JPS61285811A - Microwave circuit - Google Patents

Abstract

PURPOSE:To give a desired DC bias by connecting a lambdag/4 wavelength of distributed constant stub to an electrode to be grounded of a microwave transistor (TR). CONSTITUTION:A microstrip line 2, the distributed constant stub 3 of lambdag/4 (lambdag=propagation wavelength) wavelength and a ground conductor pattern 4 are formed on a dielectric board 5 by the print wiring technology, one of source electrodes led to both sides of the beam lead structure microwave TR 1 is connected to one terminal of the stub 3 by solder and the other is connected to the ground conductor pattern 4 by solder. Further, the gate electrode G and the drain electrode D are connected respectively to the microstrip line 2 by solder. Since the stub 3 is connected to the source S of the TR 1, a signal is grounded in terms of high frequencies and the ground conductor pattern 4 is connected to an earth block and a case by a screw 6 to apply grounding in term of DC.

Description

[Detailed Description of the Invention] [Summary] The electrode of the microwave transistor to be grounded is
The long distributed constant stub is used for high-frequency grounding and direct current connection to the ground conductor pattern, thereby simplifying the configuration for grounding and stabilizing the operation.

[Industrial application field]

The present invention relates to a microwave circuit in which a microwave transistor is connected to a microstrip line.

In a microwave circuit using a microstrip line, it is necessary to lower the grounding impedance of the microwave transistor to stabilize the operation.

[Conventional technology]

For example, as shown in the top view of FIG. 7 and the cross-sectional view of FIG. is fixed on the ground block 14 with screws, etc., and fixed with adhesive or screw 1 on this ground block 14.
5 fixes the dielectric substrate 13, and the dielectric substrate 1
The gate electrode and drain electrode of the microwave transistor 11 are connected to the microstrip line 12 on the microstrip line 3 by soldering or the like. Therefore, the source electrode of the microwave transistor 11 is directly connected to the earth block 14, forming a source-grounded microwave transistor circuit.

The conventional example shown in the top view of FIG. 9 and the cross-sectional view of FIG. or fixed with screws 25,
The gate electrode and drain electrode of the microwave transistor 21 are connected to the microstrip line 22 on the dielectric substrate 23 by soldering, etc., the source electrode is connected to the ground conductor pattern 26 by soldering, etc., and the connection point is A through hole 27 which has been subjected to metallization processing etc. is formed nearby, and the source electrode of the microwave transistor 21 is connected to the earth block 24 under the dielectric substrate 24 through the through hole 27 from the ground conductor pattern 26. It is grounded.

[Problem that the invention seeks to solve]

In the conventional microwave circuit shown in FIGS. 7 and 8, the source electrode of the microwave transistor 11 is directly connected to the earth block 13, so the grounding impedance is small and the heat dissipation characteristics are good. Widely used in microwave amplifiers, etc.

However, in order to directly fix the source electrode of the microwave transistor 11 to the ground block 14, the dielectric substrate 13 must be divided as shown in the figure, or a mounting hole into which the microwave transistor 11 will be inserted must be formed in the dielectric substrate. Board 13
It is necessary to form the Therefore, there arises a drawback that manufacturing of the dielectric substrate 13 is complicated. Further, when the microwave transistor 11 is screwed to the earth block 14, it is necessary to provide the earth block 14 with a tap for the screw. Also, the earth block 14 is not only electrical but also mechanical.
is an essential configuration, and has the disadvantage that the mounting structure is complicated and expensive.

Furthermore, the conventional microwave circuit shown in FIGS. 9 and 10 is
A microwave transistor 21 is mounted on a dielectric substrate 23, the source electrode is connected to a ground conductor pattern 26, a through hole 27 is provided near the connection point, and the source electrode is connected to the ground conductor or earth block 24 on the back side. Therefore, a step of forming the through hole 27 in the dielectric substrate 23 is added, and due to the existence of the through hole 27,
This requires precision in circuit pattern production, which has the disadvantage of increasing costs. Furthermore, since the through hole 27 is generally metallized on its inner surface, its impedance may affect the grounding characteristics.

As mentioned above, conventional microwave circuits can provide good grounding characteristics over a relatively wide band, but have the disadvantage of being expensive. Therefore, for example, in a low-cost microwave circuit to be applied to a mass-produced satellite broadcasting receiver, etc., this has been a factor that hinders price reduction.

An object of the present invention is to provide an inexpensive microwave circuit in which the production of a dielectric substrate and the mounting of microwave transistors are easy.

[Means for solving problems]

The microwave circuit of the present invention will be explained with reference to FIG. 1. A microwave transistor 1 is connected to a microstrip line 2 formed on a dielectric substrate 5, and a source electrode of the microwave transistor 1 is grounded. to the electrode that should be
A distributed constant stub 3 with a length of λg/4 that is grounded at high frequency is connected, and also connected to a grounding conductor pattern 4 in a direct current manner, and this grounding conductor pattern 4 is connected to a grounding block or the like using a screw 6 or the like. .

[Effect]

λ9/4 to the electrode to be grounded of microwave transistor 1
By connecting the long distributed constant stub 3, the electrode is short-circuited and grounded at high frequency, so it is possible to reduce the grounding impedance due to parasitic elements such as parasitic resistance and parasitic reactance in the target frequency band. In terms of direct current, it can be connected via the ground conductor pattern 4 to provide a desired direct current bias.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a top view of an embodiment of the present invention, in which a dielectric substrate 5
A microstrip line 2, a distributed constant stub 3 with a length of λg/4 (λ9=propagation wavelength), and a ground conductor pattern 4 are formed on the top by printed wiring technology, and are led out on both sides of the microwave transistor 1 having a beam-lead structure. One side of the source electrode S is connected to one end of the stub 3 by solder or the like, and the other side is connected to the ground conductor pattern 4 by solder or the like. Further, the gate electrode G and the drain electrode are each connected to the microstrip line 2 by solder or the like.

By connecting the stub 3 to the source electrode S of the microwave transistor 1, it is grounded in terms of high frequency, and the ground conductor pattern 4 is connected to the earth block, casing, etc. with screws 6, etc., so that DC grounding is performed.

FIG. 2 shows an equivalent circuit of the embodiment of the present invention, in which a voltage of +V is applied to the drain electrode of the microwave transistor E, a distributed constant stub 3 with a length of λ9/4 is connected to the source electrode S, and It is grounded in a DC manner, and has a parasitic impedance Z consisting of a parasitic resistance R and a parasitic reactance L in the DC grounding path. However, this parasitic impedance Z is caused by the ground conductor pattern 4, screw 6, etc., and does not affect high-frequency grounding, so that good grounding characteristics can be obtained.

Figure 3 is a grounding impedance characteristic curve diagram, and 12G
It shows a range of 11 to 13 GHz centered on Hz. In the same figure, the X mark indicates the case where the parasitic resistance R in the conventional example in which the stub 3 is not connected is set to 0.5Ω, and the parasitic reactance L is set to 0.5 nH. The grounding impedance is shown when only the stub 3 having a length set corresponding to the wavelength λg is connected and the parasitic impedance Z is not considered. Also, the circle indicates the case where the stub 3 is connected, the parasitic resistance R is 0.5Ω, and the parasitic reactance L is 0.5 nH. In this way, by connecting the stub 3 and grounding it at a high frequency, the grounding impedance characteristics are significantly improved compared to the case where the stub 3 is not connected.

4 and 5 are explanatory diagrams of the grounding configuration. In FIG. 4, the dielectric substrate 5 is fixed to the ground block 7 with screws 6, and the ground conductor pattern 4 and the ground block 7 are fixed to the ground block 7.
A direct current connection is made between the two. In addition, in terms of high frequency, the above-mentioned stub 3 is used. Further, FIG. 5 shows a case where a dielectric substrate 5 on which a microwave transistor 1 is mounted is fixed to a housing 9 made of sheet metal processing, etc., and is grounded at high frequency by the aforementioned stub 3, and the back surface of the dielectric substrate 5 is grounded. This figure shows a case where the ground conductor 8 and the ground conductor pattern 4 on the surface are connected by solder or the like to perform DC grounding.

FIG. 6 shows an embodiment of the present invention applied to a frequency converter, in which a signal of, for example, IGHz is applied from the input terminal IN to the gate of the microwave transistor 1 via the coupling capacitor C1 and the matching circuit MCI. A gate bias voltage VG is applied to the gate via a high frequency choke, the source of this microwave transistor 1 is grounded in terms of direct current, and the stub 3 is connected to be grounded in terms of high frequency. From local oscillator LO to circulator CIR, coupling capacitor C2, and matching circuit M
A local oscillation signal is applied via C2. In addition, R, L
, Z indicate parasitic resistance, parasitic reactance, and parasitic impedance.

An IGHz signal is applied to the gate of the microwave transistor 1, and a 13GHz signal is applied to the drain, and a 13±IGHz signal is led out to the output terminal OUT via the matching circuit MC2, the coupling capacitor C2, and the circulator CIR. For example, if a 12 GHz filter is provided, it becomes a frequency converter that converts an IGHz signal to a 12 GHz signal.

〔Effect of the invention〕

As explained above, the present invention connects the electrode to be grounded, such as the source electrode of the microwave transistor 1, in a direct current manner, and connects the distributed constant stub 3 with a length of λg/4.
Since it is grounded at high frequency, microwave
Good grounding characteristics can be obtained without forming through holes or the like on the dielectric substrate 5 on which the resistor 1 is mounted, and the stub 3 can be formed as a wiring pattern together with the microstrip line 2 and the ground conductor pattern 4. This has the advantage that the dielectric substrate 5 can be manufactured easily.

Furthermore, since the configuration is simple, automatic implementation becomes easy.

[Brief explanation of the drawing]

FIG. 1 is a top view of an embodiment of the present invention, FIG. 2 is an equivalent circuit of an embodiment of the present invention, FIG. 3 is a grounding impedance characteristic curve diagram, FIGS. 4 and 5 are diagrams explaining the grounding configuration, 6 is a block diagram of a frequency converter according to an embodiment of the present invention, FIGS. 7 and 9 are top views of the conventional example, and FIGS. 8 and 10 are cross-sectional views of the conventional example. 1 is a microwave transistor , 2 is a microstrip line, 3 is a distributed constant stub with a length of λg/4,
4 is a ground conductor pattern, 5 is a dielectric substrate, 6 is a screw, S
is a source electrode, G is a gate electrode, and D is a drain electrode. Top view of the embodiment of the present investigation Figure 1 +■ Equivalent circuit of the embodiment of the present investigation Figure 2 Grounding impedance characteristic curve diagram Figure 3 Diagram for explaining the grounding configuration Diagram for explaining the grounding configuration Figure 5 Actual example of the embodiment of this investigation Block diagram of frequency converter Fig. 6 Top view of conventional example Fig. 7 Top view of conventional example
Fig. 9 Cross-sectional view of conventional example Fig. 8 Cross-sectional view of conventional example
Figure 10

Claims (1)

[Claims] In a microwave circuit in which a microwave transistor (1) is connected to a microstrip line (2), λ_g/4 is grounded at high frequency to an electrode of the microwave transistor (1) that should be grounded. length distribution constant stub (3
) and connected to a ground conductor pattern (4) in a direct current manner.