LMX2595EVM: spur

Maryam,

I encourage you to download the new version 1.5.2 for PLLatinum sim.  We updated our simulation parameters in the database for the LMX2594. 

That being said, I think there are other issues here.

we are testing LMX2595-EVMئ We encountered the following problems:
1-In the simulation the spurious is -70 dBc but back in action was observed - 35dBc.

->  This spur is at an offset of Fout%Fosc = 8500.6 & 100  = 600 kHz.  I updated the Fout%Fosc spur for PLLaitnum Sim, so maybe that will be closer.  You can also check the spur help and it says more about this spur.  As one potential consideration, ensure that you have a high slew rate.  If you put a low amplitude sine wave, the Fout%Fosc will be higher for this device, and PLLatinum sim does not model this effect.

2-In the simulation file just enter the output frequency &fraction. amounts can be calculated automatically
BUT in the TICS Pro software  fraction amounts must be entered

->PLLatinum Sim uses a minimal GUI that gives the mathematical information needed to simulate and design;  it does not show all individual counter.  For instance, if you put a fraction of 1000000/5000000, this has the same spurs at 1/5.  If you put 1000000/5000001, this is modeled as a fraction of 1/5 with strong randomization.

This being said, you might find these things helpful:

->If you go in the menu under options, uncheck "Reduce PLL Fractions to Lowest Terms" it will let you type larger fractions.

->If you are using TICSPro, many parts, like the LMX2594 can be imported.  So what you can do is set up the LMX2594 in TICSPro, then save the file as a *.tcs file, and then go to PLLatinum Sim under File-> Interface with TICSPro-> Load TICSPro file.  This will load up the frequencies and counter values.  Furthermore, after you design the filter you can do File-> Interface with TICSPro-> Add Filter to TICSPro file.  This allows you to ammend the TICSPro file so that next time you load it, it also has many of the PLLatinum Sim settings, including loop filter.  It can still be used in TICSPro.

->Many have asked to integrate TICSPro and PLLatinum Sim, but having these separate allows the required focus to do quality work one each problem.  But as a way to address this, we are looking for ways to make the tools to better interact and communicate with each other.  We are thinking that having the TICSPro file work for both might be a good starting point for this.

3-Test conditions:
Fout=8500.6MHz
Fpd=200MHz
Fosc=100MHz

->OK, Noted.  Fout%Fosc = 600 kHz

4-The spur created 600 kHz, compared to the Central frequency.

->Definitely the Fout%Fosc Spur.

5- I wanted to better meet the measurement and simulation files attached, but I unfortunately could not.
If you need to know to give a e- mail to send files

->Spurs are tough to simulate and there are many factors that influence them.  That being said, we do want to try to match these as good as posslble.  Also, even if simulations don't perfectly match measurements, they give valuable insight into how to optimize the spurs.

->Send your email to clock_support@list.ti.com and lets see if we can get better match.  Also, be sure to try version 1.5.2 for PLLatinum Sim as I specifically updated the Fout%Fosc spur for this.

Regards,

Dean

I am looking forward to hearing from you.

SPUR.rarDear Dean Banerjee

more thanks for answering  fo my request.

Please see attached file.