The present invention provides a regulator used in an active terminator of a bus. The regulator comprises a voltage-regulated terminal, a first operational amplifier and a non-inverting input terminal thereof coupled to a reference voltage. An inverting input terminal of a second operational amplifier is coupled to the reference voltage. A control gate of a first transistor is coupled to an output terminal of the first operational amplifier. A source of the first transistor is coupled to an inverting input terminal of the first operational amplifier to form a feedback network and to provide a stable circuit of sourcing current. A control gate of a second transistor is coupled to an output terminal of the second operational amplifier and a drain of the second transistor to a non-inverting input terminal of the second operational amplifier to form the feedback network and to provide a stable circuit of sinking current. The prevent invention prevents from utility of complementary output power transistors and shoot-through current.