Home > Community > Forums > RF Design > Noise simulation in Complex filter

Email

* Required Fields

Recipients email * (separate multiple addresses with commas)

Your name *

Your email *

Message *

Contact Us

* Required Fields
First Name *

Last Name *

Email *

Company / Institution *

Comments: *

 Noise simulation in Complex filter 

Last post Mon, Apr 5 2010 8:28 AM by Megh. 2 replies.
Started by Megh 31 Mar 2010 04:03 PM. Topic has 2 replies and 2205 views
Page 1 of 1 (3 items)
Sort Posts:
  • Wed, Mar 31 2010 4:03 PM

    • Megh
    • Not Ranked
    • Joined on Tue, Mar 30 2010
    • Posts 2
    • Points 25
    Noise simulation in Complex filter Reply

    Cadence recommends following way to do the noise simulation in Complex filters: -

    According to principle of superposition noise can be calculated as follows:
    1. Calculate output noise (V**2/Hz) when only portI is active:
    - at Iout: Ioutn_I(f);
    - at Qout: Qoutn_I(f).
    2. Now calculate output noise (V**2/Hz) when only portQ is active:
    - at Iout: Ioutn_Q(f);
    - at Qout: Qoutn_Qf).

    Now you can calculate the total otput noise (V**2/Hz) at both outputs:
    Ioutn(f) = Ioutn_I(f) + Ioutn_Q(f);
    Qoutn(f) = Qoutn_I(f) + Qoutn_Q(f);
    ______________________________________________________________________________
    The complex BPF is made of 2 LPFs. Both of them have gain = 0dB. Also Gain is 0dB for complex out to complex input.
    Now I see that input referred noise is double that of output referred noise even though gain is 0dB .  I don't know why this is happening. Please help.
    Thanks
    Megh

    • Post Points: 20
  • Sat, Apr 3 2010 4:47 AM

    • Tawna
    • Top 25 Contributor
    • Joined on Fri, Jul 11 2008
    • Snohomish, WA
    • Posts 212
    • Points 5,625
    Re: Noise simulation in Complex filter Reply

     Hi Megh,

    You don't say what type of noise analysis you are running.... Is this ac noise, spectreRF pnoise, etc. ?  

     

    For a summary of existing noise documentation, you may want to take a look at: 

    Summary of existing documentation on various RF related noise analyses

    http://support.cadence.com/wps/mypoc/cos?uri=deeplinkmin:ViewSolution;solutionNumber=11585972

     

    (I suspect that you may be referring to COS Solution  11162588 .   You may want to consider filing a Service Request so that a Support AE can assist you in greater detail.)

    best regards,

    Tawna 

     

    Best regards, Tawna Wilsey Staff Support AE, Global Customer Support Cadence Design Systems, Inc.
    • Post Points: 20
  • Mon, Apr 5 2010 8:28 AM

    • Megh
    • Not Ranked
    • Joined on Tue, Mar 30 2010
    • Posts 2
    • Points 25
    Re: Noise simulation in Complex filter Reply

    Hello Tawna,

    Thanks for replying. I am performing AC Noise analysis.

    Please let me know what do you think on the stated problem.

    I will file an SR on this.

    Thanks

    Meghraj 

    • Post Points: 5
Page 1 of 1 (3 items)
Sort Posts:
Started by Megh at 31 Mar 2010 04:03 PM. Topic has 2 replies.