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DS560MB410: Interface forum

Hailong Liao
Prodigy 96 points
Part Number: DS560MB410

Tool/software:

While using the DS560MB410 chip to create an ACC, I noticed that regardless of the EQ compensation value settings, the S21 parameter drops sharply at 6.76GHz during the measurement of S parameters. This seems to indicate that the link breaks when the frequency exceeds 6.76GHz. What could be causing this? Is there a specific register that needs configuration?

  • 0
    TI__Mastermind 30143 points

    Hi Hailong,

    You need to force signal detect on while measuring s parameters of this device.  Please set channel register 0x05[7]=1.

    Also, while measuring s-parameters, please ensure that your input power is set low enough such that the output will remain in the linear range of the device when applying high boost.

    Are you able to share any details about your ACC project?

    Thanks,

    Drew

  • 0 in reply to Drew Miller1
    Prodigy 96 points

    Hi Drew Miller1

          While trying to reduce the input power of the network analyzer test to -7dB (the device's default value is 0dB), I found that as the input power decreases, the cutoff frequency of SDD21 also decreases,as shown in figure. When it is higher than 0dB, the cutoff frequency no longer increases.

          Also, I tried to modify the value of register 0x05[7] to 1, but it didn't work. And strangely, when I set 0x05h to 0x84 and then read its value again, I found that the value was 0x0A.It seems that I am unable to modify the value of register 0x05h. Of course, before writing to the channel registers, I set the value of global register 0xFFh to 0x03 in order to select the page.

  • 0 in reply to Hailong Liao
    TI__Mastermind 30143 points

    Hi Hailong,

    You should be able to read/write channel register 0x05 without problem.  We have set 0x05[7] = 1 in the past to measure s parameters.  I have some debug recommendations:

    • Please ensure EN_SMB is pulled high (recommend 1k to VDD)
    • Please ensure READ_EN_N is not pulled low, this holds the device in reset.  READ_EN_N should be high or floating.
    • Please ensure you have selected a channel using 0xFC.  For example, 0xFC=0x01 selects CH0
    • As you already noted, please ensure 0xFF = 0x01 or 0x03 (broadcast).

    Are you testing on our EVM, or have you created a design with this device?

    Thanks,

    Drew