Consider an n-channel MOSFET with $N_{a}=10^{16} \mathrm{~cm}^{-3}$ and $t_{a x}=12 \mathrm{~nm}=120 \AA$. The depletion region at each end of the channel can be approximated by a triangular region, as shown in Figure P11.27. Assume both the lateral and vertical depletion widths are equal to $x_{d T}$. The threshold voltage shift due to narrow-channel effects is to be limited to $\Delta V_{T}=+0.045 \mathrm{~V}$. Determine the minimum channel width $W$. Neglect short-channel effects.