JPH0329202B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a distributed constant type electromagnetic delay line, and particularly relates to a distributed constant type electromagnetic delay line.
This invention relates to an electromagnetic delay line suitable for high-frequency signals in the CHZ band or ultrahigh-speed signals with rise times of 100 ps or less.

[Prior art and its problems]

Conventionally, as shown in FIG. 7, this type of electromagnetic delay line has a ground electrode 3 formed on one main surface of a dielectric plate 1, and an elongated microstrip conductive line 5 formed on the opposite main surface. A microstrip line 7 made of the following is well known.

Note that in FIG. 7, the symbol h is the thickness of the dielectric plate 1, and the symbols t and ω are the thickness and width dimensions of the microstrip conductive line 5.

The dimensions of the microstrip line 7 configured in this way are determined by the relative permittivity and thickness of the dielectric plate 1, the width ω and thickness t of the microstrip line 5, and the characteristic impedance Zo. Generally, it is determined by

Therefore, for example, when the specific impedance Zo, the width ω and thickness t of the microstrip conductive line 5, and the relative permittivity of the dielectric plate 1 are determined, the thickness h of the dielectric plate 1 is determined, and the dielectric It is difficult to arbitrarily select the thickness of the plate 1.

Moreover, if this microstrip line 7 is used as it is as an electromagnetic delay line, it is not practical because the length is too long and it is impossible to achieve high density of the electromagnetic delay line.

Under these circumstances, the present applicant applied the above-mentioned microstrip line 7 to create an electromagnetic delay line that is compact and has improved characteristics in patent application No. 58-247506.
It was disclosed under the No.

That is, as shown in FIGS. 8 and 9,
A dielectric layer 11 with a thickness h is provided on the outer periphery of the elongated earth plate 9.
A bent line 13 having a width ω and a thickness t is formed on this dielectric layer 11 in the shape of a single-layer solenoid so as to be folded back at a pitch P to constitute a flat electrode delay line. The distance T and pitch P between the centers of the conducting lines 15 facing each other are 0<T/P.
<1.

FIG. 10 is a diagram explaining the principle of the electromagnetic delay line constructed in this way. For ease of explanation, this figure assumes that the conducting line 15 in FIG. 8 is bent at a pitch P so as to cross at right angles to the axial direction It is a vertical cross-sectional view showing only the conducting path 15 between -X.

In FIG. 10, if the conductive line 15 from which the current flows in the direction of the paper is defined as the forward conductive line 15a, and the conductive line 15 through which the current flows in the direction of the paper is defined as the backward conductive line 15b, then the bent line 13 is in the forward direction. Conductive lines 15a and reverse conductive lines 15b are alternately arranged at pitches P at intervals T.

In other words, the center of the forward conducting path 15a is the first
The center of the reverse conducting path 15b is placed on a second virtual surface V that is spaced apart from the first virtual surface U by a distance T.

The delay characteristics of such an electromagnetic delay line are
5, the positive coupling coefficient K2 between adjacent forward conductive lines 15a (the same applies between reverse conductive lines 15b) and forward conductive lines 15
Negative coupling coefficient −K1 between a and the reverse conducting line 15b
Mainly determined by.

Since the positive coupling coefficient K2 and the negative coupling coefficient -K1 cancel each other out, the delay characteristics can be changed by appropriately selecting the relationship between the magnitudes of the negative coupling coefficient -K1 and the positive coupling coefficient K2. be able to.

Here, from the left, there are two forward conducting paths 15a and one reverse conducting path 15b, a total of three (for convenience, A,
B, C), and if we focus on this and select the ratio of interval T and pitch P to T/P = 0.866, we get
Each of the conducting lines A, B, and C comes to be located at each vertex of the equilateral triangle. In this case, since the distance between conductive lines A and B and between conductive lines A and C are equal, the distance between conductive lines A and C is equal.
The magnitude of the negative coupling coefficient -K1 between conductive lines B and the positive coupling coefficient k2 between conductive lines A and C are equal in magnitude.

Then, the ratio of the interval T and pitch P is T/P>
If it is set to 0.866, the relationship of the coupling coefficient becomes k1<k2,
It can be seen that when T/P<0.866, the relationship between the coupling coefficients is k1>K2, and by appropriately selecting the ratio T/P between the interval T and the pitch P, a negative coupling coefficient -k1 can be obtained.
Since the relationship between the magnitude of the positive coupling coefficient k2 and the magnitude of the positive coupling coefficient k2 can be appropriately selected, an ultrahigh-speed electromagnetic delay line having desired delay characteristics can be easily constructed.

However, in such an electromagnetic delay line, if higher density and smaller size are realized while maintaining performance, the following problems arise.

In other words, if the pitch P of the microstrip line 13 is reduced to increase the density while keeping the width ω of the conducting line 15 the same, the thickness h of the dielectric layer 11 must be increased in order to maintain the same delay characteristics. Reduce the interval T
It becomes necessary to make it smaller.

However, as explained with reference to FIG. 7, in order to maintain the same characteristic impedance and reduce the thickness h of the dielectric layer 11, the width ω of the conducting path 15 is
If the width ω of the conductive line 15 becomes smaller, the loss of the conductive line 15 increases and the characteristics deteriorate.

[Purpose of the invention]

The present invention was made under these circumstances, and it is possible to reduce the pitch P while keeping the width ω of the conducting path large, and to reduce the thickness h and T of the dielectric layer without affecting the characteristic impedance. The aim is to provide an ultra-compact, high-density, low-loss, ultra-high-speed electromagnetic delay line that enables high density.

[Structure and effects of the invention]

In order to achieve this object, the present invention forms a dielectric layer on the outer periphery of a grounding plate, and a microstrip conductive line is formed on this dielectric layer in the shape of a single layer solenoid so as to be folded back at a pitch P. In an electromagnetic delay line, the distance T between the centers of the microstrip conducting lines facing each other across the main surface of the ground plate and the pitch P thereof are set in the range 0<T/P<1, and the ground A conductor-removed portion is formed at least in a portion of the plate that faces and overlaps the microstrip conductive line.

According to the configuration of the present invention, the inductance of the microstrip conductive line increases due to the partial conductor removed portion being formed in the ground electrode, resulting in a lack of capacitance. The deficit can be made up by making the dielectric layer thinner, so by reducing the thickness of the dielectric layer and reducing the pitch of the conductor lines while keeping the width of the microstrip conductor line large, The distance T and pitch P of the microstrip conductor lines are 0<T/P<
This makes it possible to reduce the size, increase the density, and reduce the loss.

[Embodiments of the invention]

The details of the present invention will be explained below.

First, the principle of the present invention will be explained with reference to FIG. For convenience, a microstrip line is shown as an example.

In the figure, a flat and elongated dielectric plate 1 with a thickness h
A ground electrode 19 with a thickness t is formed on the entire surface of one main surface (upper surface in the figure) of 7, and a ground electrode 19 with a thickness ω is formed on the opposite main surface (lower surface in the figure) so as to face the ground electrode 19.
An elongated microstrip conductive line 21 is formed.

The shape of this microstrip conductive line 21 is similar to the microstrip conductive line 5 in FIG.

In the portion of the ground electrode 19 that overlaps and faces the microstrip conductive line 21,
A plurality of rectangular conductor removal portions 23 are formed in parallel along the microstrip conductive line 21 at a pitch d,
A microstrip line 25 is configured.

The conductor removal part 23 is located on a side a (hereinafter referred to as side a) in the same direction as the longitudinal direction of the microstrip conductive line 21.
and a side b (hereinafter referred to as side b) in the same direction as the width ω, and the dielectric plate 17 is exposed at the conductor removal portion 23.

Next, the microstrip line 25 configured in this manner will be considered.

FIG. 5 is a diagram showing changes in the characteristics of the microstrip line 25 shown in FIG. A ground electrode 19 is formed on the upper surface, and a thickness t=
Using a sample with a length of 100 mm on which a microstrip conductive line 21 of 0.035 mm and width ω = 3.5 mm was formed, the pitch d between the conductor removed parts 23 was set to 2.5 mm, the side b was set to 3.5 mm, and the side a was The values of the characteristic impedance Zo and propagation delay time td of the microstrip line 25 are measured when the microstrip line 25 is varied (indicated by a/d for convenience).

According to this, when a/d=0, that is, a configuration similar to the conventional microstrip line 7 shown in FIG. 7, the characteristic impedance Zo=33Ω and the propagation delay time td=0.5 ns. When a/d is increased, the inductance of the microstrip conductive line 21 initially increases more than the rate of decrease in capacitance caused by the decrease in the area of the ground electrode 19 facing the microstrip conductive line 21. The rate of increase increases, and both the characteristic impedance Zo and the propagation delay time td increase.

Furthermore, as a/d increases, the capacitance continues to decrease, but the rate of increase in inductance decreases, so while the characteristic impedance Zo continues to increase, the propagation delay time td increases from a maximum value of about 0.59 ns. On the contrary, it decreases.

Then, a/d=1, that is, the earth electrode 19
When the part overlapping and facing the microstrip conductive line 21 is continuously removed, the characteristic impedance Zo=61.9Ω and the propagation delay time td=
The propagation delay time td becomes 0.43 ns, and the propagation delay time td is conversely reduced compared to the case where a/d=0. Regarding these, from the conventional concept regarding the relative permittivity of the dielectric plate and the propagation delay time, this corresponds to an equivalent increase or decrease in the relative permittivity of the fluororesin in the range of 1.66 to 3.13.

Also, the rise time as an electromagnetic delay line is
Although it tends to be slightly larger than when a/d = 0, it is 100 ps over the entire a/d change range.
Ultra high speed with a value smaller than .

Figure 6 uses the same microstrip line 25 as in Figure 4 above, and the pitch d is also 2.5mm.
When side a of the conductor removed part 23 is kept constant at 0.25 mm and side b of the conductor removed part 23 is changed (denoted as b/ω for convenience), the characteristic impedance Zo and propagation delay time td are also This is a measurement of change.

According to this, if side a of the conductor removed part 23 is kept small and side b is lengthened to make the shape of the conductor removed part 23 elongated, the rate of increase in inductance is greater than the rate of decrease in capacitance. , the increase rate of characteristic impedance Zo and propagation delay time td
The rate of increase of can be made to follow the same trend.

Note that in this case as well, an ultra-fast rise time of less than 100 ps can be obtained.

What can be seen from these figures 5 and 6 is that
The characteristics when the ground electrode 19 is partially removed, including the portion facing the microstrip conductive line 21 so as to overlap with it, are simply the conductor removed portion 23.
The propagation delay time td per unit length and characteristics of the microstrip line 25 are influenced by not only the area but also its shape and dimensions. It is possible to change impedance Zo, etc.

As a result, if a conductor removed portion 23 is formed in the ground electrode 19 of the microstrip line 25 and the shape and dimensions of this conductor removed portion 23 are appropriately changed, the characteristic impedance, which has been uniquely determined in the past, can be changed. It becomes possible to change Zo and propagation delay time td.

Therefore, the width ω of the microstrip conductive line 21
Even if the thickness h of the dielectric plate 17 is reduced without reducing , it is possible not only to obtain the desired characteristic impedance Zo but also to increase the propagation delay time td.

Next, examples of the electromagnetic delay line according to the present invention will be described based on such consideration.

1 and 2 are a front view and a side view showing an embodiment of the electromagnetic delay line of the present invention.

In both figures, a thin rectangular earth plate 27 is shown.
, a plurality of elongated conductor removal portions 29 having a width a and a length b' are formed in parallel at a pitch d along its longitudinal direction. That is, the ground plate 27 has a blind shape in which both longitudinal ends are connected.

A dielectric layer 31 is formed on the outer periphery of the ground plate 27, and both ends of the ground plate 27 protrude.

On the outer periphery of the dielectric layer 31, a microstrip conductive line 33 having a width ω and a thickness t is space-wound at a pitch P in the shape of a single layer solenoid, thereby forming an electromagnetic delay line.

In addition, in the figure, the symbol h indicates the thickness of the dielectric layer 31 on one side of the grounding plate 27, and the symbol T indicates the thickness of the dielectric layer 31 on one side of the grounding plate 27.
This is the distance between the centers of the microstrip conductive lines 33 that face each other across the main surface.

The pitch P of the microstrip conductive line 33 and the center distance T of the microstrip conductive line 33 facing each other with the ground plate 27 in between are determined as 0<T/ P
It is preferable to select in the range <1.

In the electromagnetic delay line configured in this way, as described above, the conductor removal portion 29 is partially formed in the portion of the ground plate 27 that overlaps with the microstrip conductive line 33. The inductance of the dielectric layer 31 increases, and it is necessary to increase the capacitance by that increase to maintain the same characteristic impedance. However, since the area of the conductor that forms the capacitance is reduced, The necessary capacitance can be obtained by making the thickness h sufficiently thin.

That is, since the thickness h of the dielectric layer 31 can be made sufficiently thin, the pitch P and the interval T of the microstrip conductive lines 33 can be made small.

Therefore, as mentioned above, the pitch P and the interval T
In addition to improving the characteristics by setting the relationship between And high density becomes possible.

Furthermore, the width ω of the microstrip conductive line 33
Since the propagation delay time td per unit length increases while keeping the same value, the loss per unit delay time decreases while achieving ultra-miniaturization, so that higher performance can be achieved.

The shape of the conductor removed portion 29 formed on the ground electrode 27 is not limited to the rectangular shape shown in FIG. 1 described above, but may be a circular conductor removed portion 35 as shown in FIG. It may be rectangular or the like. Further, the dimensions and mutual spacing do not need to be uniform, and may be selected according to the intended dimensions and characteristics.

The point is that at least the part of the grounding plate 27 that faces and overlaps the microstrip conductive line 33 has a structure that can change the inductance of the microstrip conductive line and the capacitance generated between the conductive line and the earth electrode. The object of the present invention can be achieved by partially forming the conductor removal portion depending on the shape and size.

Note that in conventional distributed constant type electromagnetic delay lines used at frequencies far lower than 1 GHZ, for example, 10 MHz or less, the ground electrode is divided in order to reduce eddy current loss.

However, in this type of electromagnetic delay line, the divided earth electrodes are connected to each other only at one end and the other end is open, and does not form a closed circuit against eddy currents.

In contrast, in the electromagnetic delay line of the present invention, as shown in Fig. 1, for example, divided ground plates are connected to each other at both ends, and ultra-high-speed signals are generated using the ground return line as the shortest distance on each of the input and output sides. It is based on a different concept from the conventional method of dividing the ground electrode for ultra-high-speed signals, and achieves different effects, such as making it possible to obtain good impedance characteristics for ultra-high-speed signals.

As explained above, in the electromagnetic delay line of the present invention, a microstrip conductive line is formed in the shape of a flat single-layer solenoid with pitch P on a dielectric layer formed on the outer periphery of a ground plate, and the main surface of the ground plate is The distance T and the pitch P between the microstrip conductive lines facing each other are set in the range of 0<T/P<1, and a conductor removed part is formed on the ground plate. Since the dielectric layer is placed opposite to the conductive line so as to overlap with it, the thickness of the dielectric layer can be reduced while maintaining the width of the microstrip conductive line, and the pitch of the conductive line can also be reduced.

Therefore, the distance T between the microstrip conductive lines is
and pitch P can be kept within the range of 0<T/P<1, making it possible to achieve smaller size, higher density, and lower loss.

[Brief explanation of drawings]

1 and 2 are front and side views showing one embodiment of the electromagnetic delay line according to the present invention, and FIG.
FIG. 4 is a partial perspective view showing an electromagnetic delay line for explaining the principle of the present invention; FIGS. 5 and 6 are shown in FIG. 4. A diagram showing an example of changes in characteristics in an electromagnetic delay line,
FIG. 7 is a partial perspective view showing a conventional electromagnetic delay line, FIGS. 8 and 9 are front and side views showing an electromagnetic delay line that serves as a reference for the present invention, and FIG. 10 is the electromagnetic delay line shown in FIG. It is a partial sectional view explaining a line. 1, 11, 17, 31... Dielectric layer (dielectric plate), 3, 9, 19, 27... Earth plate (earth electrode), 5, 21, 33... Conductive line (microstrip conductive line) ), 7, 25... Microstrip line, 13... Bent line, 15... Conductive line, 23, 29, 35... Conductor removal section.

Claims (1)

[Scope of Claims] 1. A flat electromagnetic delay line in which a dielectric layer is formed on the outer periphery of a grounding plate, and a microstrip conductive line is formed on this dielectric layer in the form of a single-layer solenoid so as to be folded back at a pitch P. In this case, the distance T between the centers of the microstrip conductive lines facing each other across the main surface of the ground plate and the pitch P are set in a range of 0<T/P<1, and An electromagnetic delay line characterized in that a conductor removed portion is partially formed at least in a portion facing and overlapping the microstrip conductive line.