Amongst the logic families DTL, TTL, ECL and CMOS, the family with the least power dissipation is :

CMOS has the lowest power dissipation of these families because, in either steady state, one transistor of each complementary pair is off, so almost no current flows from the supply to ground; power is drawn mainly while the gate switches. DTL and TTL draw current through resistors and saturated transistors even when idle, and ECL dissipates the most of all, because its transistors carry a constant current to keep them out of saturation.