A Compact Temperature to Frequency Converter With 3σ Inaccuracy of +0.57 °C/-0.65°C for On-Chip Thermal Monitoring

A temperature sensor plays an important role in modern high-performance processing chips. A temperature sensing core with a high sensing accuracy is proposed in this article to meet the increasing demand for on-chip thermal monitoring. A comprehensive analysis of the thermal characteristics in subthreshold current is presented to achieve optimal sensing accuracy. The thermal information contained in subthreshold current is converted into a frequency which can be easily digitized in processing chips. The dynamic offset compensation (DOC) method is proposed to improve the supply sensitivity. In addition, small area and low power are also achieved due to its simple structure and low working current. The sensor is designed and implemented in the standard 0.153- <tex-math notation="LaTeX">μ m </tex-math> CMOS technology. After a two-point calibration and systematic error removal (SER), the proposed sensor has a measuring inaccuracy of +0.57 <tex-math notation="LaTeX">∘C/-0.65 ∘C </tex-math> ( <tex-math notation="LaTeX">3σ </tex-math> ) within the temperature range of <tex-math notation="LaTeX">-40\,\,∘C~ </tex-math> 120 °C. The occupied area and power consumption of the sensor are only <tex-math notation="LaTeX">860 μ m^2 </tex-math> and <tex-math notation="LaTeX">1.3 μ W </tex-math> , respectively. With the help of DOC, the sensor can achieve a supply sensitivity of 2.1 °C/V. This combination of high accuracy, small area, and low energy consumption makes this sensor suitable for on-chip dense thermal monitoring applications.