Comparing the two PLL's ADF4150 and ADF4151 which has better performance in Phase Noise (upto 3GHz) and spurious(DC to 10GHz) Performance ?
ADF4150 has normalized in-band phase noise floor 2 dB better than ADF4151 for both integer and fractional channels, and its 1/f noise is 5 or 4 dB lower than ADF4151 (values for intiger and fractional mode).
We do not specify the performance of any of these parts to 10 GHz - ADF4150 works up to 5 GHz, while ADF4151 up to 3.5 GHz.
But the Spurious Signals Due to PFD Frequency is higher -75dBc (RF OP buffers) in ADF4150 whereas ADF4151 has -107dBc. In ADF4150 is it possible to improve this externally ? or will it affect the output phase noise performance from 10Hz offset to 10MHz offset of carrier.......
The ADF4151 does not have RF output, and the level of the spurious signal of -107dBc was measured on VCO output and with the RF buffer between VCO output and RFinput of the part.
For the ADF4150, the level of PFD spurs -75 dBc is measured on RFout pins of the part, and for VCO output (in similar condition like ADF4151) it is -90 dBc.
I have checked that once the new value of phase noise for reference or VCO were set, the program keeps these new values - i cannot see the "auto change after simulation" that you described. Could you clarify at what circumstances you see this behaviour?
To edit a model for VCO, select from menu "Libraries -> VCO Library Editor". Modelling the VCO is described in in the help available with the program - please select "Libraries -> Step-by-step guide - Modelling My VCO" for more details
Is it possible to improve the level of PFD spurs in ADF4150 by selecting RF out divide by ratio to 1 ?
If you want to improve PFD spurs, you can use the VCO output while working with ADF4150 and put a buffer between VCO output and RF input of the ADF4150 (please refer to the User Guide UG-380: http://www.analog.com/static/imported-files/user_guides/UG-380.pdf). On page 17 of the document you will see how the buffer (ADL5541 with a pasive attenuator afterwards) is placed.
I have been using ADIsimPLL3.41 for Phase noise simulation. In this tool how to set phase noise manually for VCO and Ref. Oscillator ?
Though I m able to set it by choosing Point/floor or corner/floor, it auto changes after simulation.
Is there any other option to set Phase noise or to create and import my custom VCO Library.
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