Scaling characteristics of $f_{NQS}$ and $f_t$ in NMOSFETs with and without supply voltage scaling

Extensive process and device simulations are performed to investigate the nonquasi-static transition frequency $(f_{NQS})$ behaviour of the NMOSFETs at different technology nodes, $0.5\hspace{2mm} \mu m$ to 90 nm, having same off-state leakage current $(I_{OFF})$. These studies are done with and without supply voltage scaling. $(f_{NQS})$ exhibits a turnaround in the 100 nm regime when we do the supply voltage scaling along with the transistor scaling. We attribute this effect to the reduced gate overdrive $(V_{GS}-V_t)$ and thereby to the degraded transconductance $(g_m)$. The unity gain frequency $(f_t)$ also shows a similar trend. The turnaround effect of $(f_{NQS})$ and $f_t$ disappears when $(I_{OFF})$ is allowed to go up or the gate overdrive is increased or both