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.

  • Resolved

AFE5809: AFE5809 C-bypass on INM pins Question.

Genius 3415 points

Replies: 3

Views: 151

Part Number: AFE5809

Hi there,

we are using AFE5809 for medcial ultrasound application. two questions.

1. From IC's internal structure, does AFE5809 and AFE5808A share the same IC design, except that 5809 has an additianal IQ demodulator? Also, they share the same IC PCB footprint?  

2. For Capacitor Bypass which connected to INMx pins, it is wrote "This DC offset correction circuit has a high-pass response and can be treated as a HPF. the corner frequency scales almost linearly with the value of the CBYPASS".  Could you explain in detail that how will this cap influence the DC offset correction circuits? we are not sure how to choose the corner frequency. Is there any recommend vaule in Ultrasound application, and why?

Thanks a lot!

  • Hi Yi,

    Thanks for using AFE5809 device.

    We will reply your question very soon.

    Thank you!

    Best regards,

    Chen

  • In reply to Chen Kung:

    Hi Yi,

    How are you?

    For the question #1, the answer is yes.

    They share the same design except AFE5808A not including IQ demodulator functionality.

    For the question #2:

    From AFE5809 data sheet,

    Basically data sheet suggests from your side,

    the input signal AC-coupled with 0.1uF capacitors INPx and 15nF capacitors at INMx in series to ground.

    Then LNAx will perform like a gain amplifier with HPF.

    You can change this LNA HPF response (that is corner freq) by setting the register Reg59[3:2]

    (Please see Figure 13. page 22 and table 27 page 84, in this case,

    Cbypass is fixed = 15nF)

    or also you can change Cbypass value to give you different corner freq

    (such as: please see the explanation on page 33)

    Thank you for using AFE5809 device.

    Best regards,

    Chen

  • In reply to Chen Kung:

    Thanks, Chen.

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.