Accurate, small and low-power CMOS temperature sensors designed for multi-position temperature monitoring of power management in multi-core processors are proposed. The temperature sensors utilize the temperature characteristics of the threshold voltage of a MOS transistors to sense temperature and are highly linear from 60°C to 90°C. This is the temperature range needed for the power management applications where temperature sensors are strategically placed at multiple locations in each core to protect the processor from temperature-induced reliability degradation. A temperature-to-digital converter (TDC) that does not require either a reference generator or an ADC is also introduced, and it exhibits low supply sensitivity, small die area, and low power consumption. Both analog threshold voltage based temperature sensor and a prototype TDC designed to support multi-position thermal-sensing for power management applications from 60°C to 90°C are implemented in an IBM 0.13μm CMOS process with a 1.2V power supply.A new verification approach with several variants for identifying the number of stable equilibrium points in supply-insensitive bias generators, references, and temperature sensors based upon self-stabilized feedback loops is introduced. This provides a simple and practical method for determining if these circuits require a “start-up” circuit and, if needed, for verifying that the startup circuit is effective at eliminating undesired stable equilibrium points in the presence of process and temperature variations. These undesired stable equilibrium points are often referred to as Trojan states. It will be shown that some widely used approaches for verification do not guarantee Trojan states have been removed. Some of the methods introduced appear to be more practical to work with than others. A group of benchmark circuit with Trojan states will be introduced and used to demonstrate the effectiveness of the new method.
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