Sony Corporation

Kazuto Kitakubo

Kazumasa Kohama

Seijiro Ishizuka

Sachio Iida

Takeshi Sugiyama

Ryuji Oki

Shinichi Hirota

In a switching circuit, low insertion loss and enough isolation can be ensured at a desired frequency at the same time. An inductor is externally connected in parallel with the path between the drain and source of each of field-effect transistors built in a switching integrated circuit, and the inductor and the OFF capacitance of the field-effect transistor are made to generate parallel resonance. At this time, by suitably adjusting the inductance, low insertion loss and enough isolation are ensured at a desired frequency at the same time.

Switching circuit at high frequency with low insertion loss

A radio telephone apparatus for performing space diversity reception to communicate with base stations in a TDMA radio communication system under an operating condition in which a frame period containing a signal transmission period, a signal reception period and a base station observation period is provided, which comprises first and second antennas for signal transmission in the signal transmission period, the space diversity reception prior to each of the signal reception period and the base station observation period and signal reception in each of the signal reception period and the base station observation period, and an antenna selector operative to select one of the first and second antennas in accordance with space diversity technique to be used for receiving a data signal from a specific base station in the signal reception period and to select further one of the first and second antennas in accordance with space diversity technique to be used for receiving a data signal from one of base stations other than the specific base station in the base station observation period.

Radio telephone apparatus for performing space diversity reception to

An antenna switching circuit (55) is constructed by a circulator element (63) having three terminals, of which the first terminal (CTX) is connected to the transmitting circuit, the second terminal (CANT) is connected to a first antenna (4), and the third terminal (CRX) can be connected to the terminal resistance (64) through a first switch element (62); a second switch element (60) capable of connecting the third terminal of the circulator element to the receiving circuit; and a third switch element (61) capable of connecting a second antenna (22) to the receiving circuit, whereby, it is no longer necessary to use a duplexer circuit having large insertion loss, the whole construction can be miniaturized, and the insertion loss can be reduced.

Antenna switching circuit and wireless communication system

An electromagnetic-wave shielding device for shielding unnecessary electromagnetic radiation by covering a printed circuit board which generates electromagnetic waves, by a pair of box-like upper and lower shielding cases integrally connected to each other, include an engaged portion provided at a lower shielding case, an engaging portion provided at an upper shielding case of the shielding case pair and engaging with and disengaging from the engaged portion, and pillar-shaped portions being projected from opposing portions of the shielding cases for holding the board between the pillar-shaped portions when the engaged portion of the lower shielding case engages with the engaging portion of the upper shielding case. The printed circuit board held between the pillar-shaped portions is detachably accommodated in the shielding case pair, except for a connect for receiving external signals.

Electromagnetic-wave shielding device

In an antenna duplexer, one antenna is used by switching transmission signals and reception signals having different frequencies. The antenna duplexer includes a high-frequency switching circuit and a band-pass filter. The high-frequency switching circuit supplies the transmission signals from a transmission part to the antenna. The band-pass filter outputs the reception signals outputted from the antenna to the predetermined receiving circuit. In the band-pass filter, the frequency characteristic is selected and set to impress the frequency of the transmission signals, and simultaneously the reflected wave generated at the input end so that impedance increases at the frequency band of the transmission signals.

Antenna duplexer and transmitting/receiving apparatus using the same

A antenna switching apparatus for a dual-mode transceiver which includes a transmission and reception antenna, a transmitting circuit, a receiving circuit, and a separating filter of large insertion loss is connected to the transmission and reception antenna, the transmitting circuit, and the receiving circuit for separating a transmission high frequency signal and a reception high frequency signal having different carrier frequencies, in which transmission and reception in the digital mode of the transmission and reception switching system and the transmission and reception in the analog mode of the simultaneous transmission and reception system is possible further includes an analog-to-digital change-over switch which changes-over mutual connections among the transmission and reception antenna, the transmitting circuit, the receiving circuit and the separating filter in response to the analog or digital mode, a blocking filter of low insertion loss for blocking a high frequency band of spurious signals caused by the switching of a transmission and reception change-over switch which changes-over the transmission and reception in the digital mode and a bandpass filter of low insertion loss for passing therethrough the reception high frequency signal in the digital mode, so that power consumption in the digital mode is reduced considerably.

Dual-mode transceiver that switches out a large insertion loss filter

A high frequency PIN diode attenuator uses an inductive element in parallel with the PIN diode. The inductor resonates with the parasitic capacitance of the PIN diode to increase the attenuation level.

Growing community of inventors

Tokyo, Japan

Kazuto Kitakubo