Abstract: By mathematical proof,we identify a modified feedback emitter-coupled logic (MFECL) gate with an ECL memory-gate or D latch, because the MFECL gate is able to keep steady either of two states.Then we present a D master-slave flip-flop that consists of two ECL memory-gates.On the basis of the above theory,a five-carry shifting counter is designed using such D master-slave flip-flops.The above theory and circuits are verified through computer simulation.

Key words: memory property of feedback ECL memory-gate, D latch, D master-slave flip-flop, five-carry shifting counter