What impact does impedance have when selecting a ceramic resonator to use with a microcontroller.?
I'm looking for a 20MHz ceramic resonator with build in load capacitors and I've got my decision narrowed down to two. One has an impedance of 50 ohms and the other (slightly more expensive) one has an impedance of 30 ohms. An Atmel ATMega168 is the processor in question if that matters.