An Ultra-Low Power Temperature Sensor Based on Relaxation Oscillator in Standard CMOS

This work presents an ultra-low power CMOS temperature sensor in $0.13\mu \mathrm {m}$ standard CMOS process with an area of 0.0014mm2 and a power consumption of $0.15\mu \mathrm {W}$. CMOS transistors operating in subthreshold region generate the PTAT current, and a relaxation oscillator converts the current into frequency, which is digitalized by a following counter. The obtained oscillation frequency is nearly linear to the temperature, and a two-point calibration is applied to reduce the temperature spread in the range −0.27°C to 0.36°C.