I'd like to use the AD9910 to generate frequency ramps with a negative start freq and a positive stop freq (passing through 0). By negative, I mean a tuning word having a value between 0H80000000 and 0HFFFFFFFF. From reviewing posts on the AD9910, it appears negative frequencies are allowed. The question is: Are the sweep limit comparators implemented in offset binary or 2's complement? In other words, will the comparators recognize negative numbers as such or will this sweep setup fail ?