| Radio Frequency Identification (RFID) is a kind of automatically identifying andtracking technology, which uses radio-frequency electromagnetic fields to transferdata with method of wireless non-contact. This technology is widely used in manyfields, and has been in rapid development. Based on ISO18000-4standard, this thesisexpounds a kind of semi-active temperature sensor tag, which is suitable for thewireless communication protocol of2.45GHz ISM band. The chip mainly includesRF front-end circuit, digital baseband control unit, temperature sensors, EEPROMstorage arrays and power management module. The RF front-end is responsible formodulation and demodulation of base band signal, power management moduleprovide power supply voltage for the whole chip and the controlling for wake up ofstart circuit and battery, digital baseband control unit is used for processing datainformation where before demodulation or after modulation, temperature sensor isresponsible for the collection of temperature, EEPROM memory is used to store datawhich is related to temperature and calibration, and other important information.This article mainly makes a deep and analysis with semi-active temperaturesensor tags and EEPROM memory. Based on the temperature properties of bipolartransistor, the temperature sensor realizes simple PTAT current source, with a singlepoint calibration, the sensor can achieve very good first-order temperature coefficient.In order to extend battery life in semi-active tag and the working range, low powerconsumption is an important standard of optimizing performance in the designprocess, therefore, the SAR ADC is chosen. Because of the characteristics of smallnumber information storing, EEPROM memory is designed with the capacity of1K,in addition, since it is one of the biggest contributors to power consumption of tag, sodesigning optimization is focused on this module.The design of temperature sensor block and EEPROM memory is in the processof SMIC018um e-EEPROM, and the RF front-end module is processed in UMC018um CMOS. All of the modules are designed in the Cadence environment,including circuit design, function simulation, layout design, physical verification,parasitic parameter extraction and post simulation verification. At the same time, theESD protection, antenna effect, latch up and noise isolation are considered in the design of circuits. Through testing the chip, results can be concluded that this designrealized the measurement accuracy of1℃with range from-50℃to50℃,andreached the expected goal. |
