fourier analysis on current

Discussion in 'Cadence' started by Erik Wanta, Sep 22, 2003.

  1. Erik Wanta

    Erik Wanta Guest

    I have a current driven common emitter amplifier and I am trying to
    measure distortion with the fourier analysis. My netlist is below:

    //note term setting to perform fourier on collector current
    FOUR0 fourier fund=1M active=yes harms=5 term=Q0:c
    I1 (0 Vi) isource type=sine sinedc=0 ampl=1.5m freq=1M
    V0 (vcc! 0) vsource dc=10 type=dc
    Q0 (Vo Vi 0 0) npn
    R0 (vcc! Vo) resistor r=15
    I0 (vcc! Vi) isource dc=3m type=dc

    I run a transient and get the following output. Note that it is
    giving the results in volts, however I was expecting results in amps
    as I am specifying that I want fourier run on the collector current.
    I am getting about 76.5mA peak output current so I think it should
    read mA. Any ideas why volts?

    ========================
    Fourier Analysis `FOUR0'
    ========================

    Fundamental frequency = 1 MHz.
    Fundamental period = 1 us.

    Fourier components of V(Q0:c) for the interval from 0 s to 1 us:
    DC = 196.361 mV.

    Harm: Absolute Absolute Relative Relative
    Magnitude Phase Magnitude Phase
    1: 76.0435 mV -90.0001 Deg 0.000 dB 0 Deg <-
    normalizer
    2: 3.6818 mV -812.977 uDeg -26.300 dB 89.9993 Deg
    3: 357.375 uV 89.9967 Deg -46.559 dB 179.997 Deg
    4: 43.3991 uV 179.994 Deg -64.872 dB 269.994 Deg
    5: 5.90672 uV -89.9795 Deg -82.194 dB 20.5566 mDeg
    Total harmonic distortion = 4.86481 % (-26.2587 dB).
    RMS value of computed spectrum (excluding DC) = 76.1334 mV.
    RMS value of computed spectrum (including DC) = 210.604 mV.
    Nonperiodicity (first/last point mismatch) = -407.84 fV (-536.325 p%).
     
    Erik Wanta, Sep 22, 2003
    #1
  2. I suspect it's a bug.

    Andrew.

     
    Andrew Beckett, Sep 22, 2003
    #2
  3. Erik Wanta

    Erik Wanta Guest

    Andrew:
    Service Request Number: SR 32580844
     
    Erik Wanta, Sep 22, 2003
    #3
  4. Erik Wanta

    Erik Wanta Guest

    FYI
    This is known issue and PCR 378394 has been filed to correct this.

    Although the units are incorrect in the results, the numbers themselves
    are correct.
     
    Erik Wanta, Sep 23, 2003
    #4
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