JPH0514574Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention relates to a programmable attenuator that is equipped with a switching mechanism and whose attenuation rate can be switched by an external switching signal. This concerns an attenuator.

[Prior art]

Typically, a programmable attenuator includes a multi-stage attenuator unit that attenuates an input signal and a switching mechanism including a relay or the like that switches between the attenuator units. The attenuator unit section of any stage is selected from among the attenuator unit sections of the stages and set to a predetermined attenuation rate, thereby attenuating the input signal.

[Problem that the invention attempts to solve]

However, a programmable attenuator in which the switching mechanism is constituted by a relay has a problem in that the frequency characteristics are disturbed in a high frequency region due to capacitance coupling between the operating coil of the relay and the switching contact.

The present invention has been made in view of the above-mentioned points, and an object of the present invention is to provide a programmable attenuator with less disturbance in frequency characteristics in a high frequency region.

[Means for solving problems]

In order to solve the above problems, the present invention includes a switching mechanism having a multi-stage attenuator section that attenuates an input signal, a relay that switches the attenuator section, and a relay operating circuit that operates the relay,
In a programmable attenuator configured such that the attenuator section and the switching mechanism are housed in a conductive case, the relay and various electronic components constituting the relay operating circuit are mounted on a printed circuit board on which a ground pattern is formed, and the operating coil of the relay is mounted on a printed circuit board on which a ground pattern is formed. One end of the chip capacitor is connected to one end of the chip capacitor, the other end of the chip capacitor is connected to the ground pattern, the ground pattern is electrically connected to the conductive case, and one end of the operating coil of the relay is connected to a high frequency It is characterized by being grounded.

[Effect]

By configuring the programmable attenuator as described above, one end of the operating coil of the relay constituting the switching mechanism is electrically connected to the case at high frequency via the chip capacitor and the ground pattern. In other words, since the operating coil of the relay is grounded in the high frequency range, the capacitive coupling between the operating coil and the switching relay contact causes
The input signal is no longer output through the actuating coil, and the frequency characteristics are not disturbed in the high frequency range.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 is a diagram showing the circuit configuration of a programmable attenuator according to the present invention. In the same figure,
51 to 54 surrounded by dotted lines are relays constituting a switching mechanism, 51l to 54l are operating coils that operate the relays, 51p to 54p are switching contacts of the relays 51 to 54, D ₁ to _{D 4} are diodes, and C ₁ , _C2 are capacitors that ground the operating coils 53l and 54l at high frequencies, _Tr1 to _Tr4 are transistors that drive the relays 51 to 54, respectively, _C11 is an AC coupling capacitor, _R1 to _R3 are resistors, _C5 , _C6 are capacitors, 61a to 61d are transistors _Tr1 to
An external relay drive signal input terminal receives an external signal for driving the relays 51 to 54 via Tr ₄ , 61e is a power supply ground terminal, and 61f is a power supply terminal.

In the programmable attenuator having the circuit configuration described above, switching between AC connection and DC connection can be performed by switching the switching contact 51p of the relay 51, the grounding side or the connection side can be selected by switching the switching contact 52p of the relay 52, and the relay 53 By switching the switching contact 53p, the attenuator unit _A2 can be turned on and off, and the relay 54 can be turned on and off.
By switching the switching contact 54p, the attenuator unit section _A1 can be turned on and off.

A signal inputted from the input terminal section 60 is attenuated at a predetermined attenuation rate by the attenuator unit sections A ₁ and A ₂ according to a path selected by the switching contacts 51 p to 54 p, and outputted from the output terminal 62 .

Capacitors C ₁ and C ₂ are chip capacitors each having a capacitance of about 1000 pF, and in the high frequency range, the operating coils 53l and 54l are grounded, so that the input signal does not leak to the output through the operating coil, and good frequency characteristics can be obtained. can.

Next, the specific structure of the programmable attenuator having the above circuit configuration will be explained based on the drawings.

Figures 2 to 4 are views showing the external appearance of the programmable attenuator main body according to the present invention, where Figure 2 is an overall perspective view, Figure 3 is a view seen from the direction of arrow A in Figure 2, and Figure 4. is a view seen from the direction of arrow B in FIG.

As shown in FIGS. 2 to 4, the programmable attenuator main body 1 has the above-mentioned relay 51 on the top surface.
A printed circuit board 10 on which parts constituting a switching mechanism having 54, etc. are mounted, a ceramic package 30 on which parts constituting an attenuator unit part _A2 are mounted, and an attenuator unit part _A1 .
The device is equipped with a ceramic package 40 on which components constituting the device are mounted. On the back side of the printed circuit board 10 are relays 51 to 54 and configuring the switching mechanism.
An AC coupling capacitor C ₁₁ is installed. Also,
On the top surface of the printed circuit board 10 are transistors Tr ₁ to Tr ₄ that drive the relays 51 to 54, and resistors R ₁ to Tr 4 .
R ₃ , capacitors C ₁ to C ₆ and diodes D ₁ to _{D 4}
(See Figure 5) etc. are also implemented.

The ceramic package 30 is mounted with components such as trimmer capacitors 31 and 32 that constitute the attenuator unit A ₂ as will be described in detail later, and the ceramic package 40 also includes the attenuator unit A 2 as will be described in detail later. ₁ , components such as trimmer capacitors 41 and 42 are mounted.

Further, external signal terminals 61a to 61d and a relay power terminal 61 are provided on one side of the printed circuit board 10.
e, 61f are attached, and an output terminal 62 is attached to one end. Note that 63 is a grounding plate for connecting the grounding pattern of the printed circuit board 10 to the case as will be described later, and 64 and 65 are grounding pieces for similarly connecting the grounding pattern of the printed circuit board 10 to the case. FIG. 5 is a diagram showing the top surface of the printed circuit board 10, and as shown in the figure, there is a ground pattern 11 on the printed circuit board 10.
~14, 16, 17 and transistors Tr ₁ ~ _{Tr 4}
Common pattern 15 that commonly connects the emitters of
Each pattern is formed, and transistors Tr ₁ to _{Tr 4} , resistors R ₁ to R ₃ , capacitors C ₁ to C ₆ , diodes D ₁ to _{D 4} , etc. are mounted at predetermined locations.

The ground plate 63 is attached to one side of the printed circuit board 10, and has tongue portions 63a, 63b, 63c,
63d extend to the lower surface of the printed circuit board 10 and are electrically connected to the ground patterns 14, 13, 12, and 11, respectively. Also, ground pieces 64, 65
also extend to the lower surface of the printed circuit board 10 and are connected to ground patterns 16 and 17, respectively.

FIG. 6 is a diagram showing the circuit configuration of the attenuator unit section _A1 . In the figure, 41 and 42 are trimmer capacitors, R ₄₁ to R ₄₅ are resistors, and C ₄₁ and C ₄₂ are capacitors.

In the attenuator unit _A1 having the above configuration, a signal input from the input terminal 43 is attenuated at a predetermined attenuation rate and output from the output terminal 44.

Figures 7a and 7b show the above attenuator unit.
FIG. 4 is a diagram showing the back and front surfaces of a ceramic package 40 on which components constituting _A1 are mounted. The back surface of the ceramic package 40 has markings a and b in the same figure.
As shown in FIG. 6, various patterns such as the pattern of the output terminal 44, the pattern of the trimmer capacitors 41 and 42, and the patterns for grounding 45, 46, and 47 are formed, and the attenuator unit shown in FIG. Resistor R ₄₁ makes up the circuit of A ₁
~R ₄₅ , capacitors C ₄₁ and C ₄₂ and trimmer capacitors 41 and 42 are mounted.

Although not shown, the ceramic package ₃₀ has a pattern shown in FIGS. An attenuator unit portion _A2 having a circuit configuration substantially similar to that shown in FIG. 6 is formed.

8a, b, and c are exploded perspective views of a programmable attenuator provided with the programmable attenuator main body 1 described in detail above. In the same figure, 70 is a case, and the case 70 has trimmer capacitor adjustment holes 71a to 71 for adjusting the adjustment parts 41a, 42a and 31a, 32a of the trimmer capacitors 41, 42 and 31, 32.
d are formed, and screw holes 72a to 72c are formed on one side for electrical connection with the ground plate 63 fixed to one side of the printed circuit board 10, and screw holes 72a to 72c, which will be described later, are formed on the four corners. Screw holes 73a to 73d (73c, 73c,
73d (not shown) is formed. Furthermore, a coaxial cable input connector 74 for electrical connection to the input terminal section 60 of the printed circuit board 10 is fixed to one side of the case 70.

A lid 80 is fitted and fixed to the lower part of the case 70, and screw holes 81a to 81d are formed at the four corners of the lid 80. Also,
External signal input terminals 61a to 61d of the printed circuit board 10 and power terminal 6 are provided on one side of the lid 80.
A long hole 83 through which the terminals 1e and 61f pass is formed, and an insulating member 82 is attached to one end thereof, and a through hole through which the output terminal 62 passes is formed in the center.

When assembling the programmable attenuator having the above configuration, the printed circuit board 10 is inserted into the case 70 and fixed using fixing means such as screws (not shown). As a result, the ceramic package 40
and a trimmer capacitor 41 mounted on 30,
The adjustment parts 41a, 42a and 31a, 32a of 42, 31, 32 are fixed at positions corresponding to the trimmer capacitor adjustment holes 71a to 71d of the case 70.

Next, the core wire of the connector 74 is connected to the input terminal portion 60 of the printed circuit board 10 using a conductive wire or the like. Next, the screws 90 are passed through the screw holes 72a to 72c, and the ends of the screws are screwed into the screw holes 63a to 63c of the grounding plate 63, so that the grounding plate 63 is fixed as shown in FIG.
and case 70 are electrically connected reliably. At the same time, the grounding pieces 64 and 65 are also pressed against the inner surface of the case 70 with their elastic force to ensure electrical connection.

Next, the lid body 80 is fitted to the lower part of the case 70, and screw holes 73a to 7 formed at the four corners of the case 70 are fitted.
The lid 80 is fixed to the lower part of the case 70 by passing screws through the screws 3d and screwing their tips into the screw holes 81a to 81d formed at the four corners of the lid 80. At this time, the external signal input terminals 61a to 61 of the printed circuit board 10
d and relay power terminals 61e and 61f are connected to the lid body 8.
0 through the elongated hole 83 and led out to the outside, and the output terminal is also led out to the outside through the hole in the center of the insulating member 82. This completes the assembly of the programmable attenuator.

By configuring the programmable attenuator as described above, one ends of the capacitors C ₁ and C ₂ that ground the actuating coils 53l and 54l of the relays 53 and 54 at high frequency are connected to the nearby ground patterns 16 and 17, respectively, and are grounded. pattern, 1
6 and 17 are electrically connected to the case 70 by ground pieces 64 and 65, respectively, so that the operating coils 53l and 54l are connected to the capacitors C ₁ and C ₂ , the short ground patterns 16 and 17, the ground plate 63, and the ground piece. It will be grounded at high frequency through 64 and 65.

[Effect of idea]

As explained above, in the present invention, one end of the operating coil of the relay constituting the switching mechanism is electrically connected to the case via a chip capacitor and a ground pattern, and one end of the operating coil is grounded at high frequency. This has the excellent effect of providing a programmable attenuator with stable frequency characteristics without disturbing the frequency characteristics even in the high frequency range.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the circuit configuration of the programmable attenuator according to the present invention, FIG. 2 is a perspective view showing the main body of the programmable attenuator according to the present invention,
Figure 3 is a view seen from the direction of arrow A in Figure 1, Figure 4 is a view seen from the direction of arrow B in Figure 1, Figure 5 is a view showing the top surface of the printed circuit board, and Figure 6 is the attenuator section. A diagram showing the circuit configuration of unit _A1 , Figure 7a,
8b shows the back and front surfaces of the ceramic package, FIGS. 8a, b, and c are exploded perspective views of the programmable attenuator according to the present invention, and FIG. 9 shows the state in which the ground plate and ground piece are joined to the case. FIG. 3 is a cross-sectional view of a programmable attenuator. In the figure, 1...programmable attenuator main body, 10...printed circuit board, 11 to 14, 16,
17... Earth pattern, 30, 40... Ceramic package, 31, 32, 41, 42... Trimmer capacitor, 31a, 32a, 41a, 4
2a...adjustment section, 51-54...relay, 60...
...Input terminal section, 61a-61d...External relay drive signal input terminal, 61e, 61f...Relay power supply terminal, 62...Output terminal, 63...Earth plate, 6
4, 65...Earth piece, 70...Case, 80...
...Lid body, A ₁ , A ₂ ...Attenuator unit part.

Claims (1)

[Claims for Utility Model Registration] A switching mechanism having a multi-stage attenuator section that attenuates an input signal, a relay that switches the attenuator section, and a relay operating circuit that operates the relay, and the attenuator section and the switching mechanism In a programmable attenuator housed in a conductive case, the relay and various electronic components constituting the relay operating circuit are mounted on a printed circuit board on which a ground pattern is formed, and one end of the operating coil of the relay is connected to a chip capacitor. one end of the chip capacitor, the other end of the chip capacitor is connected to the ground pattern, the ground pattern is electrically connected to the conductive case, and one end of the operating coil of the relay is grounded at high frequency. Programmable attenuator.