Radio frequency identification tag and method for calibrating clock signals

Abstract

The invention provides a radio frequency identification (RFID) tag circuit and method for calibrating clock signals. An RFID tag circuit counts the specific duration signal emitted by a reader-writer, adjusts the clock calibration bit segment according to the counting results and writes the clock calibration bit segment into a nonvolatile memory of the tag. During next electrifying, the tag needs not to calibrate the clock again and only needs to read the clock calibration bit segment from the nonvolatile memory and adopts the clock calibration bit segment to control the circuit of an oscillator of the tag to obtain accurate clock signals. The invention ensures the clock signals generated by the tag circuit to meet the requirement of RFID protocol, correctly decodes the data sent by the reader-writer to the tag, correctly posts data back to the reader-writer, simultaneously controls the power consumption of the tag and enlarges the read-write distance of the tag.

Description

technical field [0001] The invention relates to a radio frequency identification tag for calibrating clock signals and a method for calibrating the clock signals in the circuit. Background technique [0002] Radio Frequency Identification (RFID) technology is widely used in logistics tracking, identity authentication and other applications. The RFID system usually includes tag readers and tags, such as figure 1 As shown, 1 is the reader and 2 is the tag. The reader includes one or more antennas 3 , and the tag includes one or more antennas 4 . The reader-writer 1 sends data such as commands to the tag 2 through the antenna 3, and the tag 2 processes the received commands and sends data back to the reader-writer through the antenna 4. [0003] When the reader 1 sends a command to the tag 2, it usually sends a start signal first, and then sends command data such as data 0, 1, etc. These start signals are used to synchronize the command or pass some link parameters, such as f...

AI Technical Summary

Problems solved by technology

[0014] Some high-precision capacitors and resistors can be used in the process to reduce this deviation, but this method will significantly increase the cost of the chip

In circuit design, the clock can be dynamically calibrated by a method similar to a phase-lock loop (Phase-Lock Loop), but this method will add too many circuits to the label and increase the cost of the label chip

In the protocol, a clock calibration can be performed before each communication between the reader and the tag, but this method consumes too much communication time and reduces the communication speed

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