Hi
I am trying to simulate a VCO's PSRR.
I used two methods to get the result.
The first one is to run the pxf analysis and choose the VCO output nodes as output.
Here is my setting:
The second one is to follow the instruction of the application note "PSRR Characterization Using SpectreRF Autonomous Circuits".
The only difference is "modulated" selected among "Special Analyses".
I run the simulation and compare the results of pxf and pxf modulated.
The simulation results are quite different.
Here is the simulation result:
The green line is the result of pxf modulated (SSB to PM) while the purple one is the result of pxf.
I do not understand why the two results have so large difference (>200 dB)?
and which one should be used to simulate VCO PSRR?
regards,
YCY