A Voltage-Scalable Low-Power All-Digital Temperature Sensor for On-Chip Thermal Monitoring

This brief presents a highly supply voltage-scalable, ultra-low-power, all-digital CMOS temperature sensor for on-chip thermal monitoring. The proposed all-digital temperature sensor employs a ring oscillator and a frequency counter to convert the temperature-dependent frequency changes into digital output, featuring a small area, and a high integration capability. The sensor core uses delay elements operating in the sub-threshold region to achieve low power consumption while maintaining high supply scalability. The 0.18 mu m prototype sensor occupies 0.007 mm(2) while consuming 3.92 nW at room temperature from a 0.9-V power supply. The sensing error is less than +0.67/ - 1.64 degrees C from 0 degrees C to 100 degrees C after 2-point calibration. The proposed sensor can operate across a wide range of supply voltage of 0.6 V to 1.2 V, with a supply sensitivity of 0.0019 degrees C/mV.