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 Error Vector Magnitude (EVM) simulation problem in IC615 

Last post Thu, Mar 6 2014 11:30 PM by Alex Vasjanov. 2 replies.
Started by Alex Vasjanov 06 Mar 2014 02:59 AM. Topic has 2 replies and 714 views
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  • Thu, Mar 6 2014 2:59 AM

    • Alex Vasjanov
    • Top 500 Contributor
    • Joined on Wed, Sep 25 2013
    • Vilnius, Lithuania
    • Posts 17
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    Error Vector Magnitude (EVM) simulation problem in IC615 Reply
     Hello, cadence community,

    I've stumbled upon a problem with power amplifier EVM evaluation - EVM is out of adequate bounds. At first I thought that the PA is faulty, but then I decided to create a simple DUT circuit - a resistor. This way the magnitude will decrease while the phase should stay the same.

    I've attached the schematic and the EVM output plot.

    Everthing is done strictly using MMSIM PA tutorial in IC615 (SpectreRF Workshop Power Amplifier Design Using SpectreRF MMSIM 12.1).

    The standart of interest is 802.11a (but the calculations are wrong with 802.11n as well). The PWL files for I and Q channels were generated using 802.11a_signal_generator following the guide in the above mentioned document. The carrier frequency is 5GHz, rolloff factor is 0.23, bandwidth is 1.2288MH... - every setting in the spectre state is the same as in the tutorial.

     
    So the question would be - is this a known bug with EVM estimation or is there something wrong with my configuration? Has anyone done successfull EVM measurements and if so - please share your knowledge. There is one suspicion that the 802.11a_signal_generator creates a faulty signal but I don't know how to check it. I've tried to use the cdma PWL files in Cadence rfLib, but get the same results (EVM value is not the same as in the picture above bus is inadequate).

     
    Regards,

    Aleksandr,
    • Post Points: 20
  • Thu, Mar 6 2014 10:22 AM

    • Tawna
    • Top 25 Contributor
    • Joined on Fri, Jul 11 2008
    • Snohomish, WA
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    Re: Error Vector Magnitude (EVM) simulation problem in IC615 Reply

    Hi Aleksandr,

    I believe this question would be best handled by Customer Support.

    Unfortunately, I don't have time to look into this right now.

    It is always important to list the exact IC and MMSIM subversion that you are using.  This can be found by typing in an xterm:

    virtuoso -W

    and

    spectre -W

    Best regards, Tawna Wilsey Staff Support AE, Global Customer Support Cadence Design Systems, Inc.
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    • Post Points: 20
  • Thu, Mar 6 2014 11:30 PM

    • Alex Vasjanov
    • Top 500 Contributor
    • Joined on Wed, Sep 25 2013
    • Vilnius, Lithuania
    • Posts 17
    • Points 250
    Re: Error Vector Magnitude (EVM) simulation problem in IC615 Reply

     Hello, Tawna,

     

    I'm using  the following MMSIM and Virtuoso versions:

    •  virtuoso version 6.1.5-64b
    •  virtuoso sub-version  IC6.1.5-64b.500.4
    • spectre sub-version  12.1.0.317.isr2

    And apologies for the non attached schematic in the original post. It should be visible now.

     

    Regards,

    Aleksandr.


    • Post Points: 5
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Started by Alex Vasjanov at 06 Mar 2014 02:59 AM. Topic has 2 replies.