Yutao Liu
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Posts: 76
Guangzhou, China
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Hello everyone,
I want to compare the power supply sensitivity between a LC VCO (I call it VCO1 here for convenience.) and LC VCO powered by a LDO (VCO2). One VCO1 is powered directly by 1.6V while the other is powered by LDO whose output is 1.6V as well. And I take PXF analysis to both of them, frequency range is from 1Hz to 1MHz.
The sensitivity of VCO1 is lower than that of VCO2 between the range from 1Hz to 1MHz, when I choose "absin" as the "freqaxis",. However, sensitivity of VCO1 is higher than that of VCO2 in the range from 1Hz to 1MHz offset from the oscillation frequency, when I choose "in" as the freqaxis,. Why the result change in different frequency change? Is there any problem with my simulation?
I am concerned about the low frequency supply noise rejection and I suppose the LDO would decrease the power supply sensitivity at the beginning.
Could anybody help explaining? Thanks in advance.
Regards, Yutao
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