rfmems
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SpectreRF can not distinguish phase noise and amplitude noise. Therefore the simulated VCO phase noise is actually phase noise and amplitude noise. However, the help from cadence says that, since VCO has amplitude limit mechanism, close to carrier noise is mostly phase noise.
The question is, for voltage biased VCO, I believe its true. But for current biased VCO, there is no such obvious amplitude limitation. Then, can we still say that most of the noise is phase noise? If not, how can we fairly compare the noise performance of two kinds of VCOs?
The same questions for the VCO buffers and frequency dividers, apprently the simulated phase noise is actually again AM and PM noises. The more the wave form saturated, the more phase noise than am noise. But there is not way to tell how much of them is phase noise.
Please help me if you have some hints, thanks a lot.
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