Low Phase Noise Amplifier

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ali ghafoor

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can we use LNA in place of Low Phase Noise amplifier. i need to use a Low Phase Noise amplifier having Low noise figure(less than 1 dB) but low phase noise amplifiers, i found on internet from different vendors, have poor noise figure. can i use low noise figure amplifier (which obviously possesses low noise figure). what about the phase noise characteristics of LNA ? (because LNA's datasheet possesses no information regarding phase noise)
 


You confuse two separate features. Thermal noise is the base for defining amplifier noise in low-noise amplifiers. Low phase noise means that a device affects signal phase variations. Amplifiers generally have barely detectable phase noise, much lower (30-60 dB) than oscillators. Only special amplifier makers can measure their phase noise. LNA makers do not specify their phase noise as it requires a special test equipment.
You would have to buy some LNAs and test their PN if you are interested.
 
Noise figure is such an innacurate term. It is if someone asked what your girlfriend looked like, and you said "she is generally nice". The asker would still be wondering.

Figure out the residual AM and PM that is needed in the amplifier, and go try to find that. Maybe you can tolerate close-in or far-out noise, for instance
 

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