# US 2013/0154897 A1 · Methods and Apparatus for Controlling Tunable Antenna Systems > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2013/0154897 A1 - Document ID: US20130154897A1 - Status: Published application - Kind: A1 - Application number: 13/332,193 - Filed: 2011-12-20 - Published: 2013-06-20 - Earliest claimed: 2011-12-20 - Assignees: Apple Inc. - Inventors: Robert S. Sorensen; Qingxiang Li; Matthew A. Mow; Jinku Kim - Web page: https://patentgrep.com/patent/US20130154897A1 ## CPC - H01Q 5/314: using frequency dependent circuits or components, e.g. trap circuits or capacitors - H01Q 5/328: between a radiating element and ground - H01Q 5/335: at the feed, e.g. for impedance matching - H01Q 7/005: {with variable reactance for tuning the antenna} - H01Q 23/00: Antennas with active circuits or circuit elements integrated within them or attached to them - H03J 3/20: of single resonant circuit by varying inductance only or capacitance only - H04B 1/40: Circuits - H03J 2200/11: Cellular receiver, e.g. GSM, combined with a GPS receiver - H01Q: ANTENNAS, i.e. RADIO AERIALS (radiators or antennas for microwave heating H05B6/72) - H03J: TUNING RESONANT CIRCUITS; SELECTING RESONANT CIRCUITS - H04B: TRANSMISSION ## Abstract 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. ## Claims ### Claim 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; and 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. ### Claim 2 (depends on 1) The antenna defined in claim 1 further comprising: antenna resonating structures coupled to the antenna feed via at least a capacitor, wherein the first and second terminals of the antenna tuning element is coupled to the first and second antenna feed terminals via respective inductors. ### Claim 3 (depends on 1) The antenna defined in claim 1, wherein the control circuit includes a voltage regulating circuit configured to receive the first control signal and to generate corresponding first and second voltage signals. ### Claim 4 (depends on 3) The antenna defined in claim 3, wherein the control circuit further includes a comparator circuit configured to receive the first and second voltage signals, and wherein the comparator circuit is operable to drive its output high when the first voltage signal exceeds the second voltage signal and is operable to drive its output low when the second voltage signal exceeds the first voltage signal. ### Claim 5 (depends on 4) The antenna defined in claim 4, wherein the control circuit further includes a counter circuit having a control input that is coupled to the output of the comparator circuit and having 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, and wherein the second control signal at the output of the comparator circuit is proportional to the count associated with the counter circuit. ### Claim 6 (depends on 1) The antenna defined in claim 1, wherein the antenna tuning element comprises radio-frequency switching circuitry. ### Claim 7 (depends on 6) The antenna defined in claim 6, wherein the antenna tuning element further comprises a plurality of capacitive structures couple to respective ports of the radio-frequency switching circuitry. ### Claim 8 (depends on 6) The antenna defined in claim 6, wherein the antenna tuning element further comprises a plurality of inductive structures coupled to respective ports of the radio-frequency switching circuitry. ### Claim 9 (depends on 1) The antenna defined in claim 1, wherein the antenna tuning element comprises a variable capacitor. ### Claim 10 (depends on 1) The antenna defined in claim 1 wherein the antenna comprises an antenna selected from the group consisting of: a loop antenna, an inverted-F antenna, a patch antenna, a slot antenna, a planar inverted-F antenna, and a helical antenna. ### Claim 11 A method for using an electronic device having control circuitry, transceiver circuitry, and an antenna, wherein the antenna is coupled to the transceiver circuitry via an antenna feed, wherein the control circuitry is coupled to the antenna feed, and wherein the antenna includes at least one antenna tuning circuit, the method comprising: with the control circuitry, tuning the antenna to operate in a desired frequency band by supplying a control signal to the antenna tuning circuit via the antenna feed. ### Claim 12 (depends on 11) The method defined in claim 11, wherein supplying the control signal to the antenna tuning circuit via the antenna feed comprises supplying the control signal to the antenna tuning circuit via the antenna feed during power-on-reset operations. ### Claim 13 (depends on 11) The method defined in claim 11 further comprising: with the control circuitry, supplying a power supply signal to the antenna tuning circuit via the antenna feed during normal operation. ### Claim 14 (depends on 11) The method defined in claim 11, wherein the control circuitry toggles the control signal a predetermined number of times and wherein the antenna tuning circuit includes a counter circuit, the method further comprising: with the counter circuit, determining an amount by which the antenna is to be tuned by counting the number of times the control signal toggles. ### Claim 15 The method defined in claim, wherein the antenna tuning circuit includes a control circuit and a tunable element, and wherein supplying the control signal to the antenna tuning circuit comprises configuring the control circuit to generate an additional control signal that adjusts the tunable element. ### Claim 16 A method for using an electronic device having control circuitry that supplies a direct current (DC) control signal, transceiver circuitry, and an antenna, wherein the antenna is coupled to the transceiver circuitry via an antenna feed, wherein the control circuitry is coupled to the antenna feed, and wherein the antenna includes at least one antenna tuning circuit, the method comprising: tuning the antenna by modulating the DC control signal to adjust the antenna tuning circuit. ### Claim 17 (depends on 16) The method defined in claim 16, wherein modulating the DC control signal comprises varying the DC control signal between first and second voltage levels with the control circuitry. ### Claim 18 (depends on 17) The method defined in claim 17, wherein varying the DC control signal between the first and second voltage levels comprises generating a DC control signal having a predetermined number of pulses with the control circuitry. ### Claim 19 (depends on 18) The method defined in claim 18, wherein the antenna tuning circuit includes a counter circuit, the method further comprising: with the counter circuit, determining an amount by which the antenna is to be tuned by counting the number of pulses in the DC control signal. ### Claim 20 (depends on 16) The method defined in claim 16, wherein the electronic device is configured to operate in a given radio-frequency band, the method further comprising: selecting a modulation scheme for modulating the DC control signal based on the given radio-frequency band by referring to a predetermined lookup table that is stored in the control circuitry.