non-programmable fractional N-PLL

Other Parts Discussed in Thread: LMX2581

Hello guys. 

I can not find the right goods. 

So I ask .... 

I want  to change the clock from 1.9 GHz to 2.1 GHz and the step is 100 KHz. 

I know I can user some fractional -N PLL but I want to change under 1ms. 

When I find some PLL in TI stuff, normally P.M.S ( synthesis  fact) set by I2C or some program that's why it change so slow. 

So any one know the direct control PLL ?

I really want to it.