Miniaturized, 0.01 mm2, Resistor-Based Thermal Sensor With an Energy Consumption of 0.9 nJ and a Conversion Time of 80 $\mu$ s for Processor Applications

Thermal sensing is a key power management feature in microprocessor products and other integrated circuits. There can be as many as 40 sensors on a chip. Thus, it is important for these sensors to have a highly compact area, as well as low energy. In this paper, we report a novel resistor-based thermal sensor with an area of 0.01 mm2 in 65-nm process, an energy consumption of 0.9 nJ/conversion, and a conversion speed of 80 μs. This sensor is one of the smallest, fastest, and lowest energy sensors reported which utilize resistors as the sensing element, making it optimal for CPU applications. The sensor has a competitive resolution figure of merit of 0.02 nJ·K2, as well as a relative inaccuracy of 1.4 °C, which easily meets the accuracy requirements of these applications. The circuit architecture is based on the measurement of an RC time constant using a novel amplifier/comparator circuit, along with a dynamic bias for power savings.