A high-frequency filter includes a variable frequency filter, a fixed frequency filter, and switches. The variable frequency filter varies a passband in association with frequencies used in multiple communication band. The fixed frequency filter fixes a passband in association with a frequency used in a specific communication band different from the multiple communication bands. The switches are used to switch connection configuration to the variable frequency filter or the fixed frequency filter.

A high-frequency filter includes a variable frequency filter, a fixed frequency filter, and switches. The variable frequency filter varies a passband in association with frequencies used in multiple communication band. The fixed frequency filter fixes a passband in association with a frequency used in a specific communication band different from the multiple communication bands. The switches are used to switch connection configuration to the variable frequency filter or the fixed frequency filter.

A tunable Q resonator using a capacitive-piezoelectric transducer provides a flexible top electrode above an AlN resonator. The top electrode can be pulled electrostatically towards the resonator and substrate, forming a frictional contact with either the resonator or the combined resonator-electrode structure to the substrate, allowing for electrical tuning the Q of the resonator. With a sufficient electrostatic bias voltage V.sub.b, the resonator may be completely turned OFF, allowing for an integrated switchable AlN resonator. Such switchable resonator may be integrated into a radio frequency (RF) front end as a digitally selectable band pass filter element, obviating the need for ancillary micromechanical switches in the signal path. The device has been demonstrated with a Q approaching 9,000, together with ON/OFF switchability and electromechanical coupling up to 0.63%. Flexible positioning of the top electrode allows for actively controlling the series resonant frequency of the resonator through changes in capacitive coupling.

A ceramic resonator radio frequency filter includes a printed circuit board, one or more first coaxial resonators disposed on the printed circuit board, and one or more second coaxial resonators disposed over the one or more first coaxial resonators so that the one or more first coaxial resonators and one or more second coaxial resonators are arranged in a stacked configuration. The one or more first coaxial resonators and second coaxial resonators electrically connected to the printed circuit board.

A ceramic resonator radio frequency filter includes a printed circuit board, one or more first coaxial resonators disposed on the printed circuit board, and one or more second coaxial resonators disposed over the one or more first coaxial resonators so that the one or more first coaxial resonators and one or more second coaxial resonators are arranged in a stacked configuration. The one or more first coaxial resonators and second coaxial resonators electrically connected to the printed circuit board.

A signal processing apparatus, being configured for transmitting and receiving coherent parallel optical signals, comprises a transmitter apparatus including a first single soliton micro-resonator device and a modulator device, wherein the first single soliton micro-resonator device is adapted for creating a single soliton providing a first frequency comb, wherein the first frequency comb provides a plurality of equidistant optical carriers with a frequency spacing corresponding to a free spectral range of the first single soliton micro-resonator device, and the modulator device is adapted for modulating the optical carriers according to data to be transmitted, and a receiver apparatus including a coherent receiver device with a plurality of coherent receivers and a local oscillator device providing a plurality of reference optical signals, wherein the coherent receiver device and the local oscillator device are arranged for coherently detecting the transmitted modulated optical carriers, wherein the signal processing apparatus further includes at least one second single soliton micro-resonator device having a free spectral range being equal or approximated to the free spectral range of the first single soliton micro-resonator device and being adapted for creating at least one single soliton providing at least one second frequency comb, wherein the at least one second frequency comb provides at least one of additional optical carriers and the reference optical signals. Furthermore, a signal processing method, including transmitting and receiving coherent parallel optical signals via a communication channel is described.

A high-frequency filter includes a variable frequency filter, a fixed frequency filter, and switches. The variable frequency filter varies a passband in association with frequencies used in multiple communication band. The fixed frequency filter fixes a passband in association with a frequency used in a specific communication band different from the multiple communication bands. The switches are used to switch connection configuration to the variable frequency filter or the fixed frequency filter.

A high-frequency filter includes a variable frequency filter, a fixed frequency filter, and switches. The variable frequency filter varies a passband in association with frequencies used in multiple communication band. The fixed frequency filter fixes a passband in association with a frequency used in a specific communication band different from the multiple communication bands. The switches are used to switch connection configuration to the variable frequency filter or the fixed frequency filter.

A frequency divider apparatus includes a micro-electro-mechanical system (MEMS) divider that is configured to be driven by an input signal. The MEMS divider includes a passive mechanical device that generates multiple output signals. Each of the output signals has a frequency less than a frequency of the input signal.

A MEMS (microelectromechanical system) resonator assembly (100), comprising a support structure (102), a resonator element (101) suspended to the support structure (102), and an actuator for exciting the resonator element (101) to a resonance mode. The resonator element (101) vibrates at resonance frequency f.sub.0 and comprises at least one bulk acoustic resonator (110a, 110b). The ESR*A*f.sub.0 values of the resonator assembly (100) are in the range from 12 mm.sup.2 MHz to 83 mm.sup.2 MHZ.