JP3901458B2 - Electronic circuit unit - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electronic circuit unit used in a microwave device such as a satellite communication transmitter, and more particularly to an electronic circuit suitable for use in a circuit configuration in which a part of mounted circuit components includes a power amplifier. Regarding the unit.
[0002]
[Prior art]
In an electronic circuit unit of a satellite communication transmitter that is a microwave device, an intermediate frequency amplifier circuit, a local oscillation circuit, and a mixed power amplifier circuit are generally provided on a single circuit board. Is housed in a metal frame and covered with a cover. Here, the intermediate frequency amplifier circuit amplifies the intermediate frequency signal input to the electronic circuit unit to a certain level, and the mixed power amplifier circuit outputs the intermediate frequency signal from the intermediate frequency amplifier circuit from the local oscillation circuit by a mixer. After frequency conversion to a predetermined high-frequency signal based on the local oscillation signal, this high-frequency signal is passed through only a predetermined band by a band-pass filter, and further amplified by a power amplifier (power amplifier) until sufficient amplification is obtained. Output from the circuit unit.
[0003]
In such an electronic circuit unit for microwave equipment, for example, if a high frequency from the mixed power amplifier circuit leaks into the local oscillation circuit, the output signal may fluctuate, so a circuit component mounted on a circuit board is desired. It is necessary to shield each circuit. Therefore, conventionally, as such a shield structure, one circuit board is divided into a plurality of sections by an inner wall of the frame and a partition plate, and circuit components constituting a mixed power amplifier circuit, a local oscillation circuit, etc. are mounted in each section, respectively. It is like that.
[0004]
[Problems to be solved by the invention]
By the way, when the frequency band used for satellite communication becomes higher, for example, a frequency of 20 to 40 GHz called a millimeter wave band is used, the shield structure employed in the above-described conventional electronic circuit unit is mixed. There arises a problem that the high frequency from the power amplifier circuit cannot be reliably shielded against other circuits. In addition, when the frequency band is increased in this way, the degree of amplification required for the power amplifier of the mixed power amplifier circuit is increased, and the amount of heat generated by the power amplifier is increased accordingly. The problem of receiving occurs. Furthermore, it is difficult to obtain a power amplifier having such a large amplification degree as a package IC, and a method of wire bonding a power amplifier composed of a semiconductor bare chip is predicted. Therefore, the airtightness of the mixed power amplifier circuit including the semiconductor bare chip is expected. A new problem arises in that it is necessary to ensure sex.
[0005]
The present invention has been made in view of the actual situation of the prior art, and an object of the present invention is to provide a high-performance electronic circuit unit with less fluctuation of an output signal.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, in the electronic circuit unit of the present invention, a main casing made of a metal material, a first circuit board disposed in the main casing, and the first circuit board are partitioned. A sub housing made of a metal material disposed in the main housing in a state and a second circuit board disposed in a sealed state inside the sub housing, and the first circuit board includes an intermediate Circuit components of a frequency amplification circuit and a local oscillation circuit are mounted, and the second circuit board converts the frequency of the intermediate frequency signal input from the intermediate frequency amplification circuit and the local oscillation signal input from the local oscillation circuit. In this way, the circuit component of the mixed power amplifier circuit that amplifies the power is mounted.
[0007]
In the electronic circuit unit configured as described above, since the circuit components of the mixed power amplifier circuit are mounted on the second circuit board that is hermetically disposed inside the sub-housing, the mixed power amplifier circuit is mounted on the main housing. Not only an electrical shield but also mechanical hermeticity can be secured with respect to other circuits mounted on the first circuit board in the body, and the heat generated by the circuit components of the mixed power amplifier circuit can be transmitted through the sub casing. Heat can be easily radiated to the outside of the main housing.
[0008]
In the above configuration, it is preferable that the circuit components of the mixed power amplifier circuit include a frequency converter, a filter, and a plurality of power amplifiers, and at least a part of these power amplifiers is formed of a semiconductor bare chip. At that time, the semiconductor bare chip may be wire-bonded on the second circuit board, but if the semiconductor bare chip is inserted through the through-hole formed in the second circuit board and is opposed to the inner bottom surface of the sub casing, It is preferable because the heat generated from the semiconductor bare chip can be efficiently transmitted to the sub-housing.
[0009]
In the above configuration, the sub housing and the main housing may be formed of the same metal material. However, if the sub housing is formed of a different metal material having better thermal conductivity than the main housing, It is preferable because the amount of heat transmitted from the housing to the main housing can be suppressed.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
1 is a perspective view showing the overall configuration of an electronic circuit unit, FIG. 2 is a plan view showing an internal structure of the electronic circuit unit, and FIG. 3 is an electronic circuit unit. 4 is a perspective view of the heat radiating body, FIG. 5 is a cross-sectional view showing the internal structure of the heat radiating body, FIG. 6 is a perspective view showing the internal structure of the sub-housing, and FIG. FIG. 8 is an exploded perspective view of the mounting portion of the main housing and the heat sink as seen from the back side, FIG. 9 is a sectional view of the waveguide structure, and FIG. 10 is a satellite including an electronic circuit unit. FIG. 11 is an explanatory diagram of a circuit configuration.
[0011]
The electronic circuit unit according to the present embodiment is an application example to a satellite communication transmitter (microwave device) used in a satellite communication system. As shown in FIG. 10, this satellite communication system includes a modulator. And an indoor unit incorporating a tuner, a satellite communication transmitter, a satellite communication receiver, an outdoor unit incorporating a duplexer, a horn, and the like. In such a satellite communication system, the intermediate frequency signal input from the modulator is converted to a predetermined frequency by the satellite communication transmitter, and is output from the satellite communication transmitter as a power amplified high frequency signal. It is transmitted from the horn to the satellite via a tube and a duplexer. On the other hand, after the signal transmitted from the satellite is input from the horn, it propagates through another waveguide from the duplexer, is received by the satellite communication receiver, and is output from the satellite communication receiver to the tuner of the indoor unit.
[0012]
As shown in FIG. 11, the above-mentioned transmitter for satellite communication has an intermediate frequency amplifier circuit 1, a local oscillator circuit 2, and a mixed power amplifier circuit 3. The intermediate frequency amplifier circuit 1 has an input terminal from a modulator of the indoor unit. 2.5 GHz to 3 GHz is input via 4. The intermediate frequency signal input to the intermediate frequency amplifier circuit 1 is amplified to a certain level by the amplifier 5 and then output to the mixed power amplifier circuit 3 via the temperature corrector 6. The temperature corrector 6 compensates for a change in the amplification degree of the amplifier 5 depending on the ambient temperature, and amplifies the intermediate frequency signal when the ambient temperature increases and the amplification degree of the amplifier 5 decreases. When the reverse ambient environment temperature is lowered and the amplification degree of the amplifier 5 is increased, the intermediate frequency signal is attenuated. That is, the temperature corrector 6 functions to output an intermediate frequency signal having a substantially constant signal level to the mixed power amplifier circuit 3 even if the ambient environment temperature changes in the upward / downward direction.
[0013]
The local oscillation circuit 2 includes a voltage controlled oscillator (VCO) 7, an oscillation signal amplification circuit unit 8, and a reference oscillation circuit unit 9, and a 9 GHz oscillation signal output from the voltage control oscillator 7 is supplied from the oscillation signal amplification circuit unit 8. Input to the amplifier 10. The output of the amplifier 10, that is, the 9 GHz oscillation signal is converted into a 27 GHz oscillation signal via the triple multiplier 11, and then the mixed power amplification circuit is passed through the band-pass filter 12 that passes only the 27 GHz oscillation signal. 3 is output. On the other hand, the 40 MHz oscillation signal output from the reference oscillator 13 of the reference oscillation circuit unit 9 is converted to a frequency of 120 MHz via the next tripler 14 and then amplified by the amplifier 15 to be sampled phase detector. (Hereinafter referred to as SPD) 16. The SPD 16 receives the 120 MHz oscillation signal amplified by the amplifier 15 and the oscillation signal output from the voltage controlled oscillator 7 via the amplifier 10, and a phase comparison error signal generated by the phase difference between these two signals. Will occur. That is, a PLL circuit is constituted by the closed loop of the voltage controlled oscillator 7, the amplifier 10, the SPD 16 and the amplifier 17, and the voltage controlled oscillator 7 oscillates stably with a 9 GHz signal by this PLL circuit. The 9 GHz oscillation signal output from the voltage controlled oscillator 7 is amplified by the amplifier 10 and input to the triple multiplier 11. A part of the 40 MHz oscillation signal of the reference frequency oscillator 13 is led to the X-TAL signal output terminal 19 as a 10 MHz oscillation signal via the 1/4 frequency divider 18 to output the X-TAL signal. By being output from the terminal 19 to an external circuit (not shown), it is used as a reference oscillation signal for various circuits.
[0014]
The frequency converter 20 (mixer) of the mixed power amplifier circuit 3 includes the intermediate frequency signal (2.5 GHz to 3 GHz) output from the temperature corrector 6 of the intermediate frequency amplifier circuit 1 and the bandpass filter 12 of the local oscillator circuit 2. The 27 GHz oscillation signal output from is input and a high frequency signal of 29.5 GHz to 30 GHz is output to the output. The high-frequency signal of 29.5 GHz to 30 GHz output from the frequency converter 20 passes only a desired band by the band-pass filter 21 at the next stage, is input to the power amplifier 22, and further passes through the band-pass filter 23. After passing only the desired band, the high-frequency signal is input to the power amplifier 24. The power amplifier 24 has a certain high-frequency power level, but this time, the power amplifiers 25 and 25 in the final stage connected in parallel are now connected so that a sufficiently high power amplification level can be obtained for radiation in the air. It is input and output from the output terminal 26 (probe) to the waveguide with its output sufficiently increased.
[0015]
The electronic circuit unit according to the present embodiment is used as a satellite communication transmitter having the above-described circuit configuration. As shown in FIGS. 1 to 3, this electronic circuit unit forms a frame. A main housing 30 and a heat radiating body 31 are provided. The heat radiating body 31 includes a sub housing 32 and a heat radiating plate 33 which are joined and integrated with each other.
[0016]
The main housing 30 is formed in a substantially bottomed shape with the upper surface open, and the main housing 30 is die-cast using an aluminum material. A first waveguide groove 34 is provided on the outer surface of one side wall of the main housing 30, and an opening 30 a is formed from the side wall to a part of the bottom surface. A lid 35 is screwed to the outer surface of one side wall of the main housing 30 so as to cover the first waveguide groove 34, and the lid 35 is also die-cast using an aluminum material. ing. A first circuit board 36 is disposed inside the main housing 30, and one corner of the first circuit board 36 is cut out in accordance with the shape of the opening 30a. On the first circuit board 36, circuit components of the intermediate frequency amplifier circuit 1 and the local oscillator circuit 2 except the mixed power amplifier circuit 3 in the circuit configuration shown in FIG. Further, a cover 37 is screwed to the upper surface of the side wall of the main housing 30, and the open upper end of the main housing 30 is covered with the cover 37.
[0017]
As shown in FIGS. 4 to 6, the sub-housing 32 is formed in a bottomed shape with an open upper surface, and a second circuit board 38 is disposed therein. A cover 39 is attached to the open end of the upper surface of the sub housing 32, and the inside of the sub housing 32 is sealed by the cover 39. A second waveguide groove 40 is provided on one side surface of the sub housing 32. The sub-housing 32 and the cover 39 are made of a copper material having better thermal conductivity than aluminum, which is the material of the main housing 30, and the surface thereof is plated with gold to prevent corrosion. The mixed power amplifier circuit 3 having the circuit configuration shown in FIG. 11 is mounted on the second circuit board 38, and the intermediate frequency amplifier circuit 1 and the local oscillation circuit 2 mounted on the first circuit board 36, The mixed power amplifier circuit 3 mounted on the second circuit board 38 is partitioned inside the main housing 30 via the sub housing 32 and the cover 39.
[0018]
The second circuit board 38 is fixed to the inner bottom surface of the sub-housing 32 by screwing a plurality of mounting bodies 41 made of a metal material, and the second circuit board 38 has a plurality of regions by the mounting bodies 41. It is divided into. Although not shown, among the circuit components of the mixed power amplifier circuit 3 described above, the frequency converter 20 and the bandpass filters 21 and 23 are mounted in the respective regions on the second circuit board 38, and output terminals The probe 42, which is 26, projects from the end of the second circuit board 38 into the second waveguide groove 40 of the sub-housing 32. In addition, the power amplifiers 22, 23, and 25, which are other circuit components, are elements that require a large degree of amplification, and are all configured by the semiconductor bare chip 43. These semiconductor bare chips 43 are inserted into through-holes 38a formed in the second circuit board 38, and are fixed to the inner bottom surface of the sub-casing 32 using a conductive adhesive, and on the second circuit board 38. Are wire-bonded to a conductive pattern (not shown).
[0019]
The heat radiating plate 33 is also formed of a copper material having better thermal conductivity than aluminum, which is a material of the main housing 30, and the surface thereof is plated with nickel for preventing corrosion. The heat radiating plate 33 has a projecting protrusion 33 a, and the width of the protrusion 33 a is set slightly smaller than the opening 30 a of the main housing 30. The bottom surface of the sub housing 32 is joined and integrated on the protrusion 33a of the heat radiating plate 33 via the heat radiating sheet 44. As described above, heat is radiated by the integrated product of the sub housing 32 and the heat radiating plate 33. A body 31 is configured. The heat radiating sheet 44 is a sheet-like body having adhesiveness such as a silicon-based resin, and fine irregularities on the contact surface between the sub-casing 32 and the heat radiating plate 33 are leveled by the heat radiating sheet 44. As shown in FIG. 7, the radiator 31 is screwed to the bottom surface of the main housing 30 in a state of being inserted into the opening 30a. At this time, the protrusion 33a of the heat radiating plate 33 and the main housing 30 are fixed. A slight gap G is secured between the opening 30a and the protrusion 33a of the heat radiating plate 33 so as not to contact the main housing 30 with the gap G as a relief. Further, as shown in FIG. 8, a plurality of concave portions 45 and convex portions 46 are continuously formed on the bottom surface of the main housing 30 through the openings 30a, and the bottom surface of the main housing 30 and the heat radiating plate 33 are provided. The convex portion 46 is integrated as a contact surface. That is, the contact area between the bottom surface of the main housing 30 and the heat radiating plate 33 is reduced by the concave portions 45 positioned between the convex portions 46, and heat is hardly transmitted from the heat radiating plate 33 to the main housing 30.
[0020]
A flange portion 35a projecting in the thickness direction is integrally formed on the outer surface of the lid 35, and a waveguide hole portion 47 is formed so as to penetrate the flange portion 35a. As described above, the lid body 35 is attached to the outer surface of one side wall of the main housing 30 so as to cover the side portion of the opening 30 a, and is attached to the sub housing 32 and the main housing 30 exposed in the opening 30 a. Each is screwed. As a result, as shown in FIG. 9, the first waveguide groove 34 of the main housing 30 and the second waveguide groove 40 of the sub housing 32 are covered by the flat inner surface of the lid 35, The first and second waveguide grooves 34 and 40 and the lid 35 constitute a waveguide. Here, an inclined surface 34 a that intersects with the waveguide core approximately 45 degrees is formed at the end of the first waveguide groove 34, and the first waveguide groove 34 and the lid 35 are formed. The waveguide hole 47 is continuous in the vicinity of the inclined surface 34a. Therefore, the high-frequency signal output from the probe 42 of the mixed power amplifier circuit 3 propagates from the second waveguide groove portion 40 through the first waveguide groove portion 34 and is reflected by the inclined surface 34a, and is then guided. It is led out from the flange portion 35 a of the lid 35 through the tube hole 47. Note that another waveguide 48 indicated by a two-dot chain line in FIG. 9 is attached to the end face of the flange portion 35a, and as described above, this waveguide 48 is connected to the duplexer (see FIG. 10).
[0021]
In the electronic circuit unit configured as described above, the circuit components of the intermediate frequency amplifier circuit 1 and the local oscillation circuit 2 are mounted on the first circuit board 36 disposed in the main casing 30, and the sub casing 32 and the cover 39 are mounted. Since the circuit component of the mixed power amplifier circuit 3 is mounted on the second circuit board 38 that is hermetically disposed inside the intermediate power amplifier circuit 1 and the local oscillation circuit 2 in the main housing 30. Can be shielded reliably. Therefore, even if the frequency band used for satellite communication increases to, for example, about 30 GHz, the high frequency signal from the mixed power amplifier circuit 3 does not leak into other circuits, and fluctuations in output fluctuation can be prevented. it can.
[0022]
In addition, since the second circuit board 38 disposed inside the sub-housing 32 is sealed with the cover 39, the power amplifiers 22, 24, 25 of the mixed power amplifier circuit 3 that requires a large amplification degree are configured by the semiconductor bare chip 43. Even so, the semiconductor bare chip 43 can be prevented from being corroded by moisture or the like. Further, since the heat radiating plate 33 is integrated with the bottom surface of the sub-housing 32 to form the heat radiating body 31, the heat radiating body 31 is formed of a copper material having better thermal conductivity than the material of the main housing 30 (aluminum). The heat generated by the bare chip 43 can be easily radiated from the radiator 31 (the sub-casing 32 and the radiating plate 33) to the outside, and the temperature rise inside the main casing 30 can be suppressed. In addition, since the semiconductor bare chip 43 is inserted into the through hole 38a provided in the second circuit board 38 and is fixed to the inner bottom surface of the sub casing 32 using a conductive adhesive, the heat generated by the semiconductor bare chip 43 is generated by the sub casing 32. It can be directly transmitted to and efficiently radiated heat.
[0023]
In the above-described embodiment, the case where all the power amplifiers 22, 24, 25 of the mixed power amplifier circuit 3 are configured by the semiconductor bare chip 43 has been described. However, a part of these may be configured by the package IC. Further, the semiconductor bare chip 43 may be directly mounted on the second circuit board 38.
[0024]
【The invention's effect】
The present invention is implemented in the form as described above, and has the following effects.
[0025]
The circuit components of the intermediate frequency amplifier circuit and the local oscillation circuit are mounted on the first circuit board, the sub casing is arranged in a state separated from the first circuit board in the main casing, and the interior of the sub casing Since the circuit component of the mixed power amplifier circuit is mounted on the second circuit board disposed in a hermetically sealed state, the mixed power amplifier circuit is electrically connected to the other circuit mounted on the first circuit board in the main housing. As well as a mechanical shield, mechanical airtightness can be ensured, and the heat generated by the circuit components of the mixed power amplifier circuit can be easily radiated to the outside of the main housing through the sub housing.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an overall configuration of an electronic circuit unit according to an embodiment.
FIG. 2 is a plan view showing an internal structure of the electronic circuit unit.
FIG. 3 is an exploded perspective view of the electronic circuit unit.
FIG. 4 is a perspective view of a radiator.
FIG. 5 is a cross-sectional view showing the internal structure of the heat radiating body.
FIG. 6 is a perspective view showing an internal structure of a sub housing.
FIG. 7 is an explanatory view showing an attachment state of the main housing and the radiator.
FIG. 8 is an exploded perspective view of the attachment portion of the main housing and the heat radiating body as viewed from the back side.
FIG. 9 is a cross-sectional view of a waveguide structure.
FIG. 10 is an overall configuration diagram of a satellite communication system including an electronic circuit unit.
FIG. 11 is an explanatory diagram of a circuit configuration.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Intermediate frequency amplifier circuit 2 Local oscillation circuit 3 Mixed power amplifier circuit 20 Frequency converter 21, 23 Bandpass filter 22, 24, 25 Power amplifier 26 Output terminal 30 Main housing | casing 30a Opening 31 Radiator 32 Sub-housing 33 Radiation plate 33a Protruding portion 34 First waveguide groove 34a Inclined surface 35 Lid 35a Flange portion 36 First circuit board 37 Cover 38 Second circuit board 38a Through hole 39 Cover 40 Second waveguide groove 42 Probe 43 Semiconductor bare chip 44 Heat radiation sheet 45 Concave portion 46 Convex portion 47 Hole for waveguide

Claims (4)

A main casing made of a metal material, a first circuit board arranged in the main casing, and a sub-cabinet made of a metal material arranged in the main casing in a state of being partitioned from the first circuit board And a second circuit board that is hermetically disposed inside the sub-housing, and circuit components of an intermediate frequency amplifier circuit and a local oscillation circuit are mounted on the first circuit board. A circuit component of a mixed power amplifier circuit that amplifies power by converting the frequency of the intermediate frequency signal input from the intermediate frequency amplifier circuit and the local oscillation signal input from the local oscillator circuit is mounted on the circuit board 2. An electronic circuit unit characterized by comprising: 2. The electronic circuit unit according to claim 1, wherein the circuit components of the mixed power amplifier circuit include a frequency converter, a filter, and a plurality of power amplifiers, and at least a part of these power amplifiers is formed of a semiconductor bare chip. 3. The method according to claim 2, wherein a through hole is formed in the second circuit board, and the semiconductor bare chip is inserted through the through hole and faces the inner bottom surface of the sub casing. Electronic circuit unit. 4. The electronic circuit unit according to claim 1, wherein the sub casing is made of a metal material having better thermal conductivity than the main casing. 5.

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