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Original question:
After previous communication with you, I learned that the LMX2594integer boundary is not only related to the Phase detection frequency, but also to the reference frequency.
If you want to completely eliminate integer boundary spurs at a certain frequency, just changing the Phase detection frequency is not enough. You need to change the reference frequency.
In addition, the clock ref enters through the SysRefReq port. By using the repetition function of SYSREF, the clock ref can be output at the B output port and the original Phase noise level of the clock ref can be maintained.
In view of the above, I want to use LMX2572 to provide clock ref to LMX2594 and eliminate integer boundary spurs by changing the reference signal. Combined with my overall machine design plan, my plan is as follows:
The clock ref of LMX2572 is 125MHz, and the 125MHz is also given to the SysRefReq port. The A output port of LMX2572 always outputs a 245.76MHz clock signal to the AD chip.
By using the SYSREF repetition function of the LMX2572, the 125MHz clock is output at the B output port and provided to the LMX2594 as a clock ref. When the LMX2594 encounters integer boundary spurs related to 125MHz, the B output channel frequency of the LMX2572 is switched to 122.88MHz, thereby eliminating the integer boundary spurs.
I would like to ask if the above solution is feasible, please give me some advice.
By the way, Why is the integer boundary spur of lmx2594 partly related to the phase identification frequency and partly related to the reference frequency? Is there any relevant theoretical information? I'll study it. Thank you.
