Murata Manufacturing Co., Ltd.

Akimasa Matsushima

Yoji Maeda

Youji Maeda

Yoshikuni Higashikawa

Wataru Takegawa

Koji Kawano

Shinya Harada

Yutaka Shinza

Yoshikazu Shimamura

Hiroyuki Tetsuno

A CATV tuner includes a metallic housing having first through fourth partitioned chambers. In the first through fourth partitioned chambers, a data circuit, an input filter circuit, a first mixer circuit, a first local oscillation circuit, a first intermediate frequency circuit, and other elements are housed. In the fifth partitioned chamber, a second intermediate circuit and an IC including a second local oscillation circuit are housed. With this configuration, the CATV tuner defines an up/down tuner. The third partitioned chamber in which the first local oscillation circuit is housed and the fifth partitioned chamber in which the second local oscillation circuit is housed are located adjacent to each other. Lines and terminals are used both for a first PLL circuit and a second PLL circuit.

CATV tuner and one-chip IC used therein

An electronic apparatus includes a heat-generating device mounted on a surface of a printed circuit board and is surrounded with wall members of a housing. The wall members are connected to a ground electrode on the other surface of the printed circuit board, the ground electrode being disposed over substantially the entire surface under the heat-generating device. Lugs provided in covers are in contact with the respective ends of the wall members. The direction in which each lug is raised (direction from the base to the tip) coincides with the direction from the heat-generating device to a temperature-increase restricted region.

Electronic apparatus

A tuner includes an input terminal, first to fourth band-pass filters, an automatic gain controller, first to third amplifiers, first and second mixers, first and second voltage controlled oscillators, first and second PLL ICs, a reference oscillator circuit, and an output terminal. The second PLL IC and the reference oscillator circuit are connected through a capacitor and an amplifier. An amplifier for reference oscillation, included in the first PLL IC is connected to the reference oscillator circuit through an inductor that defines an inductance device.

Tuner

A double-balanced mixer which includes four diodes effectively connected to each other in a bridge connection on a substrate. The four diodes are formed into two sets of diodes, each one set including two of the four diodes connected to the same input line, with two twin-diodes each including two of the four diodes formed on the same semi-conductor chips being used for the two sets of the diodes.

Double-balanced mixer

A transformer device of a double-balanced mixer includes a rectangular seat member and first and second transformers aligned side by side in a lengthwise direction on a top surface of the seat member. Support members project from the top surface of the seat member to position and secure the first and second transformers along the top surface. A plurality of pin terminals extend from a bottom surface of a seat member and are adapted to project through through-holes provided in a circuit board of the double-balanced mixer. Input and output wires of the first and second transformers respectively extend along recesses formed in the sides of the seat member for coupling to the pin terminals.

Growing community of inventors

Omihachiman, Japan

Akimasa Matsushima