Sean you have not given enough info here -- I assume you mean a dc to dc multiplier but there is more than one way of doing this and the results differ.
Ray.
If your talking about a Cockroft Walton voltage multiplier then you put AC in and get DC out. I simulated this in Electronic workbench and used the o-scope to measure ripple, use AC coupling. The amount of ripple depends on a bunch of things, check out this website http://home.earthlink.net/~jimlux/hv/cw1.htm
hey random question about voltage multipliers (im only posting here because ppl have responded to this as is...lol) although they increase voltage they also decrease current, correct?
Yes. It's sort like a transformer. The power in can't be less than the power out (on a continuous basis). Since P = V*I, the output current must decrease in proportion with the voltage increase.