WO2020146932A1

WO2020146932A1 - Rfid uhf chip with hf near-field communication (nfc) means

Info

Publication number: WO2020146932A1
Application number: PCT/BR2020/050006
Authority: WO
Inventors: Laurent COURCELLE; Pedro DE ALMEIDA LÁZARO; Gerson SCARTEZZINI
Original assignee: Centro Nacional De Tecnologia Eletrônica Avançada S.A.
Priority date: 2019-01-17
Filing date: 2020-01-17
Publication date: 2020-07-23
Also published as: BR102019000990A2

Abstract

The present invention describes an integrated circuit, i.e. a chip, for a UHF tag with very low consumption and reduced surface area that, by connection to an optimized antenna, enables data to be read from the tag by a device incorporating NFC technology and that implements a "TAGS TALK ONLY" or "TAGS TALK FIRST" communication protocol, without the need for additional equipment.

Description

UHF RFID CHIP WITH FIELD HF COMMUNICATION

NEXT (NFC)

APPLICATION FIELD

The present invention applies in the field of electronic devices for "RFID" tags.

The present invention describes an integrated circuit, i.e. a chip, which works by means of UHF RFID with the possibility of reading by a device equipped with NFC technology, which is a communication by proximity field in the HF frequency range.

BACKGROUND OF THE INVENTION

Currently, the digital age is gaining momentum and innovations in this area are becoming more and more common. One of the innovations that have been experiencing exponential growth is the transfer of data between devices through NFC technology.

This NFC technology consists of exchanging information between two devices or a device and a tag, which have a compatible chip, without the use of cables or wires, and without the need to pair the devices, requiring only that the said devices are at a distance in around 3 cm.

When the NFC device communicates with a tag, said device emits a magnetic field to energize the tag, sends a command to the tag and, subsequently, the tag sends a response to the device. This mode of communication is called “READER TALK FIRST”.

The protocol compatible with NFC technology that uses the communication mode described above is standardized (standard IS014443) and defines a protocol built in several layers of communications. This makes implementing the chip on the tag relatively complex, in addition to requiring a unit for receiving commands sent by the NFC device. Thus, in order to reduce costs and add value to UHF tags with chips, the NFC communication protocol used in the present invention is of the “TAGS TALK ONLY” type, which is also called “TAGS TALK FIRST”, where the referred invention describes a UFIF tag chip that, through an optimized antenna, allows the reading of data from the tag by a device with NFC technology, with a low cost of the tag and, without this action, deteriorating

significantly the reading distance in the UFIF frequency range per distant field, that is, the reading distance can be in the range of 10 m.

TECHNICAL STATUS

US8905317B1 describes an electronic device that includes an NFC antenna and an RFID tag, wherein said RFID tag is arranged within an internal region of the antenna.

However, in this document, two separate antennas and two separate chips are used, that is, a chip for the NFC tag and a chip for the UFIF tag, thus distancing itself from the present invention, which describes a single chip that is capable of to be read by the UFIF reader and the NFC device.

WO2018122363A1 describes a tag for use in fluid containers, where said tag can be read both in UFIF, when related to long range, and in NFC, when related to short range.

In this document, the tuning of the NFC circuit is performed through the equivalent capacitance formed by the antenna inductor and the volume of liquid, when the tag is placed on top of the container containing the liquid.

Thus, the referred document is distant from the present invention, since in it, the tuning of the NFC circuit is not influenced by the contents of the container, in addition to making use of a “TAGS TALK ONLY” or “TAGS TALK FIRST” protocol . EP3076341 B1 describes a dual frequency RF identification device comprising an HF antenna to receive an HF magnetic field, an HF interface, a UHF antenna to receive a UHF electromagnetic field, a UHF interface, non-volatile memory means formed by a first non-volatile memory and a second non-volatile memory.

In this document, although the integrated circuit has the dual frequency option HF-UHF, it contains two non-volatile memories, that is, one with low consumption accessed through the UHF interface and another larger memory with higher consumption accessed through the HF interface.

Thus, the said document is distant from the present invention, since it aims to implement a chip with an extremely reduced area, without the need to use two types of memory.

US7994923B2 describes a non-contact electronic device, comprising a semiconductor integrated circuit device, a plurality of antennas (or antenna coils) for receiving high frequency signals provided by radio waves or electromagnetic waves with different frequencies.

This document protects a possible implementation of an RFID chip that works in the UHF and HF bands, however, it distances itself from the present invention, since it does not specifically protect the “TAGS TALK ONLY” or “TAGS TALK FIRST” NFC protocol in the band HF, which allows a reduction in area and chip consumption.

EP3067835B1 protects an RFID chip with two separate interfaces inside the chip, where one is an HF interface with two terminals connecting to an HF antenna, and the other is a UHF interface with two other terminals connecting to a UHF antenna.

This document differs from the present invention, as it presents connection terminals shared by the UHF and HF interfaces. US20080088417A1 describes a tag that features RFID functions and an “EAS” function, which is an anti-theft function for

merchandise. In this document, the frequency range that the tag works in is not explicitly described.

In this way, the referred document distances itself from the present invention, since it does not have an anti-theft function and works purposefully in two frequency ranges, so that the tag can be read by a long-range UHF reader and by a

device with NFC functionality in the HF frequency range.

Therefore, it can be concluded that the present invention differs from the state of the art documents presented here, since none of them refers to a single integrated circuit and a single antenna, where the integrated circuit has the ability to read a frequency UFIF and also HF frequency using a “TAGS TALK ONLY” or “TAGS TALK FIRST” protocol with devices equipped with NFC technology.

SUMMARY OF THE INVENTION

The present invention describes an integrated circuit, ie a chip, for a UFIF tag with very low consumption and reduced area, which, through the connection to an optimized antenna, allows the reading of data coming from the tag by a device with NFC technology and that implements a communication protocol such as “TAGS TALK ONLY” or “TAGS TALK FIRST”, without the need for additional equipment.

BRIEF DESCRIPTION OF THE FIGURES

The invention can be better understood through the brief description of the figure below:

Figure 1 represents the block diagram of the integrated circuit.

Figure 2 shows an example of an NFC protocol specification of the type “TAGS TALK ONLY” or “TAGS TALK FIRST”, known as NFC Barcode®.

DETAILED DESCRIPTION OF THE INVENTION The present invention describes a chip, for UHF tag of

very low consumption and reduced area, which, through the connection to an optimized antenna, allows the reading of data from the tag by a device with NFC technology and which implements a communication protocol of the type “TAGS TALK ONLY” or “TAGS TALK FIRST” without the need for additional equipment.

Through the NFC communication protocol used in the present invention, that is, the “TAGS TALK ONLY”, which is also called “TAGS TALK FIRST”, it is possible to maintain a low cost for the chip, since the said communication protocol allows that the reader issues a field and the tag only responds to a message by modulating the field issued by the reader.

Unlike the “READER TALK FIRST” communication protocol, in which the reader, in addition to issuing a field, sends commands to the tag, complicating the chip design in the tag, since it must have means to demodulate, decode and interpret the commands sent by the reader and, thus, increases its cost.

In the present invention, said chip, as shown in Figure 1, is composed of:

- supply voltage generator (1) - which collects energy at the antenna terminals and transforms the energy into direct voltage and current available for the chip;

- a power management block (2) - which regulates the voltage and provides control information for the chip;

- a signal receiving block from the UHF RFID protocol (3) - which is formed by demodulator and decoder;

- a signal emission block (4) - which is formed by an encoder;

- a digital control block (5) - which includes a non-volatile memory and implements the functionalities, such as the interpretation of commands sent by the reader and responses to the reader, the reading and writing in the non-volatile memory, etc; - a clock extraction block of the HF frequency signal (NFC) (6) - which filters signals in the UHF range;

- a field detection block (7) - which detects the presence of an HF field;

- a generator block (8) - that generates the data packet according to an NFC protocol of the type “TAGS TALK ONLY” or “TAGS TALK FIRST”;

- a modulation block (9) - which acts as a load modulator when operating with a magnetic field in the HF range.

When the tag receives a RFID UHF signal sent by a reader in the form of a modulated carrier, the part of the antenna optimized to receive an electromagnetic field in the UHF frequency range transforms the electromagnetic field into voltage at the input of the circuit, which in turn instead, it is converted into direct voltage by the supply voltage generator block (1).

The DC voltage is regulated and monitored by the power management block (2), in order to guarantee the operation of the circuit within the operating conditions.

Still in UHF mode, the carrier modulation is handled by the signal receiving and emitting block (3 and 4) and the data is sent to the digital control block (5), which interprets the data and acts according to the command Received.

The response is generated by the digital control block (5), coded and sent to the block that performs the modulation (9) by back-dispersion, which is the modulation of the reflection coefficient of the incident electromagnetic wave.

When the same tag receives an NFC field, which is in the HF frequency (13.56 MHz), emitted by a device equipped with an NFC transceiver in the form of a magnetic field, the part of the antenna optimized to receive a magnetic field in the HF frequency transforms the magnetic field into current at the input of the circuit, which, in turn, it is converted into direct voltage by the supply voltage generator block (1).

The continuous voltage is regulated and monitored by the

power management (2), in order to guarantee the operation of the circuit within the operating conditions.

A field detection block (7), detects the HF field and informs the digital control block (5) that it must enter an NFC operating mode of the type “TAGS TALK ONLY” or “TAGS TALK FIRST”.

The clock extraction block (6) extracts a clock signal at the same frequency as the HF carrier to be used as a time reference for the generation of symbols in the data packet of the NFC protocol type “TAGS TALK ONLY” or “TAGS TALK FIRST ”.

One way to implement the field detection block (7) is from a counter, which counts a certain number of clock cycles from the clock extractor and sends a warning signal to the control block (5) to enter “NFC” operating mode.

Information from the control block (5) is loaded into the generator block (8), which formats the package according to the NFC protocol of the type “TAGS TALK ONLY” or “TAGS TALK FIRST”, and sends it to the modulation block (9 ), which behaves as a load modulator when operating with a magnetic field in the HF range.

The modulation block (9) can be implemented by a transistor working as an open / closed switch, which modulates the reflection coefficient in UHF mode, by modulating the real part of the chip's input admittance, and implements a load modulation in mode NFC in the HF range.

The present invention also includes the possibility of

implementation of the modulation block (9) with two modulators in parallel, a specific modulator for the “NFC” operating mode and a specific modulator for the “RFID UHF” operating mode, modulators can be implemented either with an “open / closed” switch or as a variation of capacitance (variation of the imaginary part of the input admittance).

Another possibility also covered by the present invention is the addition of another antenna terminal, exclusive for charge modulation in the HF frequency range. This allows, for example, to obtain greater depth of load modulation, using a specific antenna, impacting even less the communication performance in the UHF frequency range.

The blocks (6), (7) and (8) and the additional functionalities of the block (5) necessary to enable the chip to be read by an NFC device, which implements an NFC protocol of the type “TAGS TALK ONLY” or “TAGS TALK FIRST ”, when implemented in silicon, represent an increase in negligible area.

When implemented within a UHF RFID integrated circuit, even if the circuit has an extremely small area, these additional blocks (5), (6), (7) and (8) are so small that they do not affect the cost of the integrated circuit , since the cost of an integrated circuit is proportional to its area.

In an NFC protocol like “TAGS TALK ONLY” or “TAGS TALK FIRST”, only the tag transmits information to the reader and, therefore, does not need to receive and interpret commands from the reader.

An example of an NFC protocol of the type “TAGS TALK ONLY” or “TAGS TALK FIRST” is the “NFC Barcode®”, as can be

shown in Figure 2.

It is important to note that an integrated circuit, which implements the functionality of a chip for UHF RFID tag and the functionality of a chip for NFC tag, requires blocks such as specific demodulator and decoder to receive commands from the NFC standard, in addition to a digital control machine able to interpret a set of mandatory commands to be able to communicate with any NFC device.

Thus, one of the advantages of the present invention in view of the state of the art is that it does not require the presence of demodulator and decoder, which would translate into a significant increase in area and, therefore, an increase in cost in the same proportions.

In other words, in the present invention, it is possible to create a chip that communicates both with an NFC device that implements an “NFC TAGS TALK ONLY” protocol, and with a long-range UHF RFID reader, which has the same cost as a chip for UFIF RFID tags and therefore cheaper than a UFIF / HF (NFC) dual frequency range chip, which would usually require a more complicated “READER TALKS FIRST” communication protocol to communicate in the HF frequency range.

The present invention was revealed in this specification in terms of its preferred modality. However, other modifications and variations are possible from the present description, being still within the scope of the invention disclosed here.

Claims

1. UHF RFID chip with FIF near-field (NFC) communication medium CHARACTERIZED by the fact that the medium of communication

Device communication (NFC) in the HF frequency band follows a “TAGS TALK FIRST’ or “TAGS TALK ONLY’ communication mode.

2. Chip, according to claim 1, CHARACTERIZED by the fact that it comprises at least: a supply voltage generator (1), a power management block (2), a signal receiving block from the UFIF RFID protocol (3), a signal emission block (4), a digital control block (5), a clock extraction block from the HF frequency signal (6), a field detection block (7), a block generator (8) and a modulation block (9).

3. Chip, according to claim 2, CHARACTERIZED by the fact that the digital control block (5) includes a non-volatile memory and implements the interpretation and response of commands sent by the reader, as well as reading and writing in the non-volatile memory .

4. Chip, according to claim 2, CHARACTERIZED by the fact that the clock extraction block of the HF frequency signal (6) filters signals in the UFIF range.

5. Chip, according to claim 2, CHARACTERIZED by the fact that the field detection block (7) detects the presence of an HF field.

6. Chip, according to claim 2, CHARACTERIZED by the fact that the generator block (8) generates a data packet according to the “TAGS TALK ONLY or“ TAGS TALK FIRST ”communication protocol, such as the“ NFC Barcode® ”.

7. Chip, according to claim 2, CHARACTERIZED by the fact that the modulation block (9) is composed of a key optimized for load modulation when communicating in the range of HF frequency and a switch optimized for backscattering when communicating in the UHF frequency range.

8. Chip, according to claim 7, CHARACTERIZED by the fact that the switch optimized for load modulation when communicating in the HF frequency range is connected to an additional and exclusive antenna terminal.