Even though today’s digital electronics is dominated by CMOS technology, there are systems still in operation that were implemented in TTL technology, the dominant BJT technology before the advent of...

Even though today’s digital electronics is dominated by CMOS technology, there are systems still in operation that were implemented in TTL technology, the dominant BJT technology before the advent of CMOS technology. depicts the interfacing of a CMOS system to a TTL system, using two ordinary inverters as an example. The CMOS inverter is of the type. The TTL inverter, whose internal details need not concern us here, is specified in terms of its terminal characteristics in the manufacturer’s data sheets. In the following, assume a CMOS process with Vtn 5 2Vtp 5 1 V, k n 5 50 A/V2 , and k p 5 20 A/V2 . (a) The TTL data sheets specify that for proper operation, a TTL gate of the so-called 7400 Series requires that when vI 5 0 V, the CMOS inverter source to the TTL gate a current iO $ 40 A at vO $ 2.4 V. Specify a lower limit on (WyL)p to meet this requirement. (b) Likewise, when vI 5 5 V, the TTL gate requires that the CMOS inverter sink from the TTL gate a current iO $ 1.6 mA at vO # 0.4 V. Specify a lower limit on (WyL)n to meet this requirement. (c) Repeat, but for a gate of the so-called 74LS00 Series (low-power Schottky TTL), which requires that the CMOS inverter source iO $ 4 A at vO $ 2.7 V when vI 5 0 V, and sink iO $ 0.4 mA at vO # 0.4 V. Comment on the differences.