A near field radio-frequency identification (RFID) probe includes a probe tip comprising a resonant coil configured to communicate with an RFID compatible device at a predetermined resonant frequency. The near field RFID probe further includes a plurality of switch capacitor networks each comprising a capacitor and an RF switch, wherein switching the plurality of switch capacitor networks changes the capacitance of the resonant coil, thereby changing the resonant frequency of the resonant coil. The near field RFID probe further includes a probe control module configured to adjust the resonant frequency of the resonant coil to maintain the predetermined resonant frequency by switching the switch capacitor networks responsive to detecting that the resonant frequency of the resonant coil has deviated from the predetermined resonant frequency.

A circuit for calibrating an injection locked oscillator is provided. The injection locked oscillator includes an injection locking input, an LC tank and an oscillator output to output an oscillator output signal. The circuit is configured to adjust a capacitance of the LC tank to different values, detect an amplitude of the oscillator output signal for each value of the different values of the capacitance while an input signal having a target frequency is applied to the injection locking input, determine a maximum amplitude of the detected amplitudes, and select a value for operating the injection locked oscillator based on the determined maximum amplitude.

A network element (200) of a cable television (CATV) network, comprising an input (204) for upstream signal transmission; at least two diplex filters (210, 212, 214) configured to be connected to said input (204), a first diplex filter (210) comprising a bandpass filter for a first upstream frequency band and a second diplex filter (212) comprising a bandpass filter for a second upstream frequency band; a switch (208) for connecting one of said at least two diplex filters to said input; wherein the network element is configured to be remotely controlled by a headend of the CATV network for selecting the diplex filter.

Disclosed is an authentication reader intended to be installed on a motor vehicle opening element, the reader including a microcontroller, at least one transmitter, at least one matching circuit and a single antenna, called primary antenna, characterized by a working frequency. The matching circuit includes switching element able to switch the matching circuit between a first mode, in which the matching circuit makes it possible to match the primary antenna to a secondary antenna of an authentication device whose resonant frequency is lower than the working frequency, and a second mode, in which the matching circuit makes it possible to match the primary antenna to a secondary antenna of an authentication device whose resonant frequency is higher than the working frequency.

A near field radio-frequency identification (RFID) probe includes a probe tip comprising a resonant coil configured to communicate with an RFID compatible device at a predetermined resonant frequency. The near field RFID probe further includes a plurality of switch capacitor networks each comprising a capacitor and an RF switch, wherein switching the plurality of switch capacitor networks changes the capacitance of the resonant coil, thereby changing the resonant frequency of the resonant coil. The near field RFID probe further includes a probe control module configured to adjust the resonant frequency of the resonant coil to maintain the predetermined resonant frequency by switching the switch capacitor networks responsive to detecting that the resonant frequency of the resonant coil has deviated from the predetermined resonant frequency.

A biasing circuit for biasing a switching transistor, wherein the switching transistor is used for switching a respective capacitor cell into/out of a capacitor array, wherein the capacitor array comprises one or more such capacitor cells, and wherein the capacitor array is coupled in parallel with a primary inductor to form an inductive/capacitive tank. The biasing circuit comprises a secondary inductor which is inductively coupled to the primary inductor, the secondary inductor configured to provide a bias signal for biasing the switching transistor.

In one embodiment, a phase detection circuit includes a current signal input to receive a current signal indicative of a current amplitude of an RF signal and a voltage signal input to receive a voltage signal indicative of a voltage amplitude of the RF signal. A high-pass filter and a low-pass filter are each configured to filter one of (i) the current signal from the current signal input or (ii) the voltage signal from the voltage signal input, wherein the high-pass filter and the low-pass filter collectively cause a substantially 90 degree offset between a phase angle of the current signal and a phase angle of the voltage signal. A phase difference circuit receives the filtered current signal and the filtered voltage signal to determine a phase angle difference between the current signal and the voltage signal.

A near field radio-frequency identification (RFID) probe includes a probe tip comprising a resonant coil configured to communicate with an RFID compatible device at a predetermined resonant frequency. The near field RFID probe further includes a plurality of switch capacitor networks each comprising a capacitor and an RF switch, wherein switching the plurality of switch capacitor networks changes the capacitance of the resonant coil, thereby changing the resonant frequency of the resonant coil. The near field RFID probe further includes a probe control module configured to adjust the resonant frequency of the resonant coil to maintain the predetermined resonant frequency by switching the switch capacitor networks responsive to detecting that the resonant frequency of the resonant coil has deviated from the predetermined resonant frequency.

A circuit for calibrating an injection locked oscillator is provided. The injection locked oscillator includes an injection locking input, an LC tank and an oscillator output to output an oscillator output signal. The circuit is configured to adjust a capacitance of the LC tank to different values, detect an amplitude of the oscillator output signal for each value of the different values of the capacitance while an input signal having a target frequency is applied to the injection locking input, determine a maximum amplitude of the detected amplitudes, and select a value for operating the injection locked oscillator based on the determined maximum amplitude.

A biasing circuit for biasing a switching transistor, wherein the switching transistor is used for switching a respective capacitor cell into/out of a capacitor array, wherein the capacitor array comprises one or more such capacitor cells, and wherein the capacitor array is coupled in parallel with a primary inductor to form an inductive/capacitive tank. The biasing circuit comprises a secondary inductor which is inductively coupled to the primary inductor, the secondary inductor configured to provide a bias signal for biasing the switching transistor.