JPH0522193A - Electric signal transmission line - Google Patents

Abstract

PURPOSE:To reduce the electric charge stored in the floating capacity of an electric signal transmission line to suppress the amplitude attenuation and to eliminate a need of a conventional resistance for impedance matching. CONSTITUTION:A first outer core 13 is covered with a second insulator 14, and the second insulator 14 is covered with a second outer core 15, and the second outer core 15 is earthed, and the non-inverted input terminal of a broad band buffer 16 is connected to an inner core 11, and the inverted input terminal and the output terminal are connected to the first outer core 13. Consequently, the electric charge stored in the floating capacity between the inner core 11 and the first outer core 13 is reduced to suppress amplitude attenuation, reflection, or the like, and the conventional resistance for impedance matching is unnecessary.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric signal transmission line for transmitting an analog signal or a digital signal in electric equipment.

[0002]

2. Description of the Related Art FIG. 6 is a schematic view of a conventional electric signal transmission line.

In FIG. 6, reference numerals 1 and 2 respectively denote an input terminal and an output terminal for an electric signal, 3 an inner core whose both ends are connected to the input terminal 1 and the output terminal 2, and 4 an insulator covering the inner core. Reference numeral 5 is an outer core that covers the insulator 4 and is grounded, and 6 is a resistor provided between the inner core and the ground.

When an electric signal is input from the input terminal 1, the electric signal is output from the output terminal 2 through the inner core 3. At this time, the inner core 3, the insulator 4 and the outer core 5 cause When the characteristic impedance of the formed single coaxial cable is Z ₀ and the impedance of the resistor 6 is R _L , impedance matching is usually performed so as to satisfy the relationship of R _L = Z ₀ in order to control reflection.

The characteristic impedance Z ₀ is established only when the electric signal has an infinite frequency, and actually depends on the frequency.

[0006]

Since the conventional electric signal transmission line is configured as described above, the resistor 6 is required to match the characteristic impedance Z ₀ ,
Moreover, since the characteristic impedance is intended for infinite frequencies, there is a problem that frequency dependence actually occurs, and the stray capacitance due to the line causes amplitude attenuation and reflection of electric signals.

The present invention has been made in order to solve the above-mentioned problems, and reduces the charge accumulated in the stray capacitance of the electric signal transmission line to control the amplitude attenuation, and moreover, as in the conventional case. The purpose is to eliminate the need for a resistor for impedance matching.

[0008]

An electric signal transmission line according to the present invention includes an inner core for transmitting an electric signal, a first insulator covering the inner core, and the first insulator. A first outer core, a second insulator covering the first outer core, and the second
A second outer core covered with an insulator and grounded; and a wideband buffer having a non-inverting input terminal connected to the inner core and an inverting input terminal and an output terminal connected to the first outer core. It has a feature.

[0009]

In the present invention, the inner core, the first insulator and the first outer core are further provided with the second insulator and the second outer core which is grounded, and the non-inverting input terminal is connected to the inner core to provide the inverting input. Since the wide band buffer having the terminals and the output terminals connected to the first outer core is provided, the wide band buffer causes the first outer core to have a low impedance, and the charge accumulated in the stray capacitance between the inner core and the first outer core is reduced. It is reduced and amplitude attenuation and reflection are suppressed,
Moreover, the conventional resistance for impedance matching becomes unnecessary.

[0010]

1 is a schematic view of a first embodiment of an electric signal transmission line according to the present invention.

In FIG. 1, 11 is an inner core whose both ends are connected to the input terminal 1 and the output terminal 2, 12 is a first insulator covering the inner core, and 13 is a first insulator covering the first insulator 12. 1 outer core, 14 is a second insulator that covers the first outer core 13, 15 is a second outer core that covers the second insulator 14 and is grounded, and 15 is a wideband buffer having a voltage follower configuration, The non-inverting input terminal is provided on the input terminal 1 side, is connected to the inner core 11, and the inverting input terminal and the output terminal are connected to the first outer core 13.

By the way, FIG. 2 is a diagram schematically showing a cross section of a part of the electric signal transmission line shown in FIG. 1, and C _B is a stray capacitance between the inner core 11 and the first outer core 13, It is a stray capacitance between C _c and the first outer core 13 and the second outer core 15.

Next, the operation will be described.

Now, when an electric signal is inputted from the input terminal 1, the electric signal is pressured from the output terminal 2 through the inner core 11. At this time, the point P ₁ on the inner core 11 shown in FIG. When a potential difference is generated between the point P ₂ on the first outer core 13 and the stray capacitance C _B between the inner core 11 and the first outer core 13 is charged, or the stray capacitance C _B is discharged, Inner core 11 transiently
Although affect the voltage of the electrical signal flowing through the, to prevent this, it is sufficient and the inner core 11 the voltage variation of the electrical signals of the first outer core 13 in the same by wideband buffer 16, thereby P ₁ point , P ₂ point does not have a potential difference, so that the voltage of the electric signal is hardly affected.

In the configuration shown in FIG. 1, the stray capacitance C _c between the first outer core 13 and the grounded second outer core 15 accumulates charges or discharges the stray capacitance C _c . Since the first outer core 13 is connected to the output terminal of the wide band buffer 16, the first outer core 13 has a low impedance, and as a result, no potential difference occurs between the points P ₁ and P _2. , The influence of the electric signal on the voltage is suppressed.

By the way, the operation described above, B the bandwidth of the wideband buffer 16, when the frequency of the input signal and f _in, is satisfied when satisfying the relationship of B >> 2f _in.

Therefore, by connecting the non-inverting input terminal of the wideband buffer 16 to the inner core 11 and connecting the inverting input terminal and the output terminal to the first outer core 13, the wideband buffer 1
6, the first outer core 13 has a low impedance,
The charges accumulated in the stray capacitance C _B between the inner core 11 and the first outer core 13 can be reduced, amplitude attenuation, reflection, etc. can be suppressed, and moreover, because of impedance matching as in the conventional case. No need for resistance.

FIG. 3 is a schematic diagram of a second embodiment of the present invention.

In FIG. 3, the same reference numerals in FIG. 1 denote the same or corresponding parts, and the difference from FIG.
A wideband buffer 16 is provided between the output side of the inner core 11 and the output terminal 2, the output terminal of the wideband buffer 16 is connected to the output terminal 2, the non-inverting input terminal is connected to the inner core 11, and the inverting input terminal and That is, the output terminal is connected to the first outer core 13.

When an electric signal of a minute voltage is input from the input terminal 1, the wide band buffer 1 passes through the inner core 11.
An electrical signal is input to the non-inverting input terminal of 6, but the electrical signal input to the non-inverting input terminal is converted into a low-impedance signal with a gain of 1 by the wideband buffer 16 and transmitted to the output terminal 2. , The inner core 11 and the first outer core 13 do not have a potential difference, and the charge accumulated in the stray capacitance C _B is reduced.

At this time, the bandwidth B of the wideband buffer 16
And the input signal frequency f _in satisfy B >> 2f _in .

Therefore, the wide band buffer 16 is connected to the output terminal 2
Even if it is provided on the side, the same effect as that of the first embodiment can be obtained.

Next, FIG. 4 is a schematic diagram of a third embodiment in which the present invention is applied to a semiconductor evaluation apparatus. In FIG. 4, the same reference numerals in FIG. 1 denote the same or corresponding parts.

As shown in FIG. 4, the DU produced by the user
T [Device Under Test] board 17
Includes an inner core 11, a first insulator 12, a first outer core 13, and a second
A line made up of the insulator 14 and the second outer core 15 is provided, a wideband buffer 19 for the driver 18 is provided, and an output terminal of the driver 18 is connected to the inner core 11.
The non-inverting input terminal of the wide band buffer 19 is connected to the inner core 11, the inverting input terminal and the output terminal of the wide band buffer 19 are connected to the first outer core 13 via the relay 20, and the input terminal of the comparator 21 is further connected to the inner core. A relay 22 is provided that is connected to the connection node 11 and connects the non-inverting input terminal of the wideband buffer 19 to the inner core 11 and the connection point to the inner core 11 of the comparator 21. Here, the second outer core 15 is grounded in the DUT board 17.

The pin-ele board 23 in the evaluation device has an inner core 11, a first insulator 12, a first outer core 13, a second insulator 14, and a second outer core 15 as in the DUT board 17. Is provided, a wideband buffer 24 for the comparator 21 is provided, the inner core 11 is connected to the input / output terminal 25, the non-inverting input terminal of the wideband buffer 24 is connected to the inner core 11, The inverting input terminal and the output terminal of the buffer 24 are connected via the relay 26 to the first outer core 13
Is connected to the second outer core 1 inside the pin eleboard 23.
5 is grounded.

The DUT board 17 and the pin-eleboard 23 are connected by the double coaxial Bogo pin ring 27.

Next, the operation will be described.

When an electric signal is output from the driver 18, the relays 20 and 22 are closed, the relay 26 is opened, and the electric signal input from the driver 18 is transmitted through the inner core 11 to the input / output terminal 25. It

At this time, since the same electric signal as that of the low-impedance inner core 11 is transmitted to the first outer core 13 by the driver broadband buffer 19, a potential difference is generated between the inner core 11 and the first outer core 13. It never happens. On the other hand, when the electric signal is taken in by the comparator 21, the relay 2
0 and 22 open, the relay 26 closes, and the electric signal input from the input / output terminal 25 is transmitted through the inner core 11 and input to the comparator 21.

At this time, since the same electric signal as that of the low-impedance inner core 11 is transmitted to the first outer core 13 by the comparator wide-band buffer 24, the space between the inner core 11 and the first outer core 13 is increased. There is no potential difference.

By the way, also in this case, the wideband buffer 19
And the relationship between the bandwidth B of 24 and the input signal frequency f _in is
B >> 2f _in is satisfied.

Therefore, as in the first embodiment, the amplitude attenuation and reflection of the electric signal can be suppressed, and the resistor is not required. Therefore, when applied to the semiconductor evaluation apparatus, highly accurate evaluation can be performed. Therefore, reliability can be improved.

Further, FIG. 5 is a schematic view of a fourth embodiment of the present invention. In FIG. 5, the same reference numerals in FIG. 4 denote the same or corresponding parts, and the wideband buffer 24 and the relay 26 in FIG. And remove relay 2
0 and 22 are also removed and these relays 20 and 22 are directly connected.

When the electric signal is output from the driver 18, the electric signal is transmitted to the input / output terminal 25 via the inner core 11, and at this time, the wide band buffer 1 is applied to the first outer core 13.
Since the same electric signal as that of the low-impedance inner core 11 is transmitted by 9, there is no potential difference between the inner core 11 and the first outer core 13.

When the electric signal is taken in by the comparator 21, the electric signal inputted from the input / output terminal 25 is inputted to the comparator 21 through the inner core 11, and at this time, the wide band buffer 19 is arranged in the first outer core 13. Since the same electric signal as that of the low-impedance inner core 11 is transmitted, there is no potential difference between the inner core 11 and the first outer core 13.

By the way, also in this case, the wideband buffer 19
The relationship between the bandwidth B of B and the input signal frequency f _in is B >> 2f
meets _in .

As described above, the structure shown in FIG.
It is possible to obtain the same effect as that of the fourth embodiment.

[0038]

As described above, according to the electric signal transmission line of the present invention, the second insulator is provided by covering the first outer core,
Since the second outer core that covers the second insulator and is grounded is provided and the non-inverting input terminal of the wideband buffer is connected to the inner core and the inverting input terminal and the output terminal are connected to the first outer core, the wideband buffer As a result, the first outer core has a low impedance, the charges accumulated in the stray capacitance between the inner core and the first outer core can be reduced, and the amplitude attenuation and reflection can be suppressed,
Moreover, the conventional resistance for impedance matching becomes unnecessary, and it is suitable as an electric signal transmission line for electronic equipment.

[Brief description of drawings]

FIG. 1 is a schematic view of a first embodiment of an electric signal transmission line according to the present invention.

FIG. 2 is a schematic diagram in which a part of FIG. 1 is cut.

FIG. 3 is a schematic diagram of a second embodiment of the present invention.

FIG. 4 is a schematic diagram of a third embodiment of the present invention.

FIG. 5 is a schematic view of a fourth embodiment of the present invention.

FIG. 6 is a schematic view of a conventional electric signal transmission line.

[Explanation of symbols]

 11 Inner Core 12 First Insulator 13 First Outer Core 14 Second Insulator 15 Second Outer Core 16, 19, 24 Wideband Buffer

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[Procedure amendment]

[Submission date] November 20, 1991

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0014

[Correction method] Change

[Correction content]

[0014] Now, when an electrical signal is inputted from the input terminal 1, the electric signal from the output terminal 2 through the inner core 11 is output, a point P ₁ on the inner core 11 shown in FIG. 2 this time When a potential difference occurs between the inner core 11 and the point P ₂ on the first outer core 13, electric charge is accumulated in the stray capacitance C _B between the inner core 11 and the first outer core 13, or the stray capacitance C _B is discharged. , Transiently the inner core 11
Although affect the voltage of the electrical signal flowing through the, to prevent this, it is sufficient and the inner core 11 the voltage variation of the electrical signals of the first outer core 13 in the same by wideband buffer 16, thereby P ₁ point , P ₂ point does not have a potential difference, so that the voltage of the electric signal is hardly affected.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0033

[Correction method] Change

[Correction content]

Furthermore, FIG. 5 is a schematic view of a fourth embodiment of the present invention, in FIG 5, FIG. 4 the same reference numerals indicate the equivalent or same components, wideband buffer 24 in FIG. 4, the relay 26 And remove relay 2
0 and 22 are also removed and these relays 20 and 22 are directly connected.

[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] 0037

[Correction method] Change

[Correction content]

As described above, the structure shown in FIG.
It is possible to obtain the same effect as that of the third embodiment.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0038

[Correction method] Change

[Correction content]

[0038]

As described above, according to the electric signal transmission line of the present invention, the second insulator is provided by covering the first outer core,
Since the second outer core that covers the second insulator and is grounded is provided and the non-inverting input terminal of the wideband buffer is connected to the inner core and the inverting input terminal and the output terminal are connected to the first outer core, the wideband buffer As a result, the first outer core has a low impedance, the charges accumulated in the stray capacitance between the inner core and the first outer core can be reduced, and the amplitude attenuation and reflection can be suppressed,
Moreover, the conventional resistance for impedance matching becomes unnecessary, and it is suitable as an electric signal transmission line for electronic equipment.

Claims (1)

Claim: What is claimed is: 1. An inner core for transmitting an electric signal, a first insulator encapsulating the inner core, and a first insulator encapsulating the first insulator.
An outer core, a second insulator covering the first outer core, a second outer core covering the second insulator and grounded, and a non-inverting input terminal connected to the inner core for inverting input An electric signal transmission line, comprising: a wide-band buffer having terminals and output terminals connected to the first outer core.