Compare the IC logic families based on their rise time in ascending order:

(A) MECL

(B) CMOS

(C) Low power schottky TTL

(D) PECL

Choose the correct answer from the options given below:

Concept: 

Rise time, tr is the time taken by the output to switch from 10% to 90% of the maximum value. Rise time is related to the Propagation delay. Propagation delay in logic gates typically refers to the rise time or fall time i.e. the time taken to change the output state based on a change in the input state. 

Analysis:

• In Emitter-coupled logic (ECL), the transistor never enters into saturation region. Hence, it is the fastest logic family with a propagation delay of around 1-2 ns.
• A typical low-power Schottky TTL gate has a propagation delay of about 10 nanoseconds.
• The propagation delay for the CMOS lies between 20 to 50 ns. 

Hence,

t_r(PECL) < t_r(MECL) < t_r(TTL) , t_r(CMOS)

Additional Information