No, 2.7V this threshold is for vdd ramps from 0V to 3.6V. 2.7V is 3/4 of 3.6V. I wanna make sure for each case threshold voltage beyond 3/4 of the vdd.
If I sizing the transistor to make this vdd 3.6V case work, then for the case vdd ramps from 0 to 3.5V, right now the threshold required is 3/4 of 3.5V which is 2.625V. it can work. In general, I for vdd ramps from 0 to 2.8, from 0 to 2.9 from 0 to 3.0, .......I can all make sure the threshold voltage for each case is beyond 3/4 of its corresponding vdd.
But when vdd is below 2.8, I mean may be ramps from 0 to 2.6V, then the Reset signal will be gone. That's why I ask for another possible structure.