1. Introduction
RFID (Radio Frequency Identification) is a non-contact automatic identification technology that enables the automatic recognition of objects and the acquisition of relevant data through radio frequency signals. It can operate in various harsh environments without requiring manual intervention. An RFID system typically consists of two main components: a reader and an electronic tag. The electronic tag stores data, and when it enters the effective range of the reader, communication occurs based on a specific protocol. RFID technology is capable of identifying high-speed moving objects and multiple tags simultaneously, making operations fast and efficient. Short-range RFID products are resistant to harsh conditions such as oil and dust, making them suitable for replacing barcodes in environments like factory assembly lines. Long-range RFID products are commonly used in transportation, with a reading distance reaching several tens of meters, such as for vehicle identification or automatic charging [6]. Additionally, due to its resistance to counterfeiting and hacking, RFID offers strong security features. Its applications are widespread, including animal tracking, car alarms, access control, parking management, production automation, and material tracking. Countries and international organizations are actively working on developing RFID standards. However, there is still no comprehensive global or domestic standard for RFID. Major existing specifications include EPC in the U.S. and Europe, UID in Japan, and the ISO 18000 series.
There are various types of RFID tags, and they can be classified in different ways. Based on power supply, they can be either active or passive. According to carrier frequency, they can be categorized into low-frequency (134.2kHz), high-frequency (13.56MHz), ultra-high-frequency (433MHz and 915MHz), and microwave (2.45GHz) [6]. Although the basic technology of RFID tags has matured, many challenges remain in their practical application in logistics and manufacturing, such as cost, signal interference, improving recognition rates, information security, privacy protection, and standardization.
The basic RFID system includes RFID tags, readers, and supporting software. The CC2430 chip is supported by a powerful integrated development environment, offering industry-standard IAR IDE for interactive debugging. It is compatible with devices operating at 2.4 GHz. Fabricated using a 0.18μm CMOS process, the chip consumes 27 mA during operation and less than 27 mA or 25 mA in receive and transmit modes, respectively. It comes in a 7 mm × 7 mm QLP package with 48 pins, where all pins are categorized into I/O, power, and control lines [5]. The CC2430’s sleep mode and quick transition to active mode make it ideal for applications requiring long battery life, especially in RFID systems. This article uses TI’s CC2430 as the core component to design active RFID tags. It operates on 3.3–4.5V, can be powered by a button battery, and has low power consumption. The peripheral circuits are minimal, and most high-frequency components are integrated within the chip, ensuring stable performance and immunity to external influences. It is well-suited for applications demanding low power consumption and high performance.
2. Label Hardware Design
2.1 Hardware Circuit Structure
A typical active RFID tag comprises an antenna, radio frequency module, control module, memory, wake-up circuit, and battery module, as shown in Figure 1. The RF module handles the modulation and demodulation of control and response signals between the tag and the reader. The controller executes the reader’s instructions, while the memory stores tag information and microcontroller control programs. The controller reads from and writes to the memory. The RF module includes both transmitting and receiving sections. The transmitter consists of a modulator, power amplifier, bandpass filter, mixer, and local oscillator, while the receiver includes a low-noise amplifier, bandpass filter, demodulator, and waveform shaper. The TI CC2430 integrates the entire wireless communication system, and with a few additional peripherals, it forms a wireless communication module, reducing system costs and simplifying label design. The CC2430 is manufactured using a 0.18μm CMOS process, consuming 27 mA during operation, and less than 27 mA or 25 mA in receive and transmit modes, respectively. It is available in a 7 mm × 7 mm QLP package with 48 pins, divided into three categories: I/O, power, and control pins. The sleep mode and rapid transition to active mode make it ideal for applications requiring long battery life, especially in RFID systems. This tag design matches the output to a 50-ohm microstrip patch antenna. Surface-mount components are used in the PCB design, reducing system complexity and the size of the label. The entire PCB measures 10 cm × 5 cm, meeting the requirements for miniaturization. The circuit diagram of the tag is shown in Figure 2.
[Image: Design of a Microwave Band Active RFID System]
[Image: Design of a Microwave Band Active RFID System]
2.2 Low Power Design of Labels
For active tags, which rely on batteries, the lifespan of the tag is limited, so energy efficiency and low power consumption are crucial to extend the operational life of the tag. The CC2430 chip, fabricated using a 0.18μm CMOS process, consumes 27 mA during operation, and less than 27 mA or 25 mA in receive and transmit modes, respectively. By incorporating a control program during the design phase, the tag can respond only within the reader’s working range, maximizing energy savings.
2.3 Reader Design
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