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# SP-Simulation : GPC Option

Last post Fri, Apr 30 2010 3:00 AM by Tawna. 3 replies.
 Started by bVenu 28 Apr 2010 11:59 PM. Topic has 3 replies and 2376 views
• #### Wed, Apr 28 2010 11:59 PM

• bVenu
• Joined on Thu, Apr 29 2010
• Posts 6
• Points 95
SP-Simulation : GPC Option
 I have a question about how to interpret the power gain circles plotted using Spectre's SP analysis For plotting the power gain circles on the Z-smith chart , there are 2 options: Frequency and Gain Level  Suppose I select sweep  "Gain level"  Start = 5dB , Stop = 20dB , step = 5 In my circuit, input port = 50-ohms , output port = 500-ohms.  Will this sweep the value of the output port impedance and create circle with all the points where the power gain is the same?Are the values that we read off the smith chart are output reflection coefficients? Are they normalised to the input port or output port resistance? Is there any technote/tutorial that explains how to use the different 'Main-Form" options in the SP analysis?ThanksVenu
• Post Points: 20
• #### Thu, Apr 29 2010 3:32 AM

• Tawna
• Joined on Fri, Jul 11 2008
• Snohomish, WA
• Posts 216
• Points 5,720
Re: SP-Simulation : GPC Option
 Hi Venu, Please check out the appendix D of the SpectreRF User guide.  The appendix is called: Plotting Spectre S-parameter Simulation Data http://support.cadence.com/wps/mypoc/cos?uri=deeplinkmin:DocumentViewer;src=pubs;q=/spectreRFvol2/spectreRFvol27.1.1/appD.html You may also want to check out the example:  LNA Design Using SpectreRF AppNotehttp://support.cadence.com/wps/mypoc/cos?uri=deeplinkmin:DocumentViewer;src=wp;q=ApplicationNotes/Custom_IC_Design/LNA_62_appnote.pdf Best regards,Tawna      Best regards, Tawna Wilsey Staff Support AE, Global Customer Support Cadence Design Systems, Inc.
• Post Points: 20
• #### Thu, Apr 29 2010 6:04 AM

• bVenu
• Joined on Thu, Apr 29 2010
• Posts 6
• Points 95
Re: SP-Simulation : GPC Option
 Hi Tawna,Thanks a ton! Great pointers.At the University we have a complete Cadence Installation, could you tell me where I can find the schematic for the differential amplifier described that LNA design spectre RF note (LNA_62_appnote). In case it comes with the installation, there must be some standard path I can search It is not present in the rfExample directory @   \$CDS/tools/dfII/samples/artist/rfExamplesrfExamples only has a single ended BJT based LNA circuit. bestVenu
• Post Points: 20
• #### Fri, Apr 30 2010 3:00 AM

• Tawna
• Joined on Fri, Jul 11 2008
• Snohomish, WA
• Posts 216
• Points 5,720
Re: SP-Simulation : GPC Option
 Hi Venu, I recommend looking in the hierarchy at:/tools/spectre/examples/SpectreRF_WorkshopIn the directory, there are appNotes there, as well as workshops - one in particular on LNAs.  For more information, please see my blog post from February 2009: "Shhhh....SpectreRF Tutorials and Appnotes - One of our best kept secrets!" http://www.cadence.com/Community/blogs/rf/archive/2009/02/09/shhhhh-spectrerf-tutorials-and-appnotes-one-of-our-best-kept-secrets.aspx Good luck and have fun!  best regards,Tawna Best regards, Tawna Wilsey Staff Support AE, Global Customer Support Cadence Design Systems, Inc.
• Post Points: 5