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AFE58JD48: Can I achieve the TGC function using DTGC?

Lv Hao
Prodigy 40 points
Part Number: AFE58JD48
Other Parts Discussed in Thread: AFE58JD16

Tool/software:

I'm currently using the AFE58JD48 to develop an ultrasonic imaging device and I have three questions at present.

Firstly, I wonder what the differences are between the DTGC and the ATGC  of the AFE58JD48. Can I control the DTGC link via SPI to achieve the TGC (Time Gain Compensation) control for B - mode imaging? Or is it more preferable to use ATGC?

Secondly, I've come across some replies on the forum stating that the drawback of the DTGC of AFE58JD48 compared to ATGC is that the adjustment step is 3dB. However, my understanding is that the ATGC control method should also have a minimum step size. Because fundamentally, they both control the quantization switch (the difference being that ATGC uses a field - effect transistor). I would like to ask what the minimum adjustment step of ATGC is. Also, if I use ATGC control, is there a relevant reference routine for FPGA?

Finally, I saw in other posts on the forum that AFE58JD16 has a "Digital - Control - Signal - TGC". I'm not certain about the difference in the DTGC function compared to that of AFE58JD48.

Thanks and I look forward to your reply.

  • +1
    TI__Expert 5915 points

    Hi,

    Vcontrol block can have either analog input (ATGC mode) or digital input (DTGC) . 

    Yes , in DTGC mode min step size is 3dB from 0 to 36dB . But the advantage here is you can eliminate noise coming from vcontrol circuit  which is input to VCNTLP/M pins.

    In ATGC since you are giving analog input there is no step size . It is limited by analog input resolution which you can give to VCNTLP/M pins.

    Architecture of AFE58JD16  and AFE58JD48 is different . In AFE58JD16 there is no option for ATGC and step size of DTGC is 0.125dB. But you can vary the attenuation from 0-8db only using this .

    Hope this clarifies your queries .

  • 0 in reply to Sachin H K
    Prodigy 40 points

    Okay, I got it. Thank you for your reply. It's been really helpful to me.