• State
  • Locked Locked
  • Replies 10 replies
  • Subscribers 53 subscribers
  • Views 310 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

CC1350: Help with antenna design

Kamil Muza
Prodigy 90 points
Part Number: CC1350
Other Parts Discussed in Thread: LAUNCHXL-CC1352P1, CC1352R, CC1352P7

Hello all,

I'm working on a design with a CC1350 and I plan on using both sub 1ghz and BLE. I want to implement a dual-band antenna design with a single PCB antenna exactly how it is in 

LAUNCHXL-CC1352P1. (Dual differential -> RF switch -> TI SWRA227 antenna (DN024)).

  1. Can I replicate this exact antenna design on LAUNCHXL-CC1352P1?
    1. If yes, can I do the impedance matching with the following balun https://www.johansontechnology.com/datasheets/0900PC15A0036/0900PC15A0036.pdf?
    2. If not, can you recommend how to achieve the same type of design as I would like to avoid having two antennas?
  • 0
    TI__Guru**** 317180 points

    - CC1350 does not have enough flash to run the full BLE stack and a sub 1-GHz application. Have you verified that the part has the required memory size?

    - CC1350 only has one RF interface. The balun you linked to require 2 RF interfaces. How have you planned to support two frequency bands with CC1350? 

  • 0 in reply to TER
    Prodigy 90 points

    Thank you for clarifying.

    If Sub-1Ghz and BLE are not supported at the same time on the CC1350 due to RAM restrictions, what is the purpose of having both PHYs? 

    If I wanted to run both BLE and Sub-1ghz, what are my options? CC1352 only?

    Yes, looks like that Balun is for a dual interface device, I completely missed that.

  • 0 in reply to Kamil Muza
    TI__Guru**** 317180 points

    The limitation is flash. You can send BLE beacons or similar and a simple sub 1 GHz application but if you need more functionality, CC1352R is required.

  • 0 in reply to TER
    Prodigy 90 points

    It seems that CC1352 is out of stock pretty much everywhere until late 2022 early 2023. Is there a way to have the CC1350 as slave and use a more powerful CPU to handle both stacks? 

  • 0 in reply to Kamil Muza
    TI__Guru**** 317180 points

    When do you plan to start production? The development of your application will take some time and the CC1352R may be back in stock before you are in production.

    The software we have runs on the CC1350. You can develop a lightweight application running on the CC1350 and develop stack(s) to run on a host MCU but that will require significant software development compared to running on CC1352R. 

  • 0 in reply to TER
    Prodigy 90 points

    I have no specific date to start production, we are a small startup and we are trying to make it ASAP. The application will be simple, SPI AD, send readings over sub 1ghz, and support for firmware OTA, I'm hoping it's not too complex. For BLE, I will probably get by using advertisement messages to put out information, not really thinking about making it a client. I guess I'm going to have to get a few CC1350 dev boards and mock it and see if flash is enough.

  • 0 in reply to TER
    Prodigy 90 points

    Followed your advice and went with CC1352P7. I'm using recommended balun for Sub1ghz 14dBm and 2.4Ghz 5dBm and passive 0402s for the 20dbm TX only. All going into the recommended SP3T switch and terminating into the DN024 pcb antenna.

    Any chance you could take a look at the schematic and give me some feedback?

  • 0 in reply to Kamil Muza
    TI__Guru**** 317180 points

    I would recommend using 0201 components for the 20 dBm path to get the layout more compact. The schematic looks good. 

  • 0 in reply to TER
    Prodigy 90 points

    I followed this https://e2e.ti.com/support/wireless-connectivity/sub-1-ghz-group/sub-1-ghz/f/sub-1-ghz-forum/825025/cc1352p-ti-recommended-baluns-for-high-power-pa-output and went with 0402 and adjusted values accordingly.

    its there any advantages to going with 0201 other than a smaller layout overall?? I would be willing to incur in the extra cost of 0201 manufacturing if it improves performance but if its just layout size, our PCB needs to be relatively big either way.

  • 0 in reply to Kamil Muza
    TI__Guru**** 317180 points

    For a 0402 layout, the nodes marked with (1) and (2) tend to get fairly close. On a couple of designs I have seen that noise from node (2) cause the 32 kHz xtal to stop since noise get injected at node (2). If you are able to do the layout with a bit of isolation between these nodes a 0402 based layout is fine. This design https://www.ti.com/lit/zip/swrc362 works fine for the 20 dBm path, you can take a look at the layout for this.