Low noise block converter

A low noise block converter includes a first printed circuit board, a second printed circuit board, and a housing. The first printed circuit board includes a metal layer disposed on a surface of the first printed circuit board. The second printed circuit board includes at least one chip. The housing includes a support surface configured to support the first printed circuit board, and a cavity formed on the support surface and configured to receive the second printed circuit board, wherein the first printed circuit board is placed on the support surface with the metal layer facing the cavity for shielding the electromagnetic fields radiated from the at least one chip.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a low noise block converter, and relates more particularly to a low noise block converter that is compact and designed to prevent electromagnetic interference between electronic components.

2. Description of the Related Art

Satellite communications requires equipment such as ground stations, low noise block down converters, transmission cables, and modulator/demodulators. The ground station receives radio frequency signals from satellites; the low noise block down converter amplifies the received radio frequency signals and converts the amplified radio frequency signals to intermediate frequency signals; and the transmission cables transmit the intermediate signals to the modulator/demodulator.

Generally, the low noise block down converter may include a radio frequency circuit and an intermediate circuit electrically connecting to the radio frequency circuit. The radio frequency circuit receives radio frequency signals, converts the radio frequency signals to intermediate signals, and transmits the intermediate signals to the intermediate circuit. When the radio frequency signals are processed, the electronic components may radiate electromagnetic waves, causing the electronic components to interfere with each other. In order to prevent the electronic components in a low noise block down converter from interfering with each other, a shield may be additionally disposed to minimize the electromagnetic interference between the electronic components. However, the addition of such a shield requires more space, increasing the weight and the manufacturing cost of the low noise block down converter.

In addition, most components of a low noise block down converter are made of metal. A larger low noise block down converter needs not only more material for construction but also a larger and stronger support for supporting it, and consequently, it becomes inconvenient to use and costs more to produce.

In view of the drawbacks of a traditional low noise block down converter, a new low noise block down converter that is designed compactly and has capability to prevent the electronic components therein from electromagnetically interfering with each other is required.

SUMMARY OF THE INVENTION

The present invention discloses a low noise block converter, which comprises a first printed circuit board, a second printed circuit board, and a housing. The first printed circuit board includes a metal layer that is disposed on a surface of the first printed circuit board. The second printed circuit board includes at least one chip, which may radiate an electromagnetic wave. The housing comprises a support surface and a cavity. The support surface is disposed within the housing and configured to support the first printed circuit board. The cavity is formed on the support surface and configured to receive the second printed circuit board. The first printed circuit board is disposed on the support surface with the metal layer facing the cavity for shielding the electromagnetic wave from the at least one chip.

To better understand the above-described objectives, characteristics and advantages of the present invention, embodiments, with reference to the drawings, are provided for detailed explanations.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1is a perspective view showing a low noise block converter1according to one embodiment of the present invention. The low noise block converter1comprises a housing11, a cover member12, a feed horn13, a first printed circuit board14, a second printed circuit board15, and a third printed circuit board16. The feed horn13is configured to receive radio frequency signals from satellites. The housing11is configured to receive the first printed circuit board14configured to process the received radio frequency signals and to generate intermediate signals, the second printed circuit board15, and the third printed circuit board16. The feed horn13connects to the housing11for guiding radio frequency signals into the housing11for signal processing. The cover member12is configured to cover the housing11to protect the circuitry and the electronic components inside the housing from external electromagnetic interference. The cover member12can be fastened using fasteners such as bolts or screws, or using adhesive material, or other means well known by persons skilled in the art. A plurality of connecting elements17may be disposed on the exterior of the housing11for connecting cables for transmitting intermediate signals.

In the present embodiment, the interior of the housing11can be partitioned into a first compartment111and a second compartment112. The first compartment111is configured to receive the first printed circuit board14and the second printed circuit board15while the second compartment112is configured to receive the third printed circuit board16. Each of the first printed circuit board14and the second printed circuit board15may respectively include a portion of an intermediate circuit, and the third printed circuit board16may be a printed circuit board including a radio frequency circuit. Separating the intermediate circuit and the radio frequency circuit into two different first and second compartments111and112can minimize the electromagnetic interference between the intermediate circuit and the radio frequency circuit. In the present embodiment, the housing11may be made of, but is not limited to, aluminum.

FIG. 2is a cross-sectional view along line A-A ofFIG. 1. Referring toFIGS. 1 and 2, the first compartment111may comprise a support surface113configured to support the first printed circuit board14. A cavity114can be formed on the support surface113for receiving the second printed circuit board15. When the second printed circuit board15is disposed within the cavity114and the first printed circuit board14is placed on the support surface113, the first printed circuit board14and the second printed circuit board15are arranged in a stacking manner.

Particularly, the second printed circuit board15may comprise at least one chip151. However, in the present embodiment, the second printed circuit board15can include, but is not limited to, three chips151. When the chip151operates, it emits electromagnetic waves. If the electromagnetic waves are not properly shielded, the electronic components on the third printed circuit board16as shown inFIG. 1may be interfered with by the electromagnetic waves. To minimize the influence of the electromagnetic waves, an absorbing material152can be provided on each chip151. The absorbing material152can absorb a portion of radiated electromagnetic waves, but its electromagnetic shielding effectiveness is limited. Therefore, another electromagnetic shielding means is required. The absorbing material152can be foam material or other material for absorbing electromagnetic energy.

Specifically, on the second printed circuit board15, through-holes153can be formed at the location where the chips151are disposed. The through-holes153correspond to the chips151, and pass through the printed circuit board15from the surface on which the chip151is disposed to an opposite surface. Within each through-hole153, a thermally conductive pillar154is disposed. The thermally conductive pillar154contacts a bottom surface of the chip151for conducting the heat generated by the chip151. In one embodiment, the material of the thermally conductive pillar154can be copper.

Furthermore, a plurality of protrusions116may be provided on a bottom surface115defining the cavity114. The protrusions116can be disposed with respect to the chips151and respectively contact the thermally conductive pillars154so that heat generated by the chips151can be conducted to the protrusions116via the thermally conductive pillars154, and can then be dissipated by the housing11to the air surrounding the housing11. In addition, the protrusion116can be configured to support the second printed circuit board15. In the present embodiment, the second printed circuit board15may be a6layer printed circuit board.

Referring toFIG. 2, the first printed circuit board14is disposed above the second printed circuit board15and supported by the support surface113. The first printed circuit board14may comprise a metal layer141. An electrical circuit and electronic components are disposed on a surface142of the first printed circuit board14, while the metal layer141is disposed on another surface opposite to the surface142. After the second printed circuit board15is received in the cavity114, the first printed circuit board14is placed on the support surface113in a fashion with the metal layer141facing the cavity114. The metal layer141is configured to effectively shield the electromagnetic energy emitted by the chips151so that the electronic components on the printed circuit board16as shown inFIG. 1may be protected from influence by the electromagnetic energy. Preferably, the metal layer141can abut against the support surface113. Such an abutting engagement design may not only prevent the escape of electromagnetic waves, but can also transfer the heat generated from the electronic components on the first printed circuit board14to the housing11so that the heat can be dissipated through the housing11. In the present embodiment, the intermediate circuit can be separated to be disposed on the first printed circuit board14and the second printed circuit board15, wherein the first printed circuit board14and the second printed circuit board15are electrically connected. Separating the intermediate circuit on two printed circuit boards14and15may allow the low noise block converter1to be more compact, reducing its volume and weight, requiring less material to construct it, and lowering its manufacturing cost. Further, the two printed circuit boards14and15each disposed with a portion of the low noise block converter1are arranged in a stacking manner, and a metal layer is disposed on a surface of the upper disposed printed circuit board14for shielding the electromagnetic energy from the chips on the lower disposed printed circuit board15such that the low noise block converter1may not need the disposition of a shield. Thus, the size, use of material, and cost can be further reduced. In the present embodiment, the metal layer141can be, but is not limited to, a copper layer. The metal layer141can be of any metal other than copper that can be disposed on a printed circuit board and used for electromagnetic interference shielding. In the present embodiment, the intermediate circuit is separated to be disposed on two printed circuit boards; however, the present invention is not limited to such an arrangement.

Referring toFIG. 2, the first printed circuit board14may further comprise an aperture143disposed with respect to one chip151on the second printed circuit board15. The aperture143is configured to permit a test probe to pass through the first printed circuit board14for testing the chip151covered by the first printed circuit board14. Usually, to shield the electromagnetic energy emitted by chips151on the second printed circuit board15received in the cavity114, the first printed circuit board14should be configured to have a sufficient size that allows the metal layer141disposed thereon to cover the cavity114. Under such a situation, after the first printed circuit board14and the second printed circuit board15are installed, the second printed circuit board15may be completely covered by the first printed circuit board14such that chips151on the second printed circuit board15cannot be accessed for testing. To resolve such issue, an aperture143is formed on the first printed circuit board14so that chips151on the second printed circuit board15can be tested. In the present embodiment, to prevent an electromagnetic wave from the chips151from propagating through the aperture143, the diameter of the aperture143is configured to be one quarter of the wavelength of the electromagnetic wave.

FIG. 3is a top view showing the support surface113in a housing11according to one embodiment of the present invention. Referring toFIGS. 2 and 3, the cavity114can preferably be formed in the support surface113such that the support surface113surrounds the opening of the cavity114; however, the present invention is not limited to such a configuration. The support surface113is configured for supporting the first printed circuit board14, for dissipating heat from the first printed circuit board14, and for preventing electromagnetic interference of the first printed circuit board14. Therefore, other configurations, for example, one in which the cavity114is disposed against one side of the first compartment111, can also meet the requirements of the present invention.

The low noise block converter includes two stacked printed circuit boards, and a metal layer is disposed on the upper printed circuit board, thereby shielding the electromagnetic energy from the chips on the lower printed circuit board so that the low noise block converter does not need a shield, and consequently its size can be reduced. Furthermore, utilizing stacked printed circuit boards can further reduce the size of the low noise block converter. As such, the low noise block converter of the present invention has advantages such as compact size, light weight, use of less material, and low manufacturing cost.