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10th May 2012, 08:22 #1
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How to add Antenna S1P parameters in Cadence Spectre and plot the Sparameter gain
Hi,
I have to simulate the gain of my designed LNA with certain antenna impedance as a source. I am using cadence spectre for the simulation.
The problem is that cadence spectre provides n1port for importing S11 parameters of antenna, which is a passive port. Therefore, if i connect the n1port at LNA input to represent antenna, i cannot simulate gain through sparameter analysis. This is because of the fact that now their is no active port at the input. I read some where from the internet that i should connect a port in series with n1port (SEE Attached figure below) for gain simulations but i think that in this case port impedance will affect the antenna impedance.
Can somebody comment that how i can do the antenna plus LNA gain simulations through Sparameters in Cadence spectre.

10th May 2012, 08:22

23rd May 2012, 13:14 #2
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Re: How to add Antenna S1P parameters in Cadence Spectre and plot the Sparameter gai
Hi,
I found out the solution for above problem.... Now i have added an ideal voltage source in series with n1p (it contains antenna s11 parameters). then i made a block symbol of vsource+n1p and added at the input of LNA.
With this configuration i am able to measure the gain of LNA+antenna chain through PSS analysis.

23rd May 2012, 13:14

23rd April 2013, 18:09 #3
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Re: How to add Antenna S1P parameters in Cadence Spectre and plot the Sparameter gai
Hello viperpaki007,
kindly, how could you add an antenna standard model or represent the antenna parameters in cadence?? please, i need a simple example by steps if you could.
thanks in advance,
Ahmed

23rd April 2013, 18:09

24th April 2013, 07:39 #4
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Re: How to add Antenna S1P parameters in Cadence Spectre and plot the Sparameter gai
Hi Ahmed,
You can add antenna one port sparameters in cadence n1p instance. after that add a vsource in series with n1p and make a component block from this circuit. This will represent antenna sparameter response in cadence
regards
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24th April 2013, 19:59 #5
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Re: How to add Antenna S1P parameters in Cadence Spectre and plot the Sparameter gai
Hello viperpaki007,
Firstly, thanks for your interest. Please, look at the attached image Is that you mean?, and i have a question what is the parameters of every instance should put?
Regards

24th April 2013, 19:59

25th April 2013, 12:57 #6
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Re: How to add Antenna S1P parameters in Cadence Spectre and plot the Sparameter gai
Hi Ahmed,
Using vsource in series with port is not a good idea. You will have to use only vsource and n1p instance and use pss analysis for finding gain/transfer function. You will not be able to use sparameter simulations with this configuration as sparameter simulations require input port.
Normally sparameter analysis require ports to be connected to input and output. However, problem with port is that you cannot put variable impedances of antenna in it. Therefore, if you are planning to use sparameter analysis then you will have to use port and create some kind of electrical model of antenna. Use this model and port together for real antenna behavior simulations. For example in my simulations, my antenna impedance had 5 ohm real part and the the reactance was increasing with frequency. Therefore, i had put 5 ohms value of port impedance in series with an ideal inductor representing antenna behavior.
ADS however, has option to put antenna s parameters file as port impedance and do the sparameter analysis.
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