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LMH6629: Spice model: linearity

David D
Intellectual 580 points
Part Number: LMH6629
Other Parts Discussed in Thread: TINA-TI

Hello,

Can you please advise if the Pspice model covers linearity of the amp (HD2,HD3, IM3, etc)?

It is not mentioned specifically in the list of features covered by the model...

Does it hides under "RF Effects"?:


* MODEL FEATURES INCLUDE OPEN LOOP GAIN AND PHASE,
* OUTPUT SWING, OUTPUT CURRENT THRU THE SUPPLY RAILS,
* OUTPUT CURRENT LIMIT, CLOAD EFFECTS, RF EFFECTS,
* SLEW RATE, COMMON MODE REJECTION WITH FREQ EFFECTS,
* POWER SUPPLY REJECTION WITH FREQ EFFECTS, INPUT
* VOLTAGE NOISE WITH 1/F, INPUT CURRENT NOISE WITH
* 1/F, INPUT BIAS CURRENT, INPUT COMMON MODE RANGE,
* INPUT OFFSET VOLTAGE WITH TEMPERATURE EFFECTS,
* INPUT CAPACITANCE, COMP PIN FUNCTION INCLUDING
* THRESHOLD AND INPUT CURRENT, AND QUIESCENT CURRENT
* VS VOLTAGE AND TEMPERATURE. SHUTDOWN PIN
* AND ITS FUNCTIONALITY IS NOT INCLUDED IN THE MODEL.

Thanks,

David.

  • +1
    Guru 140200 points

    Hi David,

    the models do usually not cover distortion effects. When you run a Fourier analysis in TINA-TI at 20MHz (gain = 10V/V) the simulation says that the second harmonic is much smaller than the third harmonic. But from the figures 19 and 20 of datasheet it should be just the opposite. So what you see in TINA-TI may be just "harmonics" artefacts which result from rounding errors at the high frequencies.

    The "RF effects" are the effects "RF" has on the frequency response. See the figures 15, 16, 17 and 18 of datasheet.

    Kai

  • +1
    Guru 48395 points

    The spice or TINA models almost never try to capture HD effects, even the full transistor level designer models struggle with HD2 accuracy while HD3 is usually pretty well captured. You should not depend on simulation for harmonic prediction, only the datasheet plots are provided and they are usually single device.