Methods and apparatus for controlling tunable antenna systems

摘要

An electronic device may include an adjustable power supply, at least one antenna, and associated antenna tuning circuitry. The antenna tuning circuitry may be an integral part of the antenna and may include a control circuit and at least one tunable element. The tunable 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. The power supply may provide power supply voltage signals to the antenna tuning circuitry via inductive coupling. The power supply voltage signals may be modulated according to a predetermined lookup table during device startup so that the control circuit is configured to generate desired control signals. These control signals adjust the tunable element so that the antenna can support wireless operation in desired frequency bands.

主权项

1. An antenna in an electronic device comprising:
an antenna feed that includes first and second antenna feed terminals; a control circuit configured to receive a first control signal from the antenna feed and configured to generate a second control signal; an antenna tuning element having a first terminal coupled to the first antenna feed terminal, a second terminal coupled to the second antenna feed terminal, and a third terminal configured to receive the second control signal; a voltage regulating circuit in the control circuit; a comparator circuit in the control circuit; and a counter circuit in the control circuit that has a control input that is coupled to the comparator circuit and has an output on which the second control signal is provided, wherein the counter circuit is configured to increment its count in response to detecting a transition at its control input, the second control signal at the output of the counter circuit is proportional to the count associated with the counter circuit, and the antenna tuning element is placed in an operating state to tune the antenna to a selected frequency based on the count as identified by the second control signal.