JPH0323692Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial field of application] The present invention relates to a variable delay line using an electromagnetic delay line element consisting of an inductance element and a capacitor, and is particularly concerned with obtaining good characteristics in ultra-high-speed digital circuits. This invention relates to an easy improvement of a variable delay line.

[Conventional technology]

Conventionally, this type of variable delay line has a configuration as shown in FIG.

In other words, an inductance element 1 wound with a conductor
A capacitor C between each predetermined turn of
A delay line element 5 is configured in which each connection point between the inductance element 1 and the capacitor C is a fixed contact 3, and a connecting conductor 9 is arranged from the input terminal 7 along the fixed contact 3. A movable contact 1 moves by alternately repeating single contact with one fixed contact 3 (indicated by a broken line) and double contact with an adjacent fixed contact 3 (indicated by a solid line) while contacting the
1.

In the figure, numeral 13 is an output terminal, and numeral 15 is a ground terminal.

The variable delay line configured in this manner has a fast rise characteristic of 1 ns or less even in an ultra-high frequency band, and the delay time can also be finely switched.

However, since the connecting conductor 9 that contacts the movable contact 11 that switches the fixed contact 3 is arranged along the fixed contact 3, in other words, along the inductance element 1, the inductance element 1 and the connecting conductor 9
Stray capacitance Cs is likely to be formed between the two. Stray capacitance Cs
are shown collectively at the right end in FIG. 6, but actually exist over the entire length of the connecting conductor 9.

And when the value of this stray capacitance Cs increases,
The output pulse waveform from the variable delay line is distorted, the rise is delayed, etc., and the delay characteristics are deteriorated.

The solid line a in FIG. 7 is an output pulse response waveform diagram originally inherent in a delay line, and the broken line b in the same figure is an output pulse response in which the rise characteristics are deteriorated due to the influence of stray capacitance Cs when a variable delay line is configured. FIG.

Note that the influence of the stray capacitance Cs on the delay characteristics in the variable delay line increases as the delay time is adjusted to increase, that is, in the above configuration, the farther the movable contact 11 is moved from the output terminal 13.

[Problem that the invention attempts to solve]

The present invention has been made to solve these conventional drawbacks, and aims to provide a variable delay line that can suppress the value of stray capacitance to a small value and provide a good output waveform.

[Means for solving problems]

In order to solve this problem, the present invention forms a delay line element consisting of an inductance element and a capacitor in an annular shape, and includes a connecting conductor and a shielding member facing along the connecting conductor with an insulator interposed therebetween. A connecting member having a shielding member located between a connecting conductor and its delay line element is disposed inside the delay line element, and a switching means connected to the connecting conductor and rotating around the connecting conductor is used to control the inductance element. It is made by switching fixed contacts formed on a conductor.

[Effect]

According to the configuration of the present invention, since the shield member is interposed between the connecting conductor and the inductance element, the shield member suppresses the stray capacitance generated between the connecting conductor and the inductance element to an extremely small value.

Furthermore, the connecting member functions as an impedance line having a predetermined impedance, and the impedance can be easily changed by appropriately selecting the dielectric constants of the connecting conductor, the shielding member, and the insulator therebetween.

〔Example〕

Examples of the present invention will be described below.

FIGS. 1 and 2 are a plan view and a front view (each partially shown in section) showing an embodiment of a variable delay line according to the present invention.

In both figures, a rectangular base 1 made of an insulator is shown.
Input/output terminals 19, 21 and a ground terminal 23 are implanted at the four corners of 7. The output terminal 21 and the ground terminal 23 are installed so as to penetrate the base 17, and only the input terminal 19 is bent in the middle of the base 17 and extends laterally through the base 17. The connecting conductor 2 passes through the pillar 27 that is integrally erected from the
5 and extends to the upper end surface of the protrusion 27.

Shield plates 29 and 31 as shield members are formed on both upper and lower surfaces of the base 17. The shield plate 31 on the upper surface side extends in a tubular shape around the outer periphery of the protrusion 27, and as shown in the cross-sectional view of FIG. 3A,
A coaxial type impedance line having a predetermined impedance is formed by opposing the connecting conductor 25 via a protrusion 27 serving as an insulator. These connecting conductors 25, pillars 27 and shield plates 31
serves as the connecting member 33.

Note that the impedance of the impedance line is preferably selected to be the impedance (R ₀ /2) of an external circuit connected to the input terminal 19, for example, the pulse generator PG shown in FIG.

On the upper surface side of the base 17, a ground electrode 37 is formed on one main surface (lower surface in the figure) of a flat donut-shaped dielectric plate 35, and a capacitance is formed at a predetermined pitch on the opposite main surface (upper surface in the figure). A composite capacitor 41 formed of a plurality of electrodes 39 is fitted onto the outer periphery of the connecting member 33 with some play, and the shield plate 31 and the earth electrode 37 are connected.

On the upper side of the composite capacitor 41, an inductance element 47 in which a conductor 45 is space-wound in a single layer solenoid shape at the same pitch as the capacitor electrode 39 is fitted with some play around a toroidal bobbin 43.
The conductor 45 and the capacitive electrode 39 are connected to form a lumped constant electromagnetic delay line element 49. One lead 51 of the inductance element 47 is connected to the output terminal 21, and the other lead (not shown)
is connected to an internal termination resistor (see Figure 6).

Above the inductance element 47 is a rotating plate 53.
A movable contact 55 is attached to the lower surface of the rotary plate 53, and the rotary plate 53 and the movable contact 55 form a switching means.

This movable contact 55 elastically contacts the connecting conductor 25 at the tip of the connecting member 33, and rotates around the connecting conductor 25 as the rotary plate 53 rotates, and connects the upper end surface side conductor 45 of the inductance element 47. We are starting to come into contact with people. That is, each conductor 45 on the upper end surface side of the inductance element 47 serves as a fixed contact 57, and the movable contact 55 slides on a fixed contact row 59 formed in an annular shape by the fixed contacts 57. Reference numeral 61 is an adjustment driver groove formed in this rotary plate 53.

The movable contact 55 is designed to make only a single contact with one fixed contact 57 depending on the purpose, or to make a single contact with one fixed contact 57 and an adjacent fixed contact 5.
It can be configured so that multiple contacts with 7 are made alternately.

These bases 17 and inductance elements 4
7 and the rotating plate 53 are housed in a housing 63 made of synthetic resin or the like, and the input/output terminals 19 and 21 and the ground terminal 23 protrude from the housing 63.

In the figure, reference numeral 65 is a ring-shaped rubber gasket press-fitted between the rotary plate 53 and the housing 63, which ensures airtightness between the rotary plate 53 and the housing 63, and is used to secure variable delay lines and other electronic components. This prevents the cleaning liquid from entering the inside of the casing 63 when the printed circuit board on which it is mounted is immersed in the cleaning liquid.

The circuit configuration of the delay line element 47 of the present invention is substantially the same as that of FIG. 6 described above.

In the variable delay line configured in this way,
When the tip of a screwdriver is inserted into the adjusting screwdriver groove 61 of the rotary plate 53 and rotated, the movable contact 5
5 rotates around the end face of the connecting conductor 25, and the connecting conductor 25 is switched to any fixed contact 57 in the fixed contact row 59 of the inductance element 47. In addition, when the connecting conductor 25 is thin, it is preferable to form the end face part wide so as to ensure reliable contact with the movable contact 55.

In implementing the present invention, the configuration of the connecting member 33 is not limited to the coaxial type configuration shown in FIG. 3A described above, but as shown in FIG. Connecting conductor 2 via protrusion 27
A stripline type configuration with 5 in between is also possible.

Furthermore, a microstrip line type configuration in which the connecting conductor 25 and the shield plate 31 are opposed to each other via the protrusion 27 as shown in FIG. 2C is also possible. Of course, an insulator such as air may be used between the connecting conductor 25 and the shield plate 31, and although the protruding pillar 27 protrudes from the substrate 17 in the above embodiment, it may be formed according to the specific configuration. It doesn't necessarily have to be something that stands out.

In the above-described embodiment, the line from the input terminal 19 to the movable contact 55 is of a strip line type in the base 17, and is of a coaxial type at the connecting member 33. However, in the present invention, any combination of the connecting members 33 shown in FIG. 3 is possible.

By the way, when the connecting member 33 is constituted by a microstrip line, stray capacitance is likely to be formed between the connecting member 33 and the conductor 45 on the side where the shield plate 31 is not arranged.

However, in this case, the shield plate 31 is connected to the output terminal 2.
By placing the shield plate 31 on the side of the conductor 45 that is close to R0, and directing the side where the shield plate 31 is not placed toward the conductor 45 that is close to the built-in terminating resistor _R0 , even if stray capacitance is formed, the effect on the output pulse waveform can be minimized. It is possible to keep it extremely small.

The reason for this is that when the movable contact 55 is located at a position where the delay time is large, the waveform deteriorates greatly due to its stray capacitance, but this occurs at a position far from the output terminal 13 in Figure 6 (a position corresponding to the left side in the figure). ), and in this case, if the stray capacitance is also on the left side in the figure, the signal current will pass through the movable contact 55 instead of passing through the stray capacitance, and the influence of the stray capacitance will be reduced. It is from.

4 and 5 show another embodiment of the variable delay line of the present invention, which uses a distributed constant type electromagnetic delay line element.

That is, the delay line element 67 includes an inductance element 73 formed by space-wounding a conductor 71 in a single-layer solenoid shape around a toroidal bobbin 69, and an outer periphery of the inductance element 73, leaving an upper end surface of the inductance element 73. It has a ground electrode 77 provided through a dielectric material 75, and is formed in a donut shape.

This delay line element 67 is fitted around the outer periphery of the connecting member 33, and the ground electrode 77 and the shield plate 31 are connected. Note that one end of the inductance element 73 is led out through the dielectric 75 and is connected to the output terminal 2.
1 and the other end is terminated.

In this variable delay line as well, since the ground electrode 77 is interposed between the inductance element 73 and the connection conductor 25 as a shield member, stray capacitance can be kept small. Further, the inner portion of the ground electrode 77 faces the connecting conductor 25 via the protrusion 27 and constitutes a coaxial type impedance line having a predetermined impedance. It is preferable to select the impedance of the generator PG (R ₀ /2) or the like.

In this embodiment, the ground electrode 77 is used as a shield member, and the inner part of the ground electrode 77 is also used as a component of an impedance line.
However, a separate shield member may be arranged between the connecting conductors 25. In this case, a delay line element may be constructed by arranging a ground electrode within the bobbin 69 in which the inductance element 73 is formed.

Further, the inductance element is not limited to being formed in the shape of a single-layer solenoid, but may be formed in an arbitrary manner such as folded back in a zigzag shape, and the delay line element may be formed in an annular shape. However, it is not necessary to form it into a perfect ring.

[Effect of idea]

As explained above, in the variable delay line of the present invention, the connecting conductor extending from the input terminal is placed facing the inductance element, but since there is a shielding member in between, there is a stray capacitance generated between the connecting conductor and the inductance element. It is easy to reduce the value of Cs to an extremely small value, and deterioration of characteristics can be prevented.

Furthermore, since the connecting member and the shielding member constitute an impedance line, good impedance matching with an external circuit is facilitated.

Furthermore, since switching of the delay time is achieved by a movable contact that rotates around the connecting conductor of the connecting member, the structure can also be miniaturized.

[Brief explanation of the drawing]

1 and 2 are a plan view and a front view (both partially shown in section) showing one embodiment of the variable delay line of the present invention, and FIGS. 3A to 3C are implementations of the connecting member in FIG. 1. A cross-sectional view showing an example; FIGS. 4 and 5 are a plan view and a front view (both partially shown in section) showing other embodiments of the variable delay line of the present invention;
FIG. 6 is a circuit diagram showing a conventional variable delay line, and FIG. 7 is an output pulse response waveform diagram of the variable delay line shown in FIG. 1, 47, 73...Inductance element, 3,
57...Fixed contact, 5,49,67...Delay line element, 9,25...Connection conductor, 11,55...Switching means (movable contact), 17...Base, 27...Insulator (protrusion) Pillar), 29, 31... Shield member (shield plate), 33... Connection member, 41... Composite capacitor, 45, 71... Conductor, 53... Switching means (rotating plate), 59... Fixed contact row , 63... housing,
77... Shield member (earth electrode), C... Capacitor, Cs... Stray capacitance.

Claims (1)

[Claims for Utility Model Registration] (1) A delay line element formed in an annular shape including an inductance element and a capacitor, a connecting conductor, and a shielding member facing the connecting conductor with an insulator interposed therebetween, a connecting member having a shielding member located between the connecting conductor and the delay line element and disposed inside the delay line element; A variable delay line comprising: switching means for switching fixed contacts formed on a conductor; (2) Utility model registration claim 1, in which the connecting member is a tubular shielding member with a connecting conductor disposed inside it.
Variable delay line as described in section. (3) Utility model registration claim No. 1 in which the connecting member is formed by disposing a connecting conductor between opposing shield plates.
Variable delay line as described in section. (4) The variable delay line according to claim 1, in which the connecting member comprises a shield plate and a connecting conductor arranged opposite each other.