Compact Resistor-Based Temperature Sensors for On-Chip Thermal Monitoring

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Advanced Systems-on-Chip (SoCs) exhibit significant self-heating and require thermal management to prevent overheating. Sensors for this application should be not only small so that they can be placed ubiquitously, but they should also achieve moderate accuracy and resolution within 1 ms so that the die temperature can be monitored with approximately 1°C of measurement error. BJTs are the traditional elements that are used to sense temperature, but they require large headroom and are difficult to miniaturize. Thermal diffusivity relies solely on lithography for its accuracy and is easy to miniaturize, but it requires a significant amount of power (a few mWs) to generate the local heat pulses that it uses to measure temperature. MOS-based temperature sensors do not require the headroom that BJT-based sensors do, but they do require a large area to minimize the effect of aging and drift. Resistors achieve superior energy efficiency, moderate accuracy (enough for thermal management), and have no headroom requirements. However, at the beginning of this work, these types of sensors were not yet miniaturized.