Use capacitor charge and discharge circuit and this will create triangular waveform. Feed this waveform to the buffer and it will become square wave after threshold voltage detected.
What kind of load are you driving? 1ns rise and fall times will be very difficult to achieve unless your load is just resistive. Is 10W an average, RMS, or peak specification?
Hey gentleman !
Hi
You can use a crystal oscillator Ic in 10 MHZ frequency and then dividing its frequency with D flip flop and then amplify it with A switch that works at Class D Region! it is very simple.
Kind Regards
Goldsmith
You'll have to explain what the driver it's driving is, though. If it's a digital driver, I don't see why having such fast edges are needed for, but if it's an analog buffer circuit then it may be necessary, and difficult.
There are exotic ways of getting fast rise and fall times, but they're usually tailored to the exact load and waveform shape. For example, a friend of mine made a circuit using a nonlinear transmission line that can produce a 300V pulse with a <1ns fall time, but it's very specialized so the same thing may not work for you.