Research On The Design Of The Low Power Consumption Of The Temperature Sensor For Passive UHF RFID Application

Passive UHF RFID technology has the merits of low cost, long operation distance, identifying multiple objects at the same time and operating well under various environments, etc. And combines passive UHF RFID and temperature sensor can not only achieve target recognition, but also can realize the collection of temperature data, and real-time observation of temperature. However, RFID tags for embedded in the temperature sensor index of higher requirements are put forward. Such as reducing power consumption and improve the precision. Temperature sensor embedded in the RFID tags in making the application scope of RFID is more and more widely. In the temperature requirements more stringent application scenario will be extremely competitive. Especially in some specific occasion, such as the storage and transport of blood, vaccine or food.The passive RFID application oriented low-power design research on temperature sensor has been discusses in this article. First of all, the RFID technology is introduced, Then the key technology of the temperature sensor which is in the passive UHF RFID tags and the temperature sensor module are instructed in details. the temperature sensor for passive RFID tags was mainly introduced. Then the system simulation of the analog-to-digital conversion module of the temperature sensor is introduced. Temperature sensor in temperature sensing module is designed, using a pair of proportion current source offset a substrate PNP transistors, Has nothing to do with the voltage gain of current bias circuit to offset PNP transistors, The dynamic matching technique is used to reduce error and increase the sensitivity of the current source, the low power consumption ADC module for the temperature sensor is designed and a kind of second order fast conversion ADC is adopted, combination the SAR ADC and second-order Sigma-delta ADC. This structure can reduce the time of the modulus conversion module, significantly improve the performance in terms of power and precision, AD converter is adopted in the second-order Sigma- delta modulator, second-order Sigma-delta modulator reduces the integrator of the requirements of the operational amplifier. But due to the AD converter is worked in a wide span supply voltage, and temperature measurement range is larger, operational amplifiers is in higher requirements, the sharing is fully-differential folded source grid structure. The switches comparator is adopted, and the structure is simple, can effectively reduce the power consumption.Temperature range for- 40?C ~ 125?C, under the condition of the working voltage of 1.8 v, the total current 2.49 u A, the total power consumption is 4.48 uw. Under the condition of the working voltage of 1.6v,the total current is 2.136 u A, total power consumption is 3.42 uw, and the temperature measurement error within ± 2?C. Finally the passive UHF RFID chip temperature sensor in the low power requirements is realized.