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ADC34J44EVM: Altering the sampling rate of the ADC

Sudeep Kumar61
Prodigy 30 points
Part Number: ADC34J44EVM
Other Parts Discussed in Thread: ADC34J44

Hello,

I have two issues with the board.

1. Working with lower sampling rates

I am working with the ADC34J44EVM and TSW14J56EVM for data acquisition.
I am using the ADC3000 GUI and HSDC Pro software.
I have used the following configuration file provided along with the ADC 3000 GUI to initialize the ADC board.
'ADC3xJxx_80MSPS_Operation_LMK_Setting.cfg'


This operates the board at 80MSPS and I could acquire the data from the TSW14J56EVM.

I need a way to work with lower sampling rates, e.g. 5MSPS or 10MSPS.

How do I configure the board for my application?

 

2. Problem in acquiring lower frequency signals

I have tested the board for various frequencies ranging from 1kHz to 10MHz at channel B using a function generator.

I acquired the data using the 80MSPS configuration file mentioned above.

I found that for frequencies lesser than 300kHz the signal started to attenuate.

How do I work with smaller signal frequencies (1-50kHz) without attenuation?

 

Regards,

Sudeep

 

 

 

  • 0
    TI__Expert 4880 points
    Sudeep,

    I have forwarded your question to a device expert. They should be with you shortly.

    Yusuf
  • 0
    TI__Expert 4025 points

    Hi Sudeep,

    The minimum sampling rate for this ADC is 10MSPS. You can reference pg. 53 of the ADC34J44 datasheet for more information on the sampling rate requirements.

    To get a 10MSPS sampling rate, a higher frequency clock can be provided to the ADC and then divided down to the desired sample rate using the clk divider option in the ADC3000 GUI under the 'Common' tab (pg. 16 of user's guide).  In the same tab, the low speed option should be selected for sampling frequencies lower than 35MHz.

    - Chloe

  • 0 in reply to Chloe Shay71
    Prodigy 30 points
    Hi,

    Thank you for your feedback.
    Please help me with the following queries

    >>minimum sampling rate for this ADC is 10MSPS. You can reference pg. 53 of the ADC34J44 datasheet.To get a 10MSPS sampling rate, a higher frequency clock can be provided to the ADC and then divided down to the desired sample rate using the clk divider option in the ADC3000 GUI under the 'Common' tab (pg. 16 of user's guide).

    The ADC34J44 ADC data sheet says that 2 registers(2Bh and 30h) values need to be changed for configuring the 10MSPS (40x mode) sampling.
    Should I create a new config file by updating those register values and use that file? The software has only 3 default files working at 80,128 and 160MSPS sampling. Need a better clarity on configuring the board for desired sampling rate.
    Also need


    >> In the same tab, the low speed option should be selected for sampling frequencies lower than 35MHz.

    What does lower than 35MHz mean. Is there a range ?
    I tried working with frequencies ranging from (1-100kHz) after enabling the low speed options, still the signal was found attenuated.
    I need the board to work in kHz range without any signal attenuation and distortion.

    Thanks in advance

    Regards
  • 0 in reply to Sudeep Kumar61
    TI__Expert 4025 points
    -The transformer at the input path has a range between 1MHz-400MHz. If you want to work with lower frequencies, you will have to DC couple. That is- remove the transformer and use a differential signal directly into the ADC or use a transformer which works at your desired frequency range.

    I tried working with frequencies ranging from (1-100kHz) after enabling the low speed options, still the signal was found attenuated.
    I need the board to work in kHz range without any signal attenuation and distortion.
    -I just want to clarify, is this the input frequency or sample rate?

    -Chloe
  • 0 in reply to Chloe Shay71
    Prodigy 30 points

    Thank you for the quick response. I will try using it in the DC coupling mode.

    To sample data at 10MSPS I have tried the following:

    I have updated the configuration file for the ADC board as referred in the ADC datasheet and loaded it through the ADC3000 GUI onto the board.

    I am using a TSW14J56EVM to capture the data from the ADC board. While using the HSDC Pro Software, I loaded the ADC34J4x_LMF_442 ini file.

    I got an error as in the following image.

     

    How do I resolve this?

    Do I need to load a different ini file and firmware?

    I need to capture data at 10MSPS with the TSW14J56EVM.

    E.g. If I apply a sine wave of 1MHz at channel B input using a signal generator, I should see 10 sample points in 1 time period if I sample at 10MSPS.