A semiconductor capacitor that includes a plurality of overlapping conductive layers and a field-effect transistor. The plurality of conductive layers include a first and second conductive layers that are spaced apart to creating a capacitance between the plurality of layers. In the semiconductor capacitor, the FET has a source, a drain and a gate. When the FET is in conduction mode, a capacitance is created between the gate and the conductive path in the semiconductor substrate between the source and the drain. The semiconductor capacitor's total capacitance is increased by coupling the drain and the source to the first conductive layer and coupling the gate to the second conductive layer.