I want to generate a 4.25 GHz using a PLL and 50 MHz crystal/oscillator.
I am confused as to what I need to look for in a PLL. In a integer-N PLL, the prescalers are 16/17, 32/33, 64/65, etc. So, my understanding is that these PLLs take in the reference 50 MHz signal and then multiply it by the prescaler to generate 800/850 MHz, 1600/1650 MHz, 3200/3250 MHz, etc respectively. Most integer-N PLLs have a prescaler upto 64/65 only and hence I am limited to 3200/3250 MHz. So, I wont be able to generate a 4.25 GHz signal using 50 MHz crystal.
So, is my understanding correct? If not, can someone guide me as to what the mistake is.
If I am correct, do I need to use a higher frequency crystal or are there other PLLs available which can be used to generate the desired frequency using 50 MHz crystal?
Note: I have taken the data of prescalers from the Analog Devices ICs