Digital Systems: Principles and Design

145Different Types of Logic Gates

3. Both transistors T and T can be made on a silicon as one pair of the multi collector

junction transistors. The current sources at the input terminals are made using a p-n-

p circuit for each. The emitter of a grounded base p-n-p transistor act as a current

injector or sink (if input terminal is at logic 0). The p-n-p collector gets the current

through an external resistance connected to V

BB

+ supply. Figure 6.8(b) also shows

the input terminals and current source circuits and three collector junctions transis-

tor in place of T and T and fabrication of the I

2

L circuit. Figure 6.8(c) shows the

physical placements ...