Communicate through RX/TX pins

- Having 2 leds representing nRF5340 and RPi status

- Normal and soft reset button (Soft reset is to clear some configurations on nordic)

PCB:

1st layer - GND

2nd layer - N/A

3rd layer - VDD-nRF

4th layer - GND

I have some difficulties still on the pcb antenna (still learning about it) and tried to follow the guides and recomendations for it.

The board can be found in: umesh.pdf

Thank you for your help,

David Abreu

[Martin Sivertsen]

Hi David,

Do you have Gerber files for the board as well?

Best regards,

Martin S.

[DavidAbreu99]

Hello,

The gerber files are in the following archive.

1205.gerber.zip

My best regards,

David Abreu.

[Martin Sivertsen]

Thanks David,

I'll take a look at this and get back to you over the weekend with some feedback.

Best regards,

Martin S.

[Martin Sivertsen]

Hi David,

Some comments and feedback:

• You need to follow our reference layout for the nRF5340 for component placement and layout.
• Read this page at the same time: https://infocenter.nordicsemi.com/topic/ps_nrf5340/chapters/ref_circuitry.html?cp=3_0_0_8_2
• The RF path needs two matching networks, one to adjust the output impedance from the nRF5340 to 50 ohms and subdue harmonics, and the other to adjust the impedance of the antenna to 50 ohms, see the graphic below (this is for a different chip, so disregard L2 and the component values)
  
• The transmission line between the two aforementioned matching networks needs to be 50 ohms (+/- 10%) which can be achieved using a coplanar waveguide
  
• Place the antenna matching network right up to the antenna feed point
• Connect this part directly to the ground plane
  
• I would have a full coper pour on all four layers and add via stitching to connect the ground copper layers together-
• Add vias right next to all ground pads.

Please get back to us when you have updated the design.

Best regards,

Martin S.

[DavidAbreu99]

Hello,

thank you for your feedback and i'll get to it, but i have one starting question.

You mention a use of a second pi-network for the antenna itself for impedance matching, i'm using a layout directly from Texas ti for a BLE 2.4GHz antenna in which paper they mention 

The IFA was designed to match an impedance of 50 ohm at 2.45 GHz. Thus no additional matching components are necessary.

With this in mind do i still need to add a second pi-network matching circuit?

I'll get started on the other points you refered.

My best regards,

David Abreu