UGC NET CSE | June 2008 | Part 2 | Question: 7

Question

Among the logic families $\text{RTL, TTL, ECL}$ and $\text{CMOS}$, the fastest family is :

• A. $\text{ECL}$
• B. $\mathrm{CMOS}$
• C. $\text{TTL}$
• D. $\text{RTL}$

   

Answer 1

Correct Answer is (A) ECL.

Emitter-Coupled Logic (ECL) is generally considered the fastest among the mentioned logic families: RTL (Resistor-Transistor Logic), TTL (Transistor-Transistor Logic), ECL (Emitter-Coupled Logic), and CMOS (Complementary Metal-Oxide-Semiconductor).

ECL operates on the principle of direct coupled transistors without any need for a clock signal, which allows it to have very fast switching speeds. However, it is also associated with higher power consumption and heat dissipation compared to other families. While ECL is fast, the choice of the logic family often depends on the specific application requirements and trade-offs between speed, power consumption, and other factors.