Question about change in frequency

[nafnaf]

what factors should i consider to be able my circuit to handle very fast change of frequency ?

example
at 1s 400Mhz
at 1s+1us 900Mhz
at 1s+1us + 2ns 111Mhz

 

[chuckey]

Are you talking about a swept oscillator? 400 -> 900 MHZ in 1micro sec looks feasible. 900 -> 111 in 2 ns is not achieveable. You will need to switch the outputs from continuosly running oscillators.
Frank