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TINA/Spice: TINA T&M Spectrum Signal Analyzer vertical units

Eduardo Bartolome
Expert 4680 points
Other Parts Discussed in Thread: TINA-TI

Tool/software: TINA-TI or Spice Models

Hi,

Can you give a simple example on what the "Power spectrum" and "Amplitude spectrum" readings vertical units are? For instance, with an input tone of x(t)=sin(wt), assuming there was no leakage, what would it be the Power [dBm] or Ampl. [dB] showing? Wanted to do a simple test but leakage is killing me... (I got a separate post on that :) )

Thank you!

  • 0
    TI__Mastermind 31255 points
    Eduardo,

    What is the version of TINA you are using?

    Thanks,
    JC
  • 0 in reply to JC Zhu
    TI__Expert 4680 points

    Hi JC,

    Version 9.3.150.328 SF-TI

    Build date: Wednesday, November 23, 2016, 6:47:16 PM

    By the way, I think there is also a sync^2 envelop being applied to the original signal Fourier transform due to linear (1st order) interpolation. Still I don't seem to be able to make the numbers match...

    Thank you!
    Edu

  • 0 in reply to Eduardo Bartolome
    TI__Genius 9775 points

    Edu,

    I am not 100% sure your question, but I think if I understand correctly, basically for single tone FFT, then usually 2Vpp sinewave will be +10dBm and it's 0 dB.

    The equation is basically sinewave Vpp is converted either to Vrms or Vamplitude. So for 2Vpp, this means Vrms of about 0.707 and Vamplitude of 1Vpp.

    dB: 20*log(Vamplitude)

    dBm: 10 * log (power into 50 ohms) where Power = Vrms^2 / R

    Hope this answer your questions

    Herman

  • 0 in reply to Herman Theodorus
    TI__Expert 4680 points
    Hi Herman,

    Just to summarize our conversation... The first one seems right (dB seems to mean dBV) but the 2nd one although it is the standard, does not seem to match what TINA T&M is doing... The result is actually around 30dBm. Even if you just compute power as Vrms^2 (without the 50), one doesn't get 30dBm.

    Thank you,
    Edu