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Amplifier phase noise

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Jul 18, 2006
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What factors do affect the buffer ampliifer phase noise? In Lo chain, I have several buffer amplifiers in cascade. If I want to minimize the amplifier chain effect on synthesizer phase noise, what kind of amplifiers (technology?) I should choose? Low NF amps or what. LO buffers usually are saturated stages. How do they affect on the phase noise at the LO chain? Does the amplifier AM2PM characteristics have any effect on phase noise?

Many questions but thank you in advance for your answers

the topology may be like limiting amplifiers , like cherry hopper , i have seen some use the ordinary common source with inductor load ,

i think u need to optimize the NF of the buffer , so it will not elevate the overall phase noise of the signal

about the nonlinear effects u can use a feedback in the buffer so that the gain will be less , and the linearity is high so u can avoid nonlinear distortion in the RF signal

so sorry i am not experinced , but these are my thoughts maybe someone experinced , correct me


I think the noise performance will be decided by Gain of your 1st LNA & signal to noise ratio of L.O

the noise factor of the buffer affect the phase noise of the output of the LO

Amp impact to phase noise depends on Noise Figure, outer noise sources and Am to Pm conversion
You can simulate behaviour amp model in ADS and examin this

yeah , ADS can simulate all these effects , specially the AM to PM , coz the oscillator output is large signal


Klouly, I have ADS software. I want to learn how to use it, do you know what are the best place online that provide a free crash course on how to use it?

there is a lot of example in ads help document
you can find easily for VCO PN simulation example.

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