An elastic wave filter has an unbalanced signal terminal, first and second balanced signal terminals, and first through fifth IDT electrodes arranged in ordinal order between a pair of grating reflectors. Wiring electrodes of the third and fifth IDT electrodes are disposed adjacent a ground electrode of the fourth IDT electrode, wiring electrodes of the second and third IDT electrodes are disposed adjacent one another, and ground electrodes of the first and second IDT electrodes are disposed adjacent one another. The unbalanced signal terminal is connected to the wiring electrodes of the first, third, and fifth IDT electrodes, and the first and second balanced signal terminals are connected to the wiring electrodes of the second and fourth IDT electrodes, respectively. A pitch gradation of pitch spacing between electrode fingers in each of the first, second, and third IDT electrodes on one side of a center line in the third IDT electrode is gradually reduced by a first spacing α, and a pitch gradation of pitch spacing between electrode fingers in each of the third, fourth, and fifth IDT electrodes on the other side of the center line is gradually reduced by a second spacing β (β≠α), as the distance from the center line increases.

A resonator array comprises substantially paralleled first and second resonant layers having resonating masses. A first set of lateral drive electrodes cause the first resonating mass to vibrate along an axis in a first geometric plane. A second set of lateral drive electrodes cause the second resonating mass to vibrate along an axis in a second geometric plane in an opposite direction of the first resonating mass by about 180 degrees. Rotation in the system causes the masses to vibrate out-of-plane in opposite directions. The opposite vibrational directions of the first and second resonating masses produces a balanced system with small motion in a bonding area between the stacked resonators. As a result, there is minimal propagation of mechanical waves from the balanced system to a substrate resulting in lower anchor loss and a high Q-factor.

A resonator array comprises substantially paralleled first and second resonant layers having resonating masses. A first set of lateral drive electrodes cause the first resonating mass to vibrate along an axis in a first geometric plane. A second set of lateral drive electrodes cause the second resonating mass to vibrate along an axis in a second geometric plane in an opposite direction of the first resonating mass by about 180 degrees. Rotation in the system causes the masses to vibrate out-of-plane in opposite directions. The opposite vibrational directions of the first and second resonating masses produces a balanced system with small motion in a bonding area between the stacked resonators. As a result, there is minimal propagation of mechanical waves from the balanced system to a substrate resulting in lower anchor loss and a high Q-factor.

An electrical component, e.g., a diplexer or a duplexer, can have one of a number of diverse arrangements for terminal surfaces on the substrate bottom. For example, the terminal surfaces for first and second filters are not disposed at the maximum distance from one another. First and second filters can be disposed as one or two discrete components on the substrate, wherein one filter can be implemented as being integrated in a multilayer substrate.

A duplexer includes a reception filter that is connected between a reception terminal and an antenna terminal and includes one or a plurality of series resonators that are acoustic wave resonators, and a transmission filter that is connected between a transmission terminal and the antenna terminal and includes one or a plurality of acoustic wave resonators, a resonance frequency of a first series resonator that is one of the one or the plurality of series resonators and is closest to the antenna terminal in the reception filter being higher than an upper limit frequency of a reception band of the reception filter.

In one embodiment, a biological information monitoring apparatus includes: an antenna assembly including at least one antenna, the antenna assembly being disposed close to an object; a signal generator configured to generate a radio-frequency (RF) signal; and a displacement detection circuit configured to detect a physical displacement of the object based on the RF signal, wherein the at least one antenna includes: a dipole antenna having a feeding point to be supplied with the RF signal, the feeding point being positioned in a center of the dipole antenna; a coaxial line configured to supply the RF signal to the feeding point; and a conductor element that has a wavelength and is short-circuited on one end to an outer conductor of the coaxial line.