This article proposes a gallium nitride (GaN)-based isolated silicon carbide (SiC) MOSFET gate driver with an on-chip metal–insulator–metal (MIM) capacitor that has high data rate and low propagation delay. The improved common-mode transient immunity (CMTI) envelope detection technique eliminates the common-mode current ( $I_{\mathrm {CM}}$ ) to improve the CMTI. In addition, the proposed isolated gate driver (IGD) with quad-drive control (QDC) technique reduces power loss and gate ringing effect. Experimental results show that the proposed IGD can achieve a slew rate of 109 kV/ $\mu \text{s}$ . At a switching frequency of 100 kHz, the efficiency of the half-bridge isolated dc–dc converter can be kept higher than 90% when $V_{\mathrm {IN}}$ changes from 800 to 1700 V, and the peak efficiency is 98.6% when $V_{\mathrm {IN}}$ = 800 V.