In one example, a circuit includes a voltage rail, a reference node, a first capacitor, and a capacitor module. The first capacitor is coupled to the voltage rail and to the reference node. The capacitor module includes a second capacitor and a switching unit. The switching unit is configured to operate in a closed state and an open state. The switching unit couples the second capacitor in parallel with the first capacitor in the closed state. The switching unit decouples the second capacitor from the first capacitor in the open state.