A method for execution by a RFID tag includes receiving, from an RFID reader, an RF signal, where the RF signal has a carrier frequency of a plurality of carrier frequencies that span a broad frequency band. The method further includes adjusting input impedance of the RFID tag over a range of input impedances, where the input impedance of the RFID tag is based on one or more of impedance of the RFID tag's antenna and tank circuit. The method further includes monitoring power level of the received RF signal over the range of input impedances. The method further includes selecting the input impedance of the range of input impedances providing a substantially maximum power level of the received RF signal, where the substantially maximum power level corresponds to the carrier frequency being substantially equal to a resonant frequency of at least one of the antenna and the tank circuit.

A method for execution by a RFID tag includes receiving, from an RFID reader, an RF signal, where the RF signal has a carrier frequency of a plurality of carrier frequencies that span a broad frequency band. The method further includes adjusting input impedance of the RFID tag over a range of input impedances, where the input impedance of the RFID tag is based on one or more of impedance of the RFID tag's antenna and tank circuit. The method further includes monitoring power level of the received RF signal over the range of input impedances. The method further includes selecting the input impedance of the range of input impedances providing a substantially maximum power level of the received RF signal, where the substantially maximum power level corresponds to the carrier frequency being substantially equal to a resonant frequency of at least one of the antenna and the tank circuit.

A method using a phase locked loop (PLL) includes receiving a reference frequency. The method further includes generating a control signal based on the reference frequency. The method further includes adjusting an output signal based on the control signal. Adjusting the output signal includes operating a plurality of switches in response to the control signal, wherein operating the plurality of switches comprises selectively electrically connecting a first ground plane to a first floating plane, wherein the first floating plane is between the first ground plane and the signal line, and the first floating plane is a same distance from a substrate as the first ground plane.

Apparatus and methods of automatically trimming a PCB-based LC circuit. The apparatus may comprise an interface to a printed circuit board (PCB). The PCB may include a PCB inductor and a PCB capacitor to form an LC circuit. The LC circuit may have an LC circuit frequency. The apparatus may comprise a variable capacitor communicatively coupled to the interface and configured to adjust an effective capacitance of the LC circuit.

A tunable inductor arrangeable on a chip or substrate comprises a first winding part connected at one end to a first input of the tunable inductor arrangement, a second winding part connected at one end to the other end of the first winding part, a third winding part connected at one end to a second input of the tunable inductor arrangement, a fourth winding part connected at one end to the other end of the third winding part, and a switch arrangement arranged. The switch arrangement tunes the tunable inductor by selectively connecting the first and fourth winding parts in parallel and the second and third winding parts in parallel, with the parallel couplings in series between the first and second inputs, or connecting the first, second, fourth and third winding parts in series between the first and second inputs. Corresponding transceivers, communication devices, methods and computer programs are disclosed.

A tunable inductor arrangeable on a chip or substrate comprises a first winding part connected at one end to a first input of the tunable inductor arrangement, a second winding part connected at one end to the other end of the first winding part, a third winding part connected at one end to a second input of the tunable inductor arrangement, a fourth winding part connected at one end to the other end of the third winding part, and a switch arrangement arranged. The switch arrangement tunes the tunable inductor by selectively connecting the first and fourth winding parts in parallel and the second and third winding parts in parallel, with the parallel couplings in series between the first and second inputs, or connecting the first, second, fourth and third winding parts in series between the first and second inputs. Corresponding transceivers, communication devices, methods and computer programs are disclosed.

An RF signal is tuned by: producing a first signal at a first frequency using a digital sequence generator; filtering the first signal using a frequency-tunable tracking filter that is tuned to the first frequency, the tracking filter comprising one or more variable resonators; tuning the tracking filter from the first frequency to a second frequency over a transition period; and tuning the first signal to the second frequency by causing the digital sequence generator to transition between two or more states during the transition period. The two or more states are selected such that, immediately after the transition period, the analog signal substantially matches a desired steady state at the second frequency.

An RF signal is tuned by: producing a first signal at a first frequency using a digital sequence generator; filtering the first signal using a frequency-tunable tracking filter that is tuned to the first frequency, the tracking filter comprising one or more variable resonators; tuning the tracking filter from the first frequency to a second frequency over a transition period; and tuning the first signal to the second frequency by causing the digital sequence generator to transition between two or more states during the transition period. The two or more states are selected such that, immediately after the transition period, the analog signal substantially matches a desired steady state at the second frequency.

Apparatus and methods of automatically trimming a PCB-based LC circuit. The apparatus may comprise an interface to a printed circuit board (PCB). The PCB may include a PCB inductor and a PCB capacitor to form an LC circuit. The LC circuit may have an LC circuit frequency. The apparatus may comprise a variable capacitor communicatively coupled to the interface and configured to adjust an effective capacitance of the LC circuit.

An apparatus is disclosed for implementing an antenna tuner. In an example aspect, the apparatus includes a substrate, an antenna disposed on or in the substrate, a radio-frequency integrated circuit disposed on the substrate, and an antenna tuner. The radio-frequency integrated circuit includes an amplification circuit. The antenna tuner is coupled between the antenna and the amplification circuit. The antenna tuner includes an inductive component disposed on or in the substrate and a capacitive component implemented within the radio-frequency integrated circuit.