Abstract:
Disclosed are a method and an apparatus of near field scan calibration, and more particularly, a method and an apparatus for near field scan calibration for calibrating a characteristic of an antenna for near field scan measurement of a semiconductor chip. The apparatus for near field scan calibration includes: a plane-type text fixture having a plane shape; an antenna positioned spaced apart from the plane-type test fixture by a set spacing distance and acquiring data including a magnetic field; and a spectrum analyzer analyzing the data acquired by the antenna.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is based on and claims priority from Korean Patent Application No. 10-2010-0132245, filed on Dec. 22, 2010, with the Korean Intellectual Property Office, the present disclosure of which is incorporated herein in its entirety by reference. 
       TECHNICAL FIELD 
       [0002]    The present disclosure relates to a method and an apparatus of near field scan calibration. More particularly, the present disclosure relates to a method and an apparatus for near field scan calibration for calibrating a characteristic of an antenna for near field scan measurement of a semiconductor chip. 
       BACKGROUND 
       [0003]    In general, it is needed that electronic apparatuses operate normally under a given electromagnetic environment and do not negatively influence other systems by restricting electromagnetic interference generated from themselves. For this reason, irradiation of electromagnetic waves is extremely suppressed or excessive resistance to the electromagnetic interference is designed, which causes a large economical burden. Therefore, balancing both sides is required. 
         [0004]    It is known that the electromagnetic waves influence human bodies and in some cases, cause cancers. The electromagnetic waves may cause malfunctions of electrical and electronic systems as well as a negative influence on the human bodies. The phenomenon is called electro magnetic compatibility (EMC). 
         [0005]    The electro magnetic compatibility (EMC) means a phenomenon in which the electrical and electronic systems are influenced by the electromagnetic waves to cause erroneous operation or a disabling state and includes both electro magnetic interference (EMI) and electro magnetic susceptibility (EMS). Meanwhile, in recent years, a measurement scope of the EMC phenomenon has been extended from a PCB level in the related art to a semiconductor chip level mounted on a PCB. The resulting standardization related to EMC measurement of a semiconductor chip is executed by the IEC and the previously established standards include IEC61967 and IEC62132. The IEC61967 is related to electromagnetic emission and the IEC62132 is related to electromagnetic immunity. Meanwhile, the IEC61967.3 and 6 suggest calibration of an antenna characteristic to be used for measurement by using a microstrip line. 
         [0006]    Since this is applied to a standard PCB and the width thereof is a narrow line of approximately 1 mm in detecting a magnetic field emitted from the entire semiconductor chip by connecting a power and signal line terminals to the microstrip line, it is difficult to calibrate an error depending on an angle or a location thereof in order to fabricate a probe for measuring the EMC. 
       SUMMARY 
       [0007]    The present disclosure has been made in an effort to provide a method and an apparatus for calibrating a characteristic of a measurement antenna with a tendency in which near field scan of a semiconductor chip is increasingly required. 
         [0008]    The present disclosure has been made in an effort to provide a method and an apparatus for calibrating an error depending on an angle or a location of a probe, which is generated by detecting a magnetic field emitted from the entire semiconductor chip by connecting an existing microstrip line. 
         [0009]    An exemplary embodiment of the present disclosure provides an apparatus for near field scan calibration, including: a plane-type text fixture; an antenna positioned spaced apart from the plane-type test fixture by a set spacing distance and acquiring data including a magnetic field; and a spectrum analyzer analyzing the data acquired by the antenna. 
         [0010]    The plane-type test fixture may have a circular shape. 
         [0011]    The plane-type test fixture may have a polygonal shape including a triangular shape or a quadrangular shape. 
         [0012]    The spacing distance between the plane-type test fixture and the antenna may be 1 mm. 
         [0013]    The antenna may be set as a first port and the plane-type test fixture may be set as a second port. 
         [0014]    The data acquired by the antenna may include the intensity of a spatial magnetic field generated vertically to the surface of the plane-type test fixture including a transmission coefficient and a reflection coefficient. 
         [0015]    The magnetic field may be acquired by analyzing conducted emission (CE) transferred to a conductor. 
         [0016]    The plane-type test fixture may be made of metal. 
         [0017]    Another exemplary embodiment of the present disclosure provides a method for near field scan calibration, including: feeding power to the center of a plane-type test fixture; acquiring data including a magnetic field from an antenna spaced apart from the plane-type test fixture by a set spacing distance; and calibrating a characteristic of an antenna for near field scan measurement by using the data. 
         [0018]    The plane-type test fixture may have a circular shape. 
         [0019]    The plane-type test fixture may have a polygonal shape including a triangular shape or a quadrangular shape. 
         [0020]    In the feeding of the power to the center of the plane-type test fixture, a plurality of plane-type test fixtures may be provided for each size and the power may be fed to each provided plane-type test fixture. 
         [0021]    The spacing distance between the plane-type test fixture and the antenna may be 1 mm. 
         [0022]    The antenna may be set as a first port and the plane-type test fixture may be set as a second port. 
         [0023]    In the acquiring of the data, the intensity of a spatial magnetic field generated vertically generated on the surface of the plane-type test fixture including a transmission coefficient and a reflection coefficient may be acquired. 
         [0024]    The magnetic field may be acquired by analyzing conducted emission (CE) transferred to a conductor. 
         [0025]    According to the exemplary embodiments of the present disclosure, a standard calibration method is provided to perform near field scan measurement of a semiconductor chip directly with respect to the semiconductor chip, thereby conveniently and usefully performing the relevant measurement. That is, in the method using the micro strip line in the related art, the width is small, such that it is difficult to ensure calibration data for fabricating a probe, while in the present disclosure, the calibration data for fabricating the probe can be easily ensured by using a circular test fixture or a polygonal test fixture. 
         [0026]    According to the exemplary embodiments of the present disclosure, since a standard probe can be fabricated, the standard probe can be usefully used in a near field scan measurement apparatus field. 
         [0027]    The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0028]      FIG. 1  is a diagram showing a cross-sectional structure of a microstrip line for calibration in the related art. 
           [0029]      FIG. 2  is a diagram showing a cross-sectional structure of a microstrip line for calibration in the related art viewed from another angle. 
           [0030]      FIG. 3  is a diagram showing a plane-type test fixture according to an exemplary embodiment of the present disclosure. 
           [0031]      FIG. 4  is a diagram showing a circular test fixture according to an exemplary embodiment of the present disclosure. 
           [0032]      FIG. 5  is a diagram showing a process of extracting antenna data by using a circular test fixture according to an exemplary embodiment of the present disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0033]    In the following detailed description, reference is made to the accompanying drawing, which form a part hereof. The illustrative embodiments described in the detailed description, drawing, and claims are not meant to be limiting. Other embodiments may be utilized, and other changes may be made, without departing from the spirit or scope of the subject matter presented here. 
         [0034]    As described above, the IEC61967.3 and 6 suggest calibration of an antenna characteristic to be used for measurement by using a microstrip line.  FIG. 1  is a diagram showing a cross-sectional structure of a micro strip line for calibration in the related art. 
         [0035]      FIG. 1  shows a microstrip line for calibration described in ‘Probe Calibration Procedure—Microstripline Method’ stated in an annex of the IEC61967.6. 
         [0036]    Referring to  FIG. 1 , the cross-sectional structure of a micro strip line  100  made of metal with a width of 1 mm and a length of 50 mm or longer is shown and micro strip line  100  is fabricated to have impedance (ZO) of 50 ohm. 
         [0037]    More specifically, micro strip line  100  is spaced apart from a metallic ground  120  by approximately 0.6 mm with a dielectric  110  positioned in the middle thereof and a dielectric constant ∈ γ  of the dielectric is approximately 4.7. As described above, since the width of micro strip line  100  is approximately 1 mm, it is difficult to fabricate a probe for measuring EMC. 
         [0038]      FIG. 2  is a diagram showing a cross-sectional structure of a microstrip line for calibration in the related art viewed from another angle.  FIG. 2  shows a spectrum analyzer  200  and a signal generator  220 , a magnetic field probe  250  measuring a magnetic field by a signal generated from signal generator  220 , a magnetic field probe molder  210  molding magnetic field probe  250 , a 50-ohm impedance microstrip line  230 , and a microstrip line terminal  240 . 
         [0039]    As shown in  FIG. 2 , a microstrip line test fixture connects microstrip line  230  to a power and a signal terminal at a PCB level to detect the magnetic field emitted from all chips on the PCB. Since microstrip line  230  has a narrow width of approximately 1 mm, there are many difficulties in calibration for fabricating measurement magnetic field probe  250 . An error should be calibrated depending on angles and locations of microstrip line  230  and magnetic field probe  250 , however, error calibration is very difficult due to microstrip line  230  having the narrow width. 
         [0040]    Therefore, the present disclosure suggests not the micro strip line test fixture but the circular test fixture and suggests a method for calibrating a probe characteristic by using the suggested circular test fixture. 
         [0041]      FIG. 3  shows a text fixture for evaluating an antenna characteristic according to an exemplary embodiment of the present disclosure. Hereinafter, referring to  FIG. 3 , the text fixture for evaluating the antenna characteristic according to the exemplary embodiment of the present disclosure will be described in detail. 
         [0042]    Referring to  FIG. 3 , a kind of patch antenna structure is provided as a plane type test fixture  300  instead of the existing microstrip line test fixture. Referring to  FIG. 3 , plane type rectangular test fixture  300  is shown. Further,  FIG. 3  shows a magnetic field probe  310  measuring a magnetic field generated by plane type test fixture  300  and a spectrum analyzer (not shown) analyzing the magnetic field measured by the magnetic field probe, as shown in  FIG. 2 . 
         [0043]      FIG. 3  shows rectangular test fixture  300 , but the shape of test fixture  300  is not limited thereto. Text fixture  300  may have various shapes forming a test fixture having a predetermined width. That is, the test fixture  300  may include all polygonal text fixtures having various shapes such as a triangular shape and a pentagonal shape in addition to a quadrangular shape including the rectangular shape. 
         [0044]    In the structure shown in  FIG. 3 , since upper metallic plane-type test fixture  300  has an equivalent potential, test fixture  300  has a characteristic that the magnetic field is constant in other parts except for a feed point. Therefore, since plane type test fixture  300  is constant in magnetic field depending on the location unlike the existing microstrip line test fixture, plane-type test fixture  300  is not limited to being dependent on the location. As described above, magnetic field probe  310  measures the magnetic field generated from the plane-type test fixture and provides the measured magnetic field to the spectrum analyzer (not shown). The spectrum analyzer (not shown) analyzes the magnetic field received from magnetic field probe  310  to extract optimal data. 
         [0045]    However, the quadrangular plane-type test fixture has an error depending on an angle of the probe. 
         [0046]      FIG. 4  shows a text fixture for evaluating an antenna characteristic according to another exemplary embodiment of the present disclosure. Hereinafter, referring to  FIG. 4 , the text fixture for evaluating the antenna characteristic according to another exemplary embodiment of the present disclosure will be described in detail. 
         [0047]      FIG. 4  shows a circular test fixture  400  instead of the existing micro strip line test fixture. 
         [0048]    As described above, the quadrangular plane-type test fixture has the error depending on the angle of the probe, but circular test fixture  400  has no error depending on the angle, and as a result, circular test fixture  400  can be used without limitation. That is, by such a configuration, the disadvantage of the micro strip line test fixture can be solved. 
         [0049]      FIG. 4  may also show a magnetic field probe  410  measuring a magnetic field generated from the circular text fixture and a spectrum analyzer (not shown) analyzing the magnetic field measured by the magnetic field probe similarly as  FIG. 3 . Magnetic field probe  410  measures the magnetic field generated from circular test fixture  400  and provides the measured magnetic field to the spectrum analyzer. The spectrum analyzer analyzes the magnetic field received from magnetic field probe  410  to extract optimal data. 
         [0050]      FIG. 5  shows a process of calibrating an antenna characteristic according to an exemplary embodiment of the present disclosure. Hereinafter, referring to  FIG. 5 , the process of calibrating the antenna characteristic according to the exemplary embodiment of the present disclosure will be described in detail. 
         [0051]    Referring to  FIG. 5 , the process of calibrating the antenna characteristic includes preparing a circular test fixture (S 510 ), applying data for each size of the acquired circular test fixture (S 520 ), extracting optimal antenna data (S 530 ), and fabricating an antenna probe by using the extracted data (S 540 ). 
         [0052]    More specifically, in the antenna characteristic calibrating process, first, the circular test fixture is prepared (S 510 ). Of course, optimal antenna data depending on the diameter of the circular test fixture may be acquired in advance. 
         [0053]    A magnetic field probe (antenna) is positioned at a portion spaced apart from the surface of the circular text fixture by 1 mm in order to acquire data for near field scan. Thereafter, the magnetic field probe (antenna) is set as a first port (port- 1 ) and the circular test fixture is set as a second port (port- 2 ) to acquire a reflection coefficient and a transmission coefficient of each port. 
         [0054]    In addition to the reflection coefficient and the transmission coefficient, the intensity of a spatial magnetic field (H-field) generated vertically to the surface of the circular test fixture is measured. A result of the magnetic field (H-field), which is a distribution of a conductor surface, is expressed as a unit called A/m, but in general, the result is analyzed by the spectrum analyzer and expressed as dBuV in EMC measurement. In general, the magnetic field (H-field) of the conductor surface is not shown similarly as the spatial magnetic field (H-field). In order to acquire the magnetic field (H-field) of the conductor surface, the data is acquired by analyzing not radiated emission (RE) emitted to a space but conducted emission (CE) transferred to a conductor. The acquired data of the circular test fixture is applied for each circular size (S 520 ). 
         [0055]    In general, the RE represents electromagnetic noise in which electromagnetic waves are emitted and transferred to the air and the CE represents electromagnetic noise transferred through a medium such as a signal line or a power line. 
         [0056]    The measured intensity of the magnetic field is stronger at the center than at the periphery of the conductor surface because the feed point is placed at the center to apply a signal. 
         [0057]    Through the above-mentioned process, the antenna (probe) data is extracted (S 530 ) and since the acquired data may be used as standard data at the time of fabricating the antenna for near field scan, the data are useful for EMC measurement. That is, through the method, a standard antenna for near field scan is fabricated (S 540 ). 
         [0058]    In  FIG. 5 , the process of extracting the near field scan antenna data by using the circular test fixture is shown, but the present disclosure is not limited thereto. That is, a process of extracting the near field scan antenna data by using the plane-type quadrangular text fixture shown in  FIG. 3  may also be performed similarly as the method described in  FIG. 5 . 
         [0059]    From the foregoing, it will be appreciated that various embodiments of the present disclosure have been described herein for purposes of illustration, and that various modifications may be made without departing from the scope and spirit of the present disclosure. Accordingly, the various embodiments disclosed herein are not intended to be limiting, with the true scope and spirit being indicated by the following claims.