Patent ID: 11893434
Assignee: EXCELIO TECHNOLOGY (SHENZHEN) CO., LTD.
Field: Computer technology (Electrical engineering)
Classification: CPC G | IPC G

Claim 10:
11. A method for a passive radio frequency identification (RFID) tag with a temperature sensor, comprising:
sending, by a card reader, a magnetic field to the passive RFID tag, wherein an inductor coil of the passive RFID tag couples the magnetic field to generate an induced current to power up the passive RFID tag to enter an operation state;
sending, by the card reader, a command to the passive RFID tag, wherein after a command demodulation circuit of the passive RFID tag parses the command, a control circuit for the RFID tag/sensor mode conversion of the passive RFID tag controls relevant circuits of the passive RFID tag to start operation, and transmits relevant data upstream to the card reader; and when the command sent by the card reader includes a command to start the temperature sensor, the control circuit for the RFID tag/sensor mode conversion switches to a temperature sensor mode, and outputs a voltage to a gate terminal of a switch transistor to make conduction between a source terminal and a drain terminal of the switch transistor; an electric charge outputted by a regulator circuit of the passive RFID tag supplies to other RFID tag circuits, and a temperature measurement and A/D conversion circuit, and at the same time, charges a first energy storage capacitor and a second energy storage capacitor, the other RFID tag circuits including a state machine control circuit, an energy level detection and limiting control circuit, a mode conversion circuit, and a reference voltage and bias current circuit; and
when the card reader stops sending the magnetic field to the passive RFID tag, or the magnetic field sent by the card reader becomes weak, discharging, by the first energy storage capacitor and the second energy storage capacitor, to supply power to the other RFID tag circuits and the temperature measurement and A/D conversion circuit to keep them in the operation state to perform the temperature measurement, A/D conversion, and other tasks, such that the amount of electric charge is ensured for the RFD tag to perform the temperature measurement, the accuracy of the temperature measurement by the RFID tag is ensured, and a communication distance of the RFID tag is ensured.