Methods for Validating Radio-Frequency Test Stations

• US 20140167794A1
• Filed: 12/14/2012
• Published: 06/19/2014
• Est. Priority Date: 12/14/2012
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Nath, Jayesh, Han, Liang, Mow, Matthew A., Tsai, Ming-Ju, Nickel, Joshua G., Xu, Hao, Bevelacqua, Peter, Pascolini, Mattia, Caballero, Ruben, Schiub, Robert W.
• Granted Patent: US 9,164,159 B2
• Time in Patent Office: Days
• US Class Current: 324/750.02
• 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 31/2879 related to electrical aspects, e.g. to voltage or current supply or stimuli or to electrical loads
• CPC Class Codes: G01R 31/3191 Calibration
• CPC Class Codes: G01R 35/007 Standards or reference devices, e.g. voltage or resistance standards, "golden references"

Abstract

A manufacturing system for assembling wireless electronic devices is provided. The manufacturing system may include test stations for testing the radio-frequency performance of components that are to be assembled within the electronic devices. A reference test station may be calibrated using calibration coupons having known radio-frequency characteristics. The calibration coupons may include transmission line structures. The reference test station may measure verification standards to establish baseline measurement data. The verification standards may include circuitry having electrical components with given impedance values. Many verification coupons may be measured to enable testing for a wide range of impedance values. Test stations in the manufacturing system may subsequently measure the verification standards to generate test measurement data. The test measurement data may be compared to the baseline measurement data to characterize the performance of the test stations to ensure consistent test measurements across the test stations.

Claims

1. A method of validating a plurality of test stations, comprising:

with a plurality of calibration reference structures, calibrating at least one reference test station;

testing a plurality of verification reference structures with the at least one reference test station; and

with the plurality of verification reference structures, determining whether each test station in the plurality of test stations is capable of obtaining accurate test measurement data.

2. The method defined in claim 1, wherein the verification test structures comprise impedance modeling circuitry and conductive contacts formed on a substrate, the method further comprising:

removing systematic errors associated with the substrate and the conductive contacts of the verification test structures by calibrating the at least one reference test station with the reference test structures.

3. The method defined in claim 1, wherein determining whether each test station in the plurality of test stations is capable of obtaining accurate test measurement data comprises:

with each test station in the plurality of test stations, providing test signals to the verification reference structures; and

with each test station in the plurality of test stations, measuring scattering parameters associated with the verification reference structures.

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

obtaining baseline measurement data by testing the plurality of verification reference structures with the at least one reference test station;

obtaining test measurement data by testing the plurality of verification test structures with each test station in the plurality of test stations; and

comparing the test measurement data to the baseline measurement data to determine whether each test station in the plurality of test stations is capable of obtaining accurate test measurement data.

5. The method defined in claim 4, wherein each test station in the plurality of test stations includes a vector network analyzer and a test fixture, wherein determining whether each test station in the plurality of test stations is capable of obtaining accurate test measurement data comprises:

removing systematic errors associated with the vector network analyzer and the test fixture of each test station in the plurality of test stations prior to comparing the test measurement data to the baseline measurement data.

6. The method defined in claim 1, wherein each test station in the plurality of test stations includes a test host, the method further comprising:

with the test host, generating offset data to calibrate a test station in the plurality of test stations that is incapable of obtaining accurate test measurement data.

7. The method defined in claim 1, wherein the calibration reference structures each include a transmission line structure, and wherein calibrating the at least one reference test station comprises:

with the at least one reference test station, measuring radio-frequency characteristics associated with the transmission line structure.

8. The method defined in claim 7, wherein each calibration reference structure has a respective transmission line structure, and wherein measuring the radio-frequency characteristics associated with the transmission line structure comprises:

measuring the radio-frequency characteristics of the respective transmission line structure in each of the plurality calibration reference structures.

9. The method defined in claim 8, further comprising:

measuring the radio-frequency characteristics of the respective transmission line structure in each calibration reference structure using a THRU-REFLECT-LINE (TRL) approach.

10. The method defined in claim 7, wherein the radio-frequency characteristics include scattering parameters associated with the reference test structures, and wherein calibrating the at least one reference test station further comprises:

measuring the scattering parameters associated with reference test structures using the at least one reference test station.

11. A method of calibrating a reference test station, comprising:

with the reference test station, obtaining calibration measurement data by testing a plurality of passive reference test structures; and

calibrating the reference test station by comparing the calibration measurement data to reference data.

12. The method defined in claim 11, wherein obtaining calibration measurement data comprises:

with the reference test station, measuring radio-frequency characteristics associated with each passive reference test structure in the plurality of passive reference test structures.

13. The method defined in claim 12, wherein the reference data includes predetermined radio-frequency characteristics associated with each passive reference test structure in the plurality of passive reference test structures, and wherein comparing the calibration measurement data to the reference data comprises:

comparing the measured radio-frequency characteristics to the predetermined radio-frequency characteristics.

14. The method defined in claim 12, further comprising:

with an additional reference test station, measuring radio-frequency characteristics associated with each passive reference test structure in the plurality of passive reference test structures to obtain additional test data, wherein comparing the calibration measurement data to the reference data comprises comparing the calibration measurement data the to the additional test data.

15. The method defined in claim 13, wherein the measured radio-frequency characteristics comprise scattering parameters associated with each passive reference test structure in the plurality of passive reference test structures, and wherein the predetermined radio-frequency characteristics comprise predetermined scattering parameters associated with each passive reference test structure in the plurality of passive reference test structures, the method further comprising:

comparing the measured scattering parameters to the predetermined scattering parameters.

16. A method of validating a plurality of test stations, comprising:

with each test station in the plurality of test stations, obtaining verification measurement data by testing a plurality of passive reference test structures; and

determining whether each test station in the plurality of test stations is a passing test station by comparing the verification measurement data to reference data.

17. The method defined in claim 16, wherein the reference data is generated by a reference test station using the plurality of passive reference test structures, and wherein determining whether each test station in the plurality of test stations is a passing station comprises:

comparing the verification measurement data to reference data generated by the reference test station.

18. The method defined in claim 16, wherein obtaining verification measurement data comprises:

with the test station, measuring scattering parameters associated with each passive reference test structure in the plurality of passive reference test structures.

19. The method defined in claim 18, wherein the passive reference test structures include circuitry and conductive contacts coupled to the circuitry, wherein the circuitry comprises one or more electrical components connected between the conductive contacts in a shunt configuration, and wherein measuring the scattering parameters associated with each passive reference test structure comprises:

measuring the scattering parameters associated with the one or more electrical components connected between the conductive contacts in the shunt configuration.

20. The method defined in claim 18, wherein the passive reference test structures include circuitry and conductive contacts coupled to the circuitry, wherein the circuitry comprises one or more electrical components connected between the conductive contacts in a series configuration, and wherein measuring the scattering parameters associated with each passive reference test structure comprises:

measuring the scattering parameters associated with the one or more electrical components connected between the conductive contacts in the series configuration.