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What it the OIP3 of the LT5514 as a function of input drive?

Category: Hardware
Product Number: LT5514
Software Version: NA

I'm considering the LT5514 because of the OIP3 value rated above +50dBm in my frequency range of interest. How can I determine the OIP3 as a function of drive level? Is there a model somewhere that I can use? I can't find any recent differential amplifiers in LTSpice. The reason I ask is because I see non-constant OIP3 in the datasheet plot of the AD8375 differential amplifier (Figure 11). I can understand why the (input) IIP3 might change as a function of gain in the VGA stage, but I can't understand why the OIP3 would change. I don't see OIP3 vs. drive level in other differential amplifiers and I'm concerned that there is a behavior in these high performance devices that is not able to be simulated in traditional system lineup.

I have also noticed this change in OIP3 in my measurements of the LTC6432 evaluation board.

I'm trying to design a high performance system that will use the LTC2208 ADC, but I'm unable to estimate the system linearity because of this unusual change in OIP3 as a function of drive level.

Top Replies

    •  Analog Employees 
    •  Super User 
    +1 verified

    Hi ,

    Good day.

    In an article by Kuo-Chang Chan entitled "The IP3 Specification", the OIPn can be directly related to the gain and IIPn of the device, that is, OIP(dBm) equals the sum of the…