Design Of Power Generation Circuit For Passive UHF RFID Tag Chip

RFID(Radio Frequency Identification) is a non-contact automatic identification technology, which makes use of the inductively coupled RF signal or the electromagnetic inverse scattering mechanism to realize the automatic identification of objects and the obtainment of data. Based on the application requirements, the present dissertation conducts detailed research on the physical basis, energy links, system architecture, performance index and power generation circuit of the UHF RFID tag.Power generation circuits of the passive UHF RFID tag mainly include the following modules: rectifier circuit module, the current reference source module, the voltage reference source module and regulating circuit module. Several structures of the rectifier circuit and the detailed analysis of the Dickson charge pump are given in this paper. The circuit design scheme based on threshold voltage compensation technology is used to realize the hign efficiency of energy conversion. According to the low-power low-cost demands, the sub-threshold technology has been adopted to realize the current reference and the voltage reference. Regulating circuit adopts the traditional LDO structure, and has achieved the low-power design under the precondition of system requirements. Overvoltage protection circuit scheme is employed to avoid the breakdown of the load circuit when the tag works at close range.The power generation circuits are designed in UMC 0.18 μm Embedded E2 PROM 1.8 V/5 V 2P6 M Low Leakage Process technology. Rectifier circuit has been realized by using charge pump which adopts the master-slave structure. When the input power is-5.2 dBm, the energy conversion efficiency is about 22.69%. The voltage reference source is realized by using the complete MOS structure, which has realized the output voltage of 640 mV and temperature coefficient of 16.82 ppm/℃. When the input voltage VCC is 1.8 V, the power consumption is 194 nA. The current reference source is designed using the sub-threshold technology, which has realized the output current of 99.7 nA and temperature coefficient of 48.45 ppm/℃. When input voltage VCC is 1.8 V, the power consumption is 431.4 nA. The output voltage of the regulating circuit is 1.8 V, and when the input voltage VCC is 2 V, the power consumption is 3 μA. When the input power is 12.2 dBm, the output voltage of charge pump has been limited at 3.3 V by using the overvoltage protection circuit.