Integrated circuit and method of operating an integrated circuit

A method of operating an integrated circuit, the integrated circuit comprising a first functional unit and one or more other functional units, wherein the first functional unit has an input for receiving data and an output for providing data, and wherein the method comprises testing the first functional unit and operating the first functional unit normally, wherein testing the first functional unit comprises:

• connecting the input of the first functional unit to the output of the first functional unit via a multiplexor, thereby providing a loopback path from the output of the first functional unit to the input of the first functional unit, wherein the loopback path is internal to the first functional unit;
• loading a test pattern onto the first functional unit;
• feeding a test clock signal comprising one or more clock edges to the first functional unit, thereby prompting the first functional unit to transform the test pattern into a transformed pattern;
• and
• reading the transformed pattern from the first functional unit;
• and wherein operating the first functional unit normally comprises:
• connecting the input of the first functional unit to an output of the one or more other functional units via the multiplexor;
• and
• feeding a normal clock signal to the first functional unit.