JPS62196901A - Bias superposing device for microstrip line - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a device for superimposing a bias on a microstrip line used in a microwave circuit.

<Prior art> As a first device to apply bias to a microstrip line conventionally used in a microwave circuit, there is a device that applies bias superimposition to a microstrip line (12) connected to a microwave input terminal (11). The microstrip line (14) connected to the microwave output terminal (13) is connected via a DC block capacitor (15), and the microstrip line (14) is connected to the bias terminal (16). At a predetermined position of the microstrip line (17) connected to the
A plurality of stub lines (18) with an electrical length of 4 are formed at an electrical length interval of λ/4 (see Figure 4), and a microstrip line (22) connected to the microwave input terminal (21). And Bias I! The microstrip line (24) connected to the microwave output terminal (23) is connected via a DC block capacitor (25), and the microstrip line (24) is connected to the bias terminal (26). A choke coil (27) consisting of an air-core winding coil is connected to the coil, and a bypass capacitor (28) and a through hole (29) are formed (see Fig. 5). This is also formed on a dielectric substrate.

<Problems to be Solved by the Invention> In the configuration described in (1) above, if the microwave signal has a predetermined frequency, the stub line (18) exhibits a sufficient choke effect and the transmission loss is small. However, if the microwave signal deviates from a predetermined frequency, the impedance becomes low and a sufficient choke effect cannot be exerted, and the only way to transmit signals is with high passing loss. There is a problem in that it becomes impossible to perform (see characteristic song 11B in Fig. 3). In other words, the bandwidth of the bias superimposing circuit becomes narrower.

In addition, in the configuration (2) above, since the choke coil (27) consisting of an air-core wire-wound coil has capacitance and self-induction, the microstrip line (24) in the microwave frequency band ) has the problem of increased passing loss (see characteristic curve C in Figure 3).

<Object of the invention> This invention was made in view of the above problems,
It is an object of the present invention to provide a bias superimposition device that has a sufficient choke effect over a wide bandwidth and is highly effective in suppressing transmission loss.

Means for Solving the Problems> In order to achieve the above object, the bias superimposing device of the present invention connects a straight conductor between the microstrip line and the bias superimposing terminal, and also connects the straight conductor to the bias superimposing terminal. A plurality of bypass capacitors, which also serve as supports, are installed between the middle and the ground conductor.

However, it is preferable that the linear conductor has a diameter of mm.

Further, it is preferable that the bias superimposing device is provided with a top cover having a shielding slit groove in order to reduce electromagnetic coupling between the bias superimposing terminal and the microstrip line.

Effect> With the bias superimposition device having the above configuration, when a bias signal is supplied from the bias superimposition terminal while a microwave signal is being transmitted through the microstrip line, it is possible to connect the bias superimposition circuit and the microstrip line. Since the straight conductor is supported by a bypass capacitor away from the ground conductor, and the straight conductor and the ground conductor are connected via the bypass capacitor, the characteristic impedance of the bias circuit is small. It is larger than the characteristic impedance of the strip line, suppressing signal leakage to the bias circuit,
Bias superposition can be performed with little passing loss.

Further, if the straight conductor is a pole II line, the characteristic impedance of the bias circuit can be increased, and bias superposition can be performed with less passing loss.

Furthermore, if the bias superimposition device is equipped with a top cover having a shielding slit groove in order to reduce the electromagnetic coupling between the bias superimposition terminal and the microstrip line, the characteristic impedance ZOB of the bias circuit is ZOB=601oQo1 .2 (Di +02) /
2d (however, Dl is the slit groove width, D2 is the slit groove depth, and d is the wire diameter of the straight S! conductor), so at least one of the slit groove width and the slit groove depth should be increased. Therefore, the characteristic impedance of the bias circuit 2
If 0B is set to a sufficiently large value compared to the characteristic impedance of the microstrip line, bias superimposition can be performed with little passing loss. still,
In this case, the top cover also has a shielding effect, making it possible to reduce electromagnetic coupling between the bias terminal and the microstrip line, thereby suppressing transmission loss.

<Example> Hereinafter, embodiments will be described in detail with reference to the accompanying drawings showing examples.

FIG. 1 is a schematic perspective view showing an embodiment of the bias superimposing device of the present invention, and FIG. 2 is a cross-sectional view.

A grounding conductor (2) of a predetermined width and a dielectric substrate (3) are placed at a predetermined position on the upper surface of a substrate reinforcing carrier (1) of a predetermined size.
are formed in this order, and at the center of the upper surface of the dielectric substrate (3),
A microstrip line (4a) connected to the microwave input terminal (5a), and a microstrip line (4a) connected to the bias superimposed microwave output terminal (5b).
4b) and both microstrip lines f4a) (4b
) and a DC block capacitor (4c) connected to the DC block capacitor (4c). That is, the above microstrip line (4a
) (4b), dielectric substrate (3), and ground conductor (2)
This forms a substrate width limiting structure for suppressing higher-order modes.

A bypass circuit consisting of a straight conductor (6a) consisting of a pole Il [l wire and a plurality of bypass capacitors (6b) (6) and has a width corresponding to the dielectric substrate (3) and has a rectangular cross section slit W4 (7a), and a slit groove (7a) with a rectangular cross section surrounding the linear conductor (6a). 7b
) on the shield formed with 1! [71 is fixed on the top surface of the reinforcing carrier (1), and the straight conductor (6a)
is supported by a plurality of bypass capacitors (6b) so that it is located at the center of the slit groove (7b), and the direct IIA conductor (6a) and the ground conductor (2) are connected to the plurality of bypass capacitors (6b). It is connected by a bypass capacitor (6b).

The straight conductor (6a) is, for example, 100 μm.
A pole m line having a diameter of less than mφ is used, and as the bypass capacitor (6b), for example, a small capacitance chip capacitor within a range where the impedance is sufficiently small in the microwave band is used.

Furthermore, the straight conductor (6a) is connected to the bypass capacitor (6b)! ! Connection to the conductor (2) can be easily made by connecting the terminal of the bypass capacitor (6b) to the metal substrate reinforcing carrier (1).

The operation of the bias superimposing device having the above configuration is as follows.

When a microwave signal of a predetermined frequency is supplied from the microwave input terminal (5a), the microwave signal passes through the microstrip line (4a) and a DC blocking capacitor (4c) for blocking DC bias. 4b). In this state, if a bias signal consisting of a direct current or a low frequency signal is supplied from the bias terminal (6c), the straight conductor (6a) and the plurality of bypass capacitors (6
b) is transmitted to the microstrip line (4b) through a bias circuit consisting of the microwave signal, and the bias signal is applied to the microwave signal. And the bias signal! 1! The convolved microwave signal is taken out from the bias superimposed microwave output terminal (5b).

Further, in the above case, since the bias terminal (6c) side has a higher impedance than the microstrip line (4b) side, the microwave signal rarely leaks through the bias terminal (6c). Therefore, the transmission loss of microwave signals can be significantly suppressed. (See characteristic curve A in Figure 3). As is clear from the above characteristic curve, it can be seen that the transmission loss is small over a fairly wide band.

<Effects of the Invention> As described above, the present invention can increase the characteristic impedance on the bias superimposition circuit side over a wide frequency band compared to the characteristic impedance on the microstrip line side that transmits microwave @, This has the unique effect of being able to perform bias superimposition while suppressing the passage loss of the microwave signal to a low level.

[Brief explanation of drawings]

FIG. 1 is a schematic perspective view showing an embodiment of the bias superimposing device of the present invention, FIG. 2 is a cross-sectional view, FIG. 3 is a diagram showing passage loss-frequency characteristics, and FIGS. 4 and 5 are FIG. 3 is a schematic plan view showing each conventional example. (1)... Carrier A for board reinforcement, (2)... Ground conductor, (4b)... Microstrip line, (6
a) Straight conductor, (6b) Bypass capacitor, (6C) Bias terminal, (Power) Shield top cover, (7b) Slit groove Patent applicant Sumitomo Electric Industries, Ltd. Company Figure 4 Figure 5

Claims (1)

[Claims] 1. A straight conductor is connected between the microstrip line and the bias overlapping terminal, and a plurality of bypass capacitors that also serve as supports are provided between the straight conductor and the ground conductor. A bias superimposition device for a microstrip line, characterized in that it is equipped with a. 2. The bias superimposition device for a microstrip line according to claim 1, wherein the straight conductor is an extremely thin wire. 3. The bias superimposition device for a microstrip line according to claim 1, wherein a top cover having a shielding slit groove is attached to the bias superimposition device in order to reduce electromagnetic coupling between the bias superimposition terminal and the microstrip line. .