Characteristics
Other noteworthy characteristics of the ECL family include the fact that the large current requirement is approximately constant, and does not depend significantly on the state of the circuit. This means that ECL circuits generate relatively little power noise, unlike many other logic types which typically draw far more current when switching than quiescent, for which power noise can become problematic. In cryptographic applications, ECL circuits are also less susceptible to side channel attacks such as differential power analysis.
The propagation time for this arrangement can be less than a nanosecond, making it for many years the fastest logic family.
Read more about this topic: Low-voltage Positive Emitter-coupled Logic