JPH11211766A - Automatic calibration device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To verify an automatic calibration device and a measurement system at the time when a calibration is executed by providing a plurality of standards whose value is given in advance and a verification circuit whose value is given in advance. SOLUTION: First, four types of standards, an open circuit 31, a short- circuiting circuit 32, a load circuit 33, and a through circuit 34 whose value is given in advance are successively switched by switches SW2 and SW3, thus measuring each S parameter. A verification circuit 41 is a circuit for verifying the malfunction of an automatic calibration device itself and a measurement system. An automatic calibration device 40 is connected to a network analyzer 10 by cables 12 and 13 for automatically performing calibration and verification, thus verifying and calibrating the automatic calibration device itself and the measurement system and hence positively ensuring the measurement result of a device to be measured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic calibration device used for a network analyzer.

[0002]

2. Description of the Related Art An example of the prior art will be described with reference to FIGS. First, the outline of the S parameter measurement by the network analyzer will be described. As shown in FIG. 5, the network analyzer 10 includes a measuring unit 11
, Directional couplers D1, D2, D3, and switch SW1
It consists of: Then, the measurement is performed by connecting the device to be measured with the measurement cables 12 and 13.

The measuring section 11 has a signal output P, a reference signal input channel R, and two input channels A and B.

A directional coupler D 1 distributes a signal output p and provides a reference signal input to a channel R. Further, the directional coupler D2 gives a reflection signal and a transmission signal from the device under test connected to the port P1 to the channel A. Then, the directional coupler D3 gives a reflection signal / transmission signal from the device under test connected to the port P2 to the channel B. Then, for example, the S parameters of the two-port device 20 are measured.

Here, the port of the device under test connected to the port P1 is set to 1 and the port of the device to be connected connected to the port P2 is set to 2.
Sij of the S parameter is a transfer characteristic from the port j to the port i of the device under test.

For example, when the switch SW1 is set to the a side, the S-parameter measurement of the two-port device 20 is generally as follows. S11 = signal to channel A / signal to channel R S21 = signal to channel B / signal to channel R

When the switch SW1 is set to the b side,
The S-parameter measurement of the two-port device 20 is as follows. S12 = signal to channel A / signal to channel R S22 = signal to channel B / signal to channel R

[0008] The reason for this is roughly described here is that the multiple reflection, transfer characteristics, leakage characteristics, etc. of the signal in the measurement system are added to the true S parameter as an error and measured. In the network analyzer, these errors are called error factors, and acquiring the error factors before measuring the device under test is called calibration. Then, when measuring the device under test, by removing these error factors by calculation,
This is the true S parameter.

Next, calibration in the network analyzer 10 will be described. The most common calibration of a network analyzer for measuring two-port devices is to acquire twelve error factors. It can calibrate by connecting several different S-parameter states, which are pre-valued, and knowing the measured values at that time. For this reason, calibration in the case of performing measurement of a two-port device is performed, for example, by obtaining measured values of S-parameters of four types of standard devices.

As shown in FIG. 4, a specific automatic calibration of the measurement system of the network analyzer 10 is as follows.
The automatic calibration device 30 is connected instead of the device under test.

Conventional automatic calibration device 30
Are, for example, an open circuit 31, a short circuit 32,
Load circuit 33, through circuit 34, switch SW
2, SW3 and the switch control unit 35.

FIGS. 3A to 3D show an open circuit 3
1, four short circuit 32, load circuit 33, and through circuit 34 are shown. R3 and R4 in FIG. 3C are 50Ω when the characteristic impedance of the measurement system is 50Ω.

The switches SW2 and SW3 shown in FIG.
A switch that switches between the four circuits of the above four types of standard devices.
For example, a semiconductor switch is used. Also, switch SW
2. Switch control unit 35 for controlling switching of SW3
Can be automatically performed by a control signal from the network analyzer 10 or a computer constituting the measurement system.

Then, the respective S parameters of the above-mentioned four kinds of standardized standard devices are changed over by the switches SW2 and SW.
3 is sequentially switched, and measurement is performed under device measurement conditions, and calibration is performed.

Therefore, after the calibration of the measurement system is performed, the device under test is measured, whereby accurate measurement data from which errors in the measurement system have been removed can be obtained.

However, the automatic calibration device 4
If there is a temporal change in the price of the standard device or a failure in the measurement system, the measurement data of the device to be measured will include an error caused by the change.

Further, from the measurement data of the device to be measured,
It is generally not possible to recognize faults in automatic calibration devices and measurement systems.

[0018]

As described above, after the calibration is performed by the automatic calibration device, the error due to the failure of the measurement system or the automatic calibration device is measured despite the measurement of the device under test. In some cases, the measurement results may include the measurement results, which is inconvenient for practical use. The present invention has been made in view of such a problem, and an object of the present invention is to provide an automatic calibration apparatus and an automatic calibration apparatus that can also perform verification of a measurement system at the time of performing calibration.

[0019]

That is, a first aspect of the present invention, which has been made to achieve the above object, comprises a plurality of standardized standards and a pre-verified verification circuit. The gist of the present invention is an automatic calibration device characterized in that the calibration is performed.

In order to achieve the above object, a second aspect of the present invention is to provide a plurality of standardized standards, a pre-verified verification circuit, the verification circuit, The gist of the present invention is an automatic calibration apparatus including a switch for switching between a plurality of standard devices and a switch control unit for switching the switch by a control signal.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described in the following examples.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1, the automatic calibration device 40 of the present invention includes an open circuit 31, a short circuit 32, a load circuit 33, a through circuit 34,
A verification circuit 41 is added to the conventional configuration of the switches SW2 and SW3 and the switch control unit 35. Then, an automatic calibration device 40 is connected to the network analyzer 10 with the measurement cables 12 and 13, and calibration and verification are automatically performed.

An open circuit 31, a short circuit 32, a load circuit 33, and a through circuit
, The switches SW2 and SW3, and the switch control unit 35 are the same as those in the related art, and a description thereof will be omitted. However, the switches SW2 and SW3 each have one additional circuit to be switched, which is equivalent to five circuits.

The verification circuit 41 added in the present invention is a circuit for verifying the automatic calibration device itself and the trouble of the measurement system. For example, a specific example of the verification circuit 41 is shown in FIG.
As shown in (b), a circuit completely different from the above four types of standard devices is used. For example, the resistance R1 and the resistance R2 of the verification circuit 41 use a resistance of 50Ω.

Next, the automatic calibration device 40
Will be described. First, the open circuit 31, the short circuit 32, the load circuit 33, and the through circuit 34, which are four types of standard devices which are pre-valued, are sequentially switched by the switches SW2 and SW3, and
Perform parameter measurement.

Then, calibration using the obtained S-parameters and removal of error factors by calculation are performed. Thereafter, the switches SW2 and SW3 are switched to the pre-valued verification circuit 41, and the verification is performed by comparing the data of the valued S parameter with the measured S parameter.

If the comparison result of the verification is within the allowable range, the automatic calibration apparatus and the measurement system have no problem. Conversely, if the comparison result of the verification is out of the allowable range, the automatic calibration device or the measurement system is defective.

The above operation can be automatically executed by controlling the switch control unit 35 with a control signal from the network analyzer 10, for example. Therefore, by performing the calibration with the automatic calibration device of the present invention, the verification of the automatic calibration device itself and the measurement system can be automatically performed.

Although the present embodiment has been described on the premise that a two-port device is measured, the present invention can be similarly carried out even if the device to be measured is a device having one or three or more ports. The four types of standard devices may be of any type as long as they can be calibrated, and the verification can be further improved by using two or more types of verification circuits.

[0030]

The present invention is embodied in the form described above and has the following effects. That is,
Since the automatic calibration apparatus itself and the verification of the measurement system can also be performed at the time of executing the calibration, there is an effect that the measurement results of the device to be measured can be surely guaranteed.

[Brief description of the drawings]

FIG. 1 is a block diagram in which the automatic calibration device of the present invention is connected to a network analyzer.

FIG. 2 is an example of a verification circuit of the automatic calibration device of the present invention.

FIG. 3 is a circuit example of four types of standard devices of the automatic calibration device.

FIG. 4 is a block diagram in which a conventional automatic calibration device is connected to a network analyzer.

FIG. 5 is a device measurement diagram of a network analyzer.

[Explanation of symbols]

 Reference Signs List 10 network analyzer 11 measuring unit 20 2-port device 30 automatic calibration device 31 open circuit 32 short circuit 33 load circuit 34 through circuit 35 switch control unit 40 automatic calibration device 41 verification circuit

Claims (2)

[Claims] 1. An automatic calibration apparatus, comprising: a plurality of pre-valued standard devices; and a pre-valued verification circuit. 2. A plurality of standardized devices which are pre-valued; a verification circuit which is pre-valued; a switch for switching between the verification circuit and the plurality of standard devices; An automatic calibration device, comprising: a switch control unit for controlling.