JPH10256850A - Semiconductor device and high frequency power amplifier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce power consumption in an output matching circuit used for the semiconductor device and the high frequency power amplifier. SOLUTION: An output terminal of a high frequency transistor(TR) 5 and one terminal of an MIM capacitor 9 are connected by a bonding wire 8 on a semiconductor substrate 1 where the high frequency TR 5 and the MIM capacitor 9 are integrated, and an output of the high frequency TR 5 is extracted externally via a 1st output matching circuit 3 consisting of a capacitive component of the MIM capacitor and an inductive component of the bonding wire 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor device and a high-frequency power amplifier. The high-frequency power amplifier has a function of amplifying an input signal with a high-frequency transistor and transmitting the signal to the outside. The high-frequency power amplifier is widely used by being incorporated in mobile communication devices such as mobile phones. Accordingly, high performance and low cost are strongly demanded. Generally, the output impedance of a high-frequency transistor is about several Ω, whereas the internal impedance of a transmission line for transmitting the output of the high-frequency transistor is about 50 Ω, which is a large difference. Therefore, usually, the output impedance of the high-frequency transistor is converted by an output matching circuit to take out the output to the outside. Therefore, it is necessary to improve the performance and reduce the cost of the high-frequency power amplifier with a total configuration including the output matching circuit.

[0002]

2. Description of the Related Art FIG. 2 is a diagram showing a configuration of a conventional high-frequency power amplifier. A high-frequency transistor and an output matching circuit are formed on a semiconductor substrate and a dielectric substrate, respectively.
Usually, a semi-insulating GaAs substrate is used as the semiconductor substrate 21, on which a GaAs FET is formed as the high-frequency transistor 24 by an integration process. On the semiconductor substrate 21, in addition to the high-frequency transistor 24, a driving amplifier 25 for amplifying an input signal and applying it to the gate of the high-frequency transistor 24,
A resistor 26 for gate bias of the high-frequency transistor 24, an input terminal 32 for receiving an input signal, a gate bias terminal 33 for applying a voltage to the gate of the high-frequency transistor 24 through the resistor 26, and a drain of the high-frequency transistor 24 A drain output terminal 34 for taking out output is formed. After the integration process is completed, the semiconductor substrate 21 is divided into chips and stored in a package for surface protection.

The dielectric substrate 22 is made of alumina, glass epoxy resin or the like, and an output matching circuit 23 composed of a microstrip line and a capacitance element is formed on the dielectric substrate 22 in a region shown by a dotted line in FIG. In FIG. 2, microstrip lines 29, 30, and 31 are patterned on a dielectric substrate 22 by a thick film process using a conductive paste, and discrete chip capacitors 27 and 28 are disposed thereon as capacitive elements. Is done. Chip capacitors
27 and 28 are arranged on the input side and output side of the output matching circuit 23 with the microstrip line 29 interposed therebetween. On the dielectric substrate 22, an input terminal 35 for receiving the output of the high-frequency transistor 24, a drain bias terminal 36 for applying a voltage to the drain of the high-frequency transistor 24, an output terminal 37 for extracting the output to the outside, and the like are formed. You. Components such as DC component cutting capacitors are arranged, but they are omitted.

The above-mentioned semiconductor substrate 21 and dielectric substrate 22 are arranged on a printed circuit board (not shown), and a drain output terminal 34 of the semiconductor substrate 21 and an input terminal 35 of the dielectric substrate 22 are connected by bonding wires 38. . The inductance of the bonding wire 38 functions as one of the components of the output matching circuit 23.

FIG. 3 is a diagram showing another configuration of a conventional power amplifier. While the high-frequency transistor is formed on the semiconductor substrate and the output matching circuit is formed on the dielectric substrate in the example shown in FIG. 2, the high-frequency transistor is formed in the example shown in FIG.
All the elements including the 43 and the output matching circuit 42
Integrated on top. In this case, the microstrip line and the capacitance element are also formed by the semiconductor integration process. That is, the microstrip line 4
8, 49, and 50 are formed by a thin-film process such as an electron beam evaporation method or a CVD method, and MIM capacitors 46 and 47, which are formed by laminating a metal film and an insulating film by a thin-film process, are also used for a capacitance element. . Further, the inductance component of the output matching circuit 42 is obtained by a spiral inductor 54 formed by a thin film process or a microstrip line equivalent thereto.

After the completion of the integration process, the semiconductor substrate 41 is divided into chips similarly to the semiconductor substrate 21 shown in FIG. 2 and is housed in a package for internal protection.

[0007]

As described above, since the high-frequency power amplifier takes out the output of the high-frequency transistor to the outside through the output matching circuit, the characteristics of the output matching circuit are high as described below. This has a great effect on the output and efficiency of the power amplifier.

First, it is known that a chip capacitor has a large equivalent series resistance in a high frequency range. Therefore, the output of the high frequency transistor 24 in the output matching circuit 23 shown in FIG. Causes a large power loss.

On the other hand, the value of the equivalent series resistance of the MIM capacitor is smaller than that of the chip capacitor by one digit or more.
Therefore, the power loss in the MIM capacitor in the output matching circuit 42 shown in FIG. 3 is smaller than that in the case where a chip capacitor is used. However, in the configuration shown in FIG. 3, since the microstrip lines 48, 49, and 50 are formed by a thin film process, there is a problem that the film thickness is limited to a value of about 1 μm.

In general, it is known that the resistivity of a conductor film changes depending on the film thickness, and rapidly increases when the film thickness becomes smaller than the order of μm. Therefore, the resistance of the microstrip line formed by the thin film process increases, and the power loss increases accordingly. Further, in the configuration of FIG. 3, a spiral inductor 54 formed of a strip-shaped conductive film or a microstrip line equivalent thereto is used as an inductance component provided on the input side of the output matching circuit 42, but is formed by a thin film process. Therefore, there is a problem that the film thickness is small, and accordingly, the power loss in this portion also increases. On the other hand, in the output matching circuit shown in FIG. 2, since the microstrip line is formed by a thick film process, the thickness can be reduced to about several tens of μm, and the power loss is small. As described above, FIG.
Also, the conventional configuration shown in FIG. 3 has a problem that the power loss in the output matching circuit cannot be sufficiently suppressed.

Accordingly, an object of the present invention is to reduce power consumption in an output matching circuit.

[0012]

To solve the above-mentioned problems, an output terminal of the high-frequency transistor and the MIM capacitor are provided on a semiconductor substrate on which the high-frequency transistor and the MIM capacitor are integrated.
A semiconductor device in which one end of a capacitor is connected by a bonding wire, and an output of the high-frequency transistor is taken out through a first output matching circuit including a capacity of the MIM capacitor and an inductance of the bonding wire; Alternatively, the output terminal of the high-frequency transistor and one end of the MIM capacitor are connected by a bonding wire on a semiconductor substrate on which the high-frequency transistor and the MIM capacitor are integrated, and the output of the high-frequency transistor is connected to the capacitance of the MIM capacitor and the bonding wire. And a dielectric substrate on which a second output matching circuit formed of a microstrip line and a chip capacitor is formed. Semiconductor device It is achieved by the high frequency power amplifier, characterized in that they were taken out to output to the outside via the output matching circuit of the second.

As is apparent from the above description, in order to suppress the power loss in the output matching circuit, an MIM capacitor formed by a thin film process on a semiconductor substrate is used as a capacitor, and a dielectric is used as a microstrip line. It is desirable to use one formed on a substrate by a thick film process. Such a configuration can be realized if, for example, the chip capacitors 27 and 28 in the output matching circuit 23 shown in FIG. 2 can be replaced by MIM capacitors formed on a semiconductor substrate. But,
It is difficult to mount two capacitive elements constituting an output matching circuit on a semiconductor substrate separately from a microstrip line in terms of circuit mounting.

On the other hand, as described above, since the output impedance of the high-frequency transistor is at least one digit larger than the internal impedance of the transmission line, a larger current flows on the input side of the output matching circuit than on the output side. . Therefore, in the output matching circuit 23 shown in FIG. 2, the current flowing through the chip capacitors 27 and 28 connected to both ends of the microstrip line 29 also has a large difference depending on the above-mentioned impedance difference. The power loss in the chip capacitor 27 on the output side
Power loss at

The present invention realizes an output matching circuit capable of substantially minimizing power loss by configuring only the input-side capacitive element of the output matching circuit with an MIM capacitor based on the above facts. is there. In the semiconductor device of the present invention, the MIM capacitor formed on the semiconductor substrate together with the high-frequency transistor is the output matching circuit shown in FIG.
It has a function corresponding to a chip capacitor 27 connected to the input side of 23, and an output is taken out via a first output matching circuit composed of this MIM capacitor and a bonding wire. Therefore, even if this semiconductor device is connected to the second output matching circuit and a chip capacitor having a large power loss is used in the second output matching circuit, the first and second output matching circuits are used.
The power loss of the entire output matching circuit composed of the output matching circuit is greatly reduced as compared with the configuration shown in FIG.

Further, the bonding wire connecting the MIM capacitor and the high-frequency transistor on the semiconductor substrate can reduce power loss as compared with a spiral inductor or a microstrip line formed by a thin film process. This is based on the fact that the power loss is smaller than that of a spiral inductor or a microstrip line formed by a thin film process because the bonding wire has a diameter of about several tens of μm.

A dielectric substrate on which a second output matching circuit composed of a microstrip line and a chip capacitor is formed can be connected to the semiconductor device and used as a high-frequency power amplifier. Since it can be formed by a film process, and the current flowing through the chip capacitor is small as described above, the power loss is reduced as compared with the related art.

[0018]

FIG. 1 is a diagram showing the configuration of a high-frequency power amplifier according to an embodiment of the present invention. A semi-insulating GaAs substrate is used as a semiconductor substrate, and a GaAs FET is used as a high-frequency transistor.
Can be used. On the semiconductor substrate 1, in addition to the high-frequency transistor 5 and the MIM capacitor 9, a driving amplifier 6 for amplifying an input signal and applying it to the gate of the high-frequency transistor 5, and a gate bias resistor 7 of the high-frequency transistor 5 are well-known semiconductors. An input terminal 14 for receiving an input signal, a gate bias terminal 15 for applying a voltage to the gate of the high-frequency transistor 5 through the resistor 7, and a drain from the high-frequency transistor 5. A drain output terminal 16 for taking out an output is arranged. The drain of the high-frequency transistor 5 and one end of the MIM capacitor 9 are connected by a bonding wire 8.

After the integration process is completed, the semiconductor substrate 1
Is divided into chips and packaged for surface protection. As described above, in the present invention, the first output matching circuit 3 including the MIM capacitor 9 and the inductance of the bonding wire 8 is formed on the semiconductor substrate 1 together with the high-frequency transistor 5.

The output of the high-frequency transistor 5 taken out through the first output matching circuit 3 is input to a second output matching circuit 4 formed on the dielectric substrate 2.
In FIG. 1, a dielectric substrate 2 is made of alumina, glass epoxy resin, or the like, and a second substrate indicated by a dotted line in FIG.
Output matching circuit 4 is formed. Second output matching circuit 4
Can be formed by a thick film process similar to that of the conventional output matching circuit 23 shown in FIG. That is, the microstrip lines 11, 12, and 13 are patterned on the dielectric substrate 2 by a thick film process using a conductive paste, and the chip capacitors 10 are disposed thereon. On the dielectric substrate 2, in addition to the output matching circuit 4, a drain bias terminal 18 for applying a voltage to the drain of the high-frequency transistor 5, an output terminal 19 for extracting an output to the outside, and the like are formed. Components such as DC component cutting capacitors are arranged, but they are omitted.

The above-mentioned semiconductor substrate 1 and dielectric substrate 2 are arranged on a printed circuit board, and the drain output terminal 16 of the semiconductor substrate 1 and the input terminal 17 of the dielectric substrate 2 are connected by a bonding wire or the like.

As is apparent from a comparison between FIGS. 1 and 2, in the present invention, of the two capacitive elements constituting the output matching circuit, the MIM capacitor in which the input capacitive element is monolithically formed on the semiconductor substrate is used. Since the configuration is replaced, the power loss in the output matching circuit can be reduced as compared with the conventional configuration in FIG. 2 even when the output side capacitive element is formed by a chip capacitor. The microstrip line, which is a component of the output matching circuit, is formed by a thick film process on a dielectric substrate, and the drain of the high-frequency transistor and the MIM capacitor are connected by bonding wires. Power loss can be reduced as compared with the configuration of FIG. 3 formed on a semiconductor substrate by a thin film process. further,
By removing the microstrip line occupying a large area from the semiconductor substrate, the required area of the semiconductor substrate can be reduced, which is advantageous in terms of cost as compared with the configuration of FIG.

[0023]

As described above, in the present invention, a part of the output matching circuit is formed together with the high-frequency transistor on the semiconductor substrate so as to minimize the power loss.
This is useful in reducing the power loss of a high-frequency power amplifier using this.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a high-frequency power amplifier according to the present invention.

FIG. 2 shows a configuration of a conventional high-frequency power amplifier (part 1).

FIG. 3 shows a configuration of a conventional high-frequency power amplifier (part 2).

[Explanation of symbols]

1, 21, 41 Semiconductor substrate 6, 25, 44
Driving amplifier 2,22 Dielectric substrate 7,26,45
Resistor 3 First output matching circuit 8, 38 Bonding wire 4 Second output matching circuit 9, 46, 47
MIM capacitor 5, 24, 43 High frequency transistor 10, 27, 28
Chip capacitors 11, 12, 13, 29, 30, 31, 48, 49, 50 microstrip line

Claims (2)

[Claims] 1. An output terminal of the high-frequency transistor and one end of the MIM capacitor are connected by a bonding wire on a semiconductor substrate on which the high-frequency transistor and the MIM capacitor are integrated, and the output of the high-frequency transistor is determined by the capacitance of the MIM capacitor. A semiconductor device which is taken out through a first output matching circuit including an inductance of the bonding wire. 2. An output terminal of the high-frequency transistor and one end of the MIM capacitor are connected by a bonding wire on a semiconductor substrate on which the high-frequency transistor and the MIM capacitor are integrated, and the output of the high-frequency transistor is determined by the capacitance of the MIM capacitor. A semiconductor device which is taken out through a first output matching circuit comprising the inductance of the bonding wire; and a dielectric substrate on which a second output matching circuit comprising a microstrip line and a chip capacitor is formed. A high-frequency power amplifier, wherein an output of the semiconductor device is taken out through the second output matching circuit.