AD8170 noise figure

Simple question: Is there formula for approximating the noise figure of a AD8170?  In the datasheet there are formulas for output noise voltages but I would like to know what NF would be.  I would be ok with someone that it within 1dB, just good enough.

dennis

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  • The AD8170 appears at the end of a signal attenuation chain.  In signal processing normally one would want to use a LNA before going to an attenuator after an antenna but we are not doing that to due the complexity.  The AD8170 is driving another vendor's ADC. We use the AD8170 because we have two signals that are being processed and are switched.  We were seeing "noise" present in one of our system tests.  While the amount of attn present does not help with the overall noise figure, I was curious how much NF the 8170 added.  I also know there are other ways to drive an ADC but the AD8170 has really good performance and we mainly use it for the switching aspect and P1dB performance at <100Mhz freqs.  Finding an RF switch that has fast switching, good P1dB performance for < 100MHz has been problematic.

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  • The AD8170 appears at the end of a signal attenuation chain.  In signal processing normally one would want to use a LNA before going to an attenuator after an antenna but we are not doing that to due the complexity.  The AD8170 is driving another vendor's ADC. We use the AD8170 because we have two signals that are being processed and are switched.  We were seeing "noise" present in one of our system tests.  While the amount of attn present does not help with the overall noise figure, I was curious how much NF the 8170 added.  I also know there are other ways to drive an ADC but the AD8170 has really good performance and we mainly use it for the switching aspect and P1dB performance at <100Mhz freqs.  Finding an RF switch that has fast switching, good P1dB performance for < 100MHz has been problematic.

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