An acoustic device includes a foundation structure and a transducer provided over the foundation structure. The foundation structure includes a piezoelectric layer between a top electrode and a bottom electrode. The piezoelectric layer has an active portion within an active region of the transducer, and a bi-polar border portion within a border region of the transducer. The piezoelectric material in the active portion has a first polarization. The bi-polar border portion has a first sub-portion and a second sub-portion, which resides either above or below the first sub-portion. The piezoelectric material in the first sub-portion has the first polarization, and the piezoelectric material in the second sub-portion has a second polarization, which is opposite the first polarization.

A filter circuit may include a transmission line, a quarter wave resonator, and an electrical component coupled in series with the quarter wave resonator at a first end and to the transmission line at a second end. The electrical component may be have a frequency dependent impedance. The electrical component may be an inductor, a capacitor, or an inductor in series with a capacitor. In another aspect, a filter circuit may include a transmission line, a first quarter wave resonator coupled to a first electrical component and a second quarter wave resonator coupled to a second electrical component. Each of the first and second electrical components may be coupled to the transmission line in parallel with each other. The first and the second electrical components may have a frequency dependent impedance. The first electrical component may be the same as or different from the second electrical component.

Networks and filters are disclosed. A network includes a resonator that exhibits both a resonance and an anti-resonance and an inverter circuit connected in parallel with the resonator to form a composite resonator. An anti-resonant frequency of the composite resonator is different from the resonator's anti-resonant frequency.

Systems, devices, and methods for adjusting tuning settings of tunable components, such as tunable capacitors, can be configured for calibrating a tunable component. Specifically, the systems, devices and methods can measure a device response for one or more inputs to a tunable component, store a calibration code in a non-volatile memory that characterizes the device response of the tunable component, and adjust a tuning setting of the tunable component based on the calibration code to achieve a desired response of the tunable component.

Motion-detection systems are often used to detect presence of humans. Such motion-detection systems are often based on passive infrared (PIR) sensors. Unfortunately, such detection systems are unable to reliably distinguish between humans and other entities such as animals and moving heat sources. To address this issue, it is proposed to detect a presence of real time clock (RTC) devices in addition to detecting the heat sources to better determine whether a detected entity is a human.

The present invention includes a method of creating electrical air gap or other low loss low cost RF mechanically and thermally stabilized interdigitated resonate filter in photo definable glass ceramic substrate. A ground plane may be used to adjacent to or below the RF filter in order to prevent parasitic electronic signals, RF signals, differential voltage build up and floating grounds from disrupting and degrading the performance of isolated electronic devices by the fabrication of electrical isolation and ground plane structures on a photo-definable glass substrate.

In tuning a radio frequency (RF) module including a non-volatile tunable RF filter, a desired frequency and an undesired frequency being provided by an amplifier of the RF module are detected. The non-volatile tunable RF filter is coupled to an output of the amplifier of the RF module. A factory setting of an adjustable capacitor in the non-volatile tunable RF filter is changed by factory-setting a state of a non-volatile RF switch, such that die non-volatile tunable RF filter substantially rejects die undesired frequency and substantially passes die desired frequency. The adjustable capacitor includes die non-volatile RF switch, and the factory setting of the adjustable capacitor corresponds to a factory-set state of the non-volatile RF switch. An end-user is prevented access to the non-volatile RF switch, so as prevent the end-user from modifying the factory-set state of the non-volatile RF switch.

A method of stabilizing a variable filter for an analog electromagnetic signal against circuit oscillation includes the steps of: providing a signal loop comprising a signal input, a signal output, and a plurality of variable circuit elements connected in the signal loop, the plurality of variable circuit elements comprising an adjustable resonator and an adjustable gain block, the signal loop having a variable frequency response that is characterized by a central frequency, a frequency passband, a response Q, and an operating point and a resonator response curve that are plottable in a Cartesian s-plane having an origin, a real axis, and an imaginary axis; and maintaining stability of the variable filter within an operating range by controlling the adjustable resonator and the adjustable gain block such that, in the Cartesian s-plane, the resonator response curve satisfies an orthogonality stability condition.

A radio frequency (RF) filter having a first passband and including a first circuit connected to a first node and a second node disposed on a path that connects a first terminal and a second terminal, and a second circuit connected to the first node and the second node. The first circuit includes a first filter having a second passband that includes a portion of a frequency range of the first passband and a bandwidth narrower than a bandwidth of the first passband. The second circuit includes a second filter having a third passband that includes a portion of a frequency range of the first passband and has a bandwidth narrower than the bandwidth of the first passband. The RF filter also includes a first phase shifter connected to a first terminal of the second filter; and a second phase shifter connected to a second terminal of the second filter.

A diplexer (100) includes: first and second directional couplers (106A, 106B); and first and second filters (101A, 101B). The filters (101A, 101B) each include a plurality of resonators (110A to 150A, 110B to 150B) that are electromagnetically coupled. The resonators (110A to 150A, 110B to 150B) each have a broad wall that is in a shape of a circle or a regular polygon with six or more vertices, and two resonators, which are coupled together, of the resonators (110A to 150A, 110B to 150B) are arranged such that D<R.sub.1+R.sub.2 is satisfied, where R.sub.1 and R.sub.2 represent radii of circumcircles of the broad walls of the two resonators and D represents a center-to-center distance between the two resonators.