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PSS & PNOISE simulation for VCO and PLL

Maryam Hosseini

Hi,

I am designing an injection-locked VCO, which requires a PLL to work properly. so I want to put my VCO in an Ideal PLL. I use PLLMMlib and PLL macro model wizard available in virtuoso, according to "VCO spectreRF workshop". at very first step, I chose VCO bench in PLL macro model wizard to run pss & pnoise to create a noise model of my VCO to replace it in the Ideal PLL. According to the existence of  periodic source in VCO, I must not to check the oscillator box in PSS analysis.  

However, when I do the simulation, the PSS is ok but for PNOISE, there is an error: "error (sfe-51): name conflict: value `vco_vout' of type `scalar string' encountered. expected value is of type `scalar instance'."

According to the "VCO spectreRF workshop", there are two Idc components at output nodes with the dc value of 0 and instance name "vco_vout" and "vco_vout1", "vco_vout" is chosen as the output probe in PNOISE analysis.

First, I am not sure if that is the correct way to analysis my VCO's phase noise response.

Next, I dont know if the error is because of the injected vco and the pss setups and how to fix the error.

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  • Andrew Beckett

    You must be using a very old and unsupported release, because the Noise-Aware PLL Flow stopped being supported a good 10 years ago - in fact it was removed from the documentation in MMSIM12.1 and the menus in ADE were removed early in IC616 (at the beginning of 2013). It had already been unsupported for some time before that, but we didn't remove it from the tools immediately to ensure existing users of the flow could continue using it.

    So providing support on something that has been end-of-lifed many years ago isn't really possible (you didn't mention which tool versions you're using).

    Andrew 

  • Maryam Hosseini
    in reply to Andrew Beckett

    I am using cadence 6.1.4, since it is the only tool available in our university. could you please guide me how to fix it in this version?

  • Tawna
    in reply to Maryam Hosseini

    This is no longer a recommended, nor a supported flow.  Please work with your Cadence-University contact to get the software updated to IC6.1.8.   

    PLLs are difficult to get convergence with in SpectreRF. All signals must be periodic and the circuit must respond periodically, otherwise you won't get convergence.

    This is what I recommend to designers:

    Simulating PLLs and DLLs are best accomplished with transient/transient noise analysis.  Here is some information.

    best regards,

    Tawna

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