Overview: The article overviews the role of NFC and RFID technologies as integral components in modern wireless communication systems and explores their evolution and features, highlighting their impact on various applications.

From the 1950s onward, radio frequency identification (RFID) technology has been extensively used in developing remotely operated devices.

What is RFID?

RFID is an advanced wireless technology compared to optical identification systems for the purpose of tracking and identifying items, people, animals, etc. RFID has many advantages over optical systems, including the ability to read numerous tags simultaneously, improved data storage capacity, and longer reading distances without requiring line-of-sight. 

RFID operates in various frequency ranges, which include:

  • Low-frequency (LF) range in 100 kHz
  • High-frequency (HF) range in 13.56 MHz
  • Ultra-high-frequency (UHF) ranges from 860–960 MHz, or 2.45 GHz to 5.7 GHz

RFID tags are divided into three groups: 

  • Active
  • Semi-active
  • Passive

Active RFID tags need an internal power source to operate; they can use an integrated battery or a permanent power source to power the tag. The advantage of semi-active RFID tags is that an onboard battery supply powers them. The only power source for passive RFID tags is the electromagnetic waves produced by the reader; they do not have any internal power supply. Later, a new communication protocol called NFC (near-field communication) was established based on the existing RFID standards. 

What is NFC?

NFC, as the name implies, is a short-range wireless communication technology that operates within a much narrower frequency range (13.56 MHz) and is only effective at distances shorter than 5 cm using radiowaves.

NFC was first introduced as a replacement for the Bluetooth standard, which had a significantly lower range and a reduced data rate (up to 424 kbps). In contrast to Bluetooth, NFC tags do not require batteries or active communication.

Additionally, unlike RFID, NFC allows direct two-way communication between mobile devices and NFC-capable tags. Out of the two communicating devices, one has to be active, like a smart device, and the other will be a passive device, like NFC tags. Active devices require an external power supply, while the electromagnetic power of the active device powers passive devices.

NFC operates in three modes of communication, which include:

  • Card emulation mode
  • Peer-to-peer mode
  • Reader/Writer mode

What are dynamic NFC/RFID tag ICs?

Dynamic NFC/RFID tag ICs are advanced integrated circuits that combine the capabilities of traditional NFC and RFID technologies with additional features for enhanced functionality and flexibility. These dynamic tags are designed to support contactless and wired communication, making them suitable for various applications.

An RFID/NFC system typically consists of a reader and tag comprising a microcontroller and a frontend integrated circuit, as shown in Fig. 1. Through inductive coupling, the reader powers the tag, which does not have an external power supply. The working of the RFID/NFC systems is based on the following parameters:

  • Reader type
  • Antenna structure
  • Tag antenna inductance
  • Distance between the reader device and the tag antenna
  • Coupling factor

Fig. 1: Illustration of Dynamic NFC/RFID tag ICs. Source: Rakesh Kumar, Ph.D.

Key Characteristics of Dynamic NFC/RFID Tag ICs

  • This dual interface capability allows for seamless interaction between NFC-enabled devices and host microcontrollers, enhancing various applications.
  • These tags support fast data transfer modes, enabling efficient data exchange that is useful for applications requiring rapid data updates or programming, such as software updates.
  • Many dynamic NFC/RFID tag ICs operate without an external power source by extracting energy from the RF field generated by an NFC/RFID reader. This feature is vital for low-power applications.
  • Dynamic tags often come with significant memory, and this high capacity allows for storing large amounts of data, which can be accessed via RF and wired interfaces.
  • These tags offer advanced security features, such as multiple password protections, ensuring data integrity and privacy.

Applications

Dynamic NFC/RFID tag IC systems have a wide range of applications. Recent examples of sensing applications include pairing smart devices to share information, smart posters, business cards, data logging, asset tracking, and inventory management systems. The future of the transaction industry should be contactless payments based on dynamic NFC/RFID tag IC systems. 

The application has expanded to include automation, such as IP-based access control to sensor tags, classroom access control, and smart home automation. These technologies are also used in biomedical applications in recent years. Biomedical sensor applications, intraocular pressure monitoring for glaucoma monitoring, wearable healthcare systems with an instantaneous heart rate (IHR) monitor and ECG processor, and wireless fluorimeters are a few examples from recent years.

Challenges

Even though RFID offers significant advantages over optical systems for many applications, the cost of standard RFID tags is comparatively high. It is expensive even for passive tags powered by the interrogation signal and does not require batteries. Since the existence of a chip determines the majority of the tag's cost, using planar encoders to replace the chip has been the focus of many studies in recent years, leading to the development of so-called chipless RFID technology.

A Dynamic NFC/RFID Tag IC to Consider

ST25DV04KIER6C3

NFC RFID tags with 4 Kbit of electrically erasable programmable memory (EEPROM) are called ST25DV04K by STMicroelectronics, as shown in Fig. 2. These devices have dual interfaces: 

  • An RF interface connection by ISO/IEC 15693 and ISO 18000-3 mode 1 standards powered by the received carrier electromagnetic wave.
  • An I2C interface operated from a DC power supply provides a wired communication option.
  • The device features a 256-byte volatile buffer called the Mailbox, which facilitates fast data transfer between the RF and I²C interfaces

Fig. 2: ST25DV04K-IER6C3 RF by STMicroelectronics. Source: oemsecrets

These devices provide fast transfer between the RF and contact worlds. Furthermore, the GPO pin provides information regarding incoming events, such as mailbox message availability, RF field detection, and RF activity in progress. When the environment permits, energy harvesting capability is also accessible.

Summarizing the Key Points

  • Dynamic NFC/RFID tag ICs enhance wireless communication with dual interfaces, enabling seamless interaction between NFC devices and microcontrollers for diverse applications in modern technology
  • These tags support fast data transfer modes, allowing efficient data exchange for applications like software updates, asset tracking, and smart device pairing, improving the overall user experience
  • Advanced security features, including multiple password protections, ensure data integrity and privacy for users, making dynamic NFC/RFID tag ICs suitable for sensitive applications like contactless payments

Reference

Mayukh Bhattacharyya et al., “An Ultra-Low-Power RFID/NFC Frontend IC Using 0.18 μm CMOS Technology for Passive Tag Applications,” Sensors 18, no. 5 (May 7, 2018): 1452,
https://doi.org/10.3390/s18051452.

None Herrojo et al., “Chipless-RFID: A Review and Recent Developments,” Sensors 19, no. 15 (August 1, 2019): 3385,
https://doi.org/10.3390/s19153385

Mohammadali Forouzandeh and Nemai Chandra Karmakar, “Chipless RFID tags and sensors: a review on time-domain techniques,” Wireless Power Transfer 2, no. 2 (September 1, 2015): 62–77, https://doi.org/10.1017/wpt.2015.10

“ST25DV04K - STMicroelectronics,” STMicroelectronics, n.d.,
https://www.st.com/en/nfc/st25dv04k.html