Calibration and adaptive control of antenna tuners

1. An apparatus comprising:

a radio-frequency (RF) path that includes an antenna tuner; and

calibration circuitry coupled to the antenna tuner, the calibration circuitry comprising a switched load and configured to selectively isolate an antenna from a component of the RF path.

2. The apparatus of claim 1 , wherein the calibration circuitry includes an electrostatic discharge device (ESD) coupled to an input or an output of the antenna tuner.

3. The apparatus of claim 1 , wherein the component includes the antenna tuner.

4. The apparatus of claim 1 , wherein the calibration circuitry is configured to terminate the RF path between the antenna and the component.

5. The apparatus of claim 1 , wherein the RF path includes a set of components and interconnections configured to propagate a signal from an RF source to an antenna port.

6. The apparatus of claim 1 , wherein the calibration circuitry is configurable to couple a first termination impedance to the RF path in a first configuration of the calibration circuitry, to couple a second termination impedance to the RF path in a second configuration of the calibration circuitry, and to couple a third termination impedance to the RF path in a third configuration of the calibration circuitry.

7. The apparatus of claim 1 , further comprising a detector coupled to the RF path.

8. The apparatus of claim 7 , wherein the RF path includes a transmission network between an amplifier and the antenna tuner, and wherein the detector is coupled to the RF path between the amplifier and the transmission network.

9. The apparatus of claim 7 , wherein the detector is remote from the antenna tuner to enable characterization of a circuit between the detector and the antenna.

10. The apparatus of claim 9 , wherein the circuit includes a transmission line across a printed circuit board.

11. An apparatus comprising:

means for propagating a signal from a radio-frequency (RF) source to an antenna port, the means for propagating including a means for adjusting an impedance; and

means for selectively isolating an antenna from a component of the means for propagating, the means for selectively isolating comprising a switched load.

12. The apparatus of claim 11 , wherein the means for selectively isolating includes an electrostatic discharge device (ESD) coupled to an input or an output of the means for adjusting.

13. The apparatus of claim 11 , wherein the means for propagating includes means for amplifying, and wherein the means for selectively isolating is configurable to selectively couple a first termination impedance to the means for propagating, to selectively couple a second termination impedance to the means for propagating, and to selectively couple a third termination impedance to the means for propagating.

14. The apparatus of claim 13 , wherein the means for propagating includes a transmission network between the means for amplifying and the means for selectively isolating, and further comprising a detector coupled to the means for propagating between the means for amplifying and the transmission network.

15. The apparatus of claim 11 , further comprising a detector that is remote from the means for selectively isolating to enable characterization of a circuit between the detector and the antenna.

16. The apparatus of claim 11 , wherein the means for propagating includes a transmission line across a printed circuit board.

17. A method comprising:

isolating, using calibration circuitry that includes a switched load, an antenna from a component of a radio-frequency (RF) path and coupling a calibration load to the RF path; and

after performing a calibration operation, decoupling the calibration load from the RF path and coupling the antenna to the component of the RF path.

18. The method of claim 17 , wherein coupling the calibration load to the RF path includes coupling a first termination impedance to the RF path, and further comprising:

coupling a second termination impedance to the RF path; and

coupling a third termination impedance to the RF path.

19. The method of claim 17 , further comprising displaying mismatch information, characterized S-parameters, an antenna impedance, delivered power corresponding to an antenna tuner state, or a combination thereof, at a display.

20. The apparatus of claim 1 , wherein the switched load comprises:

a first load having a first terminal coupled to ground and a second terminal selectively coupled to a main switch of the switched load;

a second load having a first terminal coupled to ground and a second terminal selectively coupled to the main switch; and

a third load having a first terminal coupled to ground and a second terminal selectively coupled to the main switch.