JPS5846571Y2 - High frequency circuit equipment - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a high-frequency circuit device, particularly a semiconductor device mounted on a metal substrate, a dielectric substrate placed between the semiconductor devices, and a device formed on the dielectric substrate. The present invention relates to a high frequency circuit device including a pair of strip lines having transmission line electrodes.

Kin Hayabusa, gallium arsenide field effect transistor (GaAsF
Due to the dramatic improvement in the characteristics of microwave semiconductor devices such as ET), the microwave band (IGHz to 20GHz)
Wideband low-noise amplifiers and high-output linear amplifiers have come into practical use.

These amplifiers use a so-called microwave integrated circuit composed of a microstrip line, active elements such as FETs and transistor diodes, and C and R passive elements.

For example, the structure of a conventional connection between a microstrip line and an FET is shown in FIG.

In such a microwave amplifier, if the feedback capacitance between the input and output is large, oscillation may occur or the gain may decrease.

Especially when the frequency increases with wideband amplifiers and linear amplifiers (
For example, Ku band 12 to 20 GHz) This influence is large.

That is, in the figure, a semiconductor device, for example, an FET chip 2, a dielectric substrate 3, 3', and transmission line electrodes 4, 4' formed thereon are mounted on a metal substrate 1 made of copper whose surface is plated with gold. In a high frequency circuit device provided with a pair of stop line lines, a feedback capacitance occurs between input and output at the opposing portions of electrodes 4 and 4'.

Therefore, in order to reduce this feedback capacitance, the structure shown in FIG. 2 is adopted.

This structure is one in which a protrusion 21 is provided on the metal base 1, and the feedback capacitance can be reduced to some extent.

By making this feedback capacitance smaller, the present invention
A further object of the present invention is to provide a high frequency circuit device that handles high frequency signals.

The present invention is characterized by having a semiconductor device mounted on a metal substrate, a dielectric substrate disposed to sandwich the semiconductor device, and a transmission line electrode formed on the dielectric substrate. In a high frequency circuit device comprising a pair of strip lines, the width of the transmission line electrode is gradually reduced in the direction of the semiconductor device in the portion where the pair of strip lines face each other, and the thickness of the dielectric substrate is gradually reduced. This is because the width of the transmission line electrode and the thickness of the dielectric substrate are gradually reduced so that they become a constant ratio.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 3 is a perspective view showing an embodiment of the present invention.

As shown in the figure, the width of the transmission line electrodes 4, 4' gradually decreases in the direction of the FET chip 2 at the portion where the pair of strip lines face each other.

In addition, the thickness of the dielectric substrate is also gradually reduced so that the ratio of the width of the transmission line electrode to the thickness of the dielectric substrate becomes constant.

In this way, by reducing the opposing areas of the transmission line electrodes 4, 4', the feedback capacitance can be reduced.

Further, by reducing the thickness of the dielectric substrate in the portion where the electrode width is reduced, the characteristic impedance of the strip line can be kept constant.

Specifically, in the figure, Wo=0.6mm, W1=0.
1 mm, t = 0.6 mm, t , = Q, l
mm, and therefore the ratio of the width of the electrode to the thickness of the dielectric substrate was 1.

Further, when the electrode spacing d=0.5 mm and alumina (Al□03) substrates with a dielectric constant ε=9.6 were used as the dielectric substrates 3 and 3', the feedback capacitance was 0.001PF.

When similar dimensions and materials are used, the feedback capacitance is 0.01 in the structure shown in Figure 1 in which the electrode width is not tapered as in the present invention.
The PF was 0.006PF in the structure shown in FIG. 2, and it became clear that the structure of the present invention could sufficiently reduce the feedback capacitance.

However, in either case, the characteristic impedance of the strip line is 50J7.

FIG. 4 is a perspective view showing another embodiment of the present invention.

In the embodiment shown in FIG. 3, the upper surface of the dielectric substrate was tapered, but in this embodiment, the lower surface of the dielectric substrate was tapered.

Thereby, the formation of the electrode pattern can be made easier than in the embodiment shown in FIG.

As explained above, according to the present invention, it is possible to reduce the feedback capacitance, thereby preventing unnecessary oscillation and decrease in gain in a high frequency circuit device.

[Brief explanation of the drawing]

1 and 2 are perspective and perspective views showing a conventional high frequency circuit device, FIG. 3 is a perspective view showing an embodiment of the high frequency circuit device according to the present invention, and FIG. 4 is a perspective view showing another embodiment of the present invention. FIG. In the figure, 1 is a metal base, 2 is an FET chip (semiconductor device), 3 and 3' are dielectric substrates, and 4 and 4' are transmission line electrodes.

Claims (1)

[Scope of utility model registration request] A high frequency device comprising a semiconductor device mounted on a metal substrate, a dielectric substrate disposed to sandwich the semiconductor device, and a pair of strip lines having transmission line electrodes formed on the dielectric substrate. In the circuit device, in a portion where the pair of strip lines face each other, the width of the transmission line electrode is gradually decreased in the direction of the semiconductor device, and the thickness of the dielectric substrate is also equal to the width of the transmission line electrode and the dielectric substrate. 1. A high-frequency circuit device characterized in that the thickness of the body substrate is gradually reduced to a certain ratio.