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Insufficient memory to run PSS analysis - how to resolve?

apaj

Hello.

I did see that there are three recent threads with very similar titles, but - unfortunately, with completely different problems described.

I use up-to-date MMSIM and IC5 (2012_2013 package installed on a 32 bit machine) and I have given a swap file to the PSS analysis. I am trying to get IIP3 post-layout simulation to run for my circuit (QRC used for extraction). I want it measured at 8 and 9 GHz with 200 MHz harmonics. I do only 6 steps for signals of power in the range of -20:5 dBm.

Nevertheless, the simulation breaks telling me - insufficient memory. During the simulation, it doesn't really use the file I gave it (<path>/Desktop/pss_swap - it's always 0 bytes). What it actually does is that it creates about twenty files called pss_swap_0, pss_swap_1, and so on, each of them about 1.2 GB. And it does this for every point of calculation.

Now, my question is, is it possible (and how?) to overcome this? If I choose a higher limit for extraction my S-parameters change, so I can not go higher on this. Less than 6 points... does it really make sense? Number of harmonics must remain the same since I need it calculated at certain frequencies. 

Do you have any suggestions how to get this done?

Thank you very much for your time and effort.

  • Thank you very much - I fliped them and we've got that solved:

    spectre -W
    sub-version  11.1.0.509.isr14

    Now, if I am not becoming to tiring, would you be so kind to have a look at the HB analysis? I am interested in th IIP3 and P1dB of my circuit at 8.2 GHz with harmonics of 200 MHz. Is the screenshot I sent in the previous post a way to do it - or something else?

    Once again, thank you very much for your time and effort!

  • I would suggest you take a look at the <MMSIMinstDir>/tools/spectre/examples/SpectreRF_workshop/rfworkshop.tar.Z file which has workshops for LNA, Mixer, Oscillators and PAs. The databases are for IC61 in the versions you're using, but at least you can look at the PDFs for a bit of guidance.

    You didn't say what kind of circuit it is. For IP3 you'd need two input tones (plus another if it's a mixer); for P1dB you'd need one input tone (plus another if it is a mixer). So your setup may or may not be correct, depending on the circuit...

    Regards,

    Andrew.

  • The circuit is (supposed to be) a low noise amplifier. However, I'd like to stop bothering you about this - I'll check the examples you mentioned, and see what happens. 

    I just have one more question - if, even after setting up the analysis as shown in the examples, I remain with the same output (insuficient memory), the only thing I can do is find a 64-bit machine? I mean, there is no some kind of system variable that controls the amount of alowable memory or something like that? 

    Thank you very much, I appriciate your time and effort very much.

  • Fundamentally a 32 bit application is limited to a 32-bit address space - that's a maximum of 2^32 bytes (about 4Gbytes). In practice it is usually a bit lower than that on most OS.

    You can't make a 32 bit application be able to access a larger amount of memory. Shooting PSS had a special trick which allowed it to write its data to disk instead (this was the swapfile) - the algorithm lent itself to that type of approach. HB doesn't though. 

    So if you need more memory, you have to run 64 bit spectre, and that requires a 64-bit OS.

    Regards,

    Andrew.

     

  •  Hello,

     it took me some time to play around with the examples provided. I got the results I needed though a different approach - Rapid IP3. The simulation results are as expected, so the approximation is justified.

     Thank you very much.

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