Thermal sensor for integrated circuit

A thermal sensor for an integrated circuit including: a Proportional To Absolute Temperature (PTAT) circuit comprising n-type MOS transistors and providing a first voltage; and a voltage generator circuit comprising a p-type MOS transistor and providing a second voltage. A reference voltage is based on the first voltage and the second voltage. At least one thermal output signal is based on the reference voltage together with the first voltage and/or the second voltage. In another aspect, an integrated circuit has a power routing arrangement, providing a power supply core voltage (VDDcore) to operate functional circuitry on the integrated circuit. One or more local thermal sensors are located on the integrated circuit, each comprising a PTAT circuit having MOS transistors using the power supply core voltage to generate a temperature-dependent voltage that varies independently of power supply core voltage variation.