It has been reported that mobility (mu(eff)) in high-k gate dielectric metal insulator semiconductor field effect transistors (MISFETs) is lower than that in conventional metal oxide semiconductor field effect transistors (MOSFETs). We investigated the influence of carrier velocity related parameters (CVRP), such as mu(eff) in the high vertical electric field (E-eff) region where gate voltage is around power supply voltage, mu(eff) in the low Eeff region where gate voltage is around threshold voltage, and saturation velocity (V-SAT), on propagation delay time (tau(pd)) of CMIS inverters using a circuit simulation. It is shown that tau(pd) is strongly affected by mu(eff) in the high Eeff region and that influences of mu(eff) in the low Eeff region and V-SAT on tau(pd) are relatively small. Physical reasons for these phenomena are understood based on consideration of influences of mobility and saturation velocity on drain current taking the effect of channel length modulation into consideration. (C) 2004 Elsevier Ltd. All rights reserved.