JP4183382B2 - Microwave circuit - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a microwave circuit mounted with a microwave device such as an FET or HEMT.
[0002]
[Prior art]
A low-noise high-frequency amplifier (hereinafter referred to as “LNA”) of a low-noise down converter (hereinafter referred to as “LNB”) that receives satellite broadcast or satellite communication, converts it into an intermediate frequency signal, and outputs it is formed on a substrate. It consists of a microwave circuit with elements incorporated in the microstrip line.
[0003]
In the LNA, a 12 GHz band RF signal received by an antenna is input from an input terminal. The input signal is amplified and output by two amplifiers incorporated in the microstrip line. The amplifier is composed of a microwave device such as a GaAsFET (gallium arsenide field effect transistor) or a HEMT (High Electron Mobility Transistor).
[0004]
In particular, a HEMT is a semiconductor device that uses high mobility electrons accumulated on a heterojunction surface of a compound semiconductor as carriers, and is widely used because it is suitable for high frequency amplification and high speed computation.
[0005]
FIG. 8 shows a conventional microwave circuit on which a HEMT is mounted. In the microwave circuit 1, a so-called leadless type HEMT 5 is disposed on a substrate 2 made of an insulator. A gate 5G, a drain 5D, and two sources 5S are exposed on the back surface of the HEMT 5.
[0006]
On the microstrip line formed on the substrate 2, a gate land 7 and a drain land 8 are provided, and two source lands 9a and 9b are provided on both sides of the microstrip line. Through holes 10a and 10b penetrating the substrate 2 are formed in the source lands 9a and 9b, and are connected to a ground pattern (not shown) formed on substantially the entire back surface of the substrate 2.
[0007]
The gate 5G, the drain 5D, and the two sources 5S of the HEMT 5 are soldered to the gate land 7, the drain land 8, and the source lands 9a and 9b, respectively. Through holes 10a in this, 10b solder is filled in, and the source land 9 a, 9 b and the ground pattern is conducted. As a result, the source 5S of the HEMT 5 is grounded.
[0008]
When a negative voltage and a positive bias voltage are respectively applied to the gate 5G and the drain 5D of the HEMT 5, the signal input from the gate 5G is amplified and output from the drain 5D.
[0009]
[Problems to be solved by the invention]
However, according to the conventional microwave circuit 1 described above, since the through holes 10a and 10b are provided in the source lands 9a and 9b, the solder applied to the source lands 9a and 9b is prevented from passing through the through holes 10a and 10b. And flows out to the back surface of the substrate 2. For this reason, there is a problem that the bonding strength of the source 5S becomes weak and the reliability of the microwave circuit 1 is low.
[0010]
In order to suppress the outflow of solder, a method of providing through holes 10a and 10b in contact with the outside of the source lands 9a and 9b as shown in FIG. However, in this case, the distances L1 and L2 between the source 5G of the HEMT 5 and the through holes 10a and 10b become longer.
[0011]
For this reason, if the distances L1 and L2 vary due to differences in the installation position of the HEMT 5 and the sizes of the source lands 9a and 9b, a potential difference occurs between the two sources 5S due to a difference in inductance. As a result, there is a problem that causes abnormal oscillation of the HEMT 5.
[0012]
An object of the present invention is to provide a microwave circuit capable of improving reliability by firmly joining a microwave device without causing abnormal oscillation.
[0020]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a source land, a drain land, and a gate land for soldering a source, drain and gate of a leadless HEMT to the surface of a substrate having a ground pattern formed on the back surface. In the microwave circuit in which the source is soldered to the source land having a through hole connected to the ground pattern and grounded , the length of the drain land and the gate land in the longitudinal direction is The source land is longer than the source land, so that the area of the source land is larger than the areas of the drain land and the gate land.
[0021]
According to this configuration, the drain and gate of the HEMT are soldered to the drain land and the gate land, respectively. The source of the HEMT is soldered to the source land having a larger area than the drain land and the gate land and having a larger amount of solder. Then, the source land and the ground pattern formed on the back surface of the substrate are made conductive by the solder in the through hole formed in the source land, and the source of the HEMT is grounded.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. For convenience of explanation, the same reference numerals are given to the same portions as those in FIGS. 8 and 9 of the conventional example. FIG. 1 is a configuration diagram illustrating an LNB including an LNA including the microwave circuit according to the first embodiment.
[0023]
Reference numeral 21 denotes a feed horn (primary radiator) connected to a parabolic antenna (not shown), and an RF signal is extracted from the feed horn 21 to the transmission line 31. The RF signal is a signal in the 12.25 to 12.75 GHz band, and is amplified by the LNA 22 and then transmitted to the band pass filter 23.
[0024]
The LNA 22 includes amplifiers 22a and 22b that amplify the RF signal. The signal that has passed through the bandpass filter 23 is transmitted to the mixer 25 of the mixing amplification unit (MMIC) 24. The mixer 25 outputs an intermediate signal (IF) of a frequency difference between the 11.3 GHz local transmission signal given from a local oscillator (LO) 27 and the input RF signal. For this reason, the frequency band of the intermediate frequency signal output from the mixer 25 is 950 to 1450 MHz.
[0025]
The intermediate frequency signal output of the mixer 25 is amplified by an intermediate frequency amplifier circuit 26 comprising an amplifier, and then is output to an output terminal 29 via a coupling capacitor C1. The output terminal 29 is connected to an input terminal of a tuner (not shown). The tuner selects a channel by selecting one of the input intermediate frequency signals.
[0026]
A DC voltage of 15 V is applied to the output terminal 29 from the tuner. One end of the high frequency choke coil L is connected to the output terminal 29, and the power supply 28 is connected to the other end. The power supply 28 supplies power to the LNA 22, the local oscillator 27, and the mixing amplifier 24 based on the applied DC voltage.
[0027]
The amplifiers 22a and 22b of the LNA 22 are composed of HEMTs. 2 and 3 are a side sectional view and a plan view showing a microwave circuit in which the HEMT is mounted. In the microwave circuit 1, a so-called leadless type HEMT 5 is disposed on a substrate 2 made of an insulator. As shown in the rear view of FIG. 4, the HEMT 5 has a gate 5G, a drain 5D, and two sources 5S exposed on the rear surface.
[0028]
On the microstrip line formed on the substrate 2, a gate land 7 and a drain land 8 are provided, and two source lands 9a and 9b are provided on both sides of the microstrip line. Through holes 10a and 10b penetrating the substrate 2 are formed in the source lands 9a and 9b, and are connected to the ground pattern 4 formed on substantially the entire back surface of the substrate 2.
[0029]
The gate 5G, the drain 5D, and the two sources 5S of the HEMT 5 are soldered to the gate land 7, the drain land 8, and the source lands 9a and 9b, respectively. Through holes 10a, 10b conductive paste 11 is filled, the source land 9 a, 9 b and the ground pattern is conductive. As a result, the source 5S of the HEMT 5 is grounded.
[0030]
When a negative voltage and a positive bias voltage are respectively applied to the gate 5G and the drain 5D of the HEMT 5 by the power supply 28 (see FIG. 1), the signal input from the gate 5G is amplified and output from the drain 5D. It is like that.
[0031]
According to the present embodiment, since the through holes 10a and 10b are filled with the conductive paste 11, the solder applied to the source lands 9a and 9b is blocked from flowing into the through holes 10a and 10b by the conductive paste 11. It is done. Accordingly, the source 5S can be firmly soldered with a sufficient amount of solder, and the reliability of the microwave circuit 1 can be improved.
[0032]
Next, FIG. 5 is a back view showing the microwave circuit of the second embodiment. In the present embodiment, the conductive paste 11 is omitted from the first embodiment shown in FIGS. 2 and 3, and through holes 10 a and 10 b opened on the ground pattern 4 formed on substantially the entire back surface of the substrate 2. A resist 13 is applied around the substrate. Other configurations are the same as those of the first embodiment.
[0033]
Then, the source 5S of the HEMT 5 is soldered by solder applied on the source lands 9a and 9b. At this time, the solder flows into the through holes 10a and 10b, but the back surface of the substrate 2 is blocked by the resist 13 and can be prevented from flowing out of the through holes 10a and 10b. Accordingly, the source 5S can be firmly soldered with a sufficient amount of solder, and the reliability of the microwave circuit 1 can be improved.
[0034]
Next, FIG. 6 is a plan view showing the microwave circuit of the third embodiment. In the present embodiment, the conductive paste 11 is omitted from the first embodiment shown in FIGS. 2 and 3, and the areas of the source lands 9a and 9b are made larger than those of the gate land 7 and the drain land 8. ing. Other configurations are the same as those of the first embodiment.
[0035]
Then, the source 5S of the HEMT 5 is soldered by solder applied on the source lands 9a and 9b. At this time, since the areas of the source lands 9a and 9b are large, the amount of solder applied on the source lands 9a and 9b increases. Thereby, even if solder flows out to the back surface of the substrate 2 through the through holes 10a and 10b, the source 5S can be soldered with a sufficient amount of solder. Accordingly, the source 5S can be firmly soldered with a sufficient amount of solder, and the reliability of the microwave circuit 1 can be improved.
[0036]
Next, FIG. 7 is a plan view showing the microwave circuit of the fourth embodiment. In the present embodiment, the conductive paste 11 is omitted from the first embodiment shown in FIGS. 2 and 3, and the through holes 10a and 10b are provided in contact with the outer periphery of the source lands 9a and 9b. 9b are connected by a connecting portion 9c made of a conductive pattern. Other configurations are the same as those of the first embodiment.
[0037]
Since the through holes 10a and 10b are provided in contact with the outer peripheries of the source lands 9a and 9b, the solder applied to the source lands 9a and 9b is prevented from flowing into the through holes 10a and 10b. Further, when the distances L1 and L2 between the source 5S and the through holes 10a and 10b become long and the distances L1 and L2 vary due to the difference in the HEMT 5 mounting position and the size of the source lands 9a and 9b, the distances L1 and L2 Differences in inductance occur between the two.
[0038]
However, the two sources 5S are maintained at the same potential by the connecting portion 9c. Therefore, the source 5S can be firmly soldered with a sufficient amount of solder to improve the reliability of the microwave circuit 1, and abnormal oscillation of the HEMT 5 can be prevented.
[0039]
In the first to fourth embodiments, the microwave circuit on which the leadless HEMT is mounted has been described. However, other types of leads such as a HEMT and a GaAsFET with leads in which leads are extended from the gate, drain, and source are described. The same effect can be obtained with a similar configuration in a microwave circuit mounted with a microwave device.
[0043]
【The invention's effect】
According to the present invention, since the area of the source land is larger than that of the gate land and the drain land, the amount of solder applied on the source land is increased. Thereby, even if solder flows out to the back surface of the substrate through the through hole, the source of the leadless HEMT can be soldered with a sufficient amount of solder. Therefore, a sufficient amount of solder can be secured to firmly solder the source, and the reliability of the microwave circuit can be improved.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing an LNB including an LNA including a microwave circuit according to a first embodiment of the present invention.
FIG. 2 is a side sectional view showing the microwave circuit according to the first embodiment of the present invention.
FIG. 3 is a plan view showing the microwave circuit according to the first embodiment of the present invention.
FIG. 4 is a back view showing the HEMT of the microwave circuit according to the first embodiment of the present invention.
FIG. 5 is a back view showing a microwave circuit according to a second embodiment of the present invention.
FIG. 6 is a plan view showing a microwave circuit according to a third embodiment of the present invention.
FIG. 7 is a plan view showing a microwave circuit according to a fourth embodiment of the present invention.
FIG. 8 is a plan view showing a conventional microwave circuit.
FIG. 9 is a plan view showing another conventional microwave circuit.
[Explanation of symbols]
1 Microwave circuit 2 Substrate 4 Ground pattern 5 HEMT
5G Gate 5D Drain 5S Source 7 Gate Land 8 Drain Land 9a, 9b Source Land 9c Connection Portion 10a, 10b Through Hole 11 Conductive Paste 13 Resist 21 Feed Horn 22 LNA
23 Band pass filter 24 Mixing amplifier 25 Mixer 26 Intermediate frequency amplifier 27 Local transmitter 28 Power supply 29 Output terminal

Claims (1)

A source land, a drain land, and a gate land for soldering the source, drain, and gate of a leadless HEMT are formed on the front surface of the substrate on which a ground pattern is formed on the back surface, and connected to the ground pattern. In the microwave circuit that solders the source to the source land provided with a hole inside and grounds the source land,
By making the length in the longitudinal direction of the source land longer than the length in the longitudinal direction of the drain land and the gate land, the area of the source land is reduced to the area of the drain land and the gate land. A microwave circuit characterized by being made wider.

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