Audioguru, the MOSFETs of a CMOS process kit is completely else than a discrete device which is designed to tolerate x*10V Vds and y*1A Ids. In integrated circuits the threshold voltage variation is much smaller. A commonly used 180nm process for example contains 3.3V devices with Vth variation of 0.6V to 0.9V, Vth variation of 1.8V core devices even smaller, like 0.4V to 0.6V. I am sure they won't have 4V Vgs with proper design, they can even operate in subthreshold region. PDKs contain low-threshold devices too, extra cost sometimes, but not impossible to work with them.