Two new bipolar complementary metal-oxide-semiconductor (BiCMOS) differential logic circuits called differential cross-coupled bootstrapped BiCMOS (DC 2 B-BiCMOS) and differential cross-coupled BiCMOS (DC 2 -BiCMOS) logic are proposed and analyzed. In the proposed two new logic circuits, the novel cross-coupled BiCMOS buffer circuit structure is used to achieve high-speed operation under low supply voltage. Moreover, a new bootstrapping technique that uses only one boot-strapping capacitor is adopted in the proposed DC 2 B-BiCMOS logic to achieve fast near-full-swing operation at 1.5 V supply voltage for two differential outputs. HSPICE simulation results have shown that the new DC 2 B-BiCMOS at 1.5 V and the new DC 2 -BiCMOS logic at 2 V have belter speed performance than that of CMOS and other BiCMOS differential logic gales. It has been verified by the measurement results on an experimental chip of three-input DC 2 B-BiCMOS OOR/XNOR gate chain fabricated by 0.8-μm BiCMOS technology that the speed of DC 2 B-BiCMOS at 1.5 V is about 1.8 times of that of the CMOS logic at 1.5 V. Due to the excellent circuit performance in high-speed, low-voltage operation, the proposed DC 2 B-BiCMOS and DC 2 -BiCMOS logic circuits are feasible for low-voltage, high-speed applications.