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# spectreRF pss analysis : formula for PAE

Last post Thu, Nov 7 2013 12:24 PM by smarjeet. 2 replies.
 Started by smarjeet 07 Nov 2013 11:50 AM. Topic has 2 replies and 2291 views
• #### Thu, Nov 7 2013 11:50 AM

• smarjeet
• Joined on Thu, Nov 7 2013
• Posts 2
• Points 25
spectreRF pss analysis : formula for PAE
 Hi,When using the direct plot option to  trace out the PAE (= Pout - Pin / Pdc) after a pss analysis, if the PAE is added to the outputs the formula which gets added to Output window reads as follows : ((100.0 * harmonic ((spectralPower(i("/PORT1/PLUS" ?result "pss_fd") v("/P_out" ?result "pss_fd")) + spectralPower(i("/PORT0/PLUS" ?result "pss_fd") v("/P_in" ?result "pss_fd"))) '(120))) /  -harmonic ((spectralPower(i("/V1/PLUS" ?result "pss_fd") v("/Vdc" ?result "pss_fd"))) '(0)))Here, PORT1 is my output port and Port0 is my input port. P_out and P_in are the output and input nets respectively. 120 refers to the index of the harmonic of interest in my analysis.Intuitively, I do not understand the following : The addition (highlighted in bold) of the two powers in the numerator, whereas from the formula of PAE, I expect there should be a difference.The negative sign (highlighted in bold) associated with the DC power in the denominatorI would be grateful if anyone could throw some light on the same. Thanks,Smarjeet
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• Post Points: 20
• #### Thu, Nov 7 2013 12:11 PM

• Tawna
• Joined on Thu, Jul 10 2008
• Snohomish, WA
• Posts 209
• Points 5,535
Re: spectreRF pss analysis : formula for PAE
 There is a worked example of this in Article 1837740In this example (and I recommend looking at this Article if you haven't already to see the assumptions that were made and the circuit that was being simulated), it explains...The spectralPower function assumes that the power is going into the selected terminal. For both the input port and the power source the power is actually coming out of the sources, resulting in a negative power value. Hence the addition of the extra negative signs to account for this, or PAE=(Pout-(-Pin))/-Pdc(total)best regards,Tawna Best regards, Tawna Wilsey Staff Support AE, Global Customer Support Cadence Design Systems, Inc.
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• Post Points: 20
• #### Thu, Nov 7 2013 12:24 PM

• smarjeet
• Joined on Thu, Nov 7 2013
• Posts 2
• Points 25
Re: spectreRF pss analysis : formula for PAE
 Dear Tawna, Thanks a tonne for the very quick and helpful reply ! smarjeet
• Post Points: 5