Abstract:
A method for acoustically isolating an acoustic resonator comprises: providing a substrate; forming a porous region in the substrate; forming the acoustic resonator on the porous region; and removing the porous region from the substrate. The removing forms a cavity that separates a portion of the acoustic resonator from the substrate. By using the techniques described herein, it is possible to form an acoustic resonator on a substrate and to form a cavity between the acoustic resonator and the substrate without depositing sacrificial material.
Abstract:
A bandpass filter includes input and output terminals, first and second acoustic resonators, and an acoustic coupling layer. The first acoustic resonator includes first and second electrodes, and a piezoelectric layer between the first and second electrodes. The first electrode of the first acoustic resonator is connected to the input terminal. The second acoustic resonator includes first and second electrodes, and a piezoelectric layer between the first and second electrodes. The acoustic coupling is provided between the second electrode of the first acoustic resonator and the first electrode of the second acoustic resonator. The output terminal is connected to the second electrode of the second acoustic resonator. A capacitor extends between the input terminal and the output terminal. The filter's frequency response includes at least two transmission zeros.
Abstract:
Systems and methods of detecting wireless channel status from acoustic discrimination of spectral content are described. In one aspect, a wireless system includes a spectrum analyzer, a detector, and a controller. The spectrum analyzer is operable to acoustically discriminate spectral content of an input electrical signal in multiple discrete frequency channels. The detector is operable to determine respective statuses of the frequency channels from the acoustically discriminated spectral content. The controller is operable to select one of the frequency channels based on the determined statuses of the frequency channels.
Abstract:
An oscillatory circuit. The oscillatory circuit includes a first oscillator, a second oscillator, and a mixer circuit. The first oscillator is configured to generate a first oscillating signal at a first frequency and has a first frequency temperature coefficient. The second oscillator is configured to generate a second oscillating signal at a second frequency and has a second frequency temperature coefficient. The second frequency is greater than the first frequency, and the second frequency temperature coefficient is less than the first frequency temperature coefficient. The mixer circuit is configured to receive the first oscillating signal from the first oscillator, to receive the second oscillating signal from the second oscillator, and to generate a mixer signal from the first and the second oscillating signals. The mixer signal comprises a signal component at a beat frequency. The beat frequency is equal to the difference between the second frequency and the first frequency.
Abstract:
A humidity sensor that includes a resonant structure and a structure for altering a resonant frequency of the resonant structure in response to a change in humidity. The structures of a humidity sensor according to the present teachings may be formed in relatively small form factors and are well suited to remote applications and providing mechanisms for compensating for temperature drift.
Abstract:
The present invention provides a first wafer and a second wafer having a device. A separation layer is formed on the first wafer. A cap is formed on the separation layer. The cap and the second wafer are bonded using a gasket. The first wafer is separated from the cap to form the semiconductor package comprised of the cap, the gasket, and the second wafer.
Abstract:
Systems and methods of detecting wireless channel status from acoustic discrimination of spectral content are described. In one aspect, a wireless system includes a spectrum analyzer, a detector, and a controller. The spectrum analyzer is operable to acoustically discriminate spectral content of an input electrical signal in multiple discrete frequency channels. The detector is operable to determine respective statuses of the frequency channels from the acoustically discriminated spectral content. The controller is operable to select one of the frequency channels based on the determined statuses of the frequency channels.
Abstract:
An RF switching circuit that incorporates a film bulk acoustic resonator (FBAR) device and one or more capacitors that are used to vary the capacitance of the FBAR device to change the frequency range that is blocked by the FBAR device. When the RF switching circuit is in a first switching state, a first set of RF signals in a first frequency range is blocked by the RF switching circuit while RF signals of other frequencies are passed by the RF switching circuit. When the RF switching circuit is in a second switching state, a second set of RF signals in a second frequency range is blocked by the RF switching circuit while RF signals of other frequencies are passed by the RF switching circuit.