JPS5929377Y2 - High frequency high power transistor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a high-frequency, high-output transistor device that can extract high output from among high-output semiconductor devices, particularly in the VHF band and the microwave band.

As is well known, in a typical transistor element, a semiconductor substrate itself serves as a collector electrode, and a base electrode and an emitter electrode are formed on the upper surface of this semiconductor substrate.

In order to amplify the power of a high-frequency signal using this transistor element, the input terminal is set as an emitter electrode or base electrode, and the output terminal is set as a collector electrode.
The common terminal is configured as an electrically grounded base electrode or emitter electrode.

That is, the collector electrode made of the semiconductor substrate itself needs to be electrically insulated from the ground electrode.

Conventionally, this type of semiconductor device usually has a transistor element 1 and an external lead electrode 3 installed on a flat stem substrate 4 made of a dielectric material with good thermal conductivity such as ceramic, as shown in FIG. A grounding heat sink 2 made of copper is provided at the bottom of the stem board 4 to improve heat dissipation. Specifically designed to reduce thermal resistance to lower bonding temperatures.

However, in such a conventional structure, if the thermal resistance is to be further reduced, the only way is to reduce the thickness of the stem substrate 4 or the thickness of the transistor element 1 chip.

However, if the stem substrate 4 is made thinner, the parasitic capacitance between the element 1 and the ground and the parasitic capacitance between the external extraction electrode 3 and the ground increase, which may have an adverse effect on the performance of the semiconductor device or cause abnormal phenomena. Sometimes it happens.

Furthermore, it is difficult to make the transistor element 1 thinner in terms of manufacturing technology, and the current state of the art is at its limit.

Furthermore, the transistor element 1 and the grounding heat sink 2 are soldered to the top and bottom of the stem board 4 via the metallized layer 5, but the thermal resistance of the metalized layer 5 itself and the brazing material itself for soldering is This cannot be ignored, and there is a thermal resistance due to the formation of two layers between the transistor element 1 and the heat dissipating body 2, and it is difficult to equalize the thickness of each film.

In addition, cracks may occur on the stem board 4 when soldering,
There were drawbacks such as an increase in the thermal resistance of the package and large variations in the thermal resistance.

An object of the present invention is to eliminate such drawbacks, to provide a high-power transistor device for high-frequency use with low thermal resistance and high performance.

According to the present invention, an input circuit in which a balun converter is provided on a dielectric substrate and an output circuit in which a conductive line is provided on another dielectric substrate are connected so that the collector electrode of the transistor is directly fixed to ground. The base electrode of the transistor is connected to one terminal of the parallel transmission line of the balun converter, which is fixed on the ground conductor in close proximity to the transistor on the ground conductor and which constitutes the input circuit, and the base electrode of the transistor is connected to the other terminal of the parallel transmission line. A high frequency, high output transistor device is obtained, wherein the base electrodes of the transistors are connected to one end of the output circuit, either directly or via a matching circuit.

According to the present invention, since the transistor element is directly connected to the ground conductor that also serves as a heat sink, heat dissipation is very good, and the thermal resistance is small, achieving high output with little variation. can do.

For example, the ground conductor is made of Cu plated with Au,
In the case of a transistor device that uses a Si substrate for the transistor element, the transistor element can be thermocompression bonded directly to the ground conductor without using a brazing material, making it easy to bond Au on the adhesive surface.
-8i eutectic alloy is formed and fixed.

Therefore, due to the inherent thermal resistance of the conventional stem substrate, and the
At least the thermal resistance of the metallized layer made of the U layer is eliminated.

The present invention will be described in detail below with reference to drawings showing one embodiment.

FIGS. 2a, 2b, and 2c are a vertical sectional view, a schematic top view, and an equivalent circuit diagram showing an embodiment of the present invention.

In FIG. 1A, a transistor element 1 is directly mounted and fixed on a ground conductor 2, and the collector electrode of the transistor element 1 is grounded.

Furthermore, dielectric substrates 6 and 7 on which a grinding input/output circuit is formed are installed on the ground conductor 2, and are connected to an external circuit by an external lead wire 3.

In the transistor device having such a structure, heat generated in the transistor element 1 is transmitted to the ground conductor 2 and dissipated.

Therefore, the temperature rise of the transistor element 1 is small, and the present invention is particularly suitable for a high-output transistor device in which the transistor element operates at a high current and consumes high power.

Furthermore, there is no need to consider the thermal resistance of the stem substrate, which has been a problem in conventional semiconductor devices, and the thermal resistance of the brazing material when brazing the stem substrate with the metallized layer and the heat sink.

Normally, the stem board is made of ceramic with good heat conductivity, but ceramic is an expensive and toxic material, so the present invention is advantageous in terms of cost and productivity. It is.

In FIGS. 2 and 2c, the balun converter forming the input side circuit of the transistor element 1 has a distributed constant line 10 on the input side dielectric substrate 6 having a length of approximately one-half wavelength at the operating frequency. At both ends of the distributed constant line 10, there are two balanced lines 11.1 having a length of about a quarter wavelength at the operating frequency.
2 are connected.

A transistor element 1 is connected to the other end of the balanced two-line line 11 and 12.
A base electrode and an emitter electrode are connected by a lead wire 8.

The characteristic impedance of the two balanced lines 11, 12 is selected to match the input impedance of the transistor element 1 and the output impedance of the balun converter.

Further, one end of the half wavelength distributed constant line 10 of the balun converter is connected to an external lead line 3 via a line 13, and the base electrode of the transistor element 1 is connected to an external lead line 8 via a lead line 8 and a line 14. Connected to line 3.

Since the lead@8 and the line 14 are part of the output circuit for impedance matching with the load connected via the external lead wire 3, their respective structures should be set to appropriate values in consideration of high frequency. selected.

A transistor device having such a configuration becomes a common-base circuit in terms of high frequency even though the collector electrode of the transistor element is directly grounded.

That is, the base electrode B of the transistor element 1, which is a common terminal, and the emitter electrode E, which is a terminal of the input circuit, are connected at high frequency to the balun converter 10 installed on the input side from the ground potential, and the parallel two-wire line 11, 12. The high frequency signal is input only between the emitter electrode E and the base electrode B.

Therefore, the high-frequency potential difference between the emitter electrode E and the base electrode B with respect to the ground potential is determined in accordance with the operating characteristics of the transistor element 1, and this becomes an output signal.

Naturally, since the collector electrode C is grounded, an output signal is generated between the ground electrode and the base electrode B, which is a high frequency common terminal.

Without damaging the basic configuration as a common base circuit, the inductance of the common terminal, which was a problem when operating transistors with a common base, no longer becomes a problem at all. The inductance of each lead wire to the side can be treated as simply a matching element of the input/output circuit.

Therefore, there is an advantage that not only performance improvement can be achieved but also abnormal phenomena can be reduced.

Also, due to thermal limitations, this type of high-power transistor
Efficient class B and C operation is performed, but according to the configuration of the present invention, the emitter electrode and base electrode of the transistor element are always at the same potential in terms of DC, due to the balun converter, and there is no connection to the input side external circuit. No RF choke circuit required.

As explained above, in conventional base common circuits, the base electrode, which serves as the common terminal, is operated by applying a ground potential, so the collector electrode, which is the substrate of the transistor element, must be insulated from the ground. I couldn't go, but
In the present invention, even if the base common circuit is similar, by installing a balun converter on the input side, the circuit can be configured without setting the base electrode and emitter electrode to ground potential, so it is possible to directly ground the collector electrode. can.

Although the above embodiment is a common base circuit in terms of high frequency, the present invention is not limited to this, and it is clear that it can also be operated as a common emitter circuit.

Although a transistor device with this configuration is suitable for high-power applications, it can also be used for low-power applications by using a DC block in the balun converter to separate the emitter electrode and base electrode of the transistor element in terms of direct current. Of course, this is possible and good results can be obtained.

[Brief explanation of drawings]

FIG. 1 is a vertical sectional view showing an example of a conventional transistor device, and FIGS. 2 a, b, and c are a vertical sectional view, a top view, and other circuit diagrams showing an embodiment of the present invention. In the figure, 1 is a transistor element, 2 is a ground conductor that also serves as a heat sink, 3 is an external lead wire, 4 is a Stella board made of beryllia porcelain, 5 is a metallized layer on the top and bottom surfaces of the stem board, and 6 is an input side circuit dielectric 7 is the output side circuit dielectric substrate, 8 is the lead wire, 10 is the 1/2 wavelength distribution line of the balun converter, 11.12 is the 1/4 wavelength parallel two-wire line,
13゜14 is the line, B is the base of the transistor $A, E
is the emitter of the transistor, and C is the collector electrode of the transistor.

Claims (1)

[Scope of utility model registration request] An input circuit consisting of a balun converter formed on a dielectric substrate with an unbalanced line as an input side and a balanced line as an output end, and an output circuit consisting of an unbalanced line on another dielectric substrate. and a high frequency, high power transistor device comprising a transistor element whose collector electrode is constituted by a transistor substrate, and a flat ground conductor, wherein the base electrode of the transistor element is connected to one side of the balanced line of the input circuit and An emitter electrode is connected to the terminal, and either the base electrode or the emitter electrode of the transistor element is connected to one end of the unbalanced line of the output circuit, either directly or through a matching circuit, and the output circuit is connected to the input circuit. . A high frequency, high output transistor device, wherein the output circuit and the transistor element are directly fixed onto the flat ground conductor and integrated.