A 1.5-V differential cross-coupled bootstrapped BiCMOS logic for low-voltage applications

Abstract

Two new bipolar complementary metal-oxide-semiconductor (BiCMOS) differential logic circuits called differential cross-coupled bootstrapped BiCMOS ((DCB)-B-2-BiCMOS) and differential cross-coupled BiCMOS (DC2-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 bootstrapping capacitor is adopted in the proposed (DCB)-B-2-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 (DCB)-B-2-BiCMOS at 1.5 V and the new DC2-BiCMOS logic at 2 V have better speed performance than that of CMOS and other BiCMOS differential logic gates. It has been verified by the measurement results on an experimental chip of three-input (DCB)-B-2-BiCMOS XOR/XNOR gate chain fabricated by 0.8-mu m BiCMOS technology that the speed of (DCB)-B-2-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 (DCB)-B-2-BiCMOS and DC2-BiCMOS logic circuits are feasible for low-voltage, high-speed applications.