This letter presents a detailed study of the temperature dependence of submicron pseudomorphic InGaAs on GaAs substrate modulation doped field‐effect transistors (MODFETs), doped‐channel metal insulator field effect transistors (MISFETs), and metal semiconductor field‐effect transistors (MESFETs). We determine similar variation in the measured extrinsic current gain cutoff frequency,FT, and similar dependencies of the effective electron velocity,veff, with reduced lattice temperature for the different field‐effect transistors. Theveff∼T−bwhere 0.15<b<0.20 over the temperature range of 300 to 110 K. These results provide direct experimental evidence that the saturated velocity of electrons is the most important parameter for high‐speed operation and with proper design these different pseudomorphic InGaAs/GaAs field‐effect transistors provide similar potential for high‐speed operation.