post more details. what is the frequency you want to generate?
does it have to be PLL or simple oscillator will do as well?
I didn't use this in a while but if you want to generate higher
frequency, you should be able to use any counter to divide output
frequency with the factor you choose (digital counter should be just fine). I am not sure about duty cycle of the divided signal so I would
either run some tests or pass this signal through another /2 counter
to make on/off times simetrical. That would require main frequency
to be reduced to 1/2 of original in order to maintain same output freq.