A level sensitive comparing device includes: a first comparator, a second comparator, and a determination circuit. The first comparator is arranged for comparing an input signal with a first reference level to generate a first comparison signal. The second comparator is arranged for comparing the input signal with a second reference level to generate a second comparison signal, wherein the second reference level is different from the first reference level. The determination circuit is coupled to the first comparator and the second comparator, and is arranged for determining whether the first comparison signal is allowed to appear at an output of the level sensitive comparing device according to at least the first comparison signal and the second comparison signal, wherein the determination circuit is composed of digital components only.