JPH03217103A - Semiconductor device - Google Patents

Abstract

PURPOSE:To obtain a small-sized transmission power amplifier element superior in stability by arranging a dielectric material just under or on the external lead part enclosed in a package and forming a matching capacitor with both of them. CONSTITUTION:The package consists of a gate lead 1, a drain lead 2, a heat sink 3 used as the source terminal, an insulator 4 which insulates the source and the gate and forms a capacitor, an insulator 5 which insulates the source and the drain, and a GaAs power FET chip 6. Normally, several pF capacitance is connected between the gate and the source in the case of an FET. The value of the capacitance is determined by areas on insulators of leads and materials (dielectric constance) and thickness of insulators. Insulators are separated from each other by the heat sink at the center for the purpose of reducing the freed back capacitance of input/output to optimize the input capacity.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a semiconductor device suitable for amplifying the transmission power of a mobile radio.

2. Description of the Related Art Conventionally, this type of semiconductor device for transmitting power amplification has obtained a high output by operating a large number of small amplification elements in parallel, and has an extremely small input impedance.

Therefore, adding a capacitor near the amplification element chip is advantageous in terms of higher output and stability. Figure 2 (
FIG. 2(b) is a plan view of the equivalent circuit of a conventional power amplification element, in which a capacitor formed of a chip other than the amplification element chip is mounted inside the package.

Problems to be Solved by the Invention In such a conventional configuration, since two semiconductor chips are used, it is difficult to miniaturize the package. Further, when a configuration is adopted in which the capacitance is removed for miniaturization, there are problems in that the external matching circuit becomes complicated and stability deteriorates.

The present invention solves these problems, and aims to provide a small and stable semiconductor device for high frequency power amplification.

Means for Solving the Problems In order to solve this problem, the present invention has a structure in which a capacitor is formed by a metal lead of a socket cage and an insulating part.

Effect: This configuration provides a compact and highly stable power amplification semiconductor device for high frequency transmission.

Embodiment FIG. 1 (Al is a sectional view of a GaAs power FET semiconductor device for 900 MHz band and 2 W output according to an embodiment of the present invention, and FIG. 1 (false) is a plan view of the same.

In FIG. 1(a) and FIG. 1(b), the package is
It consists of a gate lead 1, a drain lead 2, a heat sink 3 used as a source terminal, an insulator 4 that insulates the source and gate and forms a capacitor, an insulator 5 that insulates the source and drain, and a GaAs power FET chip 6.

Normally, in the case of the above FET, a capacitance of several pF is inserted between the gate and source.

The size of the capacitance is determined by the area of the lead on the insulator, the material (permittivity) and thickness of the insulator.

For example, if the lead area is 7+mm x 1mm, the insulator is alumina (dielectric constant 9.6), and the thickness is 0.5+m, the capacitance is approximately 8. 3 pF.

In addition to alumina, the dielectric constant of insulators is beryllia (B).
ed) 6.7 Aluminum nitride (A I
N) 4. 2-4.53 Hitacera A (Sic/BeO) 40 etc.
Can be used depending on the purpose.

Additionally, in order to reduce input/output feedback capacitance and optimize input capacitance, the insulator is separated in the center by a heat sink.

Note that this package can also be used for St bipolar transistors for the same purpose.

Effects of the Invention As is clear from the above embodiments, according to the present invention, since the insulator used in the package is used as a capacitor, a small and highly stable transmission power amplification element is constructed.

[Brief explanation of drawings]

Figure 1 (al is a cross-sectional view of a semiconductor device according to an embodiment of the present invention, Figure 1 (bl is a plan view of the same, and Figure 2 Tal is an equivalent circuit diagram of a conventional FET semiconductor device. 1 is a plan view. 1... Gate lead, 2... Drain lead, 3... Heat sink (source), 4...
...Insulator forming capacitor, 5...Insulator, 6...GaAs FET4 chip.

Claims (1)

[Claims] A semiconductor device characterized in that a dielectric material is disposed directly below or directly above an external lead section housed in a package, and a matching capacitance is formed between the two.