Rectifying and amplitude limiting circuit with multiple time constants and passive radio frequency tag

Abstract

The invention belongs to the technical field of radio frequency identification, and particularly relates to a rectifying and amplitude limiting circuit with multiple time constants, and a passive radio frequency tag containing the rectifying and amplitude limiting circuit. By applying different time constants on the control ends of two discharging paths of the rectifying and amplitude limiting circuit, namely that the analog control signals with adjusted voltage amplitude can be carried out at different switching speeds, so the switching between complete opening and complete closing of the two discharging paths is realized; the applicable discharging is carried out according to the size of charge amount at the antenna end and the energy level of the tag, so the demodulation level of the tag is improved, and the reading and writing distance of the tag is improved.

Description

technical field [0001] The invention belongs to the technical field of radio frequency identification, and specifically refers to a rectifying and limiting circuit with multiple time constants and a passive radio frequency tag including the rectifying and limiting circuit. Background technique [0002] The passive radio frequency identification (Radio Frequency Identification, RFID) tag does not have a battery itself, and it works by the electromagnetic energy sent by the card reader. Because of its simple structure, economical and practical, it has been widely used in logistics management, asset tracking and mobile medical fields. [0003] When a passive RFID tag works, it absorbs the electromagnetic energy sent by the reader from the surrounding environment. After the passive RFID tag absorbs energy, it rectifies a part of the energy into a DC power supply for the internal circuit of the passive RFID tag; the passive RFID tag also inputs another part of the energy into th...

AI Technical Summary

Problems solved by technology

When the passive RFID tag is too close to the card reader or the electromagnetic energy sent by the card reader is too strong, the load modulation signal coupled back from the RFID tag end will easily cause saturation at the receiving end of the card reader, resulting in communication failure

This kind of failure is more likely to occur in the RTF communication mode (Reader Talk First) where the reader first sends a command and then waits for the RFID tag to respond.

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