Design Of High Precision CMOS Temperature Sensor With Wide Temperature Range

Temperature sensors are closely related to production and life.Temperature monitoring is a vital part of the power IoT for intelligent and safe power supply monitoring and control of power transmission and distribution.In order to achieve accurate temperature control and overheat protection,a temperature sensor that can operate in wide temperature range is the key.This application also places demands on temperature sensors’ accuracy,cost and power consumption.The paper presents a BJT-based CMOS temperature sensor,which consists of a high accuracy temperature sensing front-end and a low-power second-order one-bit Δ-Σ ADC to meet the requirements of wide temperature range.In order to obtain a high precision temperature sensing front-end,the paper analyses the sources of error and uses techniques such as dynamic element matching(DEM),chopping and β compensation to reduce the error.This paper uses an incremental second-order Δ-Σ ADC as readout circuit and a cascoded floating-inverter-based dynamic amplifier(FIA)instead of a conventional operational transconductance amplifier(OTA)as an integrator.This integrator operates for only half the cycle and does not require additional bias circuit,significantly reducing power consumption.The gain factor is also implemented by using a charge balancing scheme to reduce sampling switches and the T-switches are used as sampling switches.As a result,the impact of switch leakage on the accuracy of the circuit is reduced.The proposed temperature sensor is designed based on TSMC 0.18μm CMOS process.It was taped out and 15 samples were tested.It can be seen from the test results that the temperature sensor achieves untrimmed inaccuracy of±1.4℃(3σ)from-50 to 150℃.This improves to±0.8℃(3σ)after one-point calibration at 40℃.The core area of the chip is 0.13mm2 and the total power consumption is 45.7μW.The duration of each temperature measurement is 10.24ms.