HI. I' m experienced in ASIC design, from schematic to layout, verification and final integration. I don't know what is the final application for the chip but I think that you should not undertake this project. A simple differential amplifier won't work as a comparator, you will need a couple of stages and hysteresis, to avoid output bouncing due to noise at the input (superimposed to a possibly slowly rising signal). Please reconsider your budget.