EARLY VOLTAGE IN VERY-NARROW-BASE BIPOLAR-TRANSISTORS

The Early voltage and hence output conductance of a bipolar transistor are classically determined solely from the base doping and width, plus the collector depletion layer capacitance charge. Here we show that for VLSI devices with very narrow base widths (less than 0.1 μm), the velocity saturation effect gives a substantial increase in Early voltage and a corresponding beneficial increase in output resistance. © 1990 IEEE