Analysis and characterization of BiCMOS for high-speed digital logic

A combined bipolar and CMOS (BiCMOS) logic gate, capable of driving large capacitive loads at high speed, is analyzed and characterized. A simple analytical model which accurately predicts the transient response of the BiCMOS gate is described. At moderate and large loads, saturation of the bipolar transistors due to collector resistance can dominate the transient response. Device scaling issues are discussed for minimizing gate delay at various loading conditions.>