Ratiometric BJT-based thermal sensor in 32nm and 22nm technologies

Thermal sensors are used in modern microprocessors to provide information for: 1) throttling at the maximum temperature of operation, and 2) fan regulation at temperatures down to 50°C. Today's microprocessors are thermally limited in many applications, so accurate temperature readings are essential in order to maximize performance. There are fairly large thermal gradients across the core, which vary for different instructions, so it is necessary to position thermal sensors near hot-spots. In addition, the locations of the hot-spots may not be predictable during the design phase. Thus it is necessary for hot-spot sensors to be small enough to be moved late in the design cycle or even after first Silicon.