Patent Application
20100252631
An integrated circuit card (“IC card”), smart card, or chip card is a pocket-sized card with an integrated circuit that can process information. Implicitly, these pocket-sized cards can receive an input which is processed and subsequently delivered as an output. A contactless card or proximity card is a specific type of IC card, namely, a contactless integrated circuit device that can be used for applications such as security access or payment systems. Proximity cards operate on the basis of communication by an electromagnetic field with a read and/or write interrogating device, generically referred to as a reader. In other configurations, IC cards have also been designed to communicate with external devices such as a host personal computer, smart card adapters and connectors, and the like.
In proximity card applications, the reader typically transmits a carrier signal which creates an electromagnetic field or “H-field”. This carrier signal can serve on the one hand to power the contactless card, which is derived by converting the electromagnetic field into a DC voltage, and on the other hand to initiate a communication between the card and the reader according to an established communication protocol. For example, if data is modulated on the carrier signal, the integrated circuit in the card can read this data and use it appropriately. Communication protocols between a contactless card and a reader have been described, for example, in ISO standards 14443 A/B, 15693, and/or 18000. Conventional proximity card applications, such as those implementing a protocol defined by ISO standard 14443, operate at a relatively low communication speed, typically less than 10 Mbit/s (“megabit per second”).
In contrast, wireless local area networks (“WLAN”), which are battery or line powered, are capable of transmitting data at a much higher speed. IEEE 802.11, and specifically 802.11b which is often described interchangeably as “Wi-Fi”, is a set of standards for WLAN computer communication. The protocols defined by these standards enable data communication at speeds much faster than those accomplished under ISO standard 14443. Wireless data communication using Wi-Fi technology may be 100 Mbit/s or faster. To enable this high speed communication, devices employing Wi-Fi technology typically utilize crystal oscillators, which can generate very precise and stable, i.e., “crystal-accurate”, frequencies.
A crystal oscillator is an electronic circuit that uses the mechanical resonance of a vibrating crystal of piezoelectric material to create an electrical signal with a very precise frequency. Namely, crystal oscillators operate with very low phase noise since the crystal mostly vibrates in one axis. Moreover, the crystal oscillator is capable of generating electrical oscillation of a natural frequency within a range of around 1 kHz to 100 MHz. The output frequency can further be a multiple of the resonance, called an overtone frequency. Additionally, the “crystal-accurate” frequency and high Q factor that crystal oscillators provide can be used to stabilize frequencies for wireless transmitters/receivers. One drawback of crystal oscillators, however, is that they are a relatively large and expensive electronic component. Thus, while crystal oscillators have been used in applications such as personal computers, mobile phones, and video game consoles, these components are undesirable for smaller devices such as smart cards.
As shown, contactless card 110 comprises a radio frequency (“RF”) interface 112 and a card module 114. Reader 130 includes an RF interface 132 that enables data communication between contactless card 110 and reader 130. As will be described in more detail below, reader 130 further includes internal circuitry 134 that, in conjunction with an induction coil (not shown) of RF interface 132, transmits a carrier signal which may include modulated data. The internal circuitry 134 further utilizes a signal generator device 136 that is configured to generate the carrier signal for high-speed data communication and therefore define the frequency at which that carrier signal is transmitted.
RF interface 112 of contactless card 110 also includes an induction coil (not shown) that detects the electromagnetic field when contactless card 110 is moved into proximity with reader 130. Presuming data is modulated on the carrier signal, card module 114 includes components enabling contactless card 110 to read the modulated data from the carrier signal and use it accordingly. It should be understood that RF interface 112 and RF interface 132 each have antennas (not shown) configured to transmit and receive the carrier signal.
Similar to reader 130, contactless card 110 comprises electronic components that are located within card module 114 and are configured to generate a response signal that can be modulated onto the carrier signal. This response signal is transmitted from the induction coil in RF interface 112 and subsequently detected by the induction coil in RF interface 132 of reader 130. Once received by reader 130, the response signal can be processed by internal circuitry 134.
Specifically, crystal oscillator 240 is utilized by card reader 230 to generate a first signal to be input to signal generator device 236. This first signal has a first frequency that, in an exemplary embodiment, is 13.56 MHz in accordance with ISO 14443. Using the mechanical resonance of a vibrating crystal of piezoelectric material, crystal oscillator 240 creates the first signal with a frequency that is “crystal-accurate” (i.e., very stable and precise). As should be understood, the 13.56 MHz carrier signal produces a 13.56 MHz H-Field, which is also “crystal-accurate”.
It is noted that the application is not limited to the first frequency of the first signal being 13.56 MHz. This first frequency may lie within the Low Frequency (LF) range, the High Frequency (HF) range, or within any ISM (industrial, scientific and medical) frequency range. For example, low frequencies such as 125 kHz or 134 kHz or high frequencies in accordance with ISO 15693 or ISO 18000 are some acceptable frequencies.
Referring back to
The frequency of the carrier signal is greater than that of the first signal. Because the application enables contactless cards to operate in much higher frequency ranges at crystal-accurate frequencies, the contactless cards can communicate with card readers at USB communication speeds, such as those of USB 1.0 having a data rate of up to 1.5 Mbit/s, USB 1.1 having a data rate of up to as 12 Mbit/s, USB 2.0 having a data rate of up to 480 MBit/s, etc., or Wi-Fi standards as described above. Thus, for example, if the frequency of the first signal is in the HF range, then the frequency of the carrier signal may be, for example, in the microwave frequency range, or any other frequency deemed suitable by the system designer for the intended purpose. Of course it is also possible for the frequency of the carrier signal to be less than the frequency of the first signal, but such a design is not a primary focus of this application.
Since the frequency of the carrier signal for high-speed data communication is controlled by signal generator device 236, which is capable of outputting the carrier signal in, for example, the microwave frequency range, data can be transmitted via the carrier signal at high speeds such as 100 Mbit/s or faster. These speeds are similar to communication protocols defined by Wi-Fi standards, USB technologies, or the like. By implementing crystal oscillator 240 in reader 230 and not in the contactless card, the overall size of the contactless card is minimized. Moreover, because the precision and stability of crystal oscillator 240 directly correlates with the cost of the crystal used, employing crystal oscillator 240 in card reader 230, and not in each contactless card, helps reduce the overall cost of system 100.
Furthermore, as shown in
In operation, the software executed by microprocessor 244 controls reader 230, and specifically, the defined application of reader 230 such as a security access or a payment system. If execution of the software dictates that data in memory 246 is to be transmitted to the contactless card, that data is first sent to the modulating device 242. Modulating device 242 is configured to modulate the carrier signal generated by the signal generator device 236 with a data signal received from microprocessor 244. Because this carrier signal is generated using phase-locked loop 238, the frequency of the carrier signal can be significantly higher than the HF range, such as in the microwave frequency range, while maintaining both the “crystal-accurate” precision and strength of the original first signal. As a result, reader 230 and contactless card 110 can communicate data at a very fast speed, such as 100 Mbit/s or more.
Reader 230 further comprises a demodulating device 248 that is coupled to RF interface 232 and microprocessor 244. Accordingly, when RF interface 232 receives a modulated response signal from a contactless card, demodulating device 248 will demodulate the signal and transfer the demodulated data to microprocessor 244 to be used accordingly.
While the exemplary embodiment of reader 230 enables communication with contactless cards in high-speed communication modes, existing infrastructures can employ the foregoing communication techniques through a hybrid mode. The hybrid mode is essentially a combination of standard high frequency radio communication based on standards such as ISO 14443, 15693 or proprietary versions, and communications based on high speed standards such as WLAN. When operating in the hybrid mode, an existing card reader 230 initiates communication with one or more contactless cards using the first signal as a carrier signal at the lower first frequency, and at some time after communication is established, increases the communication speed by employing the aforementioned techniques.
Existing contactless cards may be used enjoying the foregoing communication techniques with little or no modification. Specifically, if the existing antenna of a contactless card is a separate component from the integrated circuit, this antenna may be replaced or supplemented with a new antenna matched to the frequency of the high speed carrier signal. Alternatively, if the antenna is integrated in the integrated circuit of the contactless card, no physical modification is necessary to the contactless card. However, it should be understood that software may be loaded onto the contactless card to enable high speed communication using the inventive techniques.
Referring back to
As shown in
In operation of contactless card 310 of either embodiment, once the carrier signal is detected by RF interface 312, this carrier signal is provided to card module 314. Clock recovery device 318 in conjunction with the other components of RF interface 312 enables contactless card 310 to receive and process the higher frequency carrier signal transmitted by reader 130. The demodulating circuit 320 is provided to demodulate the carrier signal and is coupled to microprocessor 316. Applying the demodulated data, microprocessor 316 in turn can write and/or read data to and from memory 324 in accordance with the application as controlled by the card's software.
Microprocessor 316 is further coupled to modulating circuit 322, which is configured to modulate a response signal on the carrier signal. In operation, contactless card 310 employs signal generator device 332, which includes phase-locked loop 328, and is coupled to clock recovery device 318 and modulating circuit 322. At the same that RF interface 312 is receiving the high frequency carrier signal, RF interface 312 may also be concurrently detecting the first signal transmitted from the reader.
In one embodiment, contactless card 310 utilizes the “crystal-accurate” frequency of this first signal to generate a response signal. As further described above in the exemplary embodiment, this signal can have an operating frequency of 13.56 MHz. Accordingly, in a manner similar to that of reader 230, contactless card 310 inputs the first frequency of the first signal to phase-locked loop 328, which can then generate a second frequency for the response signal. Signal generator device 332 can then generate a carrier operating at the second “crystal-accurate” frequency and modulating circuit 322 can modulate data onto the carrier operating at this second frequency to provide a response signal.
This response signal can then be transmitted back to the card reader via RF interface 312 of contactless card 310. Because contactless card 310 is generating the response signal from the “crystal-accurate” first frequency of the first signal transmitted by the reader, contactless card 310 is capable of transmitting a response signal with an operating frequency in the microwave frequency range, which is also “crystal-accurate”. Accordingly, contactless card 310 is also capable of transmitting data as response signals to the reader at high speeds, such as those of Wi-Fi or USB, and, therefore, capable of transmitting data at 100 Mbit/s or faster. It is reiterated that the frequencies described above with respect to the exemplary embodiment are not intended to limit the application in any way. Rather, any frequencies may be implemented that are deemed suitable by the system designer for the intended purpose.
Finally,
While the foregoing has been described in conjunction with an exemplary embodiment, it is understood that the term “exemplary” is merely meant as an example, rather than the best or optimal. Accordingly, the application is intended to cover alternatives, modifications and equivalents, which may be included within the spirit and scope of the invention.
Additionally, in the preceding detailed description, numerous specific details have been set forth in order to provide a thorough understanding of the present invention. However, it should be apparent to one of ordinary skill in the art that the present invention may be practiced without these specific details. In other instances, well-known methods, procedures, components, and circuits have not been described in detail so as not to unnecessarily obscure aspects of the present invention.
