JPS61251217A - Microwave range amplifier - Google Patents

Abstract

PURPOSE:To prevent oscillation caused due to electromagnetic coupling between the input and output of an amplifier by forming a hole imbedding an amplifier element to a base, imbedding the amplifier element into the hole while a signal terminal is placed upward and placing a power supply shield plate on the ampli fier element via a grounding terminal of the amplifier element. CONSTITUTION:The hole 7 to imbed the amplifier element 3 via a package is provided to the dielectric base 8, the amplifier element 3 is imbedded to the hole 7 while taking upside down and the electromagnetic shield plate 2 is adhered closely completely onto the grounding terminal 4 of the element 3. Since the element 3 is imbedded to the hole 7 formed to the dielectric base 8, the upper face of the base 8 is made flat and the plate 2 is adhered closely onto the dielectric base 8 via the grounding electrode 4 of the element 3, then the complete electromagnetic shield between the input and output of the amplifier element 3 which have been impossible conventional is realized easily.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to an amplifier with improved stability against oscillation.

<Prior art> Generally, when constructing a microwave amplifier using an amplification element consisting of a packaged FET (or bipolar transistor), the above-mentioned A method in which the amplification element is placed and attached is widely adopted. FIG. 2 shows the conventional structure of the above amplifier. FIG. 2(a) is a top view, FIG. 2(b) is a sectional view taken along the line c-c', and FIG.
c) shows a cross-sectional view taken along line DD'.

In the figure, 1 is an input matching circuit, 3 is an amplification element with a package made of FET or bipolar transistor, 4 is a ground terminal of the amplification element 3, and 5 is a ground electrode #6 of a strip line.
is an output matching circuit, and 8 is a dielectric substrate.

9 is an electromagnetic shielding plate.

Here, when a packaged amplification element is mounted on a microstrip line without electromagnetic shielding, the input and output of the amplification element are electromagnetically coupled due to the electromagnetic field generated by the signal transmission through the strip line. Since oscillation often occurs, electromagnetic coupling has conventionally been reduced by providing an electromagnetic shielding plate 9 between the input and output of the amplification element 3, as shown in Figure @2. However, in a microstrip line, the electromagnetic field is concentrated near the line, so the method of arranging the electromagnetic shielding plate 9 on the package of the amplifying element 3 as in the conventional example described above does not allow the input/output line of the dielectric substrate 8 to A gap (shaded area a) corresponding to the package of the amplification element 3 is created nearby, and the input and output of the amplification element 3 are electromagnetically coupled through the gap a with the package, causing the amplifier to oscillate. There was a problem.

<Object of the Invention> The present invention has been made to overcome the above-mentioned problems, and provides a microwave band amplifier with extremely excellent stability against oscillation by preventing electromagnetic coupling between the input and output of the amplifying element. The purpose is to

<Embodiments> Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows an embodiment of a microwave band amplifier according to the present invention. The figure (a) is a top view, and the figure (b) is its A-A'
A cross-sectional view taken along the line, and FIG. 3(c) is a cross-sectional view taken along the line BB'. In the figure, 2 is an electromagnetic shielding plate, and 7 is a hole provided in a dielectric substrate 8 for embedding the amplifying element 3. In this figure, the same parts as in Figure #J2 are indicated by the same symbols.

In this embodiment, the dielectric substrate 8 is provided with a hole 7 for embedding the amplifying element 3 with a package, which is thicker than the conventional example shown in FIG.
is buried upside down, and the electromagnetic shielding plate 2 is completely brought into close contact with the ground terminal 4 of the amplifying element 3.

In the conventional example, as described above, the package of the amplification element 3 was mounted on the dielectric substrate 8 in a protruding manner, so the electromagnetic shielding plate 9 always had a gap a corresponding to the cross-sectional shape of the package of the amplification element 3. , which occurs near the portion of the dielectric substrate where the electromagnetic field is most concentrated, making it impossible to completely electromagnetically shield the input and output of the amplification element 3. However, in this embodiment, since the amplification element 3 is embedded in the hole 7 formed in the dielectric substrate 8, the upper surface of the dielectric substrate 8 is flat, and the electromagnetic shielding plate 2 is placed on the dielectric substrate 8. Since the amplification element 3 can be brought into close contact with the amplification element 3 through the ground electrode 4, complete electromagnetic shielding between the input and output of the amplification element 3, which was previously impossible, can be easily realized. As a result, it is possible to obtain an extremely stable amplifier that does not generate oscillations caused by electromagnetic coupling between the input and output of the amplifier element, which has been a major problem in the past.

<Effects of the Invention> As explained above, the present invention has an extremely effective advantage of being able to prevent oscillations caused by electromagnetic coupling between input and output of an amplifier.

[Brief explanation of drawings]

FIG. 1 shows an embodiment of a microwave band amplifier according to the present invention, in which (a) is a top view, (color) is a cross-sectional view taken along line A-A', and (c) is a cross-sectional view taken along line A-A'. 2 shows a conventional microwave band amplifier, FIG. 2 (a) is a top view, and FIG. ) is D
A cross-sectional view taken along the -D' line is shown. In the figure, l: input matching circuit, 2: electromagnetic shielding plate, 3: amplifier element,
4: Ground terminal, 5: Ground electrode, 6: Output matching circuit, 7: Hole,
8: @Electric board. Agent Patent attorney Aihiko Fuku (2 others) vE1 diagram

Claims (1)

[Claims] 1. Form a hole in the substrate for embedding the amplification element, embed the amplification element in the hole with the signal terminal section on the upper side, and place an electromagnetic shielding plate over the amplification element via the ground terminal of the amplification element. A microwave band amplifier characterized by the following.