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How to Specify Phase Noise as an Instance Parameter in Spectre Sources (e.g. vsource, isource, Port)

Comments(8)Filed under: Spectre RF, spectreRF, analogLib, phase noise, noise profiles, port

Last year, I wrote a blog post entitled Modeling Oscillators with Arbitrary Phase Noise Profiles.  We now have an easier way to do this.  

Starting in MMSIM 13.1, you can specify the phase noise as an instance parameter in Spectre sources, including port, vsource and isource. The use model is similar to the existing noise file/noise vector approach. The only difference is the addition of a Noise type parameter, which indicates whether you are specifying a noise voltage spectrum or SSB phase noise, the latter of which is modeled as pure-PM.

A command-line (netlist) example would look something like this:

PORT0 (in 0) port r=50 type=sine freq=1G dbm=10 noisetype=ssbphasenoise noisevec=[ 100K -110 1M -140 10M -160 100M -165 ]

v0 (vsource_out 0) vsource type=sine freq=2G fundname="f1"  noisetype=ssbphasenoise noisevec=[ 100K -110 1M -140 10M -160 100M  -165 ]


Below is what the IC6.1.6 GUI looks like for the analogLib port, showing how to enter phase noise data directly into the port Edit Object Properties/Add Instance form:


In the port Edit Properties/Add Instance form, scroll down to the bottom:
  • Click Display Noise Parameters. The form will expand.
  • Specify Noise Type. In this example, choose SSB phase noise(dBc). 
    The noise can also be specified as the spectral density, Noise voltage(V^2/Hz).
  • Select Noise Entry Method
    • For File, enter the Noise file name.
    • For Noise/Frequency points, specify the Num. of noise/freq pairs. The form will expand. Enter the Frequency and Noise data for each Noise/Frequency point, as shown above.

 For more information,  type in an xterm 'spectre -h port', 'spectre -h vsource', or 'spectre -h isource'.


Best regards,







By LI ZHong on May 27, 2014
We once use to design the PCB for us, and they also do the RF simulation, hope they can help you with this issue.

By Aba on June 24, 2014
Dear Tawna,  I am trying to determine the bias current and the size of a bipolar transistor at the input of a LNA for minimum noise figure by simulation with ADE L.  Can you please provide indications on how to set the tool to sweep the base voltage and plot NFmin as a function of the transistor base voltage,  Best Regards, Aba

By Tawna on June 24, 2014
Hi Aba,  Please post your question to the RF community (since it's a new question)  rather than commenting on an existing blog.  You'll get a quicker response that way.    

By Mina Abdallah on July 30, 2014
Very interesting and helpful option. It will help characterizing the effect of PN on other more complex systems.
I was just looking around today on a way to model arbitrary PN, and I'm very excited about this feature.
I just have two questions:
1. Is this feature available for square wave sources, and how would it be considered in PN/Jitter simulations?
2. By SSB do you mean one side from PN skirt as in the PN simulation, or the SSB representation of PSD of the noise?
I'm asking because it will differ by a factor of 3 dBs

By Tawna on July 30, 2014
Hi Mina,    This is not supported for square waves (only sinusoids).   Please contact Cadence Customer Support and request an enhancement CCR.  (More customer interest=greater chance of supporting this feature.)

By Tawna on July 30, 2014
Finishing my thoughts....  When set to ssbphasenoise, the noise data represents single-sideband phase noise in dBc.  The frequencies are offset from carrier.    (what you see when you plot phase noise after a pnoise simulation)  
This is also noted in the SpectreRF User Guide (MMSIM13.1.1) and Spectre User Guide (MMSIM 13.1.1).

By Silpa on September 25, 2014
Hi..I tried to add noise in the same way as u mentioned.But there is no option like 'noise type' in both port and also vsource from analogLib.What should I do?

By Tawna on September 26, 2014
Hi Silpa,  You probably need to use a later version of IC and/or Spectre.   Try IC6.1.6 and MMSIM 13.1.1 or later releases.

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