USOO6236223B1 (12) United States Patent (10) Patent No.: US 6,236,223 B1 Brady et al. (45) Date of Patent: May 22, 2001 (54) METHOD AND APPARATUS FOR WIRELESS O 527 321 2/1993 (EP). RADIO FREQUENCY TESTING OF RFID O 646 983 4/1995 (EP). INTEGRATED CIRCUITS WO 98/16070 4/1998 (WO). (75) Inventors: Michael John Brady, Brewster; OTHER PUBLICATIONS Dah-Weih Duan, Yorktown, both of NY (US) “RF Measurements On SIEGET Bipolar Transistors: Pre dicting Performance Straight From The Wafer, By: Jakob (73) Assignee: Intermec IP Corp., Woodland Hills, Huber and Gerhard Lohninger: XP000598992 Applications CA (US) Discrete Semiconductors Mar. 1, 1996, pp. 34-36. (*) Notice: Subject to any disclaimer, the term of this “Multifunction Credit Card Package”, IBM Technical Dis patent is extended or adjusted under 35 closure Bulletin, vol. 38, No. 08, Aug. 1995, p. 17. U.S.C. 154(b) by 0 days. “A Low-Power CMOS Integrated Circuit for Field-Pow ered Radio Frequency Identification Tag”. By Friedman et al., 1997 IEEE International Solid State Circuits Confer (21) Appl. No.: 09/247,900 ence, Paper SA 17.5, pp. 294, 295, 474. (22) Filed: Feb. 10, 1999 * cited by examiner Related U.S. Application Data (60) Provisional application No. 60/107.593, filed on Nov. 9, 1998. Primary Examiner Safet Metahic ASSistant Examiner-E PLeRoux (51) Int. Cl." ................................................. G01R 31/26 (74) Attorney, Agent, or Firm-O'Melveny & Myers (52) U.S. Cl. .............................................................. 324/765 (58) Field of Search ... ... 324/754, 72.5, (57) ABSTRACT 324/764, 601, 605, 763, 765, 158 P, 752; A method and apparatus for wireless radio frequency (RF) 713/189, 168; 714/733, 30; 370/225, 390, testing of radio frequency identification integrated circuits 400; 361/777, 774, 780; 174/260, 261; (RFIDIC) is disclosed. A fixture is provided for physically 340/870.01-870.44 and electrically contacting the RFID IC to feed an RF interrogating signal into the RFID IC and receive an RF (56) References Cited return signal generated in response thereto. The fixture is U.S. PATENT DOCUMENTS coupled to a tester via first and Second couplers (interconnected to the fixture and tester, respectively) which 4,075,632 2/1978 Baldwin et al. establish a wireleSS link for transmitting and receiving the 4,360,810 11/1982 Landt. RF interrogation signal and the RF return Signal thereby (List continued on next page.) allowing full and accurate RF characterization of the RFID IC. FOREIGN PATENT DOCUMENTS O 294963 12/1988 (EP). 56 Claims, 8 Drawing Sheets 2OO US 6,236,223 B1 Page 2 U.S. PATENT DOCUMENTS 5,606,323 2/1997 Heinrich et al. 5,635,693 6/1997 Benson et al. E. HE kN 5,673,037 9/1997 Cesar et al.. 2 a? Y-2 oelle. 5,680,106 10/1997 Schrott et al.. S. Setti et al. 5,682,143 10/1997 Brady et al.. 4853,705 8/1989 Landt 5,729,201 3/1998 Jahines et al. 4s64.15s 9/1989 Koelle et al. 5,729,697 3/1998 Schkolnicket al. 4.888,591 12/1989 Landt et al. 5,736,929 4/1998 Schrott et al. 4,999,636 3/1991 Landt et al.. 5,737,710 4/1998 Anthonyson. 5,028,866 7/1991 Wiese. 5,739,754 4/1998 Schrott et al. 5,030,807 7/1991 Landt et al. 5,767,789 6/1998 Afzali-Ardakani et al. 5,055,659 10/1991 Hendricket al.. 5,771,021 6/1998 Veghte et al. 5,336.988 8/1994 Chmielewski et al. 5,777,561 7/1998 Chieu et al. 5,479,160 12/1995 Koelle. 5,786,626 7/1998 Brady et al.. 5,485,520 1/1996 Chaum et al. 5,812,065 9/1998 Schrott et al. 5,504,485 4/1996 Landt et al. 5,821,859 10/1998 Schrott et al.. 5,510,795 4/1996 Koelle. 5,825,329 10/1998 Veghte et al. 5,521,601 5/1996 Kandur et al. 5,826.328 10/1998 Brady et al.. 5,528.222 6/1996 Moskowitz et al. 5,828,318 10/1998 Cesar et al. 5,538,803 7/1996 Gambino et al. 5,828,693 10/1998 Mays et al.. 5,550,547 8/1996 Chan et al. 5,831,532 11/1998 Gambino et al.. 5,552.778 9/1996 Schrott et al. 5,850, 181 12/1998 Heinrich et al. 5,554,974 9/1996 Brady et al.. 5,850,187 * 12/1998 Carrender et al. .............. 340/825.54 5,563,583 10/1996 Brady et al.. 5,874,902 2/1999 Heinrich et al. 5,565,847 10/1996 Gambino et al.. 6,049,308 4/2000 Hietala et al. ....................... 343/700 U.S. Patent May 22, 2001 Sheet 1 of 8 US 6,236,223 B1 112 1. 1 OO 122 -------- are are - Tester ------- 2OO F. G. 2A U.S. Patent May 22, 2001 Sheet 2 of 8 US 6,236,223 B1 2OO e XXXX &XXXXXXXYYXY. XXXXXXXXXXXXXXX & F.G. 2C U.S. Patent May 22, 2001 Sheet 3 of 8 US 6,236,223 B1 U.S. Patent May 22, 2001 Sheet 4 of 8 US 6,236,223 B1 3OO U.S. Patent May 22, 2001 Sheet 5 of 8 US 6,236,223 B1 FG. 4A U.S. Patent May 22, 2001 Sheet 6 of 8 US 6,236,223 B1 F.G. 4B U.S. Patent May 22, 2001 Sheet 7 of 8 US 6,236,223 B1 US 6,236,223 B1 1 2 METHOD AND APPARATUS FOR WIRELESS fixture is provided for physically and electrically contacting RADIO FREQUENCY TESTING OF RFID the circuit to feed an RF interrogating Signal into the circuit INTEGRATED CIRCUITS and receive an RF return Signal generated in response thereto. The fixture is coupled to a tester via first and Second This application claims benefit of Provisional No. 5 couplers (interconnected to the fixture and tester, 60/107,593, filed Nov. 9, 1998. respectively) which establish a wireless radio frequency link for transmitting and receiving the RF interrogation and FIELD OF THE INVENTION return Signals. The present invention relates generally to radio frequency Advantages provided by the present invention include: (1) (RF) transponderS Such as radio frequency identification the ability to perform wireless RF testing on RFID IC's (RFID) transponders, and more specifically to a method and without packaging the chips into RFID transponders; (2) the apparatus for testing radio frequency circuits, particularly provision of full and accurate RF characterization of RFID radio frequency integrated circuits Such as radio frequency IC's; (3) the capacity to perform wireless RF testing of RFID identification integrated circuits (RFID IC). IC's in high volume and at low cost. 15 It is to be understood that both the foregoing general BACKGROUND OF THE INVENTION description and the following detailed description are exem Conventional methods and apparatus for testing radio plary and explanatory only and are not restrictive of the frequency integrated circuits (RFIC) require the use of radio invention claimed. The accompanying drawings, which are frequency (RF) contacts. For example, a wafer containing incorporated in and constitute a part of the Specification, unsingulated RFIC chips (dies) may be placed on a probe illustrate an embodiment of the invention and together with Station whereupon a probe is used to make contact with each the general description, Serve to explain the principles of the RFIC. Once this connection is established, interrogating invention. signals modulated on an RF signal are fed into the RFIC, and the responses (the returned signal) are analyzed in order to BRIEF DESCRIPTION OF THE DRAWINGS determine whether the RFID functions properly. 25 The numerous objects and advantages of the present Alternatively, the RFIC's may first be singulated from the invention may be better understood by those skilled in the art wafer and packaged in plastic packages. The RF test can by reference to the accompanying figures in which: then be performed by placing the packaged chip on a "load FIG. 1 is a block diagram depicting a System providing a board.” Such load boards comprise circuit boards containing method and apparatus for performing wireleSS RF testing of fixtures for mounting the packaged RFIC in a temporary RFID IC's in accordance with the present invention; manner and a circuit for feeding an RF interrogation Signal FIG. 2A is an isometric view illustrating an exemplary into the packaged RFIC to facilitate testing. embodiment of the system shown in FIG. 1 utilized for In either testing method, the RF interrogating Signals are testing unsingulated RFID IC's in a wafer; sent from a tester to the RFIC through a cable (e.g., a coaxial 35 FIG. 2B is an isometric view illustrating an alternative cable). Thus, the entire testing circuit consists of wired embodiment of the system shown in FIG. 2A wherein the connections, and the testing signals (i.e., the interrogating apparatus is automated; Signal and the responded signal) are well contained in a FIG. 2C is an isometric view illustrating an alternative guide wave structure. While use of such “wired” test appa embodiment of the system shown in FIG. 2B adapted for use ratus and methods provides Satisfactory testing of most 40 with multiple wafers of RFID IC's; RFICs, some functionalities of radio frequency identifica FIG. 2D is an isometric view illustrating an alternative tion integrated circuits (RFID IC) require a “wireless” RF embodiment of the system shown in FIG. 2B having mul test (i.e., a “field’ test). For example, Some circuits of the tiple testing assemblies, RFIDIC, which are supposed to operate in the RF field, may FIG.