A SAW filter comprising a piezoelectric substrate and at least two filter tracks formed on the substrate, each having at least two IDT electrodes for input and output. The two filter tracks have substantially the same phase within a pass band, while it is substantially inverse-phased outside the pass band. For realizing the above-described conditions, input IDT electrode of one filter track is connected in parallel with input IDT electrode of the other filter track, while output IDT electrode of one filter track is connected in parallel with output IDT electrode of the other filter track. Furthermore, frequency values of said two filter tracks substantially coincide at a point 3dB lower from the peak transfer function value. Thus the above-configured SAW filter of the present invention is smaller in the overall size and offers a broad pass band and a steep attenuation characteristic.

Surface-acoustic-wave filter

An FBAR-based duplexer that comprises a first port, a second port, a third port, a first band-pass filter connected between the first port and the third port and a series circuit connected between the second port and the third port. The first band-pass filter includes a first ladder circuit having shunt and series elements. Each of the elements of the first ladder circuit comprises a film bulk acoustic resonator (FBAR). The series circuit includes a 90° phase shifter in series with a second band-pass filter. The second band-pass filter includes a second ladder circuit having shunt and series elements. Each of the elements of the second ladder circuit comprises a film bulk acoustic resonator. A band-pass filter comprising shunt elements and series elements in which the series elements and the shunt elements are connected to form a ladder circuit, and each of the elements includes a film bulk acoustic resonator (FBAR).

Duplexer incorporating thin-film bulk acoustic resonators (FBARs)

A power transmitting antenna 105, which is arranged on the ground, and a power receiving antenna 107, which is arranged at the bottom of the vehicle 101, set up resonances at substantially the same resonant frequency and produce magnetic coupling between them. When the power receiving antenna 107 enters the zone in which the power transmitting antenna 105 is located, power is transmitted to the vehicle. By setting H, which is the distance between the power transmitting and receiving antennas that face each other, so that H satisfies 0.11xW1 ≦ H ≦ 0.26 x W1 with respect to the width W1 of the power transmitting antenna, the transmission characteristic can be stabilized.

Electric power supply system for vehicle

An amplifier chain that switches between a saturated mode of operation and a linear mode of operation comprises at least two amplifier stages. A switch is associated with the first amplifier stage and dampens the gain of the amplifier chain when the switch is closed. In a first embodiment, this is done by bypassing the first amplifier stage. In second and third embodiments, this is done by providing a feedback loop to the first amplifier stage. Dynamic device scaling and changing the bias may also be used to affect the performance of the amplifier chain.

Switched gain amplifier circuit

In a dielectric filter, from the top surface to the bottom surface of a substantially rectangular dielectric block, inner-conductor holes are formed. On the inner surfaces of the inner-conductor holes, inner conductors are formed except where non-conductor portions are formed in proximity to one of the top and bottom surfaces, in which the apertures of the inner-conductor holes are formed. On the outer surface of the dielectric block, an outer conductor is formed substantially over the entire outer surface, and input and output electrodes isolated from the outer conductor are coupled with the non-conductor portions in the respective inner-conductor holes at the ends of the dielectric block in the direction of array of the inner-conductor holes. In one of the surfaces in which the apertures of the inner-conductor holes are formed, or in one of the surfaces at the ends of the dielectric block in the direction of array of the inner-conductor holes, a concavity is formed, the inner surface thereof being covered with the outer conductor.

Dielectric filter, dielectric duplexer, and communication apparatus

A surface-acoustic-wave filter couples a two-port surface-acoustic-wave resonator filter circuit coupled in parallel or in series with a two-port impedance circuit. The two-port impedance circuit has an impedance that creates a pole of attenuation, by making the open-circuit impedance of the surface-acoustic-wave filter equal to the short-circuit impedance. High attenuation over a wide range of stopband frequencies is obtained in this way, combined with steep roll-off between the passband and stopband.

Surface-acoustic-wave filters with poles of attenuation created by impedance circuits

PROBLEM TO BE SOLVED: To inhibit degradation and destruction of series arm resonators of a surface acoustic wave filter by reducing the currents flowing through the series arm resonators to lower the applied power SOLUTION: A surface acoustic wave filter to be disclosed comprises a plurality of series arm resonators in which a first series arm resonator connected to an input terminal, a second series arm resonator connected to an output terminal, and a third arm resonator connected between the first and second series arm resonators, are respectively connected in series, a plurality of parallel arm resonators including a first parallel arm resonator connected in parallel to the first series arm resonator and a second arm resonator connected in parallel to the third series arm resonator, and a ground terminal to which the first and second parallel arm resonators are connected, wherein the resonance frequency of the third series arm resonator is different from the resonance frequency of the first series arm resonator and that of the second series arm resonator COPYRIGHT: (C)2007,JPO&INPIT

Surface acoustic wave filter

In a mobile communication device, a power amplifier amplifies the power of a signal to be transmitted. A transmitter filter limits the frequency band of the amplified signal to a predetermined frequency band for transmission. The signal limited in frequency band is transmitted via an antenna. Output power control circuitry controls the output power of the signal to be transmitted and has an output power sensor and an automatic power control circuit. The output power sensor succeeds the transmitter filter in the direction of flow of the signal to be transmitted, and senses the output power of the signal. The automatic power control circuit controls the gain of the power amplifier such that the output power sensed by the output power sensor coincides with a preselected reference value.

Mobile communication device having an output power sensor succeeding a transmission filter

A polar SAW (Surface Acoustic Wave) filter includes a band-pass ladder type SAW filter having a SAW resonator. A two-terminal pair circuit is serially connected to the band-pass ladder type SAW filter and includes a plurality of inductors. The polar SAW filter has attenuation poles in each of the higher-frequency and lower-frequency attenuation ranges of a pass band.

Saw filter with an attenuation pole including a band-pass ladder type of saw filter having a saw resonator

An antenna duplexer has a first filter and a second filter coupled to respective signal terminals and to a common node. The common node is coupled to an antenna terminal. The first filter has a higher-frequency passband than the second filter. A transmission-line circuit, inserted between the first filter and the common node, increases the impedance of the first filter in its lower stopband. The transmission-line circuit includes an internal node, a first transmission line coupling the internal node to the common node, a second transmission line coupling the internal node to the first filter, and a grounding circuit such as a capacitor coupling the internal node to ground. The grounding circuit further enhances the lower stopband impedance of the first filter.

Tomokazu Komazaki

Papers

Surface-acoustic-wave filters with poles of attenuation created by impedance circuits

Surface acoustic wave filter

Mobile communication device having an output power sensor succeeding a transmission filter

Saw filter with an attenuation pole including a band-pass ladder type of saw filter having a saw resonator

Antenna duplexer with divided and grounded transmission line