Radio-frequency test system with tunable test antenna circuitry

• US 9,404,965 B2
• Filed: 12/20/2013
• Issued: 08/02/2016
• Est. Priority Date: 12/20/2013
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Nickel, Joshua G., Tong, Erica J., Venkataraman, Vishwanath
• Primary Examiner(s): Vazquez, Arleen M
• Assistant Examiner(s): YENINAS, STEVEN LEE
• Application Number:
  US14/137,770
• Publication Number:
  US 20150177277A1
• Time in Patent Office: 956 Days
• Field of Search: 324/750.16, 324/750.26, 324/754, 324/754.31, 324/756.01, 324/754.03, 324/629, 324/750.01, 324/750.02, 324/750.18, 324/750.27, 343/702, 343/703, 455/67.12, 455/67.11, 4552261-2264, 455/423, 455/424, 455/425, 455/67.13, 455/67.14, 455/68, 455/69, 455/115.1, 455/115.2, 455/418, 455/419, 455/420
• US Class Current: 1/1
• CPC Class Codes: G01R 31/2822 of microwave or radiofrequency circuits of attenuation, gain, e.g. using network analyzers G01R27/28
• CPC Class Codes: G01R 31/3025 Wireless interface with the DUT

Abstract

A test system is provided for performing radio-frequency tests on an electronic device under test (DUT) having multiple antennas. The test system may include a test unit for generating radio-frequency test signals, a test enclosure, and a test antenna fixture. The test fixture may include tunable antenna circuitry, antenna tuning elements, a test sensor, a microcontroller, a battery, and a solar cell that charges the battery, each of which is mounted on a test fixture within the test enclosure. The test sensor may be used to detect stimuli issued by the DUT. In response to detecting the stimuli, the microcontroller may send control signals to the antenna tuning elements to configure the antenna circuitry in different modes. Each of the different modes may be optimized to test a selected one of the multiple antennas in the DUT when operating using different radio access technologies and at different frequencies.

Claims

1. A method for using a test system to characterize a device under test, wherein the test system includes a sensor, a controller, and tunable test antenna circuitry that includes at least one test antenna coupled to at least one antenna tuning element, the method comprising:

with the sensor, detecting a stimulus of a given value from the device under test;

in response to detecting the stimulus, alerting the controller with the sensor;

in response to being alerted, placing the tunable test antenna circuitry in a selected one of a plurality of predetermined states with the controller, wherein the given value of the stimulus indicates which of the plurality of predetermined states to make the selected state; and

while the tunable test antenna circuitry is placed in the selected one of the plurality of predetermined states, transmitting radio-frequency test signals to the device under test using the at least one test antenna, wherein the sensor comprises a sensor selected from the group consisting of;

a microphone, a visible light sensor, a motion sensor, and a camera.

2. The method defined in claim 1, further comprising:

loading the device under test with a test operating system so that the device under test generates stimuli according to a predetermined test sequence.

3. The method defined in claim 1, further comprising:

placing the device under test within a radio-frequency test cell.

4. The method defined in claim 3, wherein the test system further includes a test host, the method further comprising:

removing the device under test from the radio-frequency test cell;

after the device under test has been removed from the radio-frequency test cell, connecting the device under test to the test host;

while the device under test is connected to the test host, retrieving test data from the device under test; and

with the test host, determining whether the device under test is a passing device based on the retrieved test data.

5. The method defined in claim 3, wherein placing the device under test within the radio-frequency test cell comprises placing the device under test within a transverse electromagnetic cell.

6. The method defined in claim 1, further comprising:

placing the tunable test antenna circuitry in a first state that is optimized for testing a first radio access technology with which the device under test is operated; and

placing the tunable test antenna circuitry in a second state that is optimized for testing a second radio access technology with which the device under test is operated.

7. The method defined in claim 1, wherein placing the tunable test antenna circuitry in a selected one of the plurality of predetermined states with the controller comprises using the controller to adjust at least one radio-frequency switch in the tunable test antenna circuitry.

8. The method defined in claim 7, wherein placing the tunable test antenna circuitry in a selected one of the plurality of predetermined states with the controller comprises using the controller to adjust at least one phase shift circuit in the tunable test antenna circuitry.

9. The method defined in claim 1, wherein the test system includes a microcontroller, a solar cell mounted on a substrate, and a battery mounted on the substrate, and wherein placing the tunable test antenna circuitry in a selected one of the plurality of predetermined states with the controller comprises using the microcontroller to tune the tunable test antenna circuitry, the method further comprising:

powering the microcontroller with the battery; and

charging the battery with the solar cell.

10. The method defined in claim 1, further comprising:

with the device under test, receiving the radio-frequency test signals from the at least one test antenna and computing performance metrics that reflect the quality of the received radio-frequency test signals.

11. The method defined in claim 10, wherein the at least one antenna tuning element comprises a tuning element selected from the group consisting of:

a switch and a phase shift circuit.

12. A method for using a test system to characterize a device under test, wherein the test system includes a sensor, a controller, and tunable test antenna circuitry formed separately from the sensor, wherein the sensor comprises a sensor selected from the group consisting of:

a microphone, a visible light sensor, a motion sensor, and a camera, the method comprising;

with the sensor, detecting a stimulus from the device under test;

in response to detecting the stimulus, alerting the controller with the sensor;

in response to being alerted, placing the tunable test antenna circuitry in a selected one of a plurality of predetermined states with the controller;

while the tunable test antenna circuitry is placed in the selected one of the plurality of predetermined states, transmitting radio-frequency test signals to the device under test using the tunable test antenna circuitry; and

with the device under test, receiving the radio-frequency test signals from the at least one test antenna and computing performance metrics that reflect the quality of the received radio-frequency test signals.

13. The method defined in claim 12, wherein the device under test has first and second opposing ends, the device under test has a first antenna located at the first end, and the device under test has a second antenna located at the second end.

14. The method defined in claim 13, wherein transmitting radio-frequency test signals to the device under test while the tunable test antenna circuitry is placed in the plurality of predetermined states comprises transmitting radio-frequency test signals in a first predetermined state and a second predetermined state, the first antenna is tested when the tunable test antenna circuitry is placed in the first predetermined state, the second antenna is tested when the tunable test antenna circuitry is placed in the second predetermined state, and placing the tunable test antenna circuitry in a selected one of a plurality of predetermined states with the controller in response to being alerted comprises switching the tunable test antenna circuitry from the first predetermined state to the second predetermined state in response to being alerted.

15. The method defined in claim 14, wherein the radio-frequency test signals are transmitted to the first antenna with a first beam pattern when the tunable test antenna circuitry is placed in the first predetermined state, the radio-frequency test signals are transmitted to the second antenna with a second beam pattern when the tunable test antenna circuitry is placed in the second predetermined state, and the first beam pattern is different than the second beam pattern.

16. The method defined in claim 14, wherein the tunable test antenna circuitry transmits radio-frequency test signals in a first direction when the tunable test antenna circuitry is placed in the first predetermined state and the tunable test antenna circuitry transmits radio-frequency test signals in a second direction that is different than the first direction when the tunable test antenna circuitry is placed in the second predetermined state.

17. The method defined in claim 14, wherein only the first antenna is tested when the tunable test antenna circuitry is placed in the first predetermined state and only the second antenna is tested when the tunable test antenna circuitry is placed in the second predetermined state.

18. A method for using a test system to characterize a device under test, wherein the test system includes a sensor, a controller, and tunable test antenna circuitry that includes at least one test antenna coupled to at least one antenna tuning element, and the sensor comprises a sensor selected from the group consisting of:

a microphone, a visible light sensor, a motion sensor, and a camera, the method comprising;

loading the device under test with a test operating system so that the device under test generates stimuli according to a predetermined test sequence;

placing the device under test within a radio-frequency test cell;

while the tunable test antenna circuitry is placed in a first predetermined state of a plurality of predetermined states, transmitting radio-frequency test signals to the device under test using the at least one test antenna;

with the device under test, receiving the radio-frequency test signals from the at least one test antenna and computing performance metrics that reflect the quality of the received radio-frequency test signals;

with the sensor, detecting a stimulus of the predetermined test sequence of stimuli, wherein the stimulus has a given value;

in response to detecting the stimulus, placing the tunable test antenna circuitry in a second predetermined state of the plurality of predetermined states with the controller, wherein the given value of the stimulus causes the controller to place the tunable test antenna circuitry in the second predetermined state;

while the tunable test antenna circuitry is placed in the second predetermined state, transmitting additional radio-frequency test signals to the device under test using the at least one test antenna; and

with the device under test, receiving the additional radio-frequency test signals from the at least one test antenna and computing additional performance metrics that reflect the quality of the received additional radio-frequency test signals.

19. The method defined in claim 18, wherein the device under test has first and second opposing ends, the device under test has a first antenna located at the first end, the device under test has a second antenna located at the second end, only the first antenna is tested when the tunable test antenna circuitry is placed in the first predetermined state, and only the second antenna is tested when the tunable test antenna circuitry is placed in the second predetermined state.

20. The method defined in claim 19, wherein the radio-frequency test signals are transmitted to the first antenna with a first beam pattern when the tunable test antenna circuitry is placed in the first predetermined state, the radio-frequency test signals are transmitted to the second antenna with a second beam pattern when the tunable test antenna circuitry is placed in the second predetermined state, and the first beam pattern is different than the second beam pattern.