Murata Manufacturing Co., Ltd.

Masao Uno

Takashi Hiroshima

Katsuo Ito

Shinji Goma

Atsushi Inoue

Bunjiro Murata

Yoji Maeda

Kazunori Kinoshita

Yoshiyuki Mashimo

Hidemori Akagi

Tatsuo Bizen

Toshio Hata

Kazuhiro Tsuji

You Funada

Toru Yaoeda

Kouichi Kongo

Shielding cases each include a pair of opposed first surfaces with catching pieces protruding therefrom and a pair of second surfaces without catching pieces. A motherboard forms substrates each including a pair of opposed first side surfaces with catching grooves and a pair of second side surfaces without catching grooves when it is divided. The shielding cases are mounted on the motherboard such that the intervals A between the second surfaces of two adjacent shielding cases are equal to or less than the widths B of cutting allowances for cutting the motherboard. The motherboard is cut from the opposite side of a surface of the motherboard on which the shielding cases are mounted at predetermined positions where the second side surfaces are formed on each substrate. In this manner, the motherboard is divided into electronic components with shielding cases.

Electronic component with shielding case and method of manufacturing the same

A miniaturized oscillator that is manufactured with greatly reduced production time and cost includes transmission lines defining resonance circuits provided on a circuit assembly board. In this state, the impedance of each transmission line is measured. Then, according to the transmission line impedance, chip components having impedances necessary to obtain a predetermined frequency are selected and mounted on the circuit substrate. With this arrangement and method of formation, the resulting oscillator oscillates at the desired oscillation frequency and it is not necessary to trim the transmission lines in order to achieve this result. Since the oscillator does not require time to make frequency adjustments and does require use of a trimming apparatus, no deterioration in the electric characteristics due to laser trimming occurs. In addition, it is unnecessary to provide an electrode land for making frequency adjustments. As a result, the entire oscillator is miniaturized.

Oscillator, method for producing oscillator, and communication apparatus incorporating same

In the path from the output of a charging pump to a control voltage terminal including the inside of a loop filter, voltage application means for applying a direct-current voltage of a predictable value to the control voltage terminal is given, resulting in a PLL circuit. In the PLL circuit, first, a fixed direct-current voltage is applied to the control voltage terminal from the voltage application means. The oscillation frequency of a voltage-controlled oscillator may be adjusted by making use of a trimming area as a oscillation frequency adjustment mechanism. Therefore, the oscillation frequency of the voltage-controlled oscillator can be quickly adjusted using fewer pieces of equipment.

PLL circuit which quickly adjusts VCO bias voltages

An oscillator includes a multi-layered base. Circuit patterns are formed on a first main surface and the inside of the multi-layered base. Holes through which wiring patterns of the individual layers of the base are connected are formed within the multi-layered base. Electronic components are mounted on the first main surface of the multi-layered base. First and second reverse electrodes, which serve as external terminals to be connected to an external source, are formed on a second main surface of the multi-layered base. The first reverse electrode serves as a ground electrode, and the second reverse electrodes serve as terminal electrodes. The reverse electrodes are electrically connected to the circuit patterns via the holes. The reverse electrodes are located farther inward than the lateral surfaces of the multi-layered base. A shield cover is placed to tightly cover the first main surface of the multi-layered base. It is thus possible to provide a miniaturized, less expensive, and easy-to-mount oscillator module in which unwanted radiation characteristics are improved.

Oscillator module having a multi-layered base with a cover

The size precision of a surface mountable electronic part is improved and a production thereof is simplified. The surface mountable electronic part is constructed such that a circuit substrate is housed in a shield case of which an end side is open, and the shield case is a resin case having a shield film. A connection pattern is formed on the inner surface of the case, with one end of the connection pattern being disposed so as to correspond to an external connection land of the circuit substrate, and with the other end of the connection pattern extending to the open end of the case.

Surface mountable electronic part

A UHF transistor mixer circuit includes a transistor having a base to which an inputted high-frequency signal and a local oscillation signal are inputted. A bias voltage is applied to the base from a direct current voltage source through an inductor constructed with a microstripline. A low-pass filter which prevents signal components in the UHF band from being passed therethrough is provided between the base and the voltage source, and more particularly between the inductor and the direct current voltage source. The local oscillation signal is prevented from flowing toward the direct current voltage source by the low-pass filter, and therefore, the intermodulation distortion of the mixer circuit can be improved.

UHF transistor mixer circuit

A UHF band transistor mixer circuit includes a frequency converting transistor to a base of which a received high-frequency signal and a local oscillation signal are applied. A collector of the frequency converting transistor is connected to a low-pass filter from which a desired frequency signal, i.e., an intermediate frequency signal is outputted. A series resonance circuit having a series resonance frequency point existing in a frequency region between both the signals is connected between an emitter of the frequency converting transistor and a reference potential.

UHF band transistor mixer circuit

A feedthrough capacitor arrangement which comprises a frame having a first recess, printed circuit boards disposed in the vicinity of the frame, a feedthrough capacitor having an outer electrode and a central electrode placed in the first recess and a shield member for pressing the feedthrough capacitor placed in the first recess thereby to hold the feedthrough capacitor in association with the frame. In this arrangement, the outer electrode of the feedthrough capacitor is soldered to the frame and to the shield member while the central electrode is soldered to conductor patterns on the printed circuit boards.

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Ishikawa-ken, Japan

Masao Uno