JPH11352162A - Frequency characteristic measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a frequency characteristic measuring device capable of enhancing measuring accuracy without lengthening the measuring time. SOLUTION: A frequency characteristic measuring device is approximately constituted by a high frequency generator; a measuring instrument; and a computer controlling the high frequency generator and the measuring instrument. Actually, the measuring device is a network analyzer or an impedance analyzer. In the case where a damping characteristic of a piezoelectric resonator is measured by using the frequency characteristic measuring device, the variation of a damping quantity is rapid in an area of frequencies f2-f3 and the variation of the damping quantity is loose in the area of frequencies f5-f6. Namely, since the most important portion of the damping characteristic is the area of the frequencies f2-f3, a measuring frequency step of the area of the frequency f2-f3 is reduced and measuring points are increased compared with conventional measuring points. Since an accuracy of the area of frequencies f5-f6 may be low, the measuring frequency step is enlarged to decrease the measuring points as compared with conventional measuring points.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a frequency characteristic measuring device, and more particularly to a frequency characteristic measuring device for electronic components such as a filter and an oscillator.

[0002]

2. Description of the Related Art Conventionally, as a measuring device used for measuring frequency characteristics of a filter, an oscillator, or the like, a measuring device which measures at predetermined frequency steps (digitally),
What measures continuously (analog) is known.

[0003]

However, in the case of a conventional measuring device which measures at predetermined frequency steps, frequency steps of measurement can be set only at equal intervals.
Therefore, if the interval between the frequency steps is narrowed in order to measure the frequency characteristics of a filter or the like with high accuracy, there has been a problem that the measurement time is prolonged in proportion thereto. Also, in the case of a measuring device that performs continuous measurement, there is a problem in that if the frequency characteristic is to be measured with high accuracy, the sweep speed of the measurement frequency must be reduced, and the measurement time is long.

It is an object of the present invention to provide a frequency characteristic measuring device capable of improving the measuring accuracy without increasing the measuring time.

[0005]

In order to achieve the above object, a frequency characteristic measuring apparatus according to the present invention comprises: a high frequency generator for generating a high frequency signal in a predetermined frequency range;
A measuring instrument for measuring a predetermined electric variable, and a high-frequency signal of a predetermined frequency range is sequentially generated and swept from the high-frequency generator, and the predetermined electric variable of the device under test is measured at predetermined frequency steps. A controller for making the measurement by the measuring device, wherein the frequency step of the measurement by the measuring device is changed in an arbitrary frequency section during one cycle of the sweep of the high frequency signal from the high frequency generator.

With the above configuration, the frequency step of measurement is reduced in an important frequency section (for example, a portion where the change is abrupt) in terms of frequency characteristics, so that the number of measurement points is increased as compared with the related art. For example, in a portion where the change is constant, the number of measurement points can be reduced by increasing the frequency step of measurement, and highly accurate measurement can be performed without increasing the number of measurement points.

Further, the frequency characteristic measuring apparatus according to the present invention is characterized in that the frequency step of measurement by the measuring device is made different for each sweep cycle of the high frequency signal from the high frequency generator, and the measuring device performs a predetermined electric variable in a plurality of cycles. It is characterized by measuring.

With the above configuration, in the first sweep cycle, the frequency step of measurement is made relatively large, and a frequency section (for example, a maximum portion and a minimum portion) that is important in frequency characteristics is detected at a small number of measurement points. Next, in the subsequent sweep cycle, only the frequency section that is important in the frequency characteristic is measured with high accuracy by reducing the frequency step of the measurement. That is, since only important frequency sections are measured with high accuracy, an increase in measurement points is suppressed.

Further, the frequency characteristic measuring device according to the present invention is characterized in that a plurality of kinds of electric variables are measured by the measuring device during one cycle of the sweep of the high frequency signal from the high frequency generator. With the above configuration, a plurality of types of electrical variables can be efficiently measured during one cycle of sweeping.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a frequency characteristic measuring apparatus according to the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows a frequency characteristic measuring device 1. The measuring device 1 generally includes a high-frequency generator 2, a measuring device 3, and a computer 5 that controls the high-frequency generator 2 and the measuring device 3. Specifically, it is a network analyzer, an impedance analyzer, or the like.

The computer 5 performs a series of measurements and processes at high speed and rationally according to a program stored in advance. That is, the high frequency generator 2 applies a control signal from the computer 5 to the device under test 60 connected to the measurement terminals 12 and 13 while sweeping a high frequency signal in a predetermined frequency range. Then, the measuring device 3 measures the electromagnetic characteristics of the device under test 60 for each predetermined frequency. The obtained measurement data is sent to the computer 5 and processed by the computer 5.

The frequency characteristic measuring device 1 having the above configuration
Next, a case where a piezoelectric resonator is set as the DUT 60 will be described as an example. As shown in FIG. 2, the piezoelectric resonator 60 is housed in the case main body 51 in a state of being sandwiched between the pair of terminals 61 and 62. The piezoelectric resonator 60 includes a piezoelectric substrate 60a and vibration electrodes 60b and 60c formed on the front and back surfaces of the piezoelectric substrate 60a. The piezoelectric substrate 60a is made of PZT, quartz, ZnO, or the like. The piezoelectric resonator 60 vibrates in the plane vibration mode, but is not necessarily limited to this vibration mode. The case body 51 has a substantially box shape with one surface opened, and has a terminal groove 52 on one side surface. External connection part 61 of terminals 61 and 62
a and 62a are led out from the terminal groove 52. Lid 55
Has a flat plate shape capable of closing the upper opening of the case body 51. The measurement may be performed before the piezoelectric resonator 60 is built in the case.

In the first embodiment, during one-cycle sweep of a high-frequency signal from the high-frequency generator 2, the frequency step of measurement by the measuring device 3 is changed in an arbitrary frequency section, so that the attenuation characteristic of the piezoelectric resonator 60 is reduced. The measuring device 1 that can measure the following will be described.

FIG. 3 shows the damping characteristics of the piezoelectric resonator 60.
In the frequency range from f2 to f3, the amount of attenuation changes rapidly,
In the region of the frequencies f5 to f6, the change in the amount of attenuation is gradual. In other words, the most important part in the attenuation characteristic is the frequency f2
Since the frequency range is from f3 to f3, the frequency step of the measurement in the frequency range from f2 to f3 is reduced to increase the number of measurement points as compared with the related art. For example, when the piezoelectric resonator 60 is used as a filter, the region of the frequencies f2 to f3 substantially coincides with the pass band, and the frequency step of the measurement is set to one of the pass band width.
/ 10 or less. On the other hand, the region of frequencies f5 to f6 is a spurious occurrence region, so that the waveform becomes gentle. Since the accuracy may be low, the frequency step of the measurement is increased to reduce the number of measurement points as compared with the related art. For example, the frequency step of the measurement may be 1/100 of the peak spurious bandwidth.
About 2.

In the respective regions of the frequencies f1 to f2 and f3 to f4, the change of the attenuation is substantially constant, and the region is theoretically calculated in the computer 5 using a function approximation method such as an interpolation method. Since a substantially accurate characteristic can be estimated, the frequency step of the measurement is set to be larger than that in the range of frequencies f2 to f3 and smaller than that in the range of frequencies f5 to f6. Also, since there is no need to measure the region of the frequencies f4 to f5, the frequency is skipped.

As described above, not all attenuation characteristics are measured at the same frequency step, but the total measurement speed can be increased by changing the frequency step as needed. In addition, the most important part in terms of the attenuation characteristics is that the frequency step is reduced and the accuracy is made higher than before, so that the measurement time can be prevented from being lengthened while increasing the measurement accuracy.

Next, in the second embodiment, the impedance characteristic of the piezoelectric resonator 60 is measured in a plurality of cycles by changing the frequency step of the measurement by the measuring device 3 for each sweep cycle of the high frequency signal from the high frequency generator 2. The measuring device 1 that can be used will be described.

FIG. 4 shows the impedance characteristics of the piezoelectric resonator 60. In FIG. 4, fr and fa are a resonance frequency and an anti-resonance frequency of the piezoelectric resonator 60, respectively. In the first sweep cycle, the frequency range including the resonance frequency fr and the anti-resonance frequency fa is set so that the frequency step of measurement is constant and relatively large, and the number of measurement points f1 and f
2, measured at f10. In this first measurement cycle,
In the impedance characteristic, the most important frequency section, that is, the region of frequencies f3 to f5 including the minimum value of the impedance, and the frequency f6 including the maximum value of the impedance
The area of f8 is detected in the computer 5.

Next, in the subsequent sweep cycle, as shown in FIG. 5, the region of frequencies f3 to f5 and the frequencies f6 to f
Only in the region of No. 8, the frequency step of measurement is reduced to increase the number of measurement points, and the impedance characteristic is measured with high accuracy. In general, the frequency step of the measurement in the subsequent sweep cycle is reduced by half that of the previous sweep cycle.
Set as follows. Hereinafter, the sweep cycle is repeated while reducing the frequency step of the measurement as necessary. In this way, since the impedance characteristic is measured with high accuracy only in the necessary frequency section, the number of measurement points can be suppressed. Therefore, it is possible to increase the measurement accuracy and not to lengthen the measurement time.

Next, a description will be given of a third embodiment of the measuring apparatus 1 in which the measuring device 3 can measure the impedance characteristic and the phase characteristic during the one-cycle sweep of the high-frequency signal from the high-frequency generator 2.

FIG. 6 shows impedance characteristics (see the solid line 21) and phase characteristics (see the solid line 22). In one sweep cycle, the impedance characteristic is measured in the frequency range from f1 to f2, and the phase characteristic is measured in the frequency range from f3 to f4. In this way, the impedance characteristics and the phase characteristics can be efficiently measured during one cycle of the sweep, so that the measurement accuracy can be improved without increasing the measurement time.

The frequency characteristic measuring device according to the present invention is not limited to the above embodiment, but can be variously modified within the scope of the invention. The first, second, and third embodiments need not be independent, and may be arbitrarily combined. Also,
Although the embodiment has been described by taking the piezoelectric resonator as an example,
The present invention is not necessarily limited to this, and may be any such as an inductor element and a capacitor element. Further, the electrical variables include reactance, resistance, inductance, capacitance, impedance, phase, and electrical characteristics derived therefrom. Further, in the third embodiment, the impedance and the phase are measured in relation to the frequency, but one of them may be measured in relation to something other than the frequency (for example, the input voltage or the like).

[0024]

As is apparent from the above description, by changing the frequency step of the measurement by the measuring instrument in an arbitrary frequency section during the one-cycle sweep of the high-frequency signal from the high-frequency generator, the frequency characteristic is improved. In the important frequency section, the measurement frequency step is made smaller to increase the number of measurement points, and conversely, in other frequency sections, the measurement frequency step is increased to reduce the number of measurement points. The measurement can be performed with high accuracy without increasing the number of measurements.

In addition, the frequency step of measurement by the measuring instrument is made different for each sweep cycle of the high-frequency signal from the high-frequency generator, and a predetermined electric variable is measured by the measuring instrument for a plurality of cycles. Make the frequency step of the measurement relatively large, detect the important frequency section in the frequency characteristic with few measurement points,
In the subsequent sweep cycle, only the frequency section important in the frequency characteristics is measured with high accuracy by reducing the frequency step of the measurement. In this way, it is possible to measure only important frequency sections with high accuracy and suppress an increase in measurement points.

Furthermore, a plurality of types of electrical variables are measured by a measuring device during one cycle of a high-frequency signal from a high-frequency generator, so that a plurality of characteristics can be efficiently measured during one-cycle sweep. As a result, the measurement accuracy can be improved without increasing the measurement time.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an example of a frequency characteristic measuring device according to the present invention.

FIG. 2 is an exploded perspective view showing a configuration example of a piezoelectric resonator.

FIG. 3 is a graph showing an attenuation characteristic for explaining the first embodiment of the frequency characteristic measuring device shown in FIG. 1;

FIG. 4 is a graph showing impedance characteristics for describing a second embodiment of the frequency characteristic measuring device shown in FIG. 1;

FIG. 5 is a graph showing impedance characteristics for explaining a measurement procedure following FIG. 4;

FIG. 6 is a graph illustrating impedance characteristics and phase characteristics for describing a third embodiment of the frequency characteristic measuring device illustrated in FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Frequency characteristic measuring device 2 ... High frequency generator 3 ... Measuring instrument 5 ... Computer (controller)

Claims (3)

[Claims] 1. A high-frequency generator for generating a high-frequency signal in a predetermined frequency range, a measuring device for measuring a predetermined electric variable, and a high-frequency signal in a predetermined frequency range generated by the high-frequency generator sequentially and swept. And a controller for causing the measuring device to measure a predetermined electric variable of the device under test at predetermined frequency steps, and wherein a desired frequency is determined during one-cycle sweep of the high-frequency signal from the high-frequency generator. A frequency step of measurement by the measuring device in a section is different. 2. A high-frequency generator for generating a high-frequency signal in a predetermined frequency range, a measuring device for measuring a predetermined electric variable, and a high-frequency signal in a predetermined frequency range generated by the high-frequency generator in sequence and swept. And a controller that causes the measuring device to measure a predetermined electrical variable of the device under test at each predetermined frequency step, wherein the measurement by the measuring device is performed every sweep cycle of the high-frequency signal from the high-frequency generator. Different frequency steps
A predetermined electrical variable is measured in a plurality of cycles by the measuring device. 3. A high-frequency generator for generating a high-frequency signal in a predetermined frequency range, a measuring device for measuring a predetermined electric variable, and a high-frequency signal in a predetermined frequency range generated by the high-frequency generator in sequence and swept. And a controller for causing the measuring device to measure a predetermined electric variable of the device under test every predetermined frequency step, wherein the measuring device performs a one-cycle sweep of a high-frequency signal from the high-frequency generator. Measuring a plurality of types of electrical variables by using the frequency characteristic measuring device.