Capacitor cell supporting circuit operation at higher-voltages while employing capacitors designed for lower voltages

An integrated circuit (IC) includes a functional circuit and a capacitor cell. The functional circuit may operate with one of two power supply voltages. The capacitor cell is used to provide power supply decoupling for the functional circuit, and includes multiple capacitors, each designed to withstand a maximum voltage equal to the lower of the two power supply voltages. When the functional circuit is to operate with the higher of the two power supply voltages, the capacitors in the capacitor cell are coupled in a series arrangement between power supply and ground terminals of the IC. When the functional circuit is to operate with the lower of the two power supply voltages, the capacitors in the capacitor cell are coupled in a parallel arrangement between the power supply and ground terminals. In an embodiment, the functional circuit is an input-output (I/O) circuit powered by 1.8V or 3.3V power supplies.