What Is the Working Principle of RFID Labels?

Understanding RFID labels

RFID labels, also known as electronic labels, radio frequency cards or responders, are similar to barcodes on packaging, storing information about goods. They are the real data carriers of RFID systems, used to identify target objects. Attaching RFID labels to moving or non-moving objects turns them into "smart objects" that can be tracked and managed.

Working principle of RFID labels

RFID labels are integrated circuit products that are composed of coupling components and dedicated chips. RFID label chips can be divided into four parts: resonant circuit, radio frequency (RF) interface circuit, digital control and data storage. The resonant circuit is the communication interface of the electronic label with the outside world. It couples the magnetic field signal generated by the reader antenna to provide energy and data to the electronic label. The RF interface connects the external antenna to the internal digital control circuit and E2PROM data storage, and the RF interface circuit receives the reader signal coupled by the antenna to provide energy, timing and data to the internal circuit. The digital control circuit mainly includes state machine, decoding and encoding, encryption and verification, anti-collision and other modules, which realize command coding and decoding, data verification, complete control operations of the RF interface and data storage required by the protocol, and complete the functions required by the protocol. The data storage uses E2PROM to store user data, which can be read and written according to specific requirements.

RFID labels have built-in antennas, used to send and receive RF signals, and communicate with RF antennas. At present, there are many types of RFID chips in two frequency bands: 125kHz and 13.56MHz. These chips are mature and low-priced. 13.56MHz RFID labels are the mainstream products.

RFID labels use three types of data storage: electrically erasable programmable read-only memory (E2PROM), ferroelectric random access memory (FRAM), and static random access memory (SRAM). RFID technology usually uses E2PROM.

In the automatic identification management system, each RFID label stores information about an object's attributes, status, and identification number, with a globally unique ID that is written during chip processing, cannot be modified or counterfeited, and ensures security. RFID labels are usually installed on the surface of objects and have a certain unobstructed angle of view without metal shielding.

The main electrical performance parameters of RFID labels include: operating frequency, read/write capability, data transmission rate, information data storage capacity, multi-label recognition/reading capability (also known as anti-collision capability), and information security performance.