Solid-state high power amplifier arrangement

Abstract: An integrated power amplifier arrangement such as for a TV transmitter includes a plurality of amplifier units (1,2) adjacent to which are tapered blower ducts (6c) supplied from an air chamber (6a). A power supply unit (3) is placed over an air chamber (6b). The amplifier units and power supply unit are slidably mounted and when in place are directly connected by plug-and-socket connections (3a,1d). Efficient air cooling is thus provided and yet the arrangement is economical with space and provides for easy maintenance.

Description: The present invention relates to an integrated power amplifier arrangement, used for a TV transmitter for example, which is constructed by combining a plurality of power amplifier units while employing compulsory air cooling. Conventionally, a solid-state high power amplifier arrangement is constructed as shown in Fig. 1 and Figs. 2(a) and 2(b), for example. In Fig. 1 are shown a plurality of transistor power amplifier units (referred to as "TRPA units") 11; a plurality of power supply units (referred to as "PS units") 12 for supplying electric power; a combiner unit 13 for combining the outputs of the plurality of TRPA units 11 to obtain a high power output; and a shelf 15 including individual parts 15a to 15i for accommodating the aforementioned units 11 and 13. As shown in Fig. 1, each TRPA unit 11 is accommodated on the shelf 15 through guide rails 15f and, at the same time, a plug 11b projecting from the unit 11 connects with the socket 15g. On the other hand, each PS unit 12 is also accommodated on the shelf 15 and the output of the PS unit 12 is connected through a cable 15h with the socket 15g of the bracket 15i, so that the TRPA unit 11 and the PS unit 12 are electrically connected. Moreover, the combiner unit 13 fixed on the shelf 15 is connected to the TRPA unit 11 through a socket 13a, a plug 11a and a U link 14. In Figs. 2(a) and 2(b) showing sectional diagrams of the arrangement of Fig. 1, cooling air 16 is supplied from an air chamber 15a and is distributed into heat sinks 11c of the TRPA units 11 and into the PS units 12. The cooling air 16 blown into the heat sinks 11c cools heat-producing elements 11d through the heat sinks 11c and, then, it is exhausted through an air chamber 15b and an exhaust duct 15d. On the other hand, the cooling air blown to the PS unit 12 is exhausted through an air chamber 15c and an exhaust duct 15e. In the aforementioned conventional solid-state high power amplifier arrangement shown in Figs. 2(a) and 2(b), the space M' between the TRPA unit 11 and the PS unit 12 has to be enlarged in a unit-accommodating direction because of the presence of the bracket 15i and the cable 15h. Moreover, the space N' between the TRPA unit 11 and the combiner unit 13 has to be enlarged because of the presence of the air chamber 15b. Still moreover, the total width P' becomes enlarged because of the presence of the heat sinks 11c. In addition to the units 11 and 12, on the other hand, the cable 15h, the U links 14 and the bracket 15i are required for electric connections, and the air chambers 15b and 15c and the exhaust ducts 15d are required for protection against the heat of the exhaust air. The aforementioned requirements of the conventional arrangement augment the cost of the parts and the number of assembling and wiring steps, and a long time is necessary to insert or pull out the individual units. Further, the TRPA units 11 are heavy due to the heavy heat sinks 11c so that their maintenance is troublesome. Moreover, the conventional arrangement is disadvantageous from the point of view of safety because the U links carrying the high power outputs are disposed at the front. The present invention is defined in claim 1 below, to which reference should now be made. In a preferred embodiment of the invention described in more detail below, there is provided a solid-state power amplifier arrangement including a plurality of amplifier units, a power supply unit for supplying power to the amplifier units, and a combiner unit for combining the outputs of the amplifier units, which comprises guide rails for guiding the amplifier units and the power supply unit on a shelf, connectors for connecting the amplifier units with the power supply unit and connecting the amplifier units with the combiner unit, the connectors being of plug-and-socket type, air chambers disposed between the adjacent amplifier units, respectively, and nozzles attached to the air chambers to jet cooling air onto a radiation plate of the amplifier units. Fig. 1 is a perspective diagram showing a conventional solid-state power amplifier arrangement; Figs. 2(a) and 2(b) are sectional front and side views of the arrangement shown in Fig. 1, respectively; Fig. 3 is a perspective view showing an embodiment according to the present invention; Fig. 4 is a sectional front view of the embodiment shown in Fig. 3; Fig. 5 is a sectional side view at A-A on Fig. 4; Fig. 6 is a sectional side view at B-B on Fig. 4; Fig. 7 is a sectional plane diagram at C-C on Fig. 4; Figs. 8(a) and 8(b) show a coaxial plug and a socket used in the embodiment of Fig. 3; Fig. 9 is a sectional view of the plug and the socket shown in Figs. 8(a) and 8(b); Fig. 10 is a breakdown view of the socket shown in Fig. 9; Fig. 11 is a perspective breakdown view of the embodiment shown in Fig. 3; and Figs. 12(a) and 12(b) are detailed sectional side and plan views of a cooling part applied to the embodiment. In Fig. 3, showing an embodiment of the present invention, a solid-state high power amplifier arrangement is constructed of: a plurality of transistor power amplifier units (referred to as "TRPA units" hereinafter) 1 and 2; a plurality of power supply units 3 (referred to as "PS units" hereinafter) for supplying electric power to the TRPA units 1 and 2; a signal dividing unit 5 for dividing a pre-amplified signal having weak power into the TRPA units 1 and 2; combiner units 4 for combining outputs of the TRPA units 1 and 2 to deliver a high power output; a shelf 6 for accommodating the above-specified units 1 to 5; and air chambers 6a and 6b for blowing cooling air to cool the TRPA units 1 and 2 and the PS units. As shown in Fig. 4, the TRPA unit 1 comprises: a flat plate 1a of high thermal conductivity (aluminum, for example) which is disposed at the lefthand outer side and is used as a part of a casing by itself; heat-producing elements 1b such as power transistors attached to the inner side of the flat plate 1a; guide rails 1c running on the top and bottom faces of the unit; power supply plugs 1d disposed on the back face; and a coaxial plug 1f to deliver an amplified output to the combiner unit 4. The TRPA unit 2 has a similar construction. The plug 1f is composed, as shown in Figs. 8(a) and 8(b) and Fig. 9, of outer conductors 1f-1 and inner conductors 1f-2, each of which is formed with a plurality of axial slits 1f-1a and 1f-2a, respectively, so that they have a spring property. Moreover, the output conductor 1f-1 has its leading end portion clamped by a ring 1f-1b having a spring property and its inner side counter-tapered to provide a wider opening. The TRPA unit 2 has a construction similar to that of the TRPA unit 1 except that a plate 2a of a high thermal conductivity is disposed at the righthand outer side, as shown in Fig. 4. The PS unit 3 is equipped, as shown in Fig. 3, with: sockets 3a and 3b disposed at the side which faces the TRPA units 1 and 2 to be connected to the plugs 1d and 1e of the TRPA units 1 and 2; guide rails 3c disposed on the upper and bottom faces; blower holes 3d formed in the bottom face; and exhaust ports 3e formed in the side which faces the TRPA units 1 and 2, wherein cooling air is blown through the holes 3d and the ports 3e. The combiner unit 4 is equipped with: coaxial sockets 4a to be connected to the plugs 1f of the TRPA units 1 and 2; and a coaxial plug 4b disposed at the opposite side to deliver a combined output. With reference to Figs. 8(a), 8(b), 9 and 10, the socket 4a is composed of: an outer conductor 4a-1; an inner conductor 4a-2; screws 4a-3 to fix the socket in a floating manner on the panel of the combiner unit 4; insulating bushings 4a-4; an insulating sheet 4a-5; flexible ribbon conductors 4a-6 to transmit the high-frequency high-power signal; and flexible ribbon conductors 4a-7 to ground the outer conductor 4a-1 and the inside of the combiner unit 4 to earth. In this case, the insulating sheet 4a-5 is inserted between the panel of the combined unit 4 and the outer conductor 4a-1, and the outer conductor 4a-1 is fastened by means of the screws 4a-3 through the insulating bushings 4a-4 with a margin (D₁ > D₂). Therefore, the panel of the combiner unit 4 and the outer terminal 4a-1 are fastened with a floating structure having a tolerance of one to several millimeters. To make up the floating structure, on the other hand, the outer conductor 4a-1 and the inner conductor 4a-2 are connected with the inside of the combiner unit through the flexible ribbon conductors 4a-6 and 4a-7. Fig. 11 is an breakdown perspective view showing the shelf 6. In Fig. 11, the shelf 6 is composed of the air chambers 6a and 6b, a plurality of blower ducts 6c, a plurality of guide rails 6d, 6e and 6f, a plurality of shelf plates 6g, side plates 6h and 6i, a top plate 6j and other members 6k to 6n. As shown in Fig. 4, the air chamber 6a is formed with: an intake port 6a-1 in its side, for example; a plurality of blower ports 6a-2 in its upper face to deliver cooling air to TRPA units 1 and 2 of upper and lower sides; and a plurality of blower ports 6a-3 (Fig. 6) in its upper face to deliver cooling air to the PS unit 3 of the lower side. The other air chamber 6b is formed with: an intake port 6b-1 in its side; and a plurality of blower ports 6b-2 in its upper face to deliver cooling air to the upper PS unit 3. The blower duct 6c is disposed, as shown in Figs. 12(a) and 12(b), at a constant spacing from the flat plates 1a and 2a of the TRPA units 1 and 2, and comprises: a plurality of U-sectional shaped nozzles 6c-2 having jet ports 6c-1 which are located at a location corresponding to the heat-producing elements 1b and 2b; and an air chamber 6c-4 which is joined to the nozzles 6c-2 and has upwardly sloped faces 6c-3 with respect to the flat plates 1a and 2a, giving an upwardly-tapered shape a shown. The nozzles 6c-2 are arranged in the depthwise direction of the sloped faces 6c-3. In Fig. 11, the guide rails 6d are installed to be fitted to the guide rails 1c, 2c and 3c, which are formed on the bottom faces of the TRPA units 1 and 2 and the PS units 3 as shown in Fig. 3, and have a length equal to or more than the total length of the TRPA units 1 or 2 and the PS units 3. Thus, the guide rails 6d guide the units 1 and 2 and the unit 3 in the directions W - X and Y - Z. The guide rails 6e are equipped to be engaged with the guide rails 1c and 2c, which are formed on the upper faces of the TRPA units 1 or 2, and have a length equal to or more than that of the TRPA units 1 and 2 to guide them in the directions W - X. Further, the guide rails 6f are installed to be fitted in the guide rails 3c which are formed on the upper faces of the PS units 3, and have a length equal to or more than that of the PS units 3 to guide them in the directions Y - Z. The shelf plates 6g are formed with holes, which have a size larger than the external size of the sockets 4a of the combiner unit 4, so that they can accommodate the combiner unit 4 and its guide rails 6f. Assembly of the shelf 6 thus constructed is accomplished in the following manner. The air chamber 6a is disposed at the bottom. The blower duct 6c is so attached to the air chamber 6a as to cover the blower port 6a-2 of the chamber 6a. Then, the guide rails 6d are attached, and the side plates 6h and 6i are attached to the lefthand and righthand ends. To the these side plates 6h and 6i, the shelf plates 6g, to which have been attached the guide rails 6f, are attached at the vertical center and the upper end. The air chamber 6b is placed on the central shelf plate 6g. The members 6k are attached to the front of the side plates 6h and 6i at the same level as that of the air chamber 6b. Members 6ℓ are attached to the inner centers of the side plates 6h and 6i at the same level as that of the air chamber 6b. Members 6m are interposed between the air chamber 6b and the members 6k. The guide rails 6e are attached to the lower faces of the members 6k, 6ℓ and 6m. The guide rails 6d are attached to the upper faces of the members 6k, 6ℓ and 6m and the air chamber 6b. The top plate 6j, to which have previously been attached the guide rails 6e, is attached to the upper ends of the side plates 6h and 6i and the upper end of the shelf plate 6g which in turn is disposed at the upper portion. Finally, the members 6m are so attached to the side plates 6h and 6i that they are positioned between the two ends of the members 6k. Here, the side plates 6h and 6ℓ are formed with positioning plates 6h-1 and 6i-1 so that the air chamber 6b, the shelf 6g and the members 6k may be positioned slightly higher than the guide rails 1c, 2c and 3c of the TRPA units 1 or 2 and the PS units 3. Thus, no level adjustment is required so as to simplify the assembly. Next, the method of mounting the units will be described in the following. In Figs. 3 and 9, the combiner units 4 are fixed on the plates 6g of the shelf 6, and the dividing units 5 are fixed on the members 6n. When the TRPA units 1 and 2 and the PS units 3 are to be mounted, the TRPA units 1 and 2 are mounted on the shelf 6 while being guided in the directions W - X on the guide rails 6d and 6e of the shelf 6, whereas the PS units 3 are guided from the opposite side in the directions Y - Z on the guide rails 6d and 6f. Then, the units 1, 2 and 3 are accommodated in the shelf 6, and the plugs 1d, 1e and 1f are connected to the sockets 3a, 3b and 4a. In the mounting operations, though a small misalignment may occur between the plugs and sockets due to manufacture and assembly errors, by means of the aforementioned floating structures of the sockets 3a, 3b and 3c, accurate coupling can be established. Further, in the illustrated embodiment, stable electric contact between the plugs 1f and the sockets 4a is accomplished by means of the rings 1f - 1b. Thus, the TRPA units 1 and 2, the PS units 3 and the combiner units 4 are electrically connected, completely. Furthermore, since the amplified high-frequency power output is transmitted through the plug 1f and the socket 4a, in general leakage of high frequency output may be derived from the socket 4a. However, in the embodiment, such leakage can be avoided by inserting the insulating sheet 4a-5 between the panel of the unit 4 and the other conductor 4a-1 while making a capacitor. Next, the cooling operation of the arrangement will be described in the following with reference to Figs. 4 to 7 and Figs. 12(a) and 12(b). In Fig. 4, the cooling air 7 to cool the upper and lower TRPA units 1 and 2 and the lower PS units 3 is blown from the intake port 6a-1 of the air chamber 6a and is distributed to the individual blower ducts 6c and to the lower PS units 3. As shown in Figs. 12(a) and 12(b), the cooling air 7a distributed into the individual blower ducts 6c is injected through nozzles 6c-2 and jet injection ports 6c-1 so as to impinge upon the flat plates 1a and 2a, thereby to cool the heat-producing elements 1b and 2b. Here, the nozzles 6c-2 have large port size, as compared with the diameters of the jet injection ports 6c-1, so that the flow velocity is relatively lower with low pressure loss (drop). Since the pressure drop to the jet injection ports 6c-1 is as low as negligible, the flow velocities of the jets 7a-1 can be of high speed and accordingly the heat transfer coefficient is increased. Since, moreover, the heat-producing elements 1b and 2b are cooled by the jets 7a-1 at the same temperature notwithstanding their locations in the vertical direction, the heat transfer coefficient is also increased while preventing irregularity of cooling effect dependent on the vertical locations of the heat-producing elements, thus increasing the cooling efficiency. The heat transfer coefficient is further increased because the heat-producing elements 1b and 2b are locally cooled by the jets 7a-1. Incidentally, the following equation holds between the amount of heat radiation Q and the heat transfer coefficient α: Q = α · A · ΔT, wherein A: the area of heat radiation; and ΔT: the temperature difference. On the other hand, the jets 7a-1 having taken the heat from the flat plates 1a and 2a flow along the nozzles 6c-2 and between the flat plates 1a and 2a and the air chamber 6c-4 until they are discharged to the outside. Since, at this time, the space between the flat plates 1a and 2a and the air chamber 6c-4 diverges toward the exhaust ports due to the taper shape of the air chamber 6c-4, the flow speed in the exhaust ports is not increased, and, therefore, it is not necessary to positively enlarge the space between the flat plates 1a and 2a and the air chamber 6c-4. This feature enables the arrangement to be compact. As shown in Figs. 5 and 6, on the other hand, the cooling air 7b distributed to the lower PS unit 3 cools its inside and after this, flows through the exhaust portions of the TRPA units 1 and 2. Thus, the exhaust air from the PS unit 3 is exhausted together with the exhaust air from the TRPA units 1 and 2. Moreover, the cooling air for the upper PS unit 3 is supplied from the side of the air chamber 6b and flows like that of the lower PS unit 3. Accordingly, it is unnecessary to provide exhaust ducts especially for the PS units 3. As has been described hereinbefore, in the illustrated arrangement, space M (indicated in Fig. 6) between the TRPA units and the PS units can be reduced to be equal to the size, at most, of the plugs 1d and 1e and the sockets 3a and 3b in the connected state. The height N (Fig. 6) can be reduced substantially to that of the TRPA units. Moreover, the width P (indicated in Fig. 7) can also be reduced to a reasonably small width because the blower ducts 6c have the featured shape to be sloped with respect to the flat plates 1a and 2a. Further, by inserting the individual units into the shelf, all the electric coupling points are connected by the connectors so that wiring assembly is zero. Moreover, the TRPA units 1 and 2 can be produced with a flat shape, so that the arrangement can be compact and light in weight notwithstanding the high power amplifier arrangement, and while still having good cooling efficiency. Furthermore, the power amplifier arrangement can be manufactured at a reasonable cost and is easy to assemble and maintain. Incidentally, the lines (the plug-and-socket means) transmitting high power are concealed inside for safety.

Claims: An integrated power amplifier arrangement including a plurality of amplifier units (1, 2), a power supply unit (3), a combiner unit (4) for combining the outputs of said plurality of amplifier units (1, 2), first connecting means (1d, 3a) for supplying power from said power supply unit (3) to said amplifier units (1, 2), and second connecting means (1f, 4a) for transmitting the outputs of said amplifier units (1, 2) to said combiner unit (4), characterized in that said amplifier units (1, 2) and said power supply unit (3) are accommodated on a shelf (6g) while being slidable on said shelf in respective opposite directions by means of guide rails (1c, 2c, 3c, 6d, 6e, 6f) for guiding said amplifier units (1, 2) and said power supply unit (3) on said shelf, the height of said power supply unit (3) being less than that of said amplifier units (1, 2); said combiner unit (4) is disposed above said power supply unit (3) and disposed behind said amplifier units (1, 2); said first connecting means (1d, 3a) are of plug-and-socket type and the connection is completed when said amplifer units (1, 2) and said power supply unit (3) are disposed at predetermined locations on said guide rails; and said second connecting means (1f, 4a) are of plug-and-socket type and the connection is completed when said amplifier units (1, 2) are disposed at the predetermined location on said guide rails. An integrated power amplifier arrangement as claimed in claim 1, further comprising an air chamber (6a) under said shelf (6g) on which said amplifier units (1, 2) and said power supply unit (3) are accommodated, blower ducts (6c) disposed on said air chamber (6a) and disposed between respective amplifier units (1, 2) for receiving cooling air from said air chamber (6a), and a plurality of nozzels (6c-2) attached to said blower ducts (6c) for blowing said cooling air onto radiation plates (1a) of said amplifier units (1, 2), and in which said blower ducts (6c) have an upwardly-tapered shape.

Inventors: FUJINO KAZUO C O NEC CORPORATI, IKEGAMI TOMOHITO C O NEC CORPO, YAMAMOTO TETSUMICHI C O NEC CO, YANAGIBAYASHI TAKESHI C O NEC, FUJINO, KAZUO C/O NEC CORPORATION, IKEGAMI, TOMOHITO C/O NEC CORPORATION, YAMAMOTO, TETSUMICHI C/O NEC CORPORATION, YANAGIBAYASHI, TAKESHI C/O NEC CORPORATION
Applicants: NIPPON ELECTRIC CO, NEC CORPORATION
Application year: 1988
Main classification: H05K7
IPC codes: H05K7, H03F3, H03F1, H01L23