JP3163344B2 - Adjustment method of terminal resistance value in non-reflection terminal AC / DC converter - Google Patents

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 a terminating-side resistance value in a non-reflection terminal-to-DC converter for measuring alternating current in a high frequency band of GHz.

[0002]

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

Conventionally, a converter used for this comparison is one in which a current flows through a resistance wire (heater) and the temperature rise is detected by a thermocouple.

That is, an AC voltage (current) is applied to a converter, a DC voltage (current) having the same thermoelectromotive force as an output thereof is adjusted, and the AC voltage (current) is compared with the DC voltage (current). This is to obtain the effective value of the voltage (current).

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

Conventionally, as an audio frequency single junction thermoelectric type AC / DC converter, a resistor (heater) 13 in which a resistor R for voltage division is incorporated in a coaxial line 8 as shown in FIG.
A structure in which the resistance wire (heater) 13 is fixed to a high-temperature contact of the thermocouple 10 via a bead 14 is known.

However, in this structure, a high-frequency current passing through the resistance line 13 in the coaxial line 8 radially generates an electric field and a magnetic field line around the resistance line 11, but since the thermocouple 10 is a good conductor, the electric field line is generated. Is disturbed by this, and reflection of high-frequency alternating current at the end of the coaxial line 8 occurs.

Therefore, in the AC / DC converter having this structure, the measurement of the alternating current at a frequency of 1 KHz to 1 MHz can be accurately performed, but the measurement of the high frequency alternating current of 1 MHz or more results in a measurement error.

Therefore, the inventor of the present application firstly extended the coaxial line 8 composed of the inner conductor 1 and the outer conductor 7 provided on the outer periphery of the inner conductor 1 as shown in FIGS. A non-reflection terminating resistor 9 having an insulating cylinder 2 provided with a resistive film 3 on its surface is provided.
We proposed an AC / DC converter using a non-reflection termination with a slab.

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 a thermocouple 10 is provided between the resistive film 3 and the cylinder 2 or on the back side of the cylinder 2. 1MHz
Even when measuring a high-frequency alternating current of about 10 GHz to about 10 GHz, there is no reflection at the terminal end in the coaxial line, and high-precision measurement can be performed.

The anti-reflection terminating resistor 9 used in the present invention is, as shown in FIG. 3, an exponential function or tractor-shaped compensating tube on the outer periphery of an insulating cylinder 2 having the same diameter as the inner conductor 1. 4, or an insulating cylindrical body 2 of the same diameter is provided on an extension of the inner conductor 1 in a strip line composed of an inner conductor 1 and an outer conductor 7 having a rectangular cross section as shown in FIG.
Stripline 1 having a rectangular cross section on extension of outer conductor 7
For example, the one using the non-reflection terminal of No. 2 can be adopted.

[0012]

However, in order to prevent the input power from being reflected at the end of the AC / DC converter, the characteristic impedance of the coaxial line and the non-reflection termination at the entrance of the non-reflection termination resistor are required. The impedance seen from the entrance to the resistor must be exactly equal, i.e. the resistance of the anti-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-reflection terminating resistor for this purpose is performed by making a spiral cut in the resistive film 3, but in this case, by making a spiral cut. There is a drawback that the current path becomes longer, which increases the inductance of the resistive film and prevents accurate impedance matching.

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

[0015]

In order to solve the above-mentioned problems, according to the present invention, an extension of a coaxial line composed of an inner conductor and an outer conductor provided on the outer periphery of the inner conductor has the same diameter as that of the inner conductor.
In addition, a non-reflection terminating resistor having an insulating cylinder provided with a resistive film on its surface is provided. Measures the resistance value when matching the characteristic impedance of
While etching the resistive film until the resistance reaches a predetermined value.
The present invention proposes a method of adjusting the resistance value by stopping the etching at the end of the process.

[0016]

As described above, according to the present invention, the resistive film is etched.
To adjust the resistance value while adjusting the resistance value.
You.

Therefore, according to the present invention, accurate impedance matching can be achieved without increasing the inductance of the resistive film.

When the resistance value is adjusted by etching the resistive film, the inner conductor of the coaxial cable and the terminal of the anti-reflection terminating resistor are made to have ohmic contact with, for example, a copper film, and then an etching solution having no selectivity is used. The resistance value is adjusted by etching the resistance film.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the illustrated embodiment. FIG. 1 shows a method of adjusting a resistance value by etching a resistive film. The inner conductor 2 is an insulating cylinder constituting a non-reflection terminating resistor, and 3 is a multi-element alloy resistive film.

The resistive film 3 is selected from a resistive material having a small thermal electromotive force with respect to the material of the inner conductor 1, and the resistive material having a small thermal electromotive force is 2 with respect to the copper inner conductor 1 used in this embodiment. There are ~ 3 types, all of which are alloys containing several types of metals. The resistance value of the resistance film 3 is formed lower than the characteristic impedance of the coaxial line.

The resistive film 3 is formed on the surface from the terminal end of the insulating cylinder 2 to the periphery of the terminal end of the inner conductor 1 by a sputtering method.
It adheres by a CVD method or the like.

Next, a copper film 4 is provided from the portion of the inner conductor 1 where the resistive film 3 is not attached to the terminal end boundary connecting to the insulating cylinder 2 to make ohmic contact with the inner conductor 1 and the resistive 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 terminal end of the insulating cylinder 2, and then the resistance value is measured with an etching solution having a low etching rate and no selectivity.
Etching is stopped when the resistance value reaches a predetermined value.

When the resistance value of the resistance film changes with time, the change is predicted and the resistance value is determined.

FIG. 2 shows a reference example in which the resistance value of the resistance film is adjusted by applying a discontinuous pattern to the resistance film. In FIG. 2A, the resistance is measured and reaches a predetermined value. The surface of the resistive film 3 is cut in the axial direction by a short straight line up to that point.

In FIG. 2B, the surface of the resistive film 3 is cut at a right angle in the axial direction with a short straight line until the resistance is measured and 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 to a small circle or other pattern until the resistance reaches a predetermined value. in this way,
By making discontinuous cuts in the resistive film,
The resistance value can be adjusted.

[0028]

In summary, according to the present invention, a resistive film is provided on the surface of an insulating cylinder having the same diameter as the inner conductor, on the extension of the coaxial line formed by the inner conductor and the outer conductor provided on the outer periphery thereof. When the resistance value of the non-reflective terminal resistor is matched with the characteristic impedance of the coaxial line in the AC / DC converter in which a non-reflective terminal resistor is further provided and a thermocouple is further provided in the cylinder, the resistive film is etched to adjust, since inductance is not increased, it is possible to take an accurate impedance matching.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a method for adjusting a resistance value by etching a resistance film according to an embodiment of the present invention;

FIG. 2 shows an example in which a resistance value is adjusted by applying a discontinuous pattern to a resistance film as a reference example. FIG. 2 (A) shows an example in which the surface of the resistance film is cut along a short straight line in the axial direction. B)
(C) is an example in which the surface of the resistive film is cut at a right angle in the axial direction with a short straight line, and (C) is an example in which the surface is cut at a right angle into a small circle or another pattern instead of the straight line.

FIG. 3 is a vertical side view showing an example of an AC / DC converter using a non-reflection terminal.

FIG. 4 is a longitudinal side view showing another example of the AC / DC converter using the non-reflection termination.

FIG. 5 is a diagram illustrating the principle of a conventional audio single junction thermoelectric 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 non-reflective termination resistor 10 is a thermocouple 11 is a compensating tube 12 Is a strip line 13 is a resistor (heater) 14 is a bead

Claims (1)

(57) [Claims] 1. An anti-reflection terminal having an insulating cylindrical body having the same diameter as the above-mentioned inner conductor and having a resistive film provided on the surface thereof, on an extension of a coaxial line comprising an inner conductor and an outer conductor provided on the outer periphery thereof. When matching the resistance value of the resistive film on the surface of the insulating cylinder to the characteristic impedance of the coaxial line in an AC / DC converter with a resistor and a thermocouple on the insulating cylinder, the resistive film is etched without selectivity. Etching while measuring resistance value with liquid
Stop etching when the resistance value reaches the specified value
A method for adjusting a terminal-side resistance value in a non-reflective terminal AC / DC converter.