Abstract: A decoupling integrated circuit including a substrate including first and second active regions extending in a first direction and spaced apart from each other in a second direction intersecting the first direction, a first power rail configured to receive a first power supply and including a first horizontal extension being apart from the first active region in the second direction and extending in the first direction and a first-1 protrusion protruding from the first horizontal extension in a third direction opposite to the second direction, a second power rail configured to receive a second power supply and including a second horizontal extension being apart from the second active region in the second direction and extending in the first direction and a second-1 protrusion protruding from the second horizontal extension in the second direction, the first-1 protrusion and the second-1 protrusion constituting a decoupling capacitor may be provided.