An integrated circuit comprising a plurality of sensors configured to sense variations in supply voltage levels at points within the integrated circuit is disclosed. The plurality of sensors are distributed across the integrated circuit and have transistor devices such that process variations in the transistor devices within the sensors are such that a sensing result will have a random voltage offset that has a predetermined probability of lying within a pre-defined voltage offset range. The integrated circuit is configured to transmit results from multiple ones of the plurality of sensors to processing circuitry such that the variations in the supply voltage levels can be determined with a voltage offset range that is reduced compared to the pre-defined voltage offset range.