didac
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There's a million ways to see the things in life
Posts: 247
manresa,spain
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Hi, You are right the loop filter affects the measurement, playing with the value will give you slightly different measurements of phase noise, but I think that if you follow the users guide of the ssa the amount of error will be small enough to not be noticeable. Regarding the parasitic AM/FM modulations, in a VCO noise coupled to the VDD modulates the output waveform of the circuit in AM manner while noise coupled to the VCONTROL of the VCO will transform to the frequency domain like an FM modulation, this issues can cause a bad phase noise performance. It highly depends on the setup of your measure(number of wires,use of shielded wires,type of probes,external decoupling capacitors,on-chip capacitors,layout isolation techniques...)this effect will be more or less annoying. Hope it helps,
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