A system is described for maintaining an inductive-capacitive (LC) network at resonance while the excitation frequency may be varied between a number of discrete frequencies at desired instants controlled by a modulation input, while taking into account component parameter errors due environmental and ageing as well as manufacturing tolerances. Control of the resonance while the excitation frequency changes permits the transmission of frequency modulation (FM) or frequency shift keying (FSK) information through an inductively coupled power transfer system.

A tuner circuit includes a DC (Direct Current) cut-off unit configured to cut off a DC component in a signal received from an antenna, a switching unit configured to transmit the signal by being turned on when a bias voltage is applied, a high pass filter unit configured to pass only a high frequency component in a signal having passed the switching unit, and a low noise amplifier configured to output a signal having passed a high frequency filter by amplifying the signal.

A method and apparatus for adapting an electronic device to receive digital television broadcast signals is disclosed. The device comprises a switch commandable to interpose one or more matching networks as in the RF signal path according to a channel command to match an integrated headset antenna to the tuner receiving the RF signals.

The invention relates to an HF module, the filter functionality of which can easily be expanded and which has good electrical properties. For this purpose, the module comprises two filter units with a respective HF filter and a switch having two possible switching states. The two filter units are connected in parallel.

In one embodiment, a tuning network includes: a controllable capacitance; a first switch coupled between the controllable capacitance and a reference voltage node; a second switch coupled between the controllable capacitance and a third switch; the third switch coupled between the second switch and a second voltage node; a fourth switch coupled between the second voltage node and a first inductor; the first inductor having a first terminal coupled to the fourth switch and a second terminal coupled to at least the second switch; and a second inductor having a first terminal coupled to the second terminal of the first inductor and a second terminal coupled to the controllable capacitance.

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 multiport RF switch assembly with integrated impedance tuning capability is described that provides a single RFIC solution to switch between transmit and receive paths in a communication system. Dynamic tuning is integrated into each switch sub-assembly to provide the capability to impedance match antennas or other components connected to the multiport switch. The tuning function at the switch can be used to shape the antenna response to provide better filtering at the switch/RF front-end (RFFE) interface to allow for reduced filtering requirements in the RFFE. Memory is designed into the multiport switch assembly, allowing for a look-up table or other data to reside with the switch and tuning circuit. The resident memory will result in easier integration of the tunable switch assembly into communication systems.

In one embodiment, a tuning network includes: a controllable capacitance; a first switch coupled between the controllable capacitance and a reference voltage node; a second switch coupled between the controllable capacitance and a third switch; the third switch coupled between the second switch and a second voltage node; a fourth switch coupled between the second voltage node and a first inductor; the first inductor having a first terminal coupled to the fourth switch and a second terminal coupled to at least the second switch; and a second inductor having a first terminal coupled to the second terminal of the first inductor and a second terminal coupled to the controllable capacitance.

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.

In one embodiment, a tuning network includes: a controllable capacitance; a first switch coupled between the controllable capacitance and a reference voltage node; a second switch coupled between the controllable capacitance and a third switch; the third switch coupled between the second switch and a second voltage node; a fourth switch coupled between the second voltage node and a first inductor; the first inductor having a first terminal coupled to the fourth switch and a second terminal coupled to at least the second switch; and a second inductor having a first terminal coupled to the second terminal of the first inductor and a second terminal coupled to the controllable capacitance.