Electricity: measuring and testing – Fault detecting in electric circuits and of electric components – Of individual circuit component or element
Reexamination Certificate
1999-02-10
2001-05-22
Metjahic, Safet (Department: 2858)
Electricity: measuring and testing
Fault detecting in electric circuits and of electric components
Of individual circuit component or element
Reexamination Certificate
active
06236223
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to radio frequency (RF) transponders such as radio frequency identification (RFID) transponders, and more specifically to a method and apparatus for testing radio frequency circuits, particularly radio frequency integrated circuits such as radio frequency identification integrated circuits (RFID IC).
BACKGROUND OF THE INVENTION
Conventional methods and apparatus for testing radio frequency integrated circuits (RFIC) require the use of radio frequency (RF) contacts. For example, a wafer containing unsingulated RFIC chips (dies) may be placed on a probe station whereupon a probe is used to make contact with each RFIC. Once this connection is established, interrogating signals modulated on an RF signal are fed into the RFIC, and the responses (the returned signal) are analyzed in order to determine whether the RFID functions properly. Alternatively, the RFIC's may first be singulated from the wafer and packaged in plastic packages. The RF test can then be performed by placing the packaged chip on a “load board.” Such load boards comprise circuit boards containing fixtures for mounting the packaged RFIC in a temporary manner and a circuit for feeding an RF interrogation signal into the packaged RFIC to facilitate testing.
In either testing method, the RF interrogating signals are sent from a tester to the RFIC through a cable (e.g., a coaxial cable). Thus, the entire testing circuit consists of wired connections, and the testing signals (i.e., the interrogating signal and the responded signal) are well contained in a guide wave structure. While use of such “wired” test apparatus and methods provides satisfactory testing of most RFIC's, some functionalities of radio frequency identification integrated circuits (RFID IC) require a “wireless” RF test (i.e., a “field” test). For example, some circuits of the RFID IC, which are supposed to operate in the RF field, may appear to be functioning properly with the conventional wired test methods, but may later be found to be functioning improperly when packaged into RFID transponders and placed in an RF field where the RF signal is contaminated with noises and suffers from distortions caused by the time-varying characteristics of the wireless link and interference from surrounding objects. Similarly, it is difficult to determine whether the memory of the RFID IC's will be properly written in the field even though they can be properly written using the wired testing methods. Further, the read distance of an RFID IC (or an RFID transponder) can only be truly determined through a wireless RF test with appropriate calibration. It is therefore desirable to provide a method and apparatus for performing wireless radio frequency testing of RFID IC's so that they may be more fully characterized and tested.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to novel method and apparatus for performing wireless radio frequency (RF) testing of radio frequency circuits and particularly radio frequency integrated circuits such as radio frequency identification integrated circuits (RFID IC's). A fixture is provided for physically and electrically contacting the circuit to feed an RF interrogating signal into the circuit and receive an RF return signal generated in response thereto. The fixture is coupled to a tester via first and second couplers (interconnected to the fixture and tester, respectively) which establish a wireless radio frequency link for transmitting and receiving the RF interrogation and return signals.
Advantages provided by the present invention include: (1) the ability to perform wireless RF testing on RFID IC's without packaging the chips into RFID transponders; (2) the provision of full and accurate RF characterization of RFID IC's; (3) the capacity to perform wireless RF testing of RFID IC's in high volume and at low cost.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention claimed. The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate an embodiment of the invention and together with the general description, serve to explain the principles of the invention.
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Brady Michael John
Duan Dah-Weih
Intermec IP Corp.
Leroux E P
Metjahic Safet
O'Melveny & Myers
LandOfFree
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