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DS125DF111EVM: Is there a recommended configuration for 1.25Gbps/2.5Gbps/1.244Gbps/2.488Gbps?

Part Number: DS125DF111EVM
Other Parts Discussed in Thread: DS125DF111, SIGCONARCHITECT

Is there a recommended configuration for 1.25Gbps/2.5Gbps/1.244Gbps/2.488Gbps?

We Checked 1.25Gbps is configured as follows

Address      Data

0x09            0x04

0x18            0x30

0x60            0x40

0x61            0x86

only signal Detected and CDR Unlocked.

  • Greetings,
    1). First of all, signal detect should be asserted. I don't understand why signal detect is not asserted/ Please make sure indeed there is signal at the input pins and for example with 500mV peak to peak level.
    2). For locking to the data rate you noted, please use SigconArchitect GUI with DS125DF111 profile. You can run this GUI in demo mode. In CDR tab, you can specify data rate which is integer multiple of data rates you have noted and this should be within DS125DF111 VCO range(9.8G to 12.5G).
  • Greetings,

    1)There is signal at the input pins of channel A,The Signal with (1.25Gbps or 2.488Gbps) and 500mV amplitude

    2) I used SigconArchitect GUI with DS125DF111 profile

        For example,input pins of channel A Sigal rate is 2.488G ,In CDR Tab,I set VCO Frequency 2.488 , I Check indicators Tab,only singlal Deteced and CDR unlocked ,output pins of channel A is no signal.

        I think VCO divider maybe needed ,So,In Low Level Page,I set bit 2 of register 0x09 to enable VCO divider . Register 0x18, bits 6:4,I set 0x010(Divede by 4),CDR is also unlocked.

        There is any register set error ?  Can be used for 2.488G/1.25G CDR or not?

    Best Regards.

  • Hi,

    Please note VCO must be within the range of data sheet specified 9.8Gbps to 12.5Gbps in your CDR tab settings. Then group divider setting would enable 2.488Gbps data rate lock. . Therefor, instead of VCO frequency of 2.488G in your CDR tab settings, you should have 4 X 2.488 or 9.952GHz. Then your selection of 1, 2, 4, 8 dividers would enables lock to the following data rates: 9.952/1, 9.952/2, 9.952/4. and 9.952/8 or 9.52Gbps, 4.976Gbps, 2.488Gbps, and 1.244Gbps.

    To lock to 1.25Gbps, you should use two groups: Group 0 VCO set for 9.952GHz as noted earlier and Group 1 VCO at 10GHz and you can enable 1,4 dividers to enable lock to 10Gbps or 1.25Gbps.