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.

A communication system includes a passive wireless sensor and a sensor computing device. The passive wireless sensor is operable to receive a radio frequency (RF) signal including a carrier frequency signal and a modulated sense request signal, generate a power supply voltage, determine received signal strength (RSSI) of the RF signal, and determine whether the RSSI is at a desired level. When the RSSI is at a desired level, the passive wireless sensor generates a response RF signal including the carrier frequency and a coded sense response signal representative of a sensed environmental condition. The sensed environmental condition affects impedance of a front-end of the passive wireless sensor to produce an affected impedance. The passive wireless sensor generates the coded sense response signal based on tuning the affected impedance to resonate with the carrier frequency signal. The computing device operable to: transmit the RF signal, receive the response RF signal, and generate an environmental condition value based on the coded sense response signal and environmental conversion information.

A communication system includes a passive wireless sensor and a sensor computing device. The passive wireless sensor is operable to receive a radio frequency (RF) signal including a carrier frequency signal and a modulated sense request signal, generate a power supply voltage, determine received signal strength (RSSI) of the RF signal, and determine whether the RSSI is at a desired level. When the RSSI is at a desired level, the passive wireless sensor generates a response RF signal including the carrier frequency and a coded sense response signal representative of a sensed environmental condition. The sensed environmental condition affects impedance of a front-end of the passive wireless sensor to produce an affected impedance. The passive wireless sensor generates the coded sense response signal based on tuning the affected impedance to resonate with the carrier frequency signal. The computing device operable to: transmit the RF signal, receive the response RF signal, and generate an environmental condition value based on the coded sense response signal and environmental conversion information.

An electronic device is provided. The electronic device includes a first conductive layer, a second conductive layer that is formed to be opposite to the first conductive layer. The second conductive layer includes conductors that are electrically separated, and one or more photo-conductive members connected between the conductors. The electronic device further includes an insulating layer that is interposed between the first conductive layer and the second conductive layer, one or more light sources positioned to face the one or more photo-conductive members, and a control circuit. The control circuit outputs a specified light through the light source such that an electric conductivity of the photo-conductive member increases in response to a light, from among the photo-conductive members and some conductors are electrically connected with the photo-conductive member, and a capacitance value between the first conductive layer and the second conductive layer is changed.

An electronic device is provided. The electronic device includes a first conductive layer, a second conductive layer that is formed to be opposite to the first conductive layer. The second conductive layer includes conductors that are electrically separated, and one or more photo-conductive members connected between the conductors. The electronic device further includes an insulating layer that is interposed between the first conductive layer and the second conductive layer, one or more light sources positioned to face the one or more photo-conductive members, and a control circuit. The control circuit outputs a specified light through the light source such that an electric conductivity of the photo-conductive member increases in response to a light, from among the photo-conductive members and some conductors are electrically connected with the photo-conductive member, and a capacitance value between the first conductive layer and the second conductive layer is changed.

A radio frequency identification (RFID) tag includes an antenna operable to receive a radio frequency (RF) signal having a carrier frequency. The RFID tag further includes a tank circuit coupled to the antenna. The RFID tag further includes a tuning circuit operable to determine a received power level of the RF signal at the carrier frequency, determine whether the received power level is lower than a power level threshold. When the received power level is lower than the power level threshold: tuning circuit increases the input impedance of the RFID tag, determines a most recent power level of the received RF signal, and compares the most recent power level with the received power level. When the most recent power level is greater than the received power level, the tuning circuit incrementally increases the input impedance until the received power level is substantially equal to the power level threshold.

A radio frequency identification (RFID) tag includes an antenna operable to receive a radio frequency (RF) signal having a carrier frequency. The RFID tag further includes a tank circuit coupled to the antenna. The RFID tag further includes a tuning circuit operable to determine a received power level of the RF signal at the carrier frequency, determine whether the received power level is lower than a power level threshold. When the received power level is lower than the power level threshold: tuning circuit increases the input impedance of the RFID tag, determines a most recent power level of the received RF signal, and compares the most recent power level with the received power level. When the most recent power level is greater than the received power level, the tuning circuit incrementally increases the input impedance until the received power level is substantially equal to the power level threshold.

A method includes transmitting, by a radio frequency identification (RFID) reader, a series of RF signals to RFID tags in a time sequence. A first RF signal includes a first message for responding when received signal strength corresponds to a first power level and a second RF signal includes a second message for responding when the received signal strength of the RF signal corresponds to a second power level. The method further includes receiving, by the RFID reader, a first set of responses from a first set of RFID tags that received the first and second RF signals at a received signal strength corresponding to the first power level. The method further includes receiving, by the RFID reader, a second set of responses from a second set of RFID tags that received the first and second RF signals at a received signal strength corresponding to the second power level.

A method includes transmitting, by a radio frequency identification (RFID) reader, a series of RF signals to RFID tags in a time sequence. A first RF signal includes a first message for responding when received signal strength corresponds to a first power level and a second RF signal includes a second message for responding when the received signal strength of the RF signal corresponds to a second power level. The method further includes receiving, by the RFID reader, a first set of responses from a first set of RFID tags that received the first and second RF signals at a received signal strength corresponding to the first power level. The method further includes receiving, by the RFID reader, a second set of responses from a second set of RFID tags that received the first and second RF signals at a received signal strength corresponding to the second power level.