Author Topic: Measure OIP3 performance with LTspice  (Read 2869 times)

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Offline szszjdb

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Measure OIP3 performance with LTspice
« on: October 09, 2021, 09:57:31 am »
Dear All,

Is it possible to  measure OIP3 performance of an amplifier with LTspice? How is the procedure?
Attached the circuit ,FYI.

Best Regards,
James
 

Offline szszjdb

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Re: Measure OIP3 performance with LTspice
« Reply #1 on: October 19, 2021, 02:18:06 am »
Dear All,

Does someone could give some advice?

Best Regards!
James?
 

Offline rfclown

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Re: Measure OIP3 performance with LTspice
« Reply #2 on: January 30, 2022, 03:02:34 am »
I assume no one responded because there is not a straight forward procedure to measure OIP3. I suppose you'd have to do an FFT of the output waveform to see the level of the IM3 products.
 

Offline mawyatt

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Re: Measure OIP3 performance with LTspice
« Reply #3 on: January 30, 2022, 01:49:15 pm »
The two tone IMD is probably the simplest method, another method we used in early versions of Cadence was to sweep the input power and plot the fundamental vs the 3rd harmonic. Both methods however require an FFT, the first just a single FFT and the later many.

Remember doing both awhile back to get some idea of what to expect with actual hardware, one such circuit had some unique properties like gain expansion rather than compression at higher input levels.

Best,
Curiosity killed the cat, also depleted my wallet!
~Wyatt Labs by Mike~
 


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