Hitachi Media Electronics Co., Ltd.

Hitachi, Ltd.

Osamu Hikino

Takashi Shiba

Mitsutaka Hikita

Nobuhiko Shibagaki

Kazuyuki Sakiyama

Takao Totsuka

Hiroaki Ikeda

Kazutoshi Higuchi

Shigeyuki Sudo

Masashi Ohki

Hideaki Sunayama

Yuuichi Oikawa

Masato Kijima

A high-frequency circuit has a duplexer and a filter. The duplexer performs wave separation of send and received signals as input thereto. The filter filters the input send signal. When the send and received signals of the first modulation method are input, the send signal and the received signal of the first modulation method are wave-separated and output by the duplexer. When the received signal of the first modulation method is input, the send signal and the received signal of the first modulation method are wave-separated and output by the duplexer, and the send signal of the second modulation method is filtered by the filter.

High-frequency circuit apparatus and communication apparatus using the same

A small-sized, high-performance transmission circuit is provided which avoids degradation in transmission line characteristics caused by coupling, due to a transmission line and a leader electrode to an external electrode which are oppositely facing, of the electromagnetic field induced by the transmission line and the electromagnetic field induced by the leader electrode. In order to attain the aforementioned object, the present invention comprises a first shield layer which is a first ground electrode, a second shield layer which is a second ground electrode, and a spiral-shaped transmission line facing the first shield layer and the second shield layer which is disposed between the first shield layer and the second shield layer. The spiral portion of the transmission line, when viewed from the top face or the bottom face of the transmission line, is disposed on the inside of the first shield layer and the second shield layer.

Transmission circuit, antenna duplexer, and radio-frequency switch circuit

A small-sized, low-cost radio frequency switch circuit, which has good characteristics of isolation between a transmission circuit and a reception circuit, includes a multi-layered substrate; a transmission line provided on the top surface of, or within, the multi-layered substrate; a first diode and a second diode connected respectively to both ends of the transmission line; a resistor, connected to the first diode, to apply a current to the first diode and the second diode; a first capacitor whose one end is connected to the resistor and whose other end is grounded; and a second capacitor connected in parallel to the transmission line.

Switch circuit, front end module and radio terminal including switch circuit

A compact, inexpensive antenna sharing device meeting requirements in terms of transmitter distortion characteristic and ESD characteristic is provided which separates and combines signals transmitted and received in first to third signal bands and which thereby enables an antenna terminal to be shared as a common terminal. It includes a diplexer realizing an attenuation characteristic for protection against ESD, a compound semiconductor switch with an IIP3 of 66 dBm or more, and an inexpensive PIN diode switch.

Antenna sharing device and wireless communication terminal using the same

A mobile station for preventing reduction of the line quality when it is used near the head of a human operator. Plural antennas are arranged so that the cross-correlation of the received waves becomes small. The signals received by the antennas are delayed by a delay time to prevent interference between the received signals so that the time difference of each received signal becomes at least one chip time of the spreading code or more. After that, a combiner combines the received signals, and an output signal of the combiner is inputted into a rake receiver. A reduction of the extent of the delay spreading is prevented by directivity of the antennas in use near a human body, and a decline of path diversity gain by the rake receiving is reduced.

Mobile station for spread spectrum communication

A surface acoustic wave antenna duplexer constituted by a transmitter-line filter, a receiver-line filter and an antenna terminal, the transmitter-line filter and the receiver-line filter being connected in parallel with the antenna terminal as a common terminal; wherein at least one of the transmitter-line and receiver-line filters includes a top filter using the whole of a transmitter band or a receiver band as its pass band, a surface acoustic wave resonator filter, and a transmitter or receiver terminal, the top filter, the surface acoustic wave resonator filter and the transmitter or receiver terminal being disposed in this order viewed from the antenna terminal, the surface acoustic wave resonator filter including at least one additive capacitance or inductance; and wherein a switching element is provided for varying a value of the capacitance or inductance so as to provide a function for varying a pass band frequency or an attenuation band frequency of the surface acoustic wave resonator filter.

Band-switchable surface acoustic wave antenna duplexer and mobile radio terminal

In an interdigital electrode of a surface acoustic wave device having nonexciting portions formed by removing fingers, fingers having an excitation source located nearest to a nonexciting portion in between are so positioned as to approach the nonexciting portion as compared with arrangement pitch of other fingers. Fingers having an excitation source located nearest to an end of the electrode in between are so positioned as to approach the end of the interdigital electrode as compared with arrangement pitch of other fingers. Fingers having an excitation source located in the central portion of the electrode group in between are so positioned as to approach each other as compared with arrangement pitch of other fingers.

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Yokohama, Japan

Osamu Hikino