JP2009105480A - Heat exhaustion circuit and high-output amplifier - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that when a high-output amplifier having a WBG device etc., is mounted on a resin substrate having low thermal conductivity, solder of a chip capacitor is softened or fused with heat generated due to slight loss of the chip capacitor and then the high-output amplifier greatly decreases in reliability. <P>SOLUTION: Disclosed is a heat exhaustion circuit including a dielectric rod electrically connected to a capacitor for DC-cutting of an output signal of a high-output amplifying element, and a metal island including a through-hole for connection with a ground and electrically connected to the dielectric rod to conduct heat of the capacitor, conducted in the dielectric rod, to the ground. a capacitive component of the metal island and an inductor component of the through-hole being enabled to resonate in parallel. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to exhaust heat of a high-power amplifier using a WBG (Wide Band Gap) device element or the like.

  In recent years, there has been an increasing demand for miniaturization, weight reduction, and cost reduction in RF (Radio Frequency) components such as low noise amplifiers, receivers, beacon transmitters, and high power amplifiers. For this reason, the RF component is cheaper and more workable than an alumina ceramic substrate, and an integrally formed resin substrate that forms various circuits such as a MIC (Microwave Integrated Circuit) circuit on a single substrate is being used. is there.

  Further, in a high-power amplifier which is one of RF components, conventionally, a device of several tens of watts (watt) class has been used, and power amplification has been performed at the final stage in order to obtain a higher output. However, in recent years, for example, a high-power amplifier having a WBG device of several hundred W class or the like is being used for a microwave high-power amplifier mounted on a satellite (see, for example, Patent Document 1).

JP 2006-222600 A (pages 3 to 5, FIG. 1)

  In general, an amplifier is mounted with a chip capacitor for DC (Direct Current) cut in order to supply a specified voltage to the input of the high-power amplifier. Therefore, when a device of several hundred W class is used for the amplifier, if a chip capacitor has a small resistance component, heat is generated and becomes a problem. For example, when a 100 W microwave is input to a chip capacitor having a loss of 0.1 dB (decibel), 2.3 W of heat is generated in the chip capacitor.

  The resin substrate has a thermal conductivity as small as about 1/35 compared to the alumina ceramic substrate. Therefore, when a high power amplifier having a WBG device or the like is used in combination with a resin substrate, it is difficult to exhaust heat generated by the chip capacitor with the thermal conductivity of the resin substrate. Since it is difficult to exhaust heat, the solder that fixes the chip capacitor becomes soft due to the generated heat, and in the worst case, the solder melts. This causes a problem that the reliability of the high-power amplifier is remarkably lowered.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to exhaust heat generated from a chip capacitor for DC cut or the like without affecting RF electrical characteristics.

The exhaust heat circuit according to the present invention includes:
A dielectric rod with electrodes metallized on both ends;
Metal island pattern including through holes,
An exhaust heat circuit comprising:
One end of the dielectric rod is electrically and thermally connected to a capacitor for DC-cutting the output signal of the high-power amplifier, and the other end of the dielectric rod is electrically and thermally connected to the island pattern. ,
The through hole electrically and thermally connects the island pattern and the ground,
While discharging the heat of the capacitor that conducts heat through the dielectric rod to the ground,
The capacitive component of the island pattern and the inductor component of the through hole are caused to resonate in parallel.

  According to the present invention, since the heat generated in the DC cut chip capacitor can be exhausted through the dielectric rod and the through hole, the solder for fixing the DC cut chip capacitor is not softened or melted. Thus, it is possible to maintain the reliability of the high output amplifier such as the WBG element. Also, by causing the inductor component of the through hole and the capacitance component of the metal island to resonate in parallel, the capacitance component of the dielectric rod is generated in the DC cut chip capacitor without affecting the RF electrical characteristics of the high power amplifier. It becomes possible to exhaust heat.

Embodiment 1 FIG.
Embodiment 1 of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a configuration of a microwave integrated circuit according to the first embodiment. Here, the microwave integrated circuit includes a resin substrate 11, a drain DC cut chip capacitor 12, a microstrip line 13, a metal island 14 which is a metal island pattern, a dielectric rod 15, a through hole 16, solder 17, GND ( Ground) layer 18.

  The resin substrate 11 may be a ceramic substrate. Further, the drain DC cut chip capacitor 12 is not limited to a chip as long as it is a capacitor that performs DC cut of a high-power amplified RF signal.

  FIG. 2 shows an equivalent circuit diagram of the high-power amplifier 21 including the microwave integrated circuit of FIG. Here, the high output amplifier 21 includes a drain DC cut chip capacitor 12, a WBG element 22, a metal island capacitance component 23, a dielectric rod capacitance component 24, a through-hole inductor component 25, an RF signal input terminal 26, an RF signal. An output terminal 27, a gate bias terminal 28, a drain bias terminal 29, and a gate DC cut chip capacitor 30 are included.

  In the high-power amplifier 21, a portion indicated by a broken line indicates a portion corresponding to the microwave integrated circuit shown in FIG. The WBG element 22 is not limited to a WBG element as long as it is an element that amplifies an RF signal input with high output.

  In the microwave integrated circuit of FIG. 1, a metal plating such as copper is applied to the inner wall in the vicinity of the microstrip line 13, a through hole 16 connected to the GND layer 18 is provided, and a metal island 14 including the through hole 16 is provided. The microstrip line 13 is connected by a dielectric rod 15.

  Although two through holes 16 are provided in FIG. 1, three or more through holes may be provided in order to further improve the exhaust heat effect, and the number is not limited to two. The metal island 14 is deposited, for example, in the order of Cr / Au / Ni / Au (chrome / gold / nickel / gold) from the substrate side.

  The dielectric rod 15 is made of a material having good thermal conductivity such as aluminum nitride. The thermal conductivity of aluminum nitride can be achieved at 200 W / m · K or higher, and exhibits high thermal conductivity. As a result, the heat generated in the drain DC cut chip capacitor 12 can be exhausted through the dielectric rod 15.

  In the present embodiment, the long side direction of the dielectric rod 15 is about several mm, and the short side direction is about 1 mm square. However, the size of the dielectric rod is not limited to this. In addition, the dielectric rod 15 is formed by cutting aluminum nitride into a rod shape, masking the dielectric rod 15 so as to deposit metal on both ends, and then performing metallization with a metal such as Ni (nickel) or Sn (tin). Metal-coated electrode. This makes it easy to fix the dielectric rod 15 by soldering.

  One end of the metal-covered electrode of the dielectric rod 15 is electrically connected to the drain DC cut chip capacitor 12 that DC cuts the output signal of the WBG element 22, and the one end side of the dielectric rod 15 is the drain DC cut chip. It is thermally connected to the capacitor 12. The other end of the metal-covered electrode of the dielectric rod 15 is electrically connected to the metal island 14, and the other end of the dielectric rod 15 is thermally connected to the metal island 14.

  One end of the through hole 16 is electrically and thermally connected to the metal island 14, and the other end of the through hole 16 is electrically and thermally connected to the GND layer 18. As a result, the heat of the drain DC cut chip capacitor 12 that conducts heat through the dielectric rod 15 is discharged to the ground.

  Next, the operation will be described with reference to FIGS. As shown in FIG. 2, the RF signal is input from the RF signal input terminal 26 of the high output amplifier 21, amplified by the WBG element 22, and then output from the RF signal output terminal 27. A gate DC cut chip capacitor 30 is mounted on the input side of the WBG element 22, and a drain DC cut chip capacitor 12 is mounted on the output side.

  Since the RF signal is amplified by the WBG element 22, the heat generated in the resistance component of the drain DC cut chip capacitor 12 is greater than the heat generated in the resistance component of the gate DC cut chip capacitor 30. large. Therefore, it is necessary to exhaust heat from the drain DC cut chip capacitor 12. However, since the thermal conductivity of the resin substrate 11 is small, exhaust heat from the resin substrate 11 is difficult.

  Therefore, as shown in FIG. 1, the heat generated from the drain DC cut chip capacitor 12 is discharged from the through hole 16 to the ground via the microstrip line 13, the dielectric rod 15, and the metal island 14. Here, the through hole 16 is connected to the GND layer 18 shown in FIG.

  When the heat is exhausted, the dielectric rod 15 is used, so that the capacitance component 24 of the dielectric rod may affect the electrical characteristics with respect to the RF output of the WBG element 22. That is, by seeing the capacitive component 24 of the dielectric rod, a part of the power amplified by the WBG element 22 is dissipated through the dielectric rod 15, or the frequency characteristic of the RF signal output from the WBG element 22 is flattened. In this case, ripples are generated by the capacitance component 24 of the dielectric rod, which may affect the frequency characteristics.

  Therefore, as shown in FIG. 2, by causing the inductor component 25 of the through hole and the capacitance component 23 of the metal island to resonate in parallel, the capacitance component 24 of the dielectric rod does not affect the RF electrical characteristics of the WBG element 22. Like that.

  When the metal island capacitance component 23 is C and the through-hole inductor component 25 is L, the resonance frequency f at which the admittance between the metal island capacitance component 23 and the through-hole inductor component 25 is 0 (that is, the impedance is infinite). Is as follows.

  By setting the resonance frequency for the RF signal as described above, the impedance in the capacitance component 23 of the metal island and the inductor component 25 of the through hole can be made infinite, so that it is considered to be electrically open (open). be able to. Therefore, the capacitive component 24 of the dielectric rod can be made invisible, and the capacitive component 24 of the dielectric rod does not affect the electrical characteristics of the RF output of the WGB element 22.

  An element that determines the capacitance component 23 of the metal island is the size of the metal island 14. Factors that determine the inductor component 25 of the through hole include the position, the number, the hole diameter, and the substrate thickness (through hole depth) of the through hole 16. Using these elements as parameters, the capacitance component 23 of the metal island and the inductor component 25 of the through hole are determined.

  Further, it is not necessary to limit the exhaust heat circuit using the dielectric rod 15, the metal island 14 and the through hole 16 for exhausting the heat generated from the drain DC cut chip capacitor 12 to one as shown in FIG. Two or more exhaust heat circuits may be used to increase the exhaust heat effect.

  As a result, the heat generated in the drain DC cut chip capacitor 12 can be exhausted through the dielectric rod 15 and the through hole 16, so that the solder 17 for fixing the drain DC cut chip capacitor 12 becomes soft. The reliability of the high-power amplifier 21 can be maintained without being melted or melted.

  Further, by causing the inductor component 25 of the through hole and the capacitance component 23 of the metal island to resonate in parallel, the capacitance component 24 of the dielectric rod can be used for drain DC cutting without affecting the RF electrical characteristics of the high-power amplifier 21. The heat generated in the chip capacitor 12 can be exhausted.

Embodiment 2. FIG.
The second embodiment according to the present invention will be described below with reference to the drawings. FIG. 3 is a diagram showing a configuration of a microwave integrated circuit according to the second embodiment. Reference numeral 31 denotes a metal member that metalizes the side surface of the resin substrate 11 so as to connect the metal island 14 and the GND layer 18, and covers the side surface of the resin substrate 11 using, for example, a gold ribbon or a gold-silver clad ribbon. Otherwise, the configuration is the same as in FIG.

  In the microwave integrated circuit of FIG. 3, a metal island 14 connected to the GND layer 18 by a metal member 31 is provided in the vicinity of the microstrip line 13, and the metal island 14 and the microstrip line 13 are connected by a dielectric rod 15. It has become the composition.

  A metal member 31 is coated on the side surface of the resin substrate 11 on which the dielectric rod 15 is mounted to connect the GND layer 18 and the metal island 14. That is, one end of the metal member 31 is electrically and thermally connected to the metal island 14 and the other end of the metal member 31 is electrically and thermally connected to the ground.

  Then, the heat generated from the drain DC cut chip capacitor 12 is exhausted to the ground through the microstrip line 13, the dielectric rod 15, the metal island 14, and the metal member 31.

  In the first embodiment, the capacitive component 23 of the metal rod and the inductor component 25 of the through hole are caused to resonate in parallel, so that the capacitive component 24 of the dielectric rod does not affect the electrical characteristics of the RF output of the WGB element 22. It was like that. In the second embodiment, by using the inductor component of the metal member 31 of the gold ribbon or the gold-silver clad ribbon instead of the inductor component of the through hole for parallel resonance, the electrical characteristics of the RF output of the WGB element 22 can be reduced. The capacitance component 24 of the dielectric rod can be prevented from being affected.

  Note that factors that determine the inductor component of the metal member 31 include, for example, the length and width of a gold ribbon or a gold-silver clad ribbon. The inductor component of the metal member 31 is determined using these elements as parameters.

  Thereby, compared with Embodiment 1, the area which the metal island 14 connects with the GND layer 18 becomes large, and it can improve the exhaust heat effect more.

1 is a diagram showing a configuration of a microwave integrated circuit according to a first embodiment of the present invention. 1 is an equivalent circuit diagram of a high-power amplifier including a microwave integrated circuit according to Embodiment 1 of the present invention. It is a figure which shows the structure of the microwave integrated circuit by Embodiment 2 of this invention.

Explanation of symbols

11. Resin substrate 12. 12. Drain DC cut chip capacitor Microstrip line 14. Metal Island 15. Dielectric rod 16. Through hole 17. Solder 18. GND layer 21. High power amplifier 22. WBG element 23. Capacitance component of metal island 24. Capacitance component of dielectric rod 25. Through-hole inductor component 26. RF signal input terminal,
27. RF signal output terminal,
28. Gate bias terminal,
29. Drain bias terminal 30. Chip capacitor for gate DC cut 31. Metal parts

Claims (7)

A dielectric rod with electrodes metallized on both ends;
Metal island pattern including through holes,
An exhaust heat circuit comprising:
One end of the dielectric rod is electrically and thermally connected to a capacitor for DC-cutting the output signal of the high-power amplifier, and the other end of the dielectric rod is electrically and thermally connected to the island pattern. ,
The through hole electrically and thermally connects the island pattern and the ground,
While discharging the heat of the capacitor that conducts heat through the dielectric rod to the ground,
A waste heat circuit, wherein a capacitive component of the island pattern and an inductor component of the through hole are caused to resonate in parallel. A dielectric rod with electrodes metallized on both ends;
A metal island pattern that covers the side surface of the substrate on which the dielectric rod is mounted and that is connected to the ground by covering a metal member;
An exhaust heat circuit comprising:
One end of the dielectric rod is electrically and thermally connected to a capacitor for DC-cutting the output signal of the high-power amplifier, and the other end of the dielectric rod is electrically and thermally connected to the island pattern. ,
The metal member electrically and thermally connects the island pattern and the ground,
While discharging the heat of the capacitor that conducts heat through the dielectric rod to the ground,
A waste heat circuit, wherein a capacity component of the island pattern and an inductor component of the metal member are resonated in parallel.   3. The exhaust heat circuit according to claim 1, wherein the dielectric rod is made of aluminum nitride.   The capacitance component of the island pattern is determined by the size of the island pattern, and the inductor component of the through hole is determined by the position, number, hole diameter, or depth of the through hole. The exhaust heat circuit according to 1.   3. The exhaust heat circuit according to claim 2, wherein a capacity component of the island pattern is determined by a size of the island pattern, and an inductor component of the metal member is determined by a length or a width of the metal member.   The exhaust heat circuit according to claim 2, wherein the metal member is a gold ribbon or a gold-silver clad ribbon. A high-power amplifying element for high-power amplification of the RF signal;
A capacitor for DC-cutting the output signal of the high-power amplification element;
An exhaust heat circuit for exhausting heat from the capacitor;
A high power amplifier comprising:
The high-output amplifier according to claim 1, wherein the exhaust heat circuit is the exhaust heat circuit according to claim 1.

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