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PLLATINUMSIM-SW: General usage questions

Other Parts Discussed in Thread: LMX2595

Simulator does not seem to be usable for the LMX2595.

When I use Interface with TICSPro to import .tcs file all of the settings are imported successfully, but the simulator seems to be dead. All of the results tabs (phase noise, spurs) are frozen in the states they were in before the import. I have to close and restart PLLatinum to get it working again.

Manually entering the configurations is like playing whac-a-mole. For example, I want:


input multiplier=2




output divider=2

I can't get all of these simultaneously.

output divider keeps changing to 1.99 or Fvco changes to  14000.00256, or Fout will change.

I can't manually enter feedback divide because there does not seem to be a way to enter integer part. Is it expecting improper fraction for Fnum?

Its a little irritating that Fnum & Fden do not accept cut/paste (for example from TICSPro).

The integer boundary spurs are in the wrong places, but I assume this is because the configurations are not what I want.

  • David,

    I tried saving an LMX2595 TICSPro file and it loaded fine into PLLatinum Sim without getting stuck.

    I recently did an update to version 1.6.1 that fixed several bugs.

    As for the other issue, if you do advanced mode you can see the fractional denominator.  

    Go to the menu and unclick "Main Diagram Reduces Fraction to Lowest Terms" and enter a denominator like 240000

    I'll check the program and see what is wrong with this routine that reduces the fraction and this should be fixed with the next release.

    As we just released 1.6.1, it might be a month or two.



  • David,

    I looked closer and have two more things:

    1.  The reason the tool is fighting you is that you have Fosc=100 and Fpd=240.  Fpd should be a divisor or multiple of Fosc.  So change Fosc to 120.

    2.  For the second issue, it seems it thinks the device isn't loaded, when it really is.  What I see is the first time you load the file, it works.  The second and beyond, it doesn't.  So go to another part and load it and then load in the TICSPro file. I fixed this bug for the next release.



  • Dean,

    I am setting Fpd to 240MHz with 100MHz Fosc by:

    Doubler = x2

    PreR = /5

    Mult = x6

    R = 1

    The PLLatinum tool does not have settings for these specific registers, but it seems to require entering the 240MHz manually.

    Regarding the second issue, yes relaunching PLLatimum each time does work as you pointed out, but spurs seem to be wrong.

    With RFout=7000.005MHz and Fosc=100MHz, there should be RFout%Fosc spur at 5KHz, and Fvco%Fosc at 10KHz (because VCO is at 14000.01MHz), but both are missing.

    If I reduce Fpd to 120MHz by increasing R to 2, they appear but are at 10KHz and 15KHz respectively.

    They do appear in the correct places if Fpd=100MHz.



  • David,

    I'm going to be launcing PLLatinum Sim 1.6.2 to make some other upgrades like (1) better integrated filters, (2) many buffers added, (3) other minor bug fixes and I think it fixes your file load issue, but not sure.

    For the LMX2595, you cannot use both the doubler and the input multiplier at the same time as stated on the bottom bullet in hte datasheet on page 21.

    But I did it anyways and I see that I only see the 5 kHz Fout%Fosc spur for the 1st order modulator

  • OK, following this up some more.

    1.  yes, it fixes this bug

    2.  The fractional R multiplication of 2.4 is what is throwing this off.  Technically you can't do 12/5 = 2.5, but you could do 6/5 = 1.2.  in any case, I fixed the output so it would fight you a lot less.

    3.  I'm planning to release this next week.