JPH0954120A - Adjustment method for terminal side resistance value in nonreflective terminal ac/dc converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform impedance matching without increasing inductance by etching a resistance wire with an etchant of a low speed and no selectivity for performing resistance value adjustment, when the resistance value of a resistance film of an insulator surface is matched with characteristic impedance of a coaxial line. SOLUTION: A resistance film 3 is selected from among resistance materials with less thermo-electric power than a material of an internal conductor 1, and the resistance film 3 is, in CVD manner, etc., stuck on the surface of an insulation cylinder body 2, from a terminal part of the insulation cylinder body 2 to the periphery of a terminal part of the internal conductor 1. Then a copper film 4 is provided from a part, where no resistance film 3 is stuck on the internal conductor 1, to a terminal part boundary connected to the cylinder body 2, for establishing an ohmic-contact between the internal conductor 1 and the resistance film 3, and an insulation resist 5 is provided so that the copper film is not etched. Between the internal conductor 1 and the terminal part of the cylinder body 2, a resistance measurement electrode 6 is provided, and then, a resistance value is measured with an etchant of a slow etching speed and no selectivity, and, when the resistance value becomes a specified value by etching, etching is stopped.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for adjusting the resistance value on the terminal side in a non-reflective terminal AC / DC converter for measuring AC in a high frequency band of 1 MHz to 10 GHz.

[0002]

2. Description of the Related Art In order to accurately measure an AC voltage (current), it is necessary to compare the AC voltage (current) with the DC voltage (current).

Conventionally, the converter used for this comparison is such that a current is passed through a resistance wire (heater) and the temperature rise is detected by a thermocouple.

That is, by applying an AC voltage (current) to the converter, adjusting the DC voltage (current) that produces the same thermoelectromotive force as the output, and comparing with the DC voltage (current) This is to obtain the effective value of voltage (current).

At the time of this comparison, there is a slight difference between the AC voltage and the DC voltage. This is called the AC / DC difference of the converter, and a converter with a small AC / DC difference is desirable.

Conventionally, as an audio single junction thermoelectric type AC / DC converter, as shown in FIG. 5, a resistor (heater) 13 having a voltage dividing resistor R incorporated therein is inserted into a coaxial wire 8 as shown in FIG. A structure is known in which a high temperature contact of a thermocouple 10 is fixed to a resistance wire (heater) 13 via beads 14.

However, in this structure, the resistance wire in the coaxial wire 8 is
The high-frequency current passing through 13 radially generates an electric field and magnetic lines of force around the resistance wire 11, but since the thermocouple 10 is a good conductor,
The lines of electric force are disturbed by this, and reflection of high frequency alternating current at the end of the coaxial line 8 and disturbance of the electric field distribution occur.

Therefore, in the AC / DC converter having this structure,
AC measurements at frequencies from 1KHz to 1MHz are accurate,
This results in a measurement error when measuring high-frequency AC of 1 MHz or higher.

Therefore, the inventor of the present application previously extended the coaxial wire 8 consisting of the inner conductor 1 and the outer conductor 7 provided on the outer periphery thereof as shown in FIGS. Further, a non-reflective termination resistor 9 having an insulating cylindrical body 2 having a resistance film 3 provided on the surface thereof is provided, and a thermo-couple 10 is provided on the insulating cylindrical body 2 to provide an AC / DC converter using a non-reflective termination. Proposed.

That is, in this AC / DC converter, the characteristic impedance on the coaxial line side and the characteristic impedance on the terminating resistor side are made equal, and the thermocouple 10 is provided between the resistance film 3 and the cylinder body 2 or on the back side of the cylinder body 2. 1MHz to 10GH
Even when measuring high-frequency alternating current of about z, there is no reflection at the end of the coaxial line, and high-precision measurement is possible.

As the non-reflective terminating resistor 9 used in the present invention, as shown in FIG. 3, a compensation tube having an exponential shape or a tractorial shape is provided on the outer circumference of an insulating cylindrical body 2 having the same diameter as the inner conductor 1. 11 is provided, or as shown in FIG. 4, an insulating cylinder 2 having the same diameter is provided on an extension of the inner conductor 1 in a strip line composed of the inner conductor 1 and the outer conductor 7 having a rectangular cross section. It is possible to employ a stripline 12 having a non-reflective end having a rectangular cross section as an extension of the above.

[0012]

However, in order to prevent the input power from being reflected at the terminal end of the AC / DC converter, the characteristic impedance of the coaxial line and the reflectionless termination are provided at the entrance of the reflectionless termination resistor. The impedance seen by the resistor entrance must be exactly equal, ie the resistance of the non-reflective termination resistor must be exactly matched to the characteristic impedance of the coaxial line.

The adjustment of the resistance value in the conventional non-reflective terminating resistor for this purpose is performed by making a spiral cut in the resistance film 3, but in this case, by making a spiral cut. There is a drawback in that the current path becomes long, which increases the inductance of the resistance film and prevents accurate impedance matching.

Therefore, an object of the present invention is to achieve impedance matching by a method that does not increase the inductance in a non-reflection terminal resistor.

[0015]

In order to solve the above-mentioned problems, according to the present invention, on the extension of a coaxial wire consisting of an inner conductor and an outer conductor provided on the outer periphery thereof, the same diameter as that of the inner conductor,
In addition, in the AC / DC converter in which a non-reflective terminating resistor having an insulating cylinder having a resistance film on its surface is provided, and a thermocouple is further provided on the insulating cylinder, the resistance value of the resistance film on the surface of the insulating cylinder is coaxial line. This invention proposes a method of adjusting the resistance value by etching the resistance film or making cuts of a discontinuous and irregular pattern in the resistance film when matching the characteristic impedance of the above.

[0016]

In other words, according to the present invention, the resistance film is etched,
Or, the resistance value is adjusted by making discontinuous and irregularly shaped cuts in the resistance film, so that the current becomes random, and therefore accurate impedance matching is achieved without increasing the inductance of the resistance film. You can

Here, as a concrete example of making discontinuous and irregularly shaped cuts in the resistance film, a short cut is made linearly along the axial direction of the coaxial line, or a coaxial line is formed. Mention may be made of a straight short cut in the direction perpendicular to the direction of, or a round or other pattern cut.

On the other hand, when the resistance value is adjusted by etching the resistance film, ohmic contact is made between the inner conductor of the coaxial line and the terminal of the non-reflection termination resistor, for example, with a copper film, and then the speed is slow and the selectivity is low. The resistance value is adjusted by etching the resistance film with a non-etching solution.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail with reference to the illustrated embodiments. FIG. 1 shows a method of etching a resistance film to adjust the resistance value. Reference numeral 1 denotes a copper wire forming a coaxial line. Inner conductor, 2 is an insulating cylinder that constitutes a non-reflective termination resistor, and 3 is a resistance film of a multi-component alloy.

The resistance film 3 is selected from a resistance material having a small thermoelectromotive force with respect to the material of the inner conductor 1, and a resistance material having a low thermoelectromotive force is 2 with respect to the copper inner conductor 1 used in this embodiment. There are 3 kinds, but all are alloys containing several kinds of metals. The resistance value of the resistance film 3 is lower than the characteristic impedance of the coaxial line.

The resistance film 3 is formed on the surface thereof from the end portion of the insulating cylindrical body 2 to the periphery of the end portion of the inner conductor 1 by the spatter method.
It is attached by the CVD method or the like.

Next, the copper film 4 is provided from the portion of the inner conductor 1 where the resistance film 3 is not attached to the boundary of the terminal end where it is connected to the insulating cylindrical body 2 to make ohmic contact with the inner conductor 1 and the resistance film 3. An insulating resist 5 is provided on the copper film 4 so as not to be etched.

Further, a resistance measuring electrode 6 is provided between the inner conductor 1 and the end portion of the insulating cylindrical body 2, and thereafter the resistance value is measured with an etching solution having a low etching rate and no selectivity,
The etching is stopped when the resistance value reaches a predetermined value by etching.

When the resistance value of the resistance film changes with time, the change is predicted to determine the resistance value.

FIG. 2 shows an example in which the resistance value of the resistance film is adjusted by applying a discontinuous and irregular pattern to the resistance film. In FIG. The surface of the resistance film 3 is axially cut by a short straight line until the value is reached.

In FIG. 2B, the resistance is measured, and the surface of the resistance film 3 is cut at a right angle to the axial direction with a short straight line until it reaches a predetermined value.

In FIG. 2C, instead of a straight line, the resistance is measured and the surface of the resistive film 3 is cut at right angles into a small circle or other pattern until it reaches a predetermined value.

[0028]

In summary, according to the present invention, the resistance film is provided on the surface of the insulating cylindrical body having the same diameter as the inner conductor on the extension of the coaxial wire consisting of the inner conductor and the outer conductor provided on the outer periphery of the inner conductor. When the resistance value of the non-reflective termination resistor is matched with the characteristic impedance of the coaxial line in the AC / DC converter in which the non-reflective termination resistor is provided and the thermocouple is further provided on the cylindrical body, there is a discontinuity in the resistance film. Since the resistance value is adjusted by making cuts having a regular pattern or by etching the resistance film, the current becomes random and the inductance does not increase, so that accurate impedance matching can be achieved.

[Brief description of drawings]

FIG. 1 is an explanatory view of a method of adjusting a resistance value by etching a resistance film which is an embodiment of the present invention.

FIG. 2 shows another example of adjusting the resistance value by applying a discontinuous and irregular pattern to the resistance film, which is another embodiment of the present invention. (A) shows a short straight line on the surface of the resistance film. (B) is an example of cutting the surface of the resistance film with a short straight line at a right angle to the axial direction, and (C) is a straight line instead of the straight line.
Example of cutting the surface at right angles to a small circle or other pattern

FIG. 3 is a vertical sectional side view showing an example of an AC / DC converter using a reflectionless termination.

FIG. 4 is a vertical sectional side view showing another example of an AC / DC converter using a reflectionless termination.

FIG. 5 is an explanatory diagram of the principle of a conventional audio single junction thermoelectric type AC / DC converter.

[Explanation of symbols]

 1 is an inner conductor 2 is an insulating cylinder 3 is a resistive film 4 is a copper film 5 is an insulating resist 6 is a resistance measuring electrode 7 is an outer conductor 8 is a coaxial line 9 is a reflectionless termination resistor 10 is a thermocouple 11 is a compensation tube 12 Is strip line 13 is resistor (heater) 14 is bead

Claims (5)

[Claims] 1. A non-reflective terminal having an insulating cylindrical body having the same diameter as that of the inner conductor and having a resistance film on the surface of the coaxial conductor extending from the inner conductor and the outer conductor provided on the outer periphery of the inner conductor. In an AC / DC converter that has a resistor and a thermocouple on the insulating cylinder, when the resistance value of the resistance film on the surface of the insulating cylinder is matched to the characteristic impedance of the coaxial line, the resistance film is slow and selective. A method of adjusting the resistance value on the terminal side in a non-reflective terminal AC / DC converter, characterized in that the resistance value is adjusted by etching with a non-etching etchant. 2. A non-reflective terminal having an insulating cylindrical body having the same diameter as the inner conductor and having a resistance film on the surface of the coaxial extension of the inner conductor and the outer conductor provided on the outer periphery of the inner conductor. In an AC / DC converter equipped with a resistor and a thermocouple on the insulating cylinder, when the resistance value of the resistance film on the surface of the insulating cylinder is matched with the characteristic impedance of the coaxial line, the resistance film is discontinuous and discontinuous. A method for adjusting the resistance value on the terminal side in a non-reflective terminal AC / DC converter, characterized in that the resistance value is adjusted by making cuts in a regular pattern. 3. The method according to claim 2, wherein the surface of the resistance film of the insulating cylinder is axially cut by a short straight line to form a discontinuous and irregular pattern. 4. The method according to claim 2, wherein the surface of the resistance film of the insulating cylinder is cut by a short straight line orthogonal to the axial direction to form a discontinuous and irregular pattern. 5. The method according to claim 2, wherein a small circle or other discontinuous irregular pattern is formed on the surface of the resistance film of the insulating cylinder.