JP3146264B2 - High frequency power amplifier - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-frequency power amplifier having improved characteristics of high output power amplification and heat conduction in a high-frequency band.

[0002]

2. Description of the Related Art Generally, in a high-frequency power amplifier, it is very important in terms of reliability to lower the junction temperature or channel temperature of a transistor. For this purpose, a metal with good thermal conductivity soldered to the bottom of the transistor case is fixed to a metal body such as aluminum to lower the thermal resistance and reduce the rise in junction temperature or channel temperature. I have.

Conventionally, a high-frequency power amplifier of this type has a transistor 1 and a thermal conductivity 10 as shown in FIG. 2B, which is a perspective view of FIG. 2 and FIG. The metal blocks 3 and 4 are made of a metal such as copper tungsten, and the input and output circuits of a microwave integrated circuit (MIC) made of a ceramic dielectric substrate and the like, and the input circuit 3 and the output circuit 4 are fixed to the metal block 10. Have been. The metal block 10 is fixed to a metal case 7 made of aluminum or the like by screws inserted into the holes 11 to 16 as shown in FIG. Reference numerals 8 and 9 denote adjacent integrated circuits, in which metal ribbons 17 and 18 are connected to the input circuit 3 and the output circuit 4, respectively.
Are connected using

Here, the metal block 10 requires a vertical height H2 in order to obtain a spread of heat from the transistors 1 and the input / output circuits 3 and 4 in the block in the horizontal direction.
Further, in order to reduce the contact thermal resistance with the case 7, a length L5 in the horizontal direction is required. Usually, the height of the metal block needs to be approximately the same as the length direction of the transistor 1. Further, as the length L5 of the metal block 10,
Since the heat spreads at an angle of 45 ° from the end of the transistor 10, the length of the metal block 10 needs to be at least twice the length of the transistor 1. For example, if the length of the transistor 1 is 10 mm, the height of the metal block 10 is about 10 m.
m and a length of 20 mm or more are desired. Here, since the metal block 10 is embedded in the length L7 of the concave portion of the casing 7, the length L4 × 2 of the input / output circuit and the length L7 of the transistor are set.
6 and the total length L5 of the gaps on both sides of the transistor are made slightly smaller than the length L7 of the housing recess. Therefore, the gaps 19 and 20 were L7-L5, and had a deep groove having a length H2 from the surfaces of the input / output circuits 3 and 4.

[0005]

Since this conventional high-frequency power amplifier has the above-mentioned deep gap, the metal ribbons 17 and 18 which are the high-frequency signal paths and the gaps 19 and 20 which are the installation-side paths are provided on both sides. This produces a difference in depth H between the metals. If the depth is not negligible compared to the wavelength of the high-frequency signal, a large mismatch occurs between the adjacent circuit 8 and the input circuit 3 and between the output circuit 4 and the adjacent circuit 9. This mismatch is caused by the input VSWR and output V of the high power amplifier.
It causes deterioration of SWR, amplitude deviation, output power and other characteristics. In order to reduce the contact thermal resistance between the metal block 10 and the casing 7, silicon grease or the like is applied between the metal block 10 and the casing 7. However, since these coating agents are insulative, the installation side passage is difficult. Metal block and body 7
There is also a drawback that it causes a problem of disconnection between them.

[0006]

The high-frequency power amplifier of the present invention has an input circuit and an output circuit of a high-frequency transistor comprising a microwave integrated circuit, and a metal block is fixed to the bottom of the high-frequency transistor for heat conduction. In the state,
In a high-frequency power amplifier in which the metal block is further fixed to the concave portion of the housing for heat conduction, a thin metal plate is fixed to the back surface of a dielectric plate constituting a microwave integrated circuit of the input circuit and the output circuit. A metal plate is fixed on the metal block, and is longer than the length of the metal block.

[0007]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG.
1A is a perspective view of a subassembly of a high-frequency power amplifier main body according to one embodiment of the present invention. FIG. 1B is a cross-sectional view taken along the line AA of FIG. 1 (a) and 1 (b), reference numeral 1 denotes a transistor, 2 denotes a metal block made of a metal such as copper tungsten having good thermal conductivity, and 3 and 4 denote microwave integrated circuits (MIC) made of a ceramic dielectric substrate or the like. Are connected to the input terminal and the output terminal of the transistor 1 by a ribbon, respectively. Reference numerals 5 and 6 denote metal plates fixed to the back surfaces of the input circuit 3 and the output circuit by soldering or the like. The metal plates 5 and 6 are fixed on the metal block 2 using screws 23 to 26. Metal block 2
Is fixed to the metal case 7 by screws inserted into the holes 11 and 12. Similarly, the input circuit 3 and the output circuit 4 are fixed to the housing 7 by screws inserted into holes 13 to 16 provided in the metal plates 5 and 6 on the back surface. Reference numerals 8 and 9 denote adjacent microwave integrated circuits (MICs), and metal ribbons 17 and 1 are connected to the input circuit 3 and the output circuit 4, respectively.
8 are connected. As described in the conventional example, the metal block 2 needs to have a length L1 which is substantially the same as the height of the transistor 1 and is at least twice as long as the length of the transistor 1 in the direction L10. For example, if the length L10 of the transistor 1 is 10 mm, the height of the metal block 2 is about 1
0 mm and the length L1 are desirably 20 mm or more. However, since the metal plates 5 and 6 need only be thick enough to support the dielectric plate, they are about 1 to 1.5 mm. Further, the metal plates 5 and 6 are provided with a length L2 in order to make contact with a casing 7 described later.

On the other hand, the height H1 of the gaps 21 and 22 formed between the adjacent circuits 8 and 9 is the height H2 of the gap formed by the height of the metal block in the conventional example (about 10 m in the conventional example).
m,) (in this example, 1 to 1.5 mm). Metal ribbon 1 for high-frequency signal path
If the height H1 generated between the metal on both sides of the gaps 7 and 18 and the gaps 21 and 22 which are the ground side passages can be ignored compared to the wavelength of the high-frequency signal (experimentally 1/20 wavelength The following does not affect the input VSWR, output VSWR, amplitude deviation, output power, and other characteristics of the high power amplifier. In order to reduce the contact thermal resistance between the metal block 2 and the case 7, the length of the metal plates 5 and 6 is reduced by the recess L of the case.
It is longer than L2 by L3 and is in contact with the projecting body 7. Therefore, even when silicon grease or the like is applied between the metal blocks, the passage on the ground side passes through the metal plate 5 and hits the housing 7 in addition to the metal block. There is no need to pass through the contact surface with the contact, so that no problem occurs.

[0009]

As described above, according to the present invention, only a transistor which needs heat radiation is mounted on a metal block, and an input circuit and an output circuit are mounted on another thin metal plate, so that a circuit between adjacent circuits can be provided. By reducing the depth of the gap generated in the high frequency power amplifier, it is possible to prevent the characteristics of the high frequency power amplifier from deteriorating. By bringing the above metal plate into direct contact with the body,
It also has the effect of lowering the junction temperature or the channel temperature, which is important for the reliability of the high power amplifier.

[Brief description of the drawings]

FIGS. 1A and 1B are perspective views of one embodiment of the present invention, and are cross-sectional views taken along line AA of FIG.

2A and 2B are perspective views of a conventional example, and FIG.
It is a BB sectional view of (a).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Transistor 2 Metal block 3 Input circuit 4 Output circuit 5,6 Metal plate 7 Case 8,9 Adjacent circuit 10 Metal block 11-16 Screw hole 17,18 Metal ribbon 19-22 Gap 23-26 Screw

Continuation of front page (56) References JP-A-63-200602 (JP, A) JP-A-5-191156 (JP, A) JP-A-4-297114 (JP, A) JP-A-4-296103 (JP) JP-A-4-150204 (JP, A) JP-A-5-95212 (JP, A) JP-A-4-312960 (JP, A) JP-A-63-59004 (JP, A) 58-176417 (JP, U) JP-A 5-31307 (JP, U) JP-A 56-163317 (JP, U) JP-A 55-147793 (JP, U) (58) Fields surveyed (Int. Cl. ^7, DB name) H03F 3/60 H01P 5/08 H03F 3/19 H05K 1/02

Claims (2)

(57) [Claims] 1. A high-frequency transistor comprising an input circuit and an output circuit comprising a microwave integrated circuit, wherein a metal block is fixed to a bottom surface of the high-frequency transistor for heat conduction, and heat conduction is further performed to a concave portion of the housing. For this reason, in a high-frequency power amplifier in which this metal block is fixed, a thin metal plate is fixed to the back surface of a dielectric plate constituting a microwave integrated circuit of the input circuit and the output circuit, and this metal plate is placed on the metal block. And a longer length than the length of the metal block and is also fixed to the housing. 2. The method according to claim 1, wherein the length of the thin metal plate attached to the back surface of the input / output circuit is increased so that the thin metal plate can be fixed to the housing. 2. A depth of an interval generated in the signal is set to be equal to or less than 1/20 wavelength of a wavelength of a high-frequency signal.
The high-frequency power amplifier according to any one of the preceding claims.