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How to set input power in transient simulation?

MohanB

Dear all

I am currently working on RF rectifier which has an equivalent circuit as shown in fig below.

                                                                     

I have calculated Zin = 355-j1797 at a frequency of 953 MHz. I want to study the transient behaviour of the above network for Pin = 1 dBm. I am using the port component in analogLib to give the input power were the source resistance should be equal to load resistance to ensure 1 dBm is transferred. This works fine if Zin is real.

However, I am not getting Pin= 1 dBm for the above complex Zin. I specify Source resistance =355 and impedance = -1797. Could any one tell me if there is a problem with my source properties. Am I specifying the complex impedance correctly? I am running transient simulation.

  • When you set a power level(Amplitude dBm) or voltage level Amplitude (Vpk) in the port, the assumption is that the port is properly matched (both resistive and reactive).    

    Amplitude 1 (Vpk) - When you specify the voltage on a port, you are specifying the voltage when the port is properly terminated, and not the voltage on the internal voltage source. Thus, the voltage on the internal source is set to twice the value specified on the port.

    Amplitude 1 (dBm) -  is the amplitude of the first sinusoidal waveform, in dBm.The resistance for the dBm calculation is taken from the resistance of the port. The value specified is the power delivered into a matched load. 

    See the Spectre Circuit Simulator and APS Simulator RF Analysis User Guide, section on "analoglib components used in RF simulation".   The same would apply to transient.

    best regards,

    Tawna

  • If the load is properly matched to the port as I mentioned in my previous post and you are seeing problems, please file a Case with Customer Support https://support.cadence.com  so an AE can look at this with R&D.

    best regards,

    Tawna

  • in reply to Tawna

    Hidden in the title of this thread is the fact that Mohan is running transient.

    Complex impedance (which can be specified per harmonic) is only used in hb analysis. It doesn't make sense in transient (and so is ignored) because the impedance cannot be complex across a range of frequencies (especially an unknown range which is what you have in transient) - that's not physically possible. With hb (via the "harmonic port" capability), you can specify a different complex impedance for each harmonic of the hb fundamental.

    Regards,

    Andrew.

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