Ultrahigh frequency RFID tag impedance self-adaptive circuit and implementation method thereof

Abstract

The invention discloses an ultra-high frequency RFID tag impedance self-adaptive circuit and method. The circuit comprises an antenna; a capacitor array, wherein the capacitor array comprises n capacitor branches which are connected in parallel and is selectively connected with a certain capacitor branch under the control of a control signal output by the digital circulation control circuit; a digital circulation control circuit, wherein the digital circulation control circuit is used for outputting n control signals under the control of the input enable signal and locking a value when it is scanned that the label chip starts to work due to the value; an alternating- direct current converter which is used for converting the wireless signal received by the antenna into direct current voltage; a power-on reset circuit which generates a reset signal when the direct current voltage is higher than a rated voltage; a reference voltage source circuit which generates a reference voltage required for controlling the digital circulation control circuit to work; a voltage division circuit which is used for sampling the direct current voltage to obtain divided voltage; a comparator which is used for comparing the divided voltage with a reference voltage to obtain a comparison output; and a logic circuit which is used for carrying out logic operation on the comparison output and the reset signal to obtain the input enable signal.

Description

technical field [0001] The present invention relates to radio frequency identification (Radio Frequency Identification, RFID) technology, in particular to a UHF RFID tag impedance self-adaptive circuit and its implementation method. Background technique [0002] For a UHF RFID tag, the impedance matching degree between the tag antenna and the tag chip will directly affect the reading and writing distance of the tag. However, during the actual use of the tag, changes in the external environment, process package parasitics, ambient temperature, etc. will affect the impedance matching between the tag antenna and the chip to varying degrees. When the performance of the tag is degraded due to the deterioration of the matching, it is hoped that the matching can be corrected through the automatic adjustment of the chip, so the automatic impedance matching technology of the tag comes into being. [0003] At present, the existing more mature UHF RFID adaptive impedance matching tech...

AI Technical Summary

Problems solved by technology

[0003] At present, the existing more mature UHF RFID adaptive impedance matching technology is based on the automatic search and comparison scheme, that is, the best matching point is searched or the number of times is used as the stop mark. The disadvantage of this scheme is that no matter whether the tag can be normal or not All work must find the best matching point. This solution greatly affects the inventory speed of the RFID system. Therefore, it is necessary to propose a technical means to alleviate the above problems

Images