Customizing Clock Frequencies

Hi,

1. This is no problem. Just can use the Megawizard Plug-in manager to add an altera_pll to your quartus project. Just configure your PLL for 50Mhz input and 20Mhz output and it should work fine.

2. Yes the PLLs can multiply an reference clock. I believe it can go above 1Ghz but you probably want to implement some logic and then the limiting factor is not the clock frequency but meeting the timing constraints for your design. The maximum speed of the logic depends on the what you are implementing and the speed grade of your device. But it is probably around 150-200Mhz.

I hope that helps.