How much minimum input power required for Reference signal frequency for ADF 4350 PLL?
if i use 10 MHz as reference frequency is there any effect on performance?
You can use a reference frequency up to 250 MHz and then use the R divider to generate a PFD frequency <= 32 MHz.
I did a quick ADIsimPLL simulation with the ADF4351 (which has better phase noise), 60 MHz reference, 30 MHz PFD frequency. Here is the phase noise plot:
This hits -100 dBc/Hz at 10 kHz offset at 4 GHz output frequency.
I have attached the simulation file below for you to experiment with. You will need to download ADIsimPLL first (see above).
For the ADF4350 reference signal, the minimum power requirement is:
For more information, see REFin CHARACTERISTICS in Table 1 of the ADF4350 data sheet: http://www.analog.com/static/imported-files/data_sheets/ADF4350.pdf#page=3
how much reference frequency we can use to get better performance of AD PLLs?
if i use 10 MHz what will happen?
The higher your PFD frequency, the better your phase noise performance will be. On the ADF4350, the maximum PFD frequency is 32 MHz. So you can use a 32 MHz reference frequency and send this directly into the PFD.
You can use ADIsimPLL to simulate a ADF4350 with a 10 MHz reference and a 32 MHz reference and see the difference. There is a tutorial video and download for ADIsimPLL here: www.analog.com/adisimpll
can i use 60 MHz or 100 MHz as reference instead of MHz?
If i 60 use or 100 Mhz as ref frequency , can i able to get 100 dBc/Hz @ 10 KHz for 4 GHz output frequency. At this what will be the my TCXO Phase noise?
in between ADF4350 & ADF4351 which is better device to get best phase noise around 2500 to 4100 MHz?
I want to get 100 dBc/Hz @ 10 KHz offset over all frequency band?
Will TCXO Phase noise affect my signal phase noise?
what will be phase noise requirement of reference signal?
apart all these what all are parameters will affect Phase noise?
I want to use ADF4350 or ADF4351 for better phase noise and better spurious performance?
Can u please suggest my selection is valid or not?
Thanks for your reply!
i finalized to use ADF4351 PLL for my project purpose.
Can i use 40 MHz as reference frequency to get RF out frequency from 2000-4000 MHz in steps of 500 KHz?
can u suggest how to select Reference frequency based on PFD freq, RF out freq and RF out freq Step size.
Thanks in advance.
I did this using the ADF435x evaluation board control software: http://ez.analog.com/message/38857
Thanks for your reply.
can u tell what is the relation between reference frequency & PFD freq and RF out freq Step size.
On the ADF4351, the RFout step size is defined by the PFD frequency/MOD. MOD can be set to [2 - 4095]. For example, if you have a PFD frequency of 10 MHz, you can achieve a step size of 2.5 kHz using MOD = 4000.
The higher your PFD frequency, then the lower your phase noise will be. Ideally, you should use the highest PFD frequency that still allows you to achieve your step size.
Assume a reference frequency of 10 MHz; with no dividers, this gives a PFD frequency of 10 MHz. However if you want a narrower step size, you can divide your reference frequency to a lower PFD frequency using the R-counter or Ref /2 divider. Alternatively, you can use the reference doubler to increase your PFD frequency hence reducing phase noise.
Thanks for your reply!!
I want to know what are loop filter values for the frequency band of operation 2900-4000 MHz, 210 MHz, 960 MHz and 1310 MHz?
How to select the loop filter bandwidth and loop filter values based on our requirement?
Looking forward to hear soon! if any doubts feel free to reply back.
For low pass filter design, please use ADIsimPLL.
How to select loop filter bandwidth and on what basis we can set loop filter bandwidth?
What is the trade-off of loop filter and how it will affect performance?
The main trade-off controlled by the loop bandwidth (LBW) is:
Settling time vs Phase noise and spur attenuation.
A wide LBW will give shorter settling times when jumping from one frequency to another.
A narrow LBW will attenuate phase noise and spurs.
(Note: different time scales.)
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