A 1-volt temperature sensor with duty-cycle-modulated output in 0.18 μm CMOS technology

Abstract

This paper describes the design of a low-voltage, energy-efficient smart temperature sensor to be implemented in 0.18μm standard CMOS technology. The BJT-based sensor converts the PTAT and CTAT currents to a square-wave output with a duty cycle proportional to the temperature. The main limitations of the integrated interface for low-voltage design is found from an approximating analytical calculation, which shows that the minimum supply voltage was 1.5 V. Next, the design was modified to make our principle working for a 1V supply. Simulation results of the complete sensor show that the error in temperature range of -40°C to 110°C is less than 0.5°C. However, due to the influence of leakage currents, this error rises to about 3°C for 130°C.