Patent Application
20130271328
This relates generally to testing, and more particularly, to testing electronic device structures.
Electronic devices such as computers, cellular telephones, music players, and other electronic equipment are often provided with wireless communications circuitry. In a typical configuration, the wireless communications circuitry includes an antenna that is coupled to a transceiver on a printed circuit board via a transmission line path. Circuitry such as filters, radio-frequency amplifiers, radio-frequency switches, and other conductive structures may be interposed in the transmission line path connecting the transceiver to the antenna. The antenna performance of an electronic device may depend on how accurately these radio-frequency circuits are manufactured. Manufacturing defects present in radio-frequency circuits (i.e., defects due to process variation and non-ideal fabrication environments) may have a negative impact on the device performance. For example, if defective parts are assembled in a finished device, the finished device may exhibit unsatisfactory wireless performance during production testing. Detection of faults only after assembly is complete results in costly device scrapping or extensive reworking.
It would therefore be desirable to be able to provide improved ways in which to detect faults during the manufacturing of antenna device structures.
A wireless electronic device may include antenna device structures that form part of an antenna or other device structures. Prior to being assembled within a device, an antenna structure may be tested to ensure that circuits on the antenna structure satisfy performance criteria. The circuits (e.g., low noise amplifiers, matching circuits, filters, etc.) on the antenna structure may be interconnected via signal traces (as an example).
A test system may be provided that includes a radio-frequency tester, at least one test probe with pins or other contacts, and an auxiliary test structure configured to receive the antenna device structure under test. The radio-frequency tester may generate radio-frequency test signals in a range of frequencies. The antenna device structure under test may be attached to the auxiliary test structure during testing. The auxiliary test structure may serve to provide a ground contact probe point for the test probe and may also serve to provide a ground reference place for the signal traces on the antenna device structure.
The test probe may have a signal pin that mates with a corresponding signal contact probe point on the antenna device structure and may have a ground pin that mates with the ground contact probe point on the auxiliary test structure. Coupled in this arrangement, the test signals generated from the tester may be applied to the components and associated structures on the antenna device structures. The one test probe (and optionally additional test probes) may be used to receive corresponding signals reflected and emitted from the antenna structure under test.
Reflection coefficient and forward transfer coefficient data may be computed from the transmitted and received radio-frequency signals. The forward transfer coefficient data or other test data may be compared to reference data to determine whether the antenna structure under test satisfies design criteria.
Further features of the present invention, its nature and various advantages will be more apparent from the accompanying drawings and the following detailed description.
Electronic devices such as electronic device 10 of
The antennas can include loop antennas, inverted-F antennas, strip antennas, planar inverted-F antennas, slot antennas, hybrid antennas that include antenna structures of more than one type, or other suitable antennas. Conductive structures for the antennas may, if desired, be formed from conductive electronic device structures. The conductive electronic device structures may include conductive housing structures. The housing structures may include a peripheral conductive member that runs around the periphery of an electronic device. The peripheral conductive member may serve as a bezel for a planar structure such as a display, may serve as sidewall structures for a device housing, and/or may form other housing structures. Gaps in the peripheral conductive member may be associated with the antennas.
Electronic device 10 may be a portable electronic device or other suitable electronic device. For example, electronic device 10 may be a laptop computer, a tablet computer, a somewhat smaller device such as a wrist-watch device, pendant device, headphone device, earpiece device, or other wearable or miniature device, a cellular telephone, or a media player. Device 10 may also be a television, a set-top box, a desktop computer, a computer monitor into which a computer has been integrated, or other suitable electronic equipment.
As shown in the schematic diagram of
Storage and processing circuitry 28 may be used to run software on device 10, such as internet browsing applications, voice-over-internet-protocol (VOIP) telephone call applications, email applications, media playback applications, operating system functions, etc. To support interactions with external equipment, storage and processing circuitry 28 may be used in implementing communications protocols. Communications protocols that may be implemented using storage and processing circuitry 28 include internet protocols, wireless local area network protocols (e.g., IEEE 802.11 protocols—sometimes referred to as WiFi®), protocols for other short-range wireless communications links such as the Bluetooth° protocol, cellular telephone protocols, etc.
Circuitry 28 may be configured to implement control algorithms that control the use of antennas in device 10. For example, circuitry 28 may perform signal quality monitoring operations, sensor monitoring operations, and other data gathering operations and may, in response to the gathered data and information on which communications bands are to be used in device 10, control which antenna structures within device 10 are being used to receive and process data and/or may adjust one or more switches, tunable elements, or other adjustable circuits in device 10 to adjust antenna performance. As an example, circuitry 28 may control which of two or more antennas is being used to receive incoming radio-frequency signals, may control which of two or more antennas is being used to transmit radio-frequency signals, may control the process of routing incoming data streams over two or more antennas in device 10 in parallel, may tune an antenna to cover a desired communications band, etc. In performing these control operations, circuitry 28 may open and close switches, may turn on and off receivers and transmitters, may adjust impedance matching circuits, may configure switches in front-end-module (FEM) radio-frequency circuits that are interposed between radio-frequency transceiver circuitry and antenna structures (e.g., filtering and switching circuits used for impedance matching and signal routing), may adjust switches, tunable circuits, and other adjustable circuit elements that are formed as part of an antenna or that are coupled to an antenna or a signal path associated with an antenna, and may otherwise control and adjust the components of device 10.
Input-output circuitry 30 may be used to allow data to be supplied to device 10 and to allow data to be provided from device 10 to external devices. Input-output circuitry 30 may include input-output devices 32. Input-output devices 32 may include touch screens, buttons, joysticks, click wheels, scrolling wheels, touch pads, key pads, keyboards, microphones, speakers, tone generators, vibrators, cameras, sensors, light-emitting diodes and other status indicators, data ports, etc. A user can control the operation of device 10 by supplying commands through input-output devices 32 and may receive status information and other output from device 10 using the output resources of input-output devices 32.
Wireless communications circuitry 34 may include radio-frequency (RF) transceiver circuitry formed from one or more integrated circuits, power amplifier circuitry, low-noise input amplifiers, passive RF components, one or more antennas, and other circuitry for handling RF wireless signals. Wireless signals can also be sent using light (e.g., using infrared communications).
Wireless communications circuitry 34 may include satellite navigation system receiver circuitry such as Global Positioning System (GPS) receiver circuitry 35 (e.g., for receiving satellite positioning signals at 1575 MHz) or satellite navigation system receiver circuitry associated with other satellite navigation systems. Transceiver circuitry 36 may handle 2.4 GHz and 5 GHz bands for WiFi® (IEEE 802.11) communications and may handle the 2.4 GHz Bluetooth° communications band. Circuitry 34 may use cellular telephone transceiver circuitry 38 for handling wireless communications in cellular telephone bands such as bands in frequency ranges of about 700 MHz to about 2200 MHz or bands at higher or lower frequencies. Wireless communications circuitry 34 can include circuitry for other short-range and long-range wireless links if desired. For example, wireless communications circuitry 34 may include wireless circuitry for receiving radio and television signals, paging circuits, etc. In WiFi® and Bluetooth° links and other short-range wireless links, wireless signals are typically used to convey data over tens or hundreds of feet. In cellular telephone links and other long-range links, wireless signals are typically used to convey data over thousands of feet or miles.
Wireless communications circuitry 34 may include one or more antennas 40. Antennas 40 may be formed using any suitable antenna types. For example, antennas 40 may include antennas with resonating elements that are formed from loop antenna structure, patch antenna structures, inverted-F antenna structures, closed and open slot antenna structures, planar inverted-F antenna structures, helical antenna structures, strip antennas, monopoles, dipoles, hybrids of these designs, etc. Different types of antennas may be used for different bands and combinations of bands. For example, one type of antenna may be used in forming a local wireless link antenna and another type of antenna may be used in forming a remote wireless link.
If desired, one or more of antennas 40 may be provided with multiple antenna feeds and/or adjustable components. Antennas such as these may be used to cover desired communications bands of interest. For example, a first antenna feed may be associated with a first set of communications frequencies and a second antenna feed may be associated with a second set of communications frequencies. The use of multiple feeds (and/or adjustable antenna components) may make it possible to reduce antenna size (volume) within device 10 while satisfactorily covering desired communications bands.
It may be desirable to test individual components in device 10 prior to actually assembling the components within device 10. Testing parts prior to assembly can help identify (at an early stage) potentially problematic issues that can negatively affect the performance of device 10 during normal user operation. For example, it may be desirable to characterize structures associated with antennas 40, because the integrity of these structures can often impact the antenna/wireless performance of device 10. Such types of structures that can potentially impact the radio-frequency performance of device 10 are sometimes referred to as antenna structures under test. Examples of antenna structures under test that may be characterized prior to being assembled within device 10 include conductive housing structures (e.g., conductive housing structures that form part of antennas 40), antenna feed structures (e.g., flexible antenna circuits, shorting pins, radio-frequency cables, etc.), radio-frequency amplifying circuit such as power amplifier and low noise amplifiers, matching circuits, filters, and other structural components of antennas 40.
In the unassembled state, some of these antenna structures under test may not be readily tested.
During test operations, signal pin 118 of test probe 112 is mated with a first end portion of pin 116 (as shown by dotted line 126) while signal pin 120 of test probe 114 is mated with a second end portion of pin 116 (as shown by dotted line 128). Ground pins 122 and 124 of test probes 112 and 114, however, are not connected to pin 116. If ground pins 122 and 124 are not properly terminated, common mode noise current may be generated in the direction of arrows 130. Noise current generated in this way can undesirably reduce the accuracy of test results.
Tester 202 may have at least first and second test ports 204 and 206. First test port 204 may be coupled to a first test probe 212 via radio-frequency test cable 208. Second test port 206 may be coupled to a second test probe 214 via radio-frequency test cable 210. Radio-frequency cables 208 and 210 may be coaxial cables. For example, cable 208 may have an inner signal conductor that is electrically connected to corresponding signal contact pin 220 of test probe 212 and an outer ground conductor surrounding the inner signal conductor that is electrically connected to corresponding ground contact pin 222 of test probe 212. Similarly, cable 210 may have an inner signal conductor that is electrically connected to corresponding signal contact pin 220 of test probe 214 and an outer ground conductor surrounding the inner signal conductor that is electrically connected to corresponding ground contact pin 222 of test probe 214.
Test system 200 may be used to test antenna structures under test 216 in the unassembled state (i.e., before antenna structures 216 are assembled within device 10). Antenna structures under test 216 may be attached to auxiliary test structure 218 during test operations (e.g., antenna structures under test 216 may be mounted on auxiliary test structure 218). During testing, signal pins 220 of test probes 212 and 214 may be placed in contact with suitable test points on antenna structures under test 216 (as indicated by dotted lines 224 and 226). Ground pin 222 of test probe 212 may be configured to mate with a first corresponding ground contact region on antenna structures under test 216 or, if a ground contact region is absent on structures 216, with a first corresponding ground contact point on auxiliary test structure 218. Ground pin 222 of test probe 214 may be configured to mate with a second corresponding ground contact region on antenna structures under test 216 or, if a ground contact region is absent on structures 216, with a second corresponding ground contact point on auxiliary test structure 218.
Auxiliary test structure 218 may therefore serve to provide ground contact points for test probes 212 and 214 so that the interface between antenna structures under test 216 and the test equipment is properly terminated (e.g., so that the test probes are properly terminated to 50 ohms). Test structure 218 may therefore sometimes be referred to as an auxiliary impedance reference structure or an impedance reference test fixture. The example of
During testing, tester 202 may be configured to produce radio-frequency test signals that are applied to device structures under test 216 using cables 208 and 210 and probes 212 and 214. Even without being connected to other components to form a completed antenna assembly for device 10, device structures under test 216 may emit wireless radio-frequency signals when driven using the test signals from the test probes. As test electromagnetic signals are transmitted by tester 202 and applied to device structures under test 216 through test probe 212, corresponding transmitted wireless electromagnetic test signals may be received through test probe 214 (as an example). Tester 202 may also receive reflected signals from cable 208 (i.e., signals that were reflected from device structures under test 216 in response to the signals transmitted through probe 212).
The transmitted and reflected signals gathered in this way may be used to compute a reflection coefficient (sometimes referred to as an S11 parameter or S11 scattering parameter). The transmitted signals on cable 208 and corresponding received signals on cable 210 may be used to compute a forward transfer coefficient (sometimes referred to as an S21 parameter or S21 scattering parameter). The S11 and S21 data may include magnitude and phase components.
During testing, S11 data and/or S21 data gathered using test equipment 202 may be compared to predetermined reference levels to determine whether antenna structures under test 216 satisfy design criteria. If the gathered data substantially matches the predetermined reference levels, test equipment 202 may inform an operator that device structures under test 216 are satisfactory or may take other suitable action. If the gathered data deviates from the reference data by more than an acceptable amount, test equipment 202 may inform the operator that device structures under test 216 include a fault and should be reworked or scrapped or may take other suitable action.
Auxiliary test structure 218 that is configured to receive shorting pin 216 of
During testing, pin 216 may be temporarily placed on top of test fixture 218 (see, arrows 258).
In wireless electronic devices requiring smaller form factor, one or more of antennas 40 may be provided with multiple antenna feeds and/or adjustable components. Antennas such as these may be used to cover desired communications bands of interest. For example, a first antenna feed may be associated with a first set of communications frequencies and a second antenna feed may be associated with a second set of communications frequencies. The use of multiple feeds (and/or adjustable antenna components) may make it possible to reduce antenna size (volume) within device 10 while satisfactorily covering desired communications bands. In one suitable embodiment of the present invention, the antenna feed structures (e.g., structures on which multiple antenna feeds are formed) may be characterized using test system 200 prior to being assembled within device 10. Because the antenna feed structures and the radio-frequency circuits mounted on the antenna feed structures are interposed in the transmit/receive path linking antenna 40 to wireless transceiver circuitry 90, the accuracy with which these components are manufactured may directly impact antenna performance.
An illustrative configuration for an antenna with multiple feeds of the type that may be used in implementing one or more antennas for device 10 is shown in
Each antenna feed associated with antenna 40 may, if desired, have a distinct location. As shown in
Each feed may be coupled to an associated set of conductive signal paths using terminals such as antenna signal feed terminals (+) and antenna ground antenna terminals (−). For example, path 54A may have a positive conductor 58A that is coupled to a positive antenna feed terminal in feed FA and a ground conductor 56A that is coupled to a ground antenna feed terminal in feed FA, whereas path 54B may have a positive conductor 58B that is coupled to a positive antenna feed terminal in feed FB and a ground conductor 56B that is coupled to a ground antenna feed terminal in feed FB. Paths such as paths 54A and 54B may be implemented using transmission line structures such as coaxial cables, microstrip transmission lines (e.g., microstrip transmission lines on printed circuits), stripline transmission lines (e.g., stripline transmission lines on printed circuits), or other transmission lines or signal paths. Circuits such as impedance matching circuits, filter circuits, and other circuitry may be interposed within paths 54A and 54B.
The conductive structures that form antenna resonating element 50 and antenna ground 52 may be used to form any suitable type of antenna.
In the illustrative configuration of
The illustrative examples of
A top interior view of device 10 in a configuration in which device 10 has a peripheral conductive housing member such as housing member 16 with one or more gaps 18 is shown in
One or more segments of peripheral conductive member 16 may serve as antenna resonating elements such as antenna resonating element 50 of
Using a device configuration of the type shown in
As shown in
In the illustrative example of
As shown in
Incoming signals for receiver 35 may be received through band-pass filter 64A, optional impedance matching circuits such as matching circuits M1 and M4, and low noise amplifier 86 (e.g., the signals received from feed FA may be conveyed through components such as matching filter M1, band-pass filter 64A, matching circuit M4, and low noise amplifier 86 using transmission lines paths such as transmission line path 54A of
Signals associated with transmit and receive operations for cellular transceiver circuitry 38 may be handled using notch filter 64B, optional impedance matching circuits such as matching circuits M2 and M3, antenna selection switch 88, and circuitry 98 (e.g., the components used in transmitting and receiving signals with feed FB may be conveyed through components such as matching filter M2, notch filter 64B, matching circuit M3, and circuitry 90 using transmission lines paths such as transmission line path 54B of
The transmission T that may be exhibited by notch filter 64B and band-pass filter 64A as a function of frequency f is shown in
An antenna feed structure under test such as dual-feed structure 300 may include matching circuits M1 and M4, band-pass filter 64A, low noise amplifier 86, and antenna signal feed terminals associated with feeds FA and FB (see, e.g.,
A rigid substrate support member such as support member 304 may be formed as part of substrate 302. Support member 304 may be used to provide sufficient mechanical support so that active circuit components such as GPS front end circuitry 306 (e.g., matching circuits M1 and M4, filter 64A, and low noise amplifier 86) can be properly mounted and secured to antenna feed structure 300. Support member 304 may sometimes be referred to as a stiffener. The circuits in GPS front end circuitry 306 may each have a first power supply terminal that is coupled to pad 318 and a second power supply terminal that is coupled to pads 316 (see, e.g., dotted path 322). As an example, the second power supply terminal may be coupled to a ground plane 317 that is formed as a layer within support member 304. In one suitable embodiment of the present invention, ground plane 317 may be accessible from the underside of member 304 when member 304 is mounted over a corresponding fixture during testing.
Antenna feed structure 300 may be attached to another device structure such as substrate 330 that is formed over ground plane 52 (as indicated by arrows 324). Storage and processing circuitry 28, baseband processor 88, GPS receiver 35, cellular transceiver 38, cellular front end circuitry 332 (e.g., matching circuits M2 and M3, notch filter 64B, antenna selection switch 88, band selection circuitry 98, etc.), power supply circuitry 334 (e.g., a battery configured to supply power supply voltages Vcc and Vss), and other control circuitry may be formed on substrate 330. Substrate 330 may therefore sometimes be referred to as a main logic board (MLB).
Conductive pad structures 314′, 316′, 318′, and 320′ may also be formed on substrate 330. In particular, pad 314′ may be coupled to cellular transceiver 38 via cellular front end 332 and may be configured to mate with pad 314 on antenna feed structure 300. Pad 320′ may be coupled to GPS receiver 35 and may be configured to mate with pad 320 on antenna feed structure 300. Pads 318′ and 320′ may be coupled to power supply 334 and may be mated with pads 318 and 320 on antenna feed structure 330, respectively.
During device assembly operations, assembly personnel may mate antenna feed structure 300 with main logic board 330 (e.g., to connect the wireless transceiver circuitry to corresponding feed terminals FA′ and FB') and may mate antenna feed structure 300 to antennas 40 (e.g., to connect the antenna feed points to respective locations on antenna resonating element 50 (see, e.g.,
It may be desirable to test antenna feed structure 300 (e.g., to characterize the circuits mounted on structure 300) prior to device assembly.
Antenna feed structure 300 may be mounted on test structure 218 during testing. In the mounted state (see, e.g.,
As shown in
Providing a ground reference plane for signal path 310 in antenna structure under test 300 reduces impedance mismatch between the test probe and the antenna structures under test and helps to improve the accuracy of test results associated with the performance of GPS front end 306 (e.g., ground reference 256 in substrate 254 helps reduce test variance that may be caused as a result of common mode noise current associated with signal path 310 if ground plane reference 256 were absent). The example of
Illustrative test data gathered from a single antenna structure under test 300 using test system 200 of
In general, auxiliary test structure 218 may be configured to receive any device structure under test (e.g., device structures under test that lack ground contact points).
Antenna structure under test 216 may be placed on top of auxiliary test structure 218, as indicated by arrows 350. Test structure 218 may be formed from substrate 254. Test structure 218 may include ground reference planes 256 formed on top and bottom surfaces of substrate 254. For example, a first conductive grounding portion 256-1 and a second conductive grounding portion 256-2 may be formed on the top surface of substrate 254, whereas grounding portion 256′ may be formed on the bottom surface of substrate 254. During testing when antenna structure 216 is mounted on top of auxiliary test fixture 218, portion 256-1 may serve as an auxiliary ground probe point for first contact member 402 while portion 256-2 may serve as an auxiliary ground probe point for second contact member 404. Conductive portion 256′ may serve as a ground reference plane for signal paths 406 and 408 so that radio-frequency signals conveyed through paths 406 and 408 exhibit desirable behaviors.
The performance of radio-frequency circuit 400 may be tested while a first test probe is mated to conductive members 402 and 256-1 and while a second test probe is mated to conductive members 404 and 256-2. Examples of radio-frequency circuits 400 that may be tested are shown in
Adjustable load circuitry 510 of
Illustrative steps involved in testing device structures under test 216 using a test system of the type shown in
At step 604, antenna structure under test 216 may be coupled to radio-frequency test 202 via test probes 212 and 214 to energize antenna structure under test 216 (e.g., tester 202 may generate radio-frequency test signals that are applied to antenna structure under test 216 by mating the test probes to appropriate signal and ground contact points on structures 216 and 218). At step 606, test data may be gathered from antenna structure 216 currently under test by using tester 202 to transmit test signals and to receive corresponding reflected signals.
At step 608, antenna structure under test 216 may be detached from auxiliary test structure 218 so that auxiliary test structure 218 can receive a subsequent antenna structure under test in the production line. At step 610, a test host (e.g., a personal computer) may analyze the test data (e.g., by computing S11 and S12 parameters and comparing the computed results to the baseline reference data obtained during step 600) to determine whether antenna structure under test 216 satisfies design criteria. For example, if the measured test data substantially matches the reference data, antenna structure under test 216 may be marked as a passing component and may be assembled within device 10. If, however, the measured test data deviates from the reference data by more than a predetermined amount, antenna structure under test 216 may be marked as a failing component and may be reworked or scrapped.
The foregoing is merely illustrative of the principles of this invention and various modifications can be made by those skilled in the art without departing from the scope and spirit of the invention. The foregoing embodiments may be implemented individually or in any combination.
