Methods and apparatus for performing passive antenna testing with active antenna tuning device control
A wireless electronic device may contain at least one adjustable antenna tuning element for use in tuning the operating frequency range of the device. The antenna tuning element may include radio-frequency switches, continuously/semi-continuously adjustable components such as tunable resistors, inductors, and capacitors, and other load circuits that provide desired impedance characteristics. A test system that is used for performing passive radio-frequency (RF) testing on antenna tuning elements in partially assembled devices is provided. The test system may include an RF tester and a test host. The tester may be used to gather scattering parameter measurements from the antenna tuning element. The test host may be used to ensure that power and appropriate control signals are being supplied to the antenna tuning element so that the antenna tuning element is placed in desired tuning states during testing.
1. A method for using a radio-frequency test system to test an electronic device under test that contains transceiver circuitry and a tunable antenna having an adjustable antenna tuning element, the method comprising:
placing the adjustable antenna tuning element in a plurality of tuning states to tune the tunable antenna;
while the adjustable antenna tuning element is being placed in each of the plurality of states and while the transceiver circuitry is deactivated, gathering test data from the electronic device under test with the radio-frequency test system; and
with the radio-frequency test system, gathering baseline test data by performing radio-frequency calibration on a plurality of reference electronic devices under test, wherein the adjustable antenna tuning element comprises at least one adjustable circuit selected from the group consisting of: a radio-frequency switch, a tunable resistive component, a tunable capacitive component, and a tunable inductive component.
2. The method defined in claim 1 , further comprising:
with the radio-frequency test system, comparing the test data to the baseline radio-frequency test data to determine whether the tunable antenna satisfies design criteria.
3. The method defined in claim 1 , wherein gathering the test data and the baseline test data comprises obtaining multiport scattering parameter measurements.
4. The method defined in claim 1 , wherein placing the adjustable antenna tuning element in the plurality of tuning states comprises controlling the adjustable antenna tuning element using the radio-frequency test system.
5. The method defined in claim 1 , wherein placing the adjustable antenna tuning element in the plurality of tuning states comprises configuring the adjustable antenna tuning element to exhibit different impedance values in the respective tuning states.
6. The method defined in claim 1 , wherein the radio-frequency test system comprises a radio-frequency tester, and wherein gathering the test data from the electronic device under test comprises:
sending radio-frequency test signals to the electronic device under test with the radio-frequency tester; and
receiving corresponding radio-frequency test signals from the electronic device under test with the radio-frequency tester.
7. The method defined in claim 6 , wherein gathering the test data from the electronic device under test comprises gathering scattering parameter measurements.
8. The method defined in claim 1 , wherein the electronic device under test comprises a partially assembled wireless electronic device.
9. The method defined in claim 8 , wherein gathering test data from the electronic device under test with the radio-frequency test system comprises gathering scattering parameter measurements from the electronic device under test while the transceiver circuitry in the electronic device under test is idle.
10. The method defined in claim 9 , wherein gathering the scattering parameter measurements comprises coupling the adjustable antenna tuning element to the radio-frequency test system using a contact test probe.
11. The method defined in claim 9 , wherein gathering the scattering parameter measurements comprises coupling the adjustable antenna tuning element to the radio-frequency test system using a wireless test probe.