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ADC12DJ5200RF: ADC12DJ5200:Fs/4±Fin and Fs/2-Fin have large interweaving spurs,is there any way to improve?

bai yaohua
Prodigy 10 points
Part Number: ADC12DJ5200RF
Other Parts Discussed in Thread: LMK61E2, LMX2594, , , ADC12DJ3200
  1. ADC2DJ5200RF diagram：

2.Configuration mode：

LMK61E2：Fout = 65MHz;

LMK04828B：DCLK=260MHz; SCLK=2.03125MHz, continuous mode;

LMX2594：RoutA = 5200MHz, RoutB not used;

ADC12DJ5200RF：JMODE=1, Fs=10400MSPS;

3.Questions：

  • As shown in the figure below, Fs/4±Fin and Fs/2-Fin have large interweaving spurs, which leads to unsatisfactory indicators; what may be the cause, is there any way to improve。

  • When other registers can be read and written normally, we try to adjust the value of register Bx_TIME_y, but the read value is still the default value and cannot be modified; can we modify the register value of Bx_TIME_y？

  • 0
    TI__Mastermind 20541 points

    Hi,

    Can you let me know if you are using the ADC12DJ5200RFEVM or is this you own design?

    Did you try calibrating the ADC. Section 3.10 Calibrate the ADC Device on the EVM in the users guide talks about how to calibrate the ADC. 

    https://www.ti.com/lit/ug/slau640/slau640.pdf

    Regards,

    Neeraj

  • 0 in reply to Neeraj Gill
    Prodigy 10 points

    This is my own design.

     Configuration steps:

    • Click on JESD Block Enable to stop the JESD204B block. (0x200=0x00)
    • Navigate back to the Control tab and click on Enable Calibration Block to disable calibration and allow setting changes.(0x061=0x00)
    • Click on Enable Foreground Cal and Foregroud Offset Cal.(0x062=0x05)
    • Click on Enable Calibration Block to re-enable the calibration subsystem(0x061=0x01)
    • click on JESD Block Enable to re-start the JESD204B block.(0x200=0x01)
    • Navigate back to the Control tab and click the Cal Triggered/Running button once, then click it again. This restarts the Calibration engine. (0x06C=0x00,then 0x06C=0x01)

    Power design block diagram：

  • 0 in reply to Neeraj Gill
    Prodigy 10 points

    HI，Thanks for your support

  • 0 in reply to bai yaohua
    Prodigy 10 points

    adc12dj5200rf_cfg.txt 
     reg        value
0x000  		0x30,
0x200  		0x00,
0x060  		0x01,
0x061  		0x00,
0x201  		0x01,
0x202  		0x1F,
0x029  		0x20,
0x029  		0x60,
0x02A  		0x20,
0x203  		0x01,
0x204  		0x02,
0x205  		0x00,
0x360  		0x10,
0x361  		0x10,
0x362  		0x10,
0x363  		0x10,
0x364  		0x10,
0x365  		0x10,
0x030  		0xFF,
0x031  		0xFF,
0x032  		0xFF,
0x033  		0xFF,
0x038  		0x00,
0x03B  		0x00,
0x048  		0x0E,
0x062  		0x05,
0x061  		0x01,
0x068  		0x61,
0x06B  		0x00,
0x06E  		0x88,
0x070  		0x01,
0x2B0  		0x00,
0x2B1  		0x05,
0x2B0  		0x01,
0x2B0  		0x01,
0x2B0  		0x01,
0x2B0  		0x01,
0x200  		0x01,
0x214  		0x01,
0x220  		0x00,
0x221  		0x00,
0x223  		0x10,
0x225  		0x00,
0x228  		0x00,
0x229  		0x00,
0x22A  		0x00,
0x22B  		0x00,
0x22C  		0x00,
0x22D  		0x00,
0x230  		0x00,
0x231  		0x00,
0x232  		0x00,
0x233  		0x40,
0x234  		0x00,
0x235  		0x00,
0x238  		0x00,
0x239  		0x00,
0x23A  		0x00,
0x23B  		0x80,
0x23C  		0x00,
0x241  		0x00,
0x242  		0x00,
0x243  		0x10,
0x245  		0x00,
0x248  		0x00,
0x249  		0x00,
0x24A  		0x00,
0x24B  		0x20,
0x24C  		0x00,
0x24D  		0x00,
0x250  		0x00,
0x251  		0x00,
0x252  		0x00,
0x253  		0x40,
0x254  		0x00,
0x255  		0x00,
0x258  		0x00,
0x259  		0x00,
0x25A  		0x00,
0x25B  		0x80,
0x25C  		0x00,
0x25D  		0x00,
0x2B5  		0x00,
0x2B7  		0x00,
0x2C1  		0x3F,
0x2C2  		0x00,
0x06C  		0x00,
0x06C  		0x01,

  • 0 in reply to bai yaohua
    TI__Mastermind 20541 points

    Hi Bai,

    Can you please try JMODE3 instead of JMOD3 and report if the spurs are still too large.

    Also can also read the register address 0x006 and report back the value.

    Regards,

    Neeraj

  • 0 in reply to Neeraj Gill
    Prodigy 10 points

    The register with address 0x006 does not appear in the data sheet, but we tried to read the register with address 0x006, and the return value is 0x02.

  • 0 in reply to Neeraj Gill
    Prodigy 10 points

    I found that when the sampling clock frequency becomes higher, whether it is in single-channel mode or dual-channel mode, the indicators will be significantly reduced. JMODE1-7GSPS (Fs=3.5GHz) is much better than JMODE3-5.2GSPS (Fs=5.2GHz). Whether the sampling clock input circuit needs attention.

  • 0 in reply to bai yaohua
    TI__Mastermind 20541 points

    Hi Bai,

    Just want to make sure you are calibrating the ADC once the ADC becomes warm? Because when you run the ADC at higher frequency it becomes more hot and you will need perform calibration when the temperature of the ADC changes more than 20C.

    Regards,

    Neeraj

  • 0 in reply to Neeraj Gill
    Prodigy 10 points

    When we test on ADC12DJ5200,other registers can be read and written normally, we try to adjust the value of register Bx_TIME_y, but the read value is still the default value（0x00） and cannot be modified; can we modify the register value of Bx_TIME_y？

    When we test on ADC12DJ3200, the Bx_TIME_y register can be read and written normally.

  • 0 in reply to bai yaohua
    TI__Mastermind 20541 points

    Hi Bai,

    These register are no longer available in ADC12DJ5200RF.

    Please use 0x314,0x315,0x31A and 0x31B to adjust the timing.

    Regards,

    Neeraj

  • 0 in reply to Neeraj Gill
    Prodigy 10 points

    HI Neeraj,

    Thank you very much for your support.

    When we test on ADC12DJ3200, we can read and write Bx_TIME_y register normally. Read the register whose address is 0X103, and the return value is 0X96. After collecting the data, analyze it as shown in the figure below.

    When we test on ADC12DJ5200, we read the register whose address is 0X103, and the return value is 0X00. So we made a test, set the register address 0X103 on ADC12DJ3200, the value written is 0X00, and the data is collected and analyzed as shown in the figure below.

    Through the above analysis, proper adjustment of Bx_TIME_y will improve the influence of Fs/4±Fin. I hope that ADC12DJ5200 can also allow users to modify the register value of Bx_TIME_y according to their own design. Will this function be available to customers in the future?

    Regards,

  • 0 in reply to bai yaohua
    TI__Mastermind 20541 points

    Hi Bai,

    As I mentioned the time adjustment functionality has been moved to 0x310, 0x313, 0x314,0x315,0x31A and 0x31B registers. Please use these register to adjust the timing.

    Regards,

    Neeraj