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TSW3085EVM: Change the sampling rate

Part Number: TSW3085EVM
Other Parts Discussed in Thread: DAC3482, ADS5402, LMK04828

I use a TSW 3085 as Tx and a TSW 1266 as Rx. Using signals with a sampling rate equal to that of the user guide (614,4M) I get a good SNR and the received signal is the same as the one sent.
I have a question regarding the sampling rate. Which option do I have to change in the TSW308x Evaluation Module to change the sampling rate? and the TSW1266 Evaluation Module? writing a different rate in HSDC pro does not work, I believe I need to change something in the Evaluation Module to change the sampling rate.

  • Hi,
    You will need to adjust the TSW3085 interpolation and clock rate and TSW1266 clock rate accordingly. Refer to the user's guide and datasheet for each individual EVMs respectively.
    You may also refer to the basic training on DACs and ADCs for understanding of sample rate and interpolation/decimation

  • Thanks for the answer

    I need to find the interpolation and clock rate in the TSW3085 software control. If I send a pattern with a different rate, I can not adjust the sampling rate.

    For example, using the test file:

    If I use the WCDMA_TM1_complexIF30MHz_Fdata614.4MHz_1000.tsw and I set the data rate to 614.4 M in the HSDC pro, I can see the same signal in the spectrum analyzer.

    If I use the WCDMA_TM1_complexIF30MHz_Fdata307.2MHz_1000.tsw and I set the data rate to 307.2 M in the HSDC pro, I can not see the same signal in the spectrum analyzer. I see a signal with half bandwidth.

    I would like to know where I find the interpolation and clock rate options in TSW3085 Software Control. Is it in the LMK4800 Control? Is it in Advanced? Is it in Output? Is it in the Digital? Is it in the Input? I'm sending an image of the TSW3085 control set to a rate of 614.4 M. I found the description of how it works in the manuals, but I did not find where I have to switch in the TSW3085 Software Control.

  • Hello,

    the interpolation rate is located in the digital:

    if you are using TSW1400, there is another adjustment for FPGA clock

  • Hi,

    We know that: data rate x interpolation = DAC sampling rate.

    Using DAC3482_1228p8MHz_2xInt_NCO_30MHz_single_sync_source_mode the interpolation is 2x.

    Using the WCDMA_TM1_complexIF30MHz_Fdata614.4MHz_1000.tsw and setting 614.4 SPS on the HSDC pro the system works perfectly.

    Using the WCDMA_TM1_complexIF30MHz_Fdata307.2MHz_1000.tsw and interpolation of 4 x the systen doensn't work perfectly. The bandwidht is wrong and the spectrum have many repetitions

    The system works correctly only if i setting data rate 614.4M.

    My doubt is: What do I have to change for the system to run at a rate of 307.2M? And with lower rates? Which option do I have to change in tsw 3085 Software control? I'm sorry if the answer is obvious, but I have not found it in any manual.

  • Hi,

    I think it is best that you save and send over your configuration file to review.

    Basicaly, besides interpolation change, you will need to change the following also for the TSW1400 evaluation with HSDC PRO

  • Thank you very much. In the spectrum analyzer the Tx is now running at a sampling rate of 76.8M.

    In Rx, I use Tsw 1266. What options should I change to have a 76.8M rate on the Tsw1266 Gui?

  • The ADS5402 only have non-decimation and decimate by 2 mode. You will have to either change the sample rate of the ADC to be 76.8MSPS for non-decimation mode or 76.8MSPS*2 for 2x decimation mode.

    For your learning experience, I would encourage to research a bit from the schematic and also the datasheet of the ADS5402 and LMK04828 devices on the TSW1266EVM to figure out the proper configurations for your application.
  • If i change the Clock Out 2 and 3 my sampling rate changes, but I can't reach the SPS of 77,8M. I read the User's guide, but they show a exemple with a 614,4 SPS. How in can reach the rate of 77,8 M?

    I am sending the regs I use.

    ADS5402 Registers:
    0x00 0x0000
    0x01 0x0002
    0x02 0x0780
    0x03 0x4b18
    0x0e 0xaaa8
    0x0f 0xa000
    0x1a 0x4b18
    0x2c 0x0000
    0x34 0x0000
    0x37 0x0000
    0x38 0xfff0
    0x3a 0x081b
    0x3c 0x0000
    0x3d 0x0000
    0x3e 0x0000
    LMK04800 Registers:
    0x00 0x400a819
    0x01 0x000a805
    0x02 0x400a819
    0x03 0x600a801
    0x04 0x400a819
    0x05 0x400a819
    0x06 0x2800000
    0x07 0x0400000
    0x08 0x0000800
    0x09 0x2aaaaaa
    0x0a 0x4880210
    0x0b 0x02c0880
    0x0c 0x0986003
    0x0d 0x1d81012
    0x0e 0x0100000
    0x0f 0x4008401
    0x10 0x00aa820
    0x18 0x0000006
    0x19 0x0020800
    0x1a 0x47d4000
    0x1b 0x0e000fb
    0x1c 0x0008c00
    0x1d 0x00c0005
    0x1e 0x0280005
    0x1f 0x0000000
    LMH6521 Registers:
    0x1 0x3f
    0x2 0x3f

  • Hello,

    I can only describe the high level setup that you will have to configure yourself. You will have to work with the clocking team (forum) offline to set your own LMK04800 setting

    1. you need to adjust the PLL loop 1 to still accept the 61.44MHz clock from the TSW3085 to ensure the TSW3085 are synchronized to your TSW1266 for coherent observation path for the DPD

    2. you will need to adjust PLL loop2 VCO such that the clock divider output will have divided down clock to be 77.8MHz.

    The following two main setting in the LMK04800 are the ones that you need to adjust. 

    Unfortunately this forum is not for the discussion of both system setup (for your overall transmitter and observation receiver setup) and also clocking setup. This is a task that you have to do on your own for your development. I can only provide some tips for you to continue. Good luck with your project!