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Original question:

PLLatinum Sim Tool Questions: Load Data Example

PLLatinum Sim Tool Questions: Chain Devices

Daniel Sugimura
Prodigy 150 points

Other Parts Discussed in Thread: LMK04832

Can the PLLatinum tool simulate multiple devices that are chained together to calculate the Integrated Noise?

  • +1
    TI__Mastermind 35530 points

    PLLatinum Sim supports this, provided you model each stage one at a time.

    1. Start by simulating the first device in the chain. Configure the output using Fout = the input to the next stage in the chain - this is critical to ensuring an accurate representation of the next stage's input phase noise at the specified carrier frequency.
    2. When satisfied, export the total phase noise trace.
    3. Now select the next device in PLLatinum Sim. Configure the device to use Fosc = the frequency of the previous output - this is critical to ensuring the noise trace from the previous step is not scaled up or down by frequency.
    4. Then, on the phase noise tab (intermediate or advanced feature level), in the radio button for the the Input Source (OSC) Noise, select "Load Data". Import the trace you just saved.
    5. Repeat 1-4 through the entire chain.

    As a full example, here is a complete modeling of the LMK04832 noise, using a 19.2MHz OCXO trace I found somewhere on my desktop as the reference source, a 122.88MHz VCXO in PLL1, and a 491.52MHz output at PLL2.

    Input trace (PLL, VCO, distribution path noise disabled; loop filter set to infinite bandwidth; Fout = Fvco = Fpd = Fosc = 19.2MHz):

    PLL1 trace with 122.88MHz VCXO:

    PLL2 trace with exported PLL1 output fed into PLL2 OSC load data: