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# how cadence do to calculate Z11 in a psp analysis

Last post Sun, Apr 20 2014 6:51 AM by Shady Adly. 4 replies.
 Started by Reda21 10 Apr 2014 09:06 AM. Topic has 4 replies and 260 views
• #### Thu, Apr 10 2014 9:06 AM

• Reda21
• Joined on Thu, Apr 10 2014
• Posts 2
• Points 55
how cadence do to calculate Z11 in a psp analysis
 hi,   i'm simuliting a circuit, where i connect 4 switching caps to the port, than i run a psp annalysis to get the input impedance"Z11", and i want to know how spectre do to give such result, it's for helping me understandind how the input impedance behave.
• Post Points: 20
• #### Mon, Apr 14 2014 2:56 PM

Re: how cadence do to calculate Z11 in a psp analysis
 It's not clear what you're asking here. It sounds as if you're asking how the simulator works - if so, I don't see how that helps you understand how the input impedance behaves - so something is not clear. Please clarify.Regards,Andrew
• Post Points: 20
• #### Tue, Apr 15 2014 1:07 AM

• Reda21
• Joined on Thu, Apr 10 2014
• Posts 2
• Points 55
Re: how cadence do to calculate Z11 in a psp analysis
 thank you andrew for your response.  actually, the results i got, show that the input impedance is a function of the source impedance (the impedance of the port), so there is to possible response: the psp is not the good analisys i have to run, or the input impedance do really change with the source resistance ( it's the first time i'm seeing someting like that) so my question was to know wich is the good response to my problem.
• Post Points: 35
• #### Tue, Apr 15 2014 10:16 AM

• Tawna
• Joined on Thu, Jul 10 2008
• Snohomish, WA
• Posts 212
• Points 5,625
Re: how cadence do to calculate Z11 in a psp analysis
 Hi Reda21,Let's define the question a bit more...it's not entirely clear what you are measuring and why you're using psp analysis for this.  What kind of circuit is this?    If you can use sp analysis, it's much easier to use/understand.    Say you have a 2 port circuit.  If you want to look at input impedance, then S11 is what I would plot. You may want to look at Article 11663828 Location of tutorials/information on Spectre sp and SpectreRF psp analyses on Cadence Online Support. best regards,Tawna  Reda21: thank you andrew for your response.  actually, the results i got, show that the input impedance is a function of the source impedance (the impedance of the port), so there is to possible response: the psp is not the good analisys i have to run, or the input impedance do really change with the source resistance ( it's the first time i'm seeing someting like that) so my question was to know wich is the good response to my problem. Best regards, Tawna Wilsey Staff Support AE, Global Customer Support Cadence Design Systems, Inc.
• Post Points: 5