• State TI Thinks Resolved
  • Locked Locked
  • Replies 1 reply
  • Answers 1 answer
  • Subscribers 37 subscribers
  • Views 486 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.

WEBENCH® Tools/THS4631: Help with noise calculation of Trans Impedance Amplifier

Herve Dongmo
Prodigy 40 points
Part Number: THS4631
Other Parts Discussed in Thread: TINA-TI

Tool/software: WEBENCH® Design Tools

Dear All,

 

I have designed a 1MHz Trans Impedance Amplifier around a THS4631 op-amp. My issue is that measured noise of the system is as much as 10 times higher than the simulated noise. Also, my hand calculations differs from WEBENCH predictions, in particular the current noise referred to the output. I have used the approach detailed in Jerald Graeme book (Photodiode Amplifiers – Op amp solutions) as well as the step by step noise calculation detailed in chapters 10 and 11 of Art Kay’s excellent book (Operational Amplifier Noise).

I have attached the document detailing my design as well as the WEBENCH report below.

TI Forum - Help with TIA.pdf

6505.WebenchReportsServlet.pdf

 

Can anyone help explain the discrepancies between my calculations and WEBENCH values please?  In particular, is my total current noise calculation incorrect?

Thank you for your help.

Herve.


  • 0
    TI__Genius 9775 points
    Hi Herve,

    Sorry it took a while to response. But after discussing with our team, our conclusion points to bugs within the WEBENCH Amp Tools. So for now, simply follow your hand calculation and/or simulated result (assuming you use TINA-TI for your simulation).

    Regards,
    Herman