A 0.5V BJT-based CMOS thermal sensor in 10-nm FinFET technology

A 0.5-V BJT-based thermal sensor design is first demonstrated in a 10-nm CMOS. A charge-pump technique is proposed for operating with a digital core supply voltage as low as 0.5 V without the restriction on forward junction bias (~0.7V). A switched-capacitor integrator loop is presented for process-insensitive voltage-to-frequency conversion. This thermal sensor achieves an RMS resolution of ±0.173°C, resolution FoM of 4 nJ °C
²
, and 3σ-spread accuracy of ±2.8°C at 85°C. The area is 0.01mm
²
and consumes 125uW from a 0.5-V supply. To the best of author's knowledge, this is the first BJT-based thermal sensor able to operate in sub-0.7V core supply voltage. The proposed low-voltage and small-area thermal sensor is easily to be integrated inside the CPUs, GPUs, and application process (AP) chips for real-time monitoring of hot spots.