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TRF7970A: TRF7970A

Avi Hartenstein
Prodigy 45 points
Part Number: TRF7970A

I am involved with a project using the TRF7970A for a NFC reader. I am working on the antenna design. I have some questions regarding the matching circuit design and more. I would like to communicate with an application engineer.

Thanks,

Avi Hartenstein

Beamtech Engineering

Mobile: 818- 203 4041

Email: ahcal@sbcglobal.net

  • 0
    TI__Guru*** 135355 points

    Hello Avi,

    First and foremost, have you had a chance to review our app note on antenna tuning? http://www.ti.com/lit/pdf/sloa241

    I wrote the document based on the process I have used for years in tuning antenna circuits, I think you will find it a very useful guide. If you have questions on the specifics, let me know.

  • 0 in reply to Ralph Jacobi
    Prodigy 45 points

    Ralph,

    I need to finish to read it. I started with the NXP chipset and suddelnly, my customer switched to the TI. I have several questions yet. I might have more soon

    1. Due to packaging and mechanical design considerations, I might need to move some of the matching circuitry to the other side of the twisted pair (meaning on the side of the reader chipset. I am not sure if TI provide the active input impedance of the reader chipset?

    Would it be possible to communicate via email vs. through the support forum?

    Thanks,

    Avi Hartenstein

    Beamtech Engineering

    E: ahcal@sbcglobal.net

    P: 818- 203 4041

  • 0 in reply to Ralph Jacobi
    Prodigy 45 points

    Ralph,

    I did review that document and it is very detailed. Since the objective is to match the antenna to 50 ohms, while achieving the proper Q, is the circuit topology is as critical? The reason for the question stems from the fact that I might need to move the matching circuitry to the other side of the twisted pair (except for the shunt capacitor across from the loop antenna terminals)? 

    I do have Fritz software which is lovely.

    Regards,

    Avi Hartenstein

  • 0 in reply to Avi Hartenstein
    TI__Guru*** 135355 points

    Hello Avi,

    Given you'd be using a twisted pair moving the components would be fine, but I would then suggest moving all of the tuning components (so both parallel and series caps plus the Q-damping resistor for matching circuit should stay together). Often when long cable length is included the matching circuitry for the antenna is done at the antenna and the cable is between the two 50 ohm points. The twisted pair should keep any line variance to a minimum.

    We don't go to email communications from E2E but there is a private message functionality that can used to get discussions off the public forum, if that is what you need then accept the friend request I am going to send and we can continue discussing in the private message.

  • 0 in reply to Ralph Jacobi
    Prodigy 45 points

    Ralph,

    All is clear. I did check the open to become associated. I hope it works.

    Thanks,

    Avi