JP2001274331A - Microwave semiconductor amplifier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a microwave semiconductor amplifier which has such a structure that semiconductor amplification elements are connected in a plurality of stages and which can be easily formed on an MMIC and which has a large output power. SOLUTION: The microwave semiconductor amplifier comprises a plurality of semiconductor amplification elements A1-A4 connected in a plurality of stages, and a package 11 for storing these semiconductor amplification elements A1-A4. The thickness t2 of a first substrate 124 whereon the semiconductor amplification elements including at least the one A4 in the final stage are formed is smaller than the thickness t1 of one or a plurality of second substrates 121-123 whereon the other semiconductor amplification elements are formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave semiconductor amplifier used for communication equipment and radar equipment.

[0002]

2. Description of the Related Art A conventional microwave semiconductor amplifier will be described with reference to a circuit configuration diagram of FIG. 3 taking an example in which semiconductor amplifying elements are connected in four stages. A first matching circuit M1 is connected to an input terminal IN to which microwaves are input. The first matching circuit M1 is connected to a first semiconductor amplifier A1 formed by a field effect transistor or the like. The first semiconductor amplifying element A1 is connected to a second semiconductor amplifying element A2 formed of a field effect transistor or the like via a second matching circuit M2, and the second semiconductor amplifying element A2 is connected via a third matching circuit M3. It is connected to a third semiconductor amplification element A3 formed by a field effect transistor or the like. The third semiconductor amplifying element A3 is a fourth semiconductor amplifying element A formed of a field effect transistor or the like via a fourth matching circuit M4.
4 and the fourth semiconductor amplifying element A4 is connected to the output terminal OUT via the fifth matching circuit M5.

In the above-described configuration, microwaves input from the input terminal IN are sequentially amplified by the first to fourth semiconductor amplifying elements A1 to A4 and output from the output terminal OUT.

The above-described first to fourth semiconductor amplifying elements A
1 to A4 are formed on, for example, a semi-insulating GaAs substrate having the same thickness. First to fifth matching circuits M1
To M5 are formed, for example, on a dielectric substrate. The first to fourth semiconductor amplifying elements A1 to A4 and the first to fifth matching circuits M1 to M5 are usually housed in one package in order to prevent the influence of external moisture or the like. Used in state.

Next, another conventional microwave power amplifier will be described with reference to the schematic configuration diagram of FIG. FIG. 4 shows a monolithic microwave integrated circuit (hereinafter referred to as MMIC) in which active elements such as a semiconductor amplifying element and passive elements such as a microstrip line and a capacitor are formed together on a semi-insulating GaAs substrate or the like. It is configured.

An input terminal IN is provided on the left end of the semi-insulating substrate 41.
Is formed, and an output terminal OUT is formed at the right end on the substrate 41. Between the input terminal IN and the output terminal OUT, first to fourth semiconductor amplification elements A1 to A4 formed of a field effect transistor or the like are connected in order. The microstrip line L connects between the input terminal IN and the first semiconductor amplifier A1, between the first to fourth semiconductor amplifiers A1 to A4, and between the fourth semiconductor amplifier A4 and the output terminal OUT. . A matching circuit is connected before and after the first to fourth semiconductor amplifying elements A1 to A4, but is omitted in the figure.

The first to fourth semiconductor amplifying elements A
The substrate 41 on which 1 to A4, the microstrip line L, and the like are formed is usually used in a state housed in a package.

[0008]

In a conventional microwave semiconductor amplifier, for example, when obtaining a large amplification degree, semiconductor amplification elements such as field effect transistors are connected in a plurality of stages. At this time, the output power of the semiconductor amplifying element located at the subsequent stage increases. Therefore, when the subsequent semiconductor amplifying element is formed of a field effect transistor or the like, the gate width of the field effect transistor generally increases.

For example, in the case of a microwave semiconductor amplifier in which field effect transistors are connected in four stages and the output power is 1 W, the gate widths of the first and second stage field effect transistors are 0.5 mm and the third stage is The gate width is 3 mm, and the gate width of the fourth stage is 6 mm.

When the gate width of the field effect transistor is increased, the following problem occurs. (1) The lateral width of the field-effect transistor increases and the chip size increases. (2) When the frequency becomes high, a phase difference occurs in each gate in the field-effect transistor, and the usable frequency is limited by the size of the gate width. (3) The thermal resistance of the field effect transistor increases, and the channel temperature increases. The channel temperature is set to, for example, 130 ° C. or lower, and an increase in the channel temperature lowers the reliability.

Further, there is a method in which a plurality of stages of field effect transistors constituting a microwave semiconductor amplifier are formed on a GaAs substrate by MMIC. MM for semiconductor devices
When formed with an IC, high output is restricted for the following reasons.

For example, in order to increase the output power,
When the gate width and the lateral width of the field-effect transistor are increased, a phase difference occurs between the respective gates in the field-effect transistor, and the output power and the gain decrease. As shown in FIG. 5, when the distance between the gates of the field effect transistor is reduced to reduce the width, the thermal resistance of the field effect transistor increases, and the channel temperature exceeds the allowable value.

In this case, to reduce the thermal resistance of the field effect transistor, a method of reducing the thickness of the GaAs substrate can be considered. However, when the GaAs substrate is thinned, the mechanical strength decreases. In the case where the field-effect transistor is formed in a plurality of stages, a large substrate area is required, so that a crack is easily generated.

For the reasons described above, it is difficult to configure a microwave semiconductor amplifier having a large output power with MMICs in which semiconductor amplifying elements are connected in a plurality of stages.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a microwave semiconductor amplifier having a configuration in which semiconductor amplifying elements are connected in a plurality of stages and having a large output power which can be easily formed by an MMIC.

[0016]

According to the present invention, there is provided a microwave semiconductor amplifier comprising a plurality of semiconductor amplifying elements connected in a plurality of stages and a package for accommodating the plurality of semiconductor amplifying elements. The thickness of the first substrate on which the semiconductor amplifying element including at least the last-stage semiconductor amplifying element among the amplifying elements is formed is smaller than the thickness of one or more second substrates on which other semiconductor amplifying elements are formed. It is characterized by doing.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the circuit diagram of FIG. 1 taking an example in which semiconductor amplifying elements are connected in four stages. In FIG. 1A, an input terminal IN for inputting microwaves is provided through the package 10, and a first matching circuit M1 is connected to the input terminal IN. The first matching circuit M1 is connected to a first semiconductor amplifier A1 formed by a field effect transistor. The first semiconductor amplifying element A1 is connected to a second semiconductor amplifying element A2 formed of a field effect transistor via a second matching circuit M2, and the second semiconductor amplifying element A2 is connected to a third semiconductor amplifying element A2.
It is connected to a third semiconductor amplifying element A3 formed by a field effect transistor via a matching circuit M3. The third semiconductor amplifying element A3 is connected to a fourth semiconductor amplifying element A4 formed of a field effect transistor via a fourth matching circuit M4, and the fourth semiconductor amplifying element A4 is connected to a fifth matching circuit M5.
Is connected to the output terminal OUT. First to fourth semiconductor amplifying elements A1 to A4 and first to fifth
The matching circuits M1 to M5 are all arranged on the bottom plate 11 constituting the package 10.

In the above configuration, the microwaves input from the input terminal IN are sequentially amplified by the first to fourth semiconductor amplifying elements A1 to A4 and output from the output terminal OUT. The first to fourth semiconductor amplifying elements A1 to A1
A4, and first to fifth matching circuits M1 to M5
Is usually used in a state of being housed in a package in order to prevent the influence of external moisture and the like.

Here, a state in which the first to fourth semiconductor amplifying elements A1 to A4 and the first to fifth matching circuits M1 to M5 are arranged in the package 10 will be described with reference to FIG. . FIG. 1B is a view of FIG. 1A viewed from below, and shows first to fourth semiconductor amplifying elements A1 to A1.
A4 and the first to fifth matching circuits M1 to M5 are arranged, for example, on the bottom plate 11 of the package 10.

First to fourth semiconductor amplifying elements A1 to A
4 is a separate semi-insulating GaAs substrate 121
To 124 are formed. In this case, the thickness t1 of the GaAs substrates 121 to 123 on which the first to third semiconductor amplifying elements A1 to A3 are formed is the same, and the thickness of the GaAs substrate 124 on which the fourth semiconductor amplifying element A4 of the last stage is formed is the same. The thickness t2 is made thinner than the GaAs substrates 121 to 123. Further, the back surface of the GaAs substrate 124 is Au plated 1
So-called PHS (Plated-Heat-Sink)
It has a structure.

According to the above configuration, the substrate thickness t of the amplifier circuit board 124 on which the last-stage semiconductor amplifying element A4 is formed.
2 is thinner than the substrate thickness t1 of the amplification circuit substrates 121 to 123 on which the semiconductor amplification elements A1 to A3 located at the preceding stage are formed, and a PHS structure is adopted. Therefore, the thermal resistance of the final-stage field-effect transistor or the like having a large output power is reduced, the reliability is improved, and a high-output microwave semiconductor amplifier, which is difficult to realize only with the MMIC, is realized.

Next, another embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG. An input terminal IN penetrating the package is provided at an end of the bottom plate 11 constituting the package. An amplifier circuit board 21 made of semi-insulating GaAs is arranged near the input terminal IN. An amplification circuit in which first to third semiconductor amplification elements A1 to A3 formed of field-effect transistors are connected in three stages on an amplification circuit board 21;
A microstrip line L connecting between 1 and A3 is formed as an MMIC in which active elements and passive elements are formed on a common semi-insulating substrate.

At the subsequent stage of the amplifying circuit board 21, first and second matching circuit boards 22 and 23 on which matching circuits are formed are sequentially arranged. After the second matching circuit board 23,
A chip capacitor C1 functioning as a matching circuit is arranged, and an amplifier circuit board 24 constituting a final-stage amplifier circuit is arranged downstream of the chip capacitor C1. On the amplifying circuit board 24, a discrete fourth semiconductor amplifying element A4 formed by a field effect transistor or the like is provided with an MMI.
C is formed. A chip capacitor C2 functioning as a matching circuit is disposed downstream of the amplifier circuit board 24, and a third matching circuit board 25 on which a matching circuit is formed is disposed downstream of the chip capacitor C2. The output end of the third matching circuit board 25 is connected to an output terminal OUT that passes through the package. Bias circuit boards 26 and 27 on which a bias circuit for supplying a bias voltage to each of the semiconductor amplifying elements A1 to A4 and the like are formed are disposed above and below the bottom plate 11.

The second matching circuit board 23 and the third matching circuit board 25 are made of a dielectric material. Further, the amplifier circuit board 21 in which the semiconductor amplifying elements A1 to A3 and the microstrip line L are formed of MMIC is formed of semi-insulating GaAs, and as shown in FIG.
The substrate thickness t1 is set to 100 μm. The amplifier circuit board 24 on which the fourth semiconductor amplifying element A4 is formed is made of semi-insulating GaAs, and the substrate thickness t2 is set to 30 μm as shown in FIG. PHS (Plated-Heat-Sink) structure.

In this case, as shown in FIG. 3C, the height H of the package bottom plate 11 where the amplifier circuit board 24 is arranged is determined by the height H of the package bottom plate 11 where the amplifier circuit board 21 is arranged. The height is higher than the height h, and the amplification circuit board 2
1 and the height of the upper surface of the amplifier circuit board 24, and at the same time, the height of the first to third matching circuit boards 22, 23, 25 and the chip capacitors C1, C2. When these heights are the same, the bonding operation using a wire or the like becomes easy.

According to the above configuration, the substrate thickness t2 of the amplifier circuit board 24 on which the last-stage semiconductor amplifier A4 is formed.
Is thinner than the substrate thickness t1 of the amplification circuit substrate 23 on which the semiconductor amplification elements A1 to A3 located at the preceding stage are formed,
Furthermore, a PHS structure is adopted. Therefore, the thermal resistance of the field-effect transistor constituting the semiconductor amplifying element A4 is reduced, the reliability is improved, and a high-output microwave semiconductor amplifier that is difficult to realize only with the MMIC is realized.

In the above embodiment, an example has been described in which the semiconductor amplifying element is constituted by a field effect transistor. However, an HEMT may be used instead. Also, when the final stage semiconductor amplifying element is constituted by a discrete field effect transistor or HEMT, an MIM (Meta1-Insu1ator-Met) connected to its gate input terminal is used.
a1) The capacitors can be configured on the same substrate.

According to the above configuration, the thermal efficiency of the semiconductor amplifying element constituting the final stage is improved. for that reason,
When the final stage semiconductor amplifying element is formed by a field effect transistor or the like, the gate interval can be made narrower than the gate intervals of other semiconductor amplifying elements, and a small chip having a small lateral width can be configured.

In the above-described embodiment, the thickness of the substrate on which the last-stage semiconductor amplifying element is formed is smaller than the thickness of the substrate on which the other semiconductor amplifying elements are formed.
However, not only the final stage semiconductor amplifying element but also the semiconductor amplifying element located immediately before it can be formed on a thin substrate.

Further, according to the above configuration, the final stage semiconductor amplifying element and other semiconductor amplifying elements are formed on different substrates. In this case, for example, the PHS structure can be easily applied to the substrate of the final stage semiconductor amplifying element having the highest channel temperature, so that the heat radiation effect is further improved and the reliability is also improved.

Further, a matching circuit connected immediately before and after the last-stage semiconductor amplifying element is formed using a dielectric substrate. In this case, as the area increases, the chip size of the semiconductor substrate, which is liable to cause cracking, decreases, and cracking of the semiconductor substrate is prevented.

[0032]

According to the present invention, a microwave power amplifier having a large output power which can be easily formed by an MMIC can be realized with a configuration in which amplifying elements are connected in a plurality of stages.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram for explaining an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram for explaining another embodiment of the present invention.

FIG. 3 is a schematic configuration diagram for explaining a conventional example.

FIG. 4 is a schematic configuration diagram for explaining another conventional example.

FIG. 5 is a schematic configuration diagram illustrating an interval between a source and a drain of a field-effect transistor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Package 11 ... Package bottom plate 121-124 ... Substrate on which semiconductor amplifying element was formed M1 to M5 ... Matching circuit A1 to A4 ... Semiconductor amplifying element IN ... Input terminal OUT ... Output terminal t1 ... Forming semiconductor amplifying elements A1 to A3 Thickness of substrate t2: thickness of substrate on which semiconductor amplifying element A4 is formed

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5F038 AC19 AC20 AZ01 AZ10 CA12 DF01 DF02 EZ02 EZ04 EZ07 5J067 AA04 AA41 CA35 CA91 FA16 HA09 HA12 HA16 HA24 HA29 KA12 KA29 KA68 KS11 LS12 MA08 QS04 SA13 TA01

Claims (8)

[Claims] 1. A microwave semiconductor amplifier comprising: a plurality of semiconductor amplifying elements connected in a plurality of stages; and a package for accommodating the plurality of semiconductor amplifying elements, wherein at least a last stage of the plurality of semiconductor amplifying elements is provided. A microwave characterized in that a thickness of a first substrate on which a semiconductor amplifier including a semiconductor amplifier is formed is smaller than a thickness of one or a plurality of second substrates on which other semiconductor amplifiers are formed. Semiconductor amplifier. 2. A microwave semiconductor amplifier comprising: a plurality of semiconductor amplifying elements connected in a plurality of stages; and a package for accommodating the plurality of semiconductor amplifying elements. The thickness of the first substrate on which the amplifying element is formed is smaller than the thickness of one or more second substrates on which other semiconductor amplifying elements are formed, and one or more other semiconductor amplifying elements are provided. 3. A microwave semiconductor amplifier comprising a monolithic microwave integrated circuit on a second substrate. 3. The semiconductor amplifier of the last stage is formed of a field effect transistor or HEMT, and a capacitor connected to a gate input terminal of the semiconductor amplifier is formed on a first substrate. The microwave semiconductor amplifier according to claim 2. 4. The microwave semiconductor amplifier according to claim 2, wherein the last-stage semiconductor amplifying element comprises a monolithic microwave integrated circuit. 5. The microwave semiconductor amplifier according to claim 1, wherein a metal plating layer is formed on a back surface of the first substrate. 6. The microwave semiconductor amplifier according to claim 1, wherein the height of the bottom surface of the package on which the first substrate is disposed is higher than the height of the bottom surface of the package on which the second substrate is disposed. 7. The microwave semiconductor amplifier according to claim 1, wherein a dielectric substrate on which a matching circuit is formed is arranged next to the first substrate. 8. A plurality of semiconductor amplifying elements are formed by field effect transistors or HEMTs, and the distance between the source and the drain of the last semiconductor amplifying element is made larger than the distance between the source and the drain of the other semiconductor amplifying elements. 3. The microwave semiconductor amplifier according to claim 1, wherein said width is also narrowed.