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AWR VSS - Discrepancy between Time Domain Simulator & Budget Analysis in AMP_B Output Power

MWMike

Hi, I have an AMP_B block that I'm driving into saturation, and I'm noticing around a 4 dB difference in compressed stage output power depending on if I use the Time Domain Simulator (measured with PWR_MTR, verified with PWR_SPEC), or the RF Budget Analysis (measured with SPWR_node). A side-by-side comparison is shown below, where I am sweeping the input power. The left plot shows the input and output power of the compressed stage, the right plot shows the entire chain cascaded signal power. The AMP_B block is set up with OP1dB = 19 dBm / Psat = 21 dBm, so the RF Budget analysis seems to be the more realistic of the two.

Is there something I am missing in my interpretation? Or is AMP_B not suitable for large-signal analysis with the Time Domain simulator?

Parents

  • Hi MWMike,

    I looked into this and I am seeing fairly close agreement (within 1 dB) between PWR_MTR and SPWR_node (RFB measurement) looking at just a typical RF front end architecture with 2 gain stages (AMP_B), one mixing stage, and some filtering. There could be a lot of reasons why there is disagreement between the two measurements, so it is difficult to say without a project, but I do have one thing for you to try.

    Open the PWR_MTR measurement settings and specify a center frequency and narrow bandwidth and see if you get better agreement. Also make sure you are looking at Total Power, not Total Power, Pk.

    Picture of PWR_MTR settings that I used for a 3.8 GHz output:

    If this does not resolve your issue, I would ask that you file a proper support ticket and send in a project and we can better assist you.

Reply

  • Hi MWMike,

    I looked into this and I am seeing fairly close agreement (within 1 dB) between PWR_MTR and SPWR_node (RFB measurement) looking at just a typical RF front end architecture with 2 gain stages (AMP_B), one mixing stage, and some filtering. There could be a lot of reasons why there is disagreement between the two measurements, so it is difficult to say without a project, but I do have one thing for you to try.

    Open the PWR_MTR measurement settings and specify a center frequency and narrow bandwidth and see if you get better agreement. Also make sure you are looking at Total Power, not Total Power, Pk.

    Picture of PWR_MTR settings that I used for a 3.8 GHz output:

    If this does not resolve your issue, I would ask that you file a proper support ticket and send in a project and we can better assist you.

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