Question

Motorola has offered MECL circuits in ______ logic families.

(a) 3

(b) 4

(c) 5

(d) 6

This question was addressed to me during an interview for a job.

The above asked question is from Compatibility or Interfacing in division Logic Families of Digital Circuits

Answer 1

Correct answer is (c) 5

To explain I would say: Motorola has offered MECL circuits in five logic families: MECL I, MECL II, MECL III, MECL 10000 (MECL 10K) and MECL 10H000 (MECL 10KH). The full form of MECL is Motorola emitter coupled logic. ECL is a high speed BJT. It uses BJT differential amplifier with single input and restricted current to avoid the transistor going into saturation and thus turning off operation.