Abstract:
A method for testing an Integrated Circuit (IC) with Near Field Communication (NFC) technology according to a first embodiment of the present invention includes: utilizing a BB modem of the IC to generate a known data pattern; modulating the known data pattern to generate a modulated data pattern; sending the modulated data pattern on the transmitting path to an NFC antenna of the IC and utilizing the NFC antenna to loop the modulated data pattern back to the receiving path; demodulating the modulated data pattern; and determining if the data pattern on the transmitting path is the same as the data pattern on the receiving path. When the data pattern on the transmitting path is not the same as the data pattern on the receiving path, it is determined that the IC fails.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 61/826,748, which was filed on May 23, 2013. 
    
    
     BACKGROUND 
     Near field communication (NFC) is a standards-based communication technology which enables communication between different electronic devices over a short-range distance, ranging from direct contact to a few centimeters. Devices equipped with NFC can make transactions and transmit and receive digital content simply and quickly, without requiring pairing codes or searching for wireless networks. NFC has already been implemented in Android-supported smart phones and tablets, credit cards and transportation systems, and even has the potential to replace passports in the future. 
     Please refer to  FIG. 1 , which is a diagram of an integrated circuit (IC)  100  which uses NFC technology. As illustrated in the diagram, the IC  100  is coupled to a PC/phone host  150 . The integrated circuit  100  comprises a BB modem  110 , which contains a power estimation Fast Fourier Transform (FFT) circuit  103 , a digital FE circuit  105  and a CW/modulated circuit  107 . A first analog-to-digital converter (ADC)  113  and a second ADC  115  are coupled to the BB modem  110 . These ADCs are coupled to an Rx path, wherein both the Rx path and Tx path are coupled to an antenna network  160  which includes external matching components and an NFC antenna  130 . The Rx path consists of a series of high and low pass filters coupled between a multiplier and a programmable-gain amplifier. The TX path consists of Modulator and PA Driver  190  that transmits the signal to the antenna via the external matching network. The IC  100  further comprises a crystal oscillator  120 , coupled to a MUX  125 , the output of which is coupled to a load modulator  140 , which is in turn coupled across the NFC antenna  130 . The output of the MUX  125  is inputted to a Modulator and PA driver  190 , which receives data to be transmitted from the BB modem  110  and provides the data to the antenna network  160 . The load modulator  140  is also coupled to an RF limiter  145 , an incoming field detector  155 , a full wave rectifier (FWR)  165 , and a regulator  170 . Finally, a clock recovery circuit  175  and a field detector  180  are coupled to the antenna network  160 . Please note that other circuit elements are illustrated in  FIG. 1  for completeness, but are not essential to the method of the present invention and have not been designated with a numeral. Those skilled in the art will be familiar with the particular operations of these circuit elements, and they are therefore not detailed herein. 
     Conventional testing methods for ICs such as that illustrated in  FIG. 1  use an off-chip tester circuit (not shown) to generate the testing signals. A first signal is generated by the tester circuit and passed to the IC. The IC  100  modulates this first signal to generate a modulated first signal which is transmitted via the Tx path to the antenna  130 . The antenna  130  then sends the modulated first signal back via the Rx path as a second modulated signal. The IC  100  demodulates the second modulated signal to generate a second signal, which is passed to the tester circuit. By comparing the first signal with the second signal, the tester circuit can determine whether the IC passes or fails. 
     The above method, however, is unable to test functionality of other blocks of the IC  100 , such as the clock recovery circuit  175  and full wave rectifier  165 , etc. Even though the Tx path and Rx path may function correctly, other functional blocks may be defective, which means the IC  100  will still not work as intended. Further, the prior art method requires an off-chip tester circuit for generating and comparing the first signal and second signal. 
     SUMMARY 
     A method for testing an Integrated Circuit (IC) with Near Field Communication (NFC) technology according to a first embodiment of the present invention comprises: utilizing a BB modem of the IC to generate a known data pattern; modulating the known data pattern to generate a modulated data pattern; sending the modulated data pattern on the transmitting path to an NFC antenna of the IC and utilizing the NFC antenna to loop the modulated data pattern back to the receiving path; demodulating the modulated data pattern; and determining if the data pattern on the transmitting path is the same as the data pattern on the receiving path. When the data pattern on the transmitting path is not the same as the data pattern on the receiving path, it is determined that the IC fails. 
     These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram of an integrated circuit which uses Near Field Communication Technology. 
         FIG. 2  is a flowchart detailing the steps of a method according to a first exemplary embodiment of the present invention. 
         FIG. 3  is a flowchart detailing the steps of a method according to a first exemplary embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     In order to solve the problems associated with the prior art, the present invention provides exemplary testing methods for an IC  100 , wherein the IC  100  performs a built-in self test (BIST). This removes the need for an off-chip tester circuit for providing testing signals. The prompt to start testing the IC  100  is initiated by the PC/phone host  150 , as illustrated in  FIG. 1 . The pass/fail determination for the IC will also be judged by the PC/phone host  150 . The exemplary methods of the present invention can further test the operation of other functional blocks within the IC  100 . 
     The following will refer to two exemplary embodiments. Please note that both embodiments can be applied to the same IC  100  illustrated in  FIG. 1 , as the method of the present invention does not require any circuitry which is not already present in a conventional IC  100 . Further, the two embodiments can be performed separately or combined, as will be obvious to one skilled in the art. 
     Embodiment 1 
     This first embodiment is specifically for testing the functionality of the tag emulation feature (PICC) for the Tx path, and for testing the proximity coupling device (PCD) of both the Tx path and Rx path. 
     A phase locked loop (PLL) in the IC  100  (not shown) locks to the crystal oscillator  120 , for generating an oscillating signal having a frequency of 27.12 MHz. This signal is then passed to a divide-by-2 circuit (not shown) for generating two individual clocks, each having a frequency of 13.56 MHz, which are passed to the Tx path and the Rx path. These local oscillation (LO) signals are used to synthesize the two paths. The PCD feature of the Tx path is enabled, and an electric field according to the LO signal is generated, allowing the Tx path to transmit data via the NFC antenna  130 . Please note that the LO signal is in the form of a sine wave having a frequency of 13.56 MHz, but this sine wave will not carry any data. The tag emulation feature (PICC) of the Tx path is then enabled, which allows the IC  100  to perform auxiliary carrier load modulation. 
     The BB modem  110  then generates a known data pattern which is passed to the load modulator  140 . The enabling of the PICC feature allows the load modulator  140  to perform modulation on this known data pattern. The resultant modulated signal is output to the antenna network  160  and looped back to the Rx path of the IC  100  via the NFC antenna  130 , and then demodulated. The data pattern on the Tx path is compared with the demodulated signal. If the two data patterns are the same, then not only are the Tx and Rx paths both confirmed to be functioning correctly, but functionality of the Load Modulator  140  can also be confirmed. 
     Please note that confirmation of functionality of the IC  100  by the PC/phone host  150  will only be ‘pass’ or ‘fail’, and no decision making circuitry or special software is required. 
     Please refer to  FIG. 2 , which illustrates a flowchart of the above method. The steps of the method are as follows: 
     Step  200 : Start; 
     Step  202 : Enable the PLL for synthesizing a local oscillation signal for the Rx and Tx paths; 
     Step  204 : Enable the PCD on the Tx path to generate a sine wave having a frequency of 13.56 MHz and enable the PICC on the Tx path to enable auxiliary carrier load modulation for the Tx path; 
     Step  206 : Use the BB modem to transmit a known data pattern to the Load Modulator; 
     Step  208 : Output a modulated signal to the antenna network; 
     Step  210 : Use the antenna to loop the auxiliary load modulated data back to the Rx path and perform demodulation; 
     Step  212 : Is the data pattern on the Tx path the same as the data pattern on the Rx path? If yes, go to Step  214 ; if no, go to Step  216 ; 
     Step  214 : PC/phone host determines that PICC Tx and PCD Rx pass; 
     Step  216 : PC/phone host determines that the IC fails. 
     In the first embodiment, no data is transmitted along with the signal. Using the method of the first embodiment alone provides no guarantee that transmitted data can be transmitted with 100% accuracy. A second embodiment is therefore provided. 
     Embodiment 2 
     In the second embodiment, a known data pattern is transmitted by the Tx path and looped back to the Rx path in order to confirm that data can be successfully transmitted by the IC  100 . The data pattern consists of two signals, wherein the first signal is all ONES and the second signal is all ZEROS. In this embodiment, the Power Harvest Circuitry of the IC  100 , such as the clock recovery circuit, FWR and the Regulator, can also be verified. 
     Initially, as in the first embodiment, the crystal oscillator generates a clock at 27.12 MHz, which is divided by two. Unlike the first embodiment, however, this divided clock signal is sent straight to the modulator and PA driver  190  of the Tx path, and not sent to the Rx path. The PCD of the Tx path is then enabled to generate a sine wave having a frequency of 13.56 MHz, in response to the received clock signal. 
     Electric fields and a shunting current will therefore be present in the IC circuit  100 . If the Power Harvest circuit elements (Regulator  170 , FWR  165 , Incoming Field Detector  155 , and Field Detector  180 ) detect these electric fields and shunting current, it can be verified that they are operating correctly. The PC/phone host  150  therefore reads out status signals sent from each Power Harvest circuit element and provides a Pass/Fail judgment based on the status signals. Please note that this embodiment further tests for whether data can be successfully transmitted by the IC  100 , but if any of the Power Harvest circuit elements fails the above test then the flow will not proceed to the data testing stage, as it is already confirmed that the IC  100  will not operate correctly. 
     The Regulator  170  and FWR  165  will provide a status signal confirming that an activated shunting current is detected, if both circuits are operating correctly. The Incoming Field Detector  155  will provide a status signal confirming that an ANT Field (low power wireless technology) is detected, if it is operating correctly. The Field Detector  180  will provide a status signal confirming that an RF field is detected, if it is operating correctly. 
     After confirmation of the functionality of the above elements, the modulated sine wave is sent to the Rx path by looping back through the NFC antenna  130 . The clock recovery circuit  175  will lock to this modulated sine wave and recover the original signal so it can be provided to the Rx path. In this way, the functionality of the clock recovery circuit  175  can also be confirmed. The PICC function of the Rx path is then enabled. 
     The BB engine  110  generates a data signal of a known pattern and passes this data signal directly to the modulator and PA driver  190 . The data pattern is modulated, passed to the antenna network  160 , and looped back to the Rx path via the NFC antenna  130 . The activated PICC of the Rx path can then demodulate the signal to regain the original data pattern, and compare it with the signal on the Tx path for determining whether the data patterns are the same. If they are the same, the IC  100  passes. 
     The above method is illustrated in  FIG. 3 , the steps of which are detailed as follows. 
     Step  300 : Start; 
     Step  302 : Enable LO of Tx path via the crystal oscillator; 
     Step  304 : Enable the PCD of the Tx to generate a 13.56 MHz field; 
     Step  306 : Verify the Power Harvest Circuitry; 
     Step  308 : Are all Power Harvest elements valid? If yes, go to Step  213 ; if no, go to Step  310 ; 
     Step  310 : IC fails; 
     Step  312 : Use the loop antenna to pass the LO signal on the Tx path to the Rx path and use the clock recovery circuit to recover the original signal; 
     Step  314 : Use the recovered signal as an LO signal for the Rx path and enable the PICC of the Rx path; 
     Step  316 : Use the BB modem to generate a known data pattern to the modulator of the Tx path; 
     Step  318 : Loop the modulated data pattern back to the Rx path via the loop antenna and perform demodulation; 
     Step  320 : Is the data pattern on the Tx path the same as the data pattern on the Rx path? If yes, go to Step  322 ; if no, go to Step  324 ; 
     Step  322 : The IC passes; 
     Step  324 : The IC fails. 
     As detailed in the above, by performing an RBIST, the IC  100  can confirm functionality of the Tx and Rx paths, the Power Harvest elements, and both PICC and PCD features of the IC  100 , without the need for any extra circuitry or an external testing circuit. Thus, not only are the testing methods of the present invention cheaper and simpler to implement than conventional methods, but they also can test the operation of various functional elements which cannot be tested by conventional methods. 
     Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.