Home > Community > Forums > RF Design > sp modelling of differential amplifier

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: *

 sp modelling of differential amplifier 

Last post Mon, Mar 9 2009 12:59 AM by Frank Wiedmann. 4 replies.
Started by aaamin 04 Mar 2009 11:25 AM. Topic has 4 replies and 4958 views
Page 1 of 1 (5 items)
Sort Posts:
  • Wed, Mar 4 2009 11:25 AM

    • aaamin
    • Not Ranked
    • Joined on Tue, Mar 3 2009
    • Posts 3
    • Points 75
    sp modelling of differential amplifier Reply

     I need to extract s parameters of a differential linear equalizer (high pass filter) using spectre.

    I do not have spectre RF.  How do I do four port analysis? 

    • Post Points: 20
  • Wed, Mar 4 2009 2:13 PM

    • Jim McMahon
    • Top 500 Contributor
    • Joined on Fri, Feb 20 2009
    • San Jose, CT
    • Posts 21
    • Points 355
    Re: sp modelling of differential amplifier Reply

    Assuming you want basic differential and not mixed-mode S-parameters, then you can attach a  "balun" component (from the "rfLib" library)  to both the differential input and output of your amplifer. One would then attach a "port" component (from the "analogLib") library to single-ended terminals of the balun. The port should configured with the correct impedance (e.g 50Ohms) and assigned a port number (1 and 2). Depending on your design you may also need to add DC blocking and biasing to the amplifier inputs, etc.

     The "rfLib " library is available in the cadence installation directory: $CDS_INSTALL_DIR/tools/dfII/samples/artist/rfLib

     You should now be ready to simulate the design in spectre using ADE. Setup an "sp" analysis and sweep over the desired frequencies. After the simulation completes, select "Results->Direct Plot->Main Form..." You can also use the calculator to plot S12.

    You may also want to check the RF Design Forum for addition help and suggestions.

     Jim

    • Post Points: 20
  • Thu, Mar 5 2009 1:05 PM

    • aaamin
    • Not Ranked
    • Joined on Tue, Mar 3 2009
    • Posts 3
    • Points 75
    Re: sp modelling of differential amplifier Reply

     Jim,

    Thank you for pointing to right direction. The challenge is that I do not have rfLib.

    So I tried to create balun using two xfmr elements. But cant define rout and rin of balun.

    I am not sure what port impedance to use. Considering the ckt as blakcbox, how do I select

    port imepdance?

     

    • Post Points: 35
  • Thu, Mar 5 2009 2:35 PM

    • Jim McMahon
    • Top 500 Contributor
    • Joined on Fri, Feb 20 2009
    • San Jose, CT
    • Posts 21
    • Points 355
    Re: sp modelling of differential amplifier Reply

    You should also be able to get it to work using the xfrm. The port impedance can be set by changing the port resistance parameter. The default is 50Ohms.

     Jim

    • Post Points: 5
  • Mon, Mar 9 2009 12:59 AM

    • Frank Wiedmann
    • Top 75 Contributor
    • Joined on Wed, Jul 16 2008
    • Muenchen, Bavaria
    • Posts 82
    • Points 1,275
    Re: sp modelling of differential amplifier Reply

    For the ideal balun, take a look at http://www.designers-guide.org/Analysis/diff.pdf.

    • Post Points: 5
Page 1 of 1 (5 items)
Sort Posts:
Started by aaamin at 04 Mar 2009 11:25 AM. Topic has 4 replies.