JPH051139Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] This invention is a microwave application using a PIN diode used in a signal processing circuit in the microwave band.
Concerning improvements to PIN diode T-type circuits.

[Prior Art] As a broadband absorption type variable attenuation circuit used in a microwave band signal processing circuit, a PIN diode T-type attenuation circuit in which a PIN diode is incorporated in a T-type is generally used. Such a PIN diode T-type attenuation circuit has a circuit configuration as shown in FIG. 5, for example.

That is, in the figure, 1 and 2 are an input terminal and an output terminal, respectively, and first and second PIN diodes 4 and 5 are inserted in series with the polarity shown in the transmission line 3 that connects the input and output terminals 1 and 2. ing. A third PIN diode 8 is connected between the connection point 6 of the first and second PIN diodes 4 and 5 and the ground conductor 7 in the illustrated polarity. Transmission line 3 has each PIN
Coils 9, 10, 11 as a bias circuit for supplying bias current to diodes 4, 8, 5
is connected at one end. Control terminal 1 of each coil
Capacitors 14, 15, 16 are connected between the connection points between the coils 2, 13 and the respective coils 9, 10, 11 and the ground for bypassing high frequency signal components.
Further, capacitors 17 and 18 for cutting off DC components are connected between the input terminal 1 and the first PIN diode 4 and between the output terminal 2 and the second PIN diode 5.
is inserted.

In the PIN diode T-type attenuation circuit with such a circuit configuration, the microwave signal input from the input terminal 1 is attenuated by the impedance values of the first, second, and third PIN diodes 4, 5, and 8. It is output from output terminal 2 after being attenuated by the rate. The impedance value of each PIN diode 4, 5, 8 is determined from the control terminal 12, 13 through each coil 9, 10, 11.
It is controlled by the bias current supplied to terminals 8 and 5. Therefore, by controlling this bias current, the amount of attenuation of the microwave high frequency signal can be adjusted as desired.

However, in order to obtain the above-mentioned attenuation characteristics, it is necessary to
Each circuit element constituting the PIN diode T-type attenuation circuit needs to be expressed as a lumped constant when this attenuation circuit is expressed as an equivalent circuit. In particular, each PIN diode 4, 5, and 8, which greatly influences the amount of attenuation, must be considered as a completely lumped constant.

Therefore, when implementing the PIN diode T-type attenuation circuit, it is necessary to functionally arrange each circuit element to suppress the generation of stray capacitance and the like as much as possible.

Figures 6a, b, and c are the fifth
FIG. 2 is a plan view, a sectional view, and a partially enlarged view showing the mounting arrangement of main circuit elements in the PIN diode T-type attenuation circuit shown in the figure. As shown in the figure, a dielectric 19 is disposed on the upper surface of the ground conductor 7, and a transmission line 3 formed of a band-shaped conductor is attached to the upper surface of the dielectric 19. Then, the cathode end of a chip-type third PIN diode 8 having no lead wire is fixed to the exposed portion of the ground conductor 7 from which the dielectric 19 and the transmission line 3 have been removed by, for example, solder. The tip of the cathode lead wire of the beam lead type second PIN diode 5 is connected to the anode end 20 of the chip type PIN diode 8. second
The other anode side lead wire of the PIN diode 5 is connected to the transmission line 3. Furthermore, the third PIN
The anode end 20 of the diode 8 is connected to the other end of a connection line 21 whose one end is connected to the transmission line 3 on the opposite side.

One end of the coil 10 is soldered to the transmission line 3 to which the connection line 21 is connected. Further, a cutting portion 22 is formed in the transmission line 3, and this cutting portion 22 is connected to each lead wire of the first PIN diode 4 of the beam lead type.

[Problems to be solved by the invention] However, there are still many problems in the PIN diode T-type circuit for microwaves, which is typified by the PIN diode T-type attenuation circuit in which each circuit element is mounted and arranged as shown in Figure 6. I had a problem like this. That is, in order to connect the coil 10 that supplies bias current to the anode end 20 of the chip-type third PIN diode 8, the beam-lead type first PIN
Between the diode 4 and the third PIN diode 8,
Alternatively, the coil 1 is connected between the beam lead type second PIN diode 5 and the third PIN diode 8.
It is necessary to provide a transmission line of an appropriate length to connect 0 to the third PIN diode 8. In FIG. 6, the transmission line is connected to a connecting wire 21 connecting the anode end 20 of the chip-shaped third PIN diode 8 and the transmission line 3, and this connecting wire 21 to the coil 10.
and a transmission line 3 connecting the two.

On the other hand, as mentioned above, each PIN diode 4,
Since it is necessary to regard 5 and 8 as completely lumped constants, it is necessary to set the connection distance between each PIN diode 4, 5, and 8 as short as possible. However, the sixth
With the circuit element arrangement shown in the figure, the transmission line connecting the third PIN diode 8 and the coil 10 is about 2 mm even if it is made as short as possible. However, if the distance is about 2 mm, the upper limit of the microwave high-frequency signal frequency at which an almost theoretical attenuation amount can be obtained with this PIN diode T-type attenuation circuit is limited to about 20 GHz. Therefore, this PIN diode T
There is a problem in that the microwave signal frequency band that can be used in the type attenuation circuit becomes narrow.

Furthermore, there is a problem that the entire PIN diode T-type attenuation circuit becomes larger. Furthermore, a chip-shaped third
Anode end 20 of PIN diode 8 and coil 10
A connection line 21 is required to connect the transmission line 3 to which the transmission line 3 is connected, and a process for connecting the connection line 21 is also required. As a result, the cost of materials increases and the manufacturing process becomes more complicated, increasing the manufacturing cost of the entire PIN diode T-circuit.

The present invention was developed in view of these circumstances, and its purpose is to directly connect a high-frequency signal blocking circuit element such as a coil to one end of a chip-type third PIN diode. ,each
To provide a PIN diode T-type circuit for microwaves that can shorten the connection distance between PIN diodes as much as possible, expand the microwave signal frequency range that can be used in this T-circuit, and be compact and reduce the number of manufacturing steps. It is in.

[Means for solving the problem] The present invention involves inserting first and second PIN diodes in series in the transmission line, and
Connect a third wire between the PIN diode connection point and the ground conductor.
Connect the PIN diode, and then connect each PIN to the connection point.
In a microwave PIN diode T-type circuit connected to a high-frequency signal blocking circuit element that supplies a bias current to the diode, the third PIN diode is composed of a chip-type PIN diode with one end fixed to a ground conductor, and this chip One end of a high frequency signal blocking circuit element is directly connected to the other end of a type PIN diode.

[Function] In the microwave PIN diode T-type circuit configured in this way, this
Since one end of the high frequency signal blocking circuit element that supplies bias current to the PIN diode is directly connected, the connection distance between each PIN diode can be further shortened. As a result, each PIN diode can be regarded as a lumped constant up to the high frequency range.

[Example] An example of the present invention will be described below with reference to the drawings.

Figure 1 shows the PIN diode T-type circuit of the example.
FIG. 3 is a layout diagram of main circuit elements when applied to a PIN diode T-type attenuation circuit. The same parts as in the conventional layout diagram shown in FIG. 6 are given the same reference numerals. Further, the circuit diagram of the PIN diode T-type attenuation circuit of the embodiment is the same as the conventional circuit diagram shown in FIG.

In the PIN diode T-type attenuation circuit of this embodiment, as shown in FIGS. Transmission line 3 formed by
is attached. The cathode end of a chip-type third PIN diode 8 having no lead wire is fixed to the exposed portion of the ground conductor 7 from which the dielectric 19 and the transmission line 3 have been removed by, for example, solder. The anode end 20 of the chip-type PIN diode 8 is connected to the tip of the lead wire of the beam-lead type first PIN diode 4, the tip of the lead wire of the beam-lead type second PIN diode 5, and the high-frequency signal blocking circuit. The tip 10a of the coil 10 as an element is directly connected.

The entire coil 10 is made of gold (Au), and both the wound portion and the tip 20 are made of the same gold (Au) material. In addition, the beam lead type first and second
The lead wires of the PIN diodes 4 and 5 are also made of gold (Au) material. Therefore, as shown in Figure 1c, each of these gold (Au) materials
The three tips of the lead wires of the PIN diodes 4 and 5 and the tip 10a of the coil 10 can be easily connected to the anode end 20 of the chip-shaped PIN diode 8 at once by, for example, heating.

Further, the tips of the other lead wires of the first and second PIN diodes 4 and 5 are respectively connected to the transmission line 3 facing each other via the exposed portion of the ground conductor 7.

In a PIN diode T-type attenuation circuit in which each circuit element is arranged in this way, the tip 1 of the coil 10
Since 0a is directly connected to the anode end 20 of the chip-type third PIN diode 8 along with the lead wires of the first and second PIN diodes 4 and 5, each
The connection distance between the PIN diodes 4, 5, and 8 can be significantly shortened compared to the conventional circuit layout shown in FIG. Therefore, since stray capacitances existing between each circuit element can be suppressed to a minimum, the first, second, and third PIN diodes 4 when this PIN diode T-type attenuation circuit is replaced with an equivalent circuit. , 5, and 8 can be regarded as approximately lumped constants. As a result, compared to the PIN diode T-type attenuation circuit having the circuit element arrangement shown in FIG. 6, the upper limit frequency of usable microwave signal frequencies can be significantly increased.

2 to 4 are diagrams showing examples of frequency characteristics obtained with the PIN diode T-type attenuation circuit of the embodiment shown in FIG. 1. The solid line shows the characteristics of the example circuit, and the dotted line shows the characteristics of the conventional circuit shown in FIG. Figure 2 shows the output signal of output terminal 2 when the bias current flowing through each coil 9, 10, and 11 is adjusted and the attenuation between input terminal 1 and output terminal 2 is initially set to [0 dB]. FIG. 3 is an insertion loss characteristic diagram showing a ratio to an input signal. As shown in the figure, in the conventional circuit, the characteristics deteriorate significantly at about 20 GHz, whereas in the example circuit, the characteristics do not deteriorate significantly up to about 30 GHz.

FIG. 3 is a characteristic diagram showing the amount of return loss at the input terminal 1. It can be seen that the amount of change in return loss in the example circuit is much larger than the return loss in the conventional circuit at frequencies of 10 GHz or higher, and has good characteristics.

Further, FIG. 4 is a characteristic diagram showing the amount of attenuation at the output terminal 2 in the example circuit when the above-mentioned attenuation amounts are initially set to 0 dB, 10 dB, 20 dB, and 30 dB, respectively. As shown in the figure, almost flat frequency characteristics exceeding 30 GHz are obtained.

Furthermore, since the tip 10a of the coil 10 is directly connected to the anode end 20 of the chip-type third PIN diode 8, it is necessary to use the connecting wire 21 used in the circuit element arrangement of the conventional circuit shown in FIG. There is no. Further, there is no need to form a cutting section 22 for connecting the first PIN diode 4 in the middle of the transmission line 3. Furthermore, the number of connection points between each circuit element can be significantly reduced compared to the number of connection points in the circuit element arrangement of a conventional circuit.

In this way, the number of elements used and the number of manufacturing steps can be significantly reduced, so the entire circuit can be made smaller and manufacturing costs can be reduced.

Note that the present invention is not limited to the embodiments described above. It is obvious that the present invention can also be applied to a configuration in which the polarities of the PIN diodes 4, 5, and 8 are reversed as shown in FIG. Furthermore, in the example, a microwave PIN diode T-type circuit is used.
Although the case where the present invention is applied to a PIN diode T-type attenuation circuit has been described, it is also possible to apply it to other switching circuits.

[Effects of the invention] As explained above, according to the invention, a high frequency signal blocking circuit element such as a coil is directly connected to one end of the chip-type third PIN diode. Therefore, the connection distance between each PIN diode can be shortened as much as possible, and the microwave signal frequency range that can be used in this circuit can be expanded. Furthermore, it is possible to reduce the size and the number of manufacturing steps, which in turn can reduce manufacturing costs.

[Brief explanation of the drawing]

Fig. 1 is a circuit element layout diagram of a PIN diode T-type attenuation circuit to which a microwave PIN diode T-type circuit according to an embodiment of the present invention is applied, and Figs. 2 to 4 show the effects of the same embodiment. Frequency characteristic diagram, Figure 5 is a circuit diagram showing a general PIN diode T-type attenuation circuit, Figure 6 is a circuit element layout diagram of a conventional PIN diode T-type attenuation circuit, and Figure 7 is a PIN diode T-type attenuation circuit. FIG. 3 is a diagram illustrating another example of a circuit that can be used as a circuit. 1...Input terminal, 2...Output terminal, 3...Transmission line, 4...First PIN diode, 5...Second
PIN diode, 6... Connection point, 7... Ground conductor, 8... Third PIN diode, 9, 10, 1
1... Coil, 14, 15, 16, 17, 18...
... Capacitor, 19 ... Dielectric, 20 ... Anode end.

Claims (1)

[Claims for Utility Model Registration] First and second PIN diodes are inserted in series in the transmission line, and a third PIN diode is connected between the connection point of the first and second PIN diodes and a ground conductor. , and a microwave PIN diode T further connected to the connection point with a high frequency signal blocking circuit element that supplies a bias current to each of the PIN diodes.
In the circuit, the third PIN diode is a chip-type PIN diode with one end fixed to the ground conductor, and one end of the high-frequency signal blocking circuit element is directly connected to the other end of the chip-type PIN diode. A microwave PIN diode T-type circuit featuring: