Abstract: BiCMOS technology.has a most important effect in realizing super high speed circuits systems. On the basis of the conventional BiOMOS theory, a unified non-linear analytical delaytime model for BiCMOS digital circuits is presented by fully considering some low temperature effects, such as current driving capability enhancement of MOSFET, current gain and cutoff frequency decadence, forword turn on voltage of emitter-base junction increment of BJT,and the junction capacitance reduction of the system. The conculsions obtained have important significance in the optimization design for low temperatures super high speed BiCMOS circuits.

Key words: BiCMOS, low temperature, delaytime