JP3171466B2 - Vector voltage ratio measuring method and vector voltage ratio measuring device - 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 measuring a vector voltage ratio.
For example, the present invention relates to a method and an apparatus for measuring a vector voltage ratio at high speed by using one A / D converter in an apparatus for measuring impedance of an LCR component or the like.

[0002]

TECHNICAL BACKGROUND For example, an object to be measured such as an LCR component
In order to perform impedance measurement of DUT)
It is necessary to measure the vector ratio between the voltage between the terminals of the DUT and the current flowing between the terminals. Usually, the current is subjected to current / voltage conversion by using a current measuring resistor, and then the current is converted to the voltage. Find the vector ratio. By the way,
There is known a method of measuring the terminal-to-terminal voltage V _pot and the converted voltage (current / voltage converted current) V _cur using one integrating A / D converter. In this method, the two voltages V and V are converted using one A / D converter.
it is possible to cancel the proportional error of the A / D converter by the measurement of the _pot and _{V cur.} Therefore, the above method has an advantage that a highly accurate vector voltage ratio can be measured by a simple circuit configuration and a correction operation.

In order to determine the vector voltage ratio, usually, the converted voltage V of the current flowing through the DUT is twice obtained to determine the vector voltage of the voltage V _pot across the DUT.
_In order to obtain the vector voltage of _cur , two measurements, a total of four measurements, are required. Normally, a sine wave signal of a certain frequency
When measuring the ° component or the 90 ° component using an integrating A / D converter , the integration time requires one cycle or more. Therefore, the conventional model requires four or more periods for one vector voltage measurement , and there is a limit to shortening the measurement time.

There is also a conventional method in which a part of a measurement signal is applied to a local signal for phase detection to reduce the number of integrations to three times. In this method, a local signal is generated from the measurement signal. There is a problem that an error is easily generated. In addition, a method of using a plurality of integrating A / D converters and ending the measurement of the vector voltage by one integration is also employed. If this method is used, high-speed measurement can be performed, but the circuit configuration becomes complicated and the correction operation becomes very complicated. Furthermore,
When an integrating A / D converter is used, offset voltage processing is required, and usually, an operation of rotating the detection phase by 180 ° and performing integration again is required. Is twice as large as In addition, as used in some network analyzers,
There is also known a method of performing high-speed measurement by performing a phase detection portion using software. In this method, three A / D converters are used, and the measurement of three voltages can be completed in one cycle of the intermediate frequency. However, the number of components increases and the tracking error of the circuit up to the A / D converter is reduced. There are problems such as additional errors.

[0005]

Is an object of the present invention to be one that is proposed to solve the above problems without impairing the simplicity of the circuit configuration and the correction operation, the order of one cycle of the measurement signal time It is an object of the present invention to provide a vector voltage ratio measuring method and a vector voltage ratio measuring device capable of terminating the measurement at a time.

[0006]

SUMMARY OF THE INVENTION In the present invention, a sine wave signal is applied to any two terminals of a DUT, and a voltage _Vpot between the two terminals and a converted voltage _Vcur obtained by converting a value of a current flowing between the two terminals into a voltage value are obtained. Via a switch operating at a timing shorter than 1/4 of the sine wave signal period (90.degree . When one sine wave period is 360.degree . ), For example, at 1/8 of the sine wave period. Output to the A / D converter. In the A / D converter, the voltages V _pot and V _cur
At least one before the switch performs the next switching operation.
Sampling, preferably at a cycle of 1/4 of the measurement cycle.

[0007] For example, an A / D converter operates with a voltage V
_{The pot} and the conversion voltage V _cur may be sampled alternately every time the switch is operated, or when the voltage V _pot is input, the V _pot is sampled continuously plural times, and the switch operates. Then, after the input is switched to the converted voltage _Vcur , the sampling of the _Vcur may be continuously performed the same number of times as described above. In this case, sampling data with a phase difference of 90 ° is obtained as a pair,
A plurality of sets of sampling data of a pair of voltages V _pot having a phase difference of 0 ° and a pair of converted data V _cur having a phase difference of 90 ° are obtained. Conventionally, when the sampling with the voltage V _pot or the converted voltage V _cur is performed with a phase difference of 90 ° , the time when the first sampling (0 ° ) is performed and 2
The A / D converter did not operate during the period between the time when the second sampling (90 ° ) is performed, but in the present invention, for example, 0 ° sampling and 90 ° sampling of the voltage V _pot are performed . Conversion voltage V
_Since 0 ° or 90 ° sampling of the _cur is performed, one A / D converter can be effectively used. Then, the signal processing unit performs digital signal processing on the sampling data of the voltage V _pot and the converted voltage V _cur by a known method, so that vector voltages of V _pot and V _cur can be obtained.

By the way, the voltage V thus obtained is
Vector voltage _pot are those in the coordinate system based on the sampling phase of the _{V pot} (first coordinate system), vector voltage conversion voltage _{V cur is} the coordinate system based on the sampling phase of the _{V cur} (second (Coordinate system). Therefore, the 0 ° component and the 90 ° component of the vector voltage in each coordinate system are set to 0 ° in the same coordinate system .
A correction for converting the component into a 90 ° component is required. This correction can be performed by a simple vector rotation operation or a complex number operation. Normally, correction is performed to match one coordinate system with the other coordinate system.

When the voltage V _pot is being input, sampling of the V _pot is performed a plurality of times continuously, and after the switch is operated and the input is switched to the converted voltage V _cur , the sampling of the V _cur is performed. when the same number of rows as said continuously, i.e., switching device voltage V _pot, if during that selects one of the converted voltage V _cur, performing a plurality of successive sampling measurement time , The vector voltage ratio can be measured with higher accuracy.

[0010]

DETAILED DESCRIPTION FIG. 1 is a block diagram showing the configuration of a basic circuit for implementing the present onset bright. In the figure, a measurement signal from a signal source 1 that outputs a sine wave voltage or a sine wave current is given to a DUT (coil, capacitor, resistor, etc.) 2 and
The voltage V _pot between the terminals of the DUT 2 and the converted voltage V _cur via the current / voltage converter 3 are input to the switch 4.
The switch 4 receives the input V _pot and the
And alternately switched to output a good beauty _{V cur.} An amplifier 5 is provided next to the switch 4, and a signal from the switch 4 is output to the low-pass filter 6 via the amplifier 5. The low-pass filter 6 of the present invention is provided particularly for anti-aliasing, and is effective for preventing aliasing that occurs when the sampling interval is short.

An A / D converter is provided downstream of the low-pass filter 6.
A converter 7 is provided, and the converter 7 performs sampling at a timing having a certain relationship with the switching timing of the switch 4 as described later. As the A / D converter 7, a high-speed A / D converter such as a successive approximation type or a flash type is usually used. Then, the sampling data from the A / D converter 7 is temporarily stored in a storage means such as a register, not shown, Shin
Signal processing means (in this embodiment, the microprocessor (CP
U) 8 ) Performs processing such as calculation of a 0 ° component or a 90 ° component described later, correction by a vector rotation operation, and the like on the data to calculate a vector specific voltage. Thereafter, the vector specific voltage is converted into, for example, an analog voltage signal and sent to an appropriate output device or the like. In this embodiment, since the phase detection is realized by software, a phase detection circuit is not required.

Hereinafter, the relationship between the switching timing by the switch 4 and the sampling timing of the A / D converter 7 will be mainly described with reference to FIGS. 2 (A) to 2 (C). FIG. 2A is a diagram showing both waveforms of the voltage V _pot and the converted voltage V _cur . Both have an arbitrary phase but the same period. Here, the switch 4 in FIG. 1 outputs its output to V at a period (45 ° interval) of ８ of the measurement signal period.
_The output is alternately switched from _pot to _Vcur or vice versa and output to the next stage. FIG. 2B is a timing chart showing the state of switching of the switch 4 and the switching state SW.
Indicates that V _pot is on and V _cur is off at a high level, and V _pot is off and V _cur is on at a low level. The switching is performed at a timing irrelevant to the phase of the measurement signal.

[0013] A / D converter 7 performs sampling of the _{V pot} or _{V cur} in the same cycle of the switching as shown in FIG. (C). However, when the sampling period is short, it is preferable that the sampling be performed after the output of the switch 4 is in a steady state. In FIG. 10C, sampling is performed near the intermediate portion between the switching operations. Note that in FIG.
the sampling time of the _{pot t X0, t X1, t} X2,
, And the sampling time of _Vcur is set to t _Y0 , t
_{, Y 1} , t _Y2 ,... Now V
_pot of _{t X0, t X1, t X2} , the sampling value in ··· X0, X1, X2, ··· , V cur of t
_{Y0, t} Y1, _t Y2, the sampling value in ··· Y0, Y1, Y2, and .... Of these, for example, a sampling numerical sequence X ^T = [X0 for V _pot
X1 X2 ^{X3] T} to _N ¹ T = ^[1 0 -1
^0] _T, is multiplied by ^{N 2 T = [0 -1 0} 1] T, can be determined two orthogonal components of the vector voltage _{V pot} (0 ° component _{V POT0} and 90 ° component _{V pot90)} . That is, the 0 ° component V of V _pot
pot0 is

[0014]

[Number 1] ^{_{V pot0 = X T · N 1}} /2 = (X0-X2) / 2, V 90 ° component _{V Pot90} the _pot is

[0015]

[Number 2] ^{_{V pot90 = X T · N 2}} /2 = (- X1 + X
3) / 2. Similarly, a sampling numerical sequence X ^T of V _cur = [Y0 Y1 Y2 Y3] ^T
The ^{_{N 1 T = [1 0 -1}} 0] T, N 2 T = [0 -
1 0 1] ^T , two orthogonal components V _cur0 and V _cur90 of the vector voltage of V _cur can be obtained. That is, the 0 ° component V of _Vcur
cur0 is

[0016]

Equation 3] ^{_{V cur0 = Y T · N 1}} /2 = (Y0-Y2) / 2 90 ° component _{V Cur90} is

[0017]

[Number 4] ^{_{V cur90 = Y T · N 2}} /2 = (- Y1 + Y
3) / 2. By the way, in the method of the present invention, sampling of V _pot and V _cur is not performed in the same phase. That is, the coordinate system based on the sampling phase of V _{pot and} the coordinate system based on the sampling phase of V _cur are not the same. Therefore, V _pot0 , V
_It is necessary to convert the _pot90 and _Vcur0 , _Vcur90 into the same coordinate system, but this conversion can be easily corrected by a vector rotation operation or a complex number operation as described below. For example, in order to adjust V _cur to the phase of V _pot , the corrected value of V _cur is _calculated as V _cur0 ′, V _cur0 ′
_{Assuming that} the corrected value of _cur90 is _Vcur90 ,

[0018]

[Number 5] _{V cur0 '= V cur0 · cos45} ° + V cur90 · sin45 ° = (V cur0 + V cur90) / 2 1/2 V cur90' = -V cur0 · sin45 ° + V
_cur90 · cos45 ° = (− _Vcur0 + _Vcur90 ) / ^21/2 , and the vector voltage ratio (0 ° component is V
_pot0 / _Vcur0 ', 90 [ deg.] component is _Vpot90 /
_Vcur90 ') can be easily obtained.

In the above embodiment, the switching cycle of the switch 4 is set to 4
5 ° (１ ／ of the measurement cycle) is set, but if the angle is smaller than 90 ° (１ ／ of the measurement cycle), 60 ° (１ ／ of the measurement cycle) and 30 ° (1 of the measurement cycle) / 12) can be employed. For example, FIG.
The switching cycle of the switching unit 4 is set to 60 ° (１ ／ of the measurement cycle) as shown in FIG. 7. For example, the first sampling for V _pot is performed at 45 ° after the switching time t _X0, and the first sampling for V _cur is performed. _Is performed at 45 ° from the switching time t _Y0 , the second sampling for V _pot is performed at 15 ° from the switching time t _X1 , and the second sampling for V _{cur is} 15 ° from the switching time t _Y1 . Perform at the time of elapse. Similarly, sampling of V _pot and V _cur is performed at time t.
_{X2, t} Y2, _t X3, if successively performed at _{t Y3, V pot0} in the same manner as described _{above, V pot90, V cur0, V
cur90} can be determined. And, for example, V
_{The phases of cur0} and _Vcur90 are changed to _Vpot0 and V
_A vector voltage ratio can be obtained by _performing correction to match the _{pot 90} (in this case, correction is performed to delay V _cur0 and V _{cur 90} by 60 ° ). In this case, the measurement time can be reduced to about 2/3 times as compared with the related art.

Further, in the above embodiment, only one sampling is performed between a certain switching time and the next switching time, but a plurality of samplings can be performed during the period. For example, as shown in FIG. 3B, when the switching cycle is set to 45 ° as in FIG.
seeking XN0 and XN1 was sampled twice (15 ° and 30 ° from the switching time) between the switching time _{t XN} and _{t YN} for _pot, switching time for similarly _{V cur t YN} and _{t X N + 1} Request YN0 and YN1 perform sampling twice between. Where N
Are 0, 1, 2,...

X00 and X10, X20 and X3
0, Y00 and Y10 and Y20 and Y30 from FIG.
As described in (C), the measurement result of the first vector voltage ratio is obtained, and X01 and X11, X21 and X31,
Similarly, the measurement result of the second vector voltage ratio can be obtained from Y01 and Y11 and from Y21 and Y31. By doing so, more accurate measurement can be performed.

Also, as shown in FIG. 3C, when the switching time is set to 60 ° similarly to FIG. 3A, two times between the certain switching time and the next switching time (from the switching time). 2
0 ° and 40 ° ), and X00 and X10, X20 and X30, Y00 and Y1
0, Y20 and Y30, the measurement results of the first vector voltage ratio were calculated as X01 and X11, X21 and X31, Y01 and Y1.
By obtaining the measurement result of the second vector voltage ratio from 1, Y21 and Y31, more accurate measurement can be performed. In the above embodiment, the case where the impedance of the DUT is obtained has been described. However, the present invention is not limited to this.
It is suitably used for a device that needs to measure a vector voltage ratio, for example, a measuring instrument that needs to determine a vector ratio between a reference voltage and a test voltage, such as a network analyzer, and can perform high-speed measurement.

[0023]

As described in the foregoing, in performing the sampling of 0 ° or 90 ° of the converted voltage V _cur between 0 ° Sampling Sampling and 90 ° of the voltage V _pot according to this onset bright Thus, high-speed measurement of about one cycle of the measurement signal is possible even though one A / D converter is used. The invention is also applicable to measuring vector voltage ratios from relatively high to low frequencies.

Further, the switching device is configured to control the voltage V _pot and the conversion voltage V
_When a plurality of continuous samplings are performed during a period in which one of the _curs is selected, the vector voltage ratio measurement can be performed with higher accuracy while the measurement time is greatly reduced. As a result, for example, the measurement of the impedance of the DUT at 100 Hz and 120 Hz can be completed in about 10 msec, and the number of components that can be inspected per unit time in the production line can be increased. The inspection cost per unit can be reduced. Also, in the R & D department, the number of measurements per unit time can be increased, and characteristics such as impedance change with time can be measured more finely.

[Brief description of the drawings]

1 is a block diagram showing an example basic circuit configuration of the onset bright applies.

[Figure 2] is a diagram showing an embodiment of the present onset bright, (A) the figure showing the waveform of the measurement signal, (B) is a diagram showing an operating state of the switching unit, (C) an A / D converter FIG. 4 is a diagram showing sampling timings of the first embodiment.

Figure 3 is a view showing another embodiment of the present onset bright, (A) is a diagram showing the sampling timing of the operating state and A / D converter switching device in the case of a 60 ° the switching period of the switching device (B) is a diagram showing an embodiment in which the switching unit performs sampling twice before the next operation when the switching unit period is 45 ° , and (C) shows the embodiment when the switching unit period is 60 ° . FIG. 10 is a diagram showing an embodiment in which the switch performs sampling twice before performing the next operation in a certain case.

Claims (6)

(57) [Claims] 1. A sine wave measurement signal is supplied to two terminals of an object to be measured , and a voltage V _pot between the two terminals and a converted voltage V _cur obtained by converting a value of a current flowing between the two terminals into a voltage value are obtained by: The two voltages V _pot and V _cur are output to an A / D converter via a switch that operates so as to select them, and the A / D converter samples the voltage V _pot and the converted voltage V _cur at predetermined timings, respectively. A vector voltage ratio measuring method for obtaining a vector voltage ratio by subjecting the sampling data to digital signal processing, wherein the switch is operated at a timing shorter than a quarter of the measurement signal period; / D converter by said sampling of both the voltage V _pot and V _cur, the switching device is by performing at least once before the next switching operation, 0 ° component of the voltage _{V pot} in a first coordinate system based on the sampling phase of the voltage _{V pot} and 90 ° components as well as the converted voltage V
seeking a 0 ° component and 90 ° components of the converted voltage _{V cur} in the second coordinate system based on the sampling phase of the _cur, after this, both voltages _{V pot} and V in both coordinate systems
_By correcting each of the 0 ° component and the 90 ° component of the _cur into each component in the same rotation coordinate, both voltages V
A vector voltage ratio measuring method, wherein a vector voltage ratio between a _pot and V _cur is obtained. 2. The two voltages by the A / D converter.
V _pot And V _cur Sampling of the measurement signal
It is characterized in that it is performed in each cycle of 1/4 of the signal cycle
The method for measuring a vector voltage ratio according to claim 1. 3. The method according to claim 1, wherein the switch is set to １ ／ of the measurement signal period.
3. The device according to claim 1, wherein the device is operated in a cycle of
2. The method for measuring a vector voltage ratio according to the item 1. 4. A sine wave measurement signal is applied to two terminals of a measured object.
The source of the signal A current for converting the value of the current flowing between the two terminals into a voltage value /
A voltage converter; The voltage V between the two terminals _pot And from the current / voltage converter
Conversion voltage V _cur When And both voltages V _pot Or
V _cur A switch for selecting and outputting The voltage from the switch is input and the voltage V _pot And before
Conversion voltage V _cur And at a predetermined timing
A / D converter to pull, The data sampled by the A / D converter is
Signal processing means for performing digital signal processing; A vector voltage ratio measuring device comprising: The switch is shorter than a quarter of the measurement signal period.
Work at the right time, In the A / D converter, the switching device performs a next switching operation.
At least once before the voltage V _pot And V
_cur Sampling The signal processing means is configured to control the voltage V _pot Sampling
The voltage V in a first coordinate system based on phase _pot Of 0
° component and 90 ° component, and conversion voltage V _cur The sun
The converted voltage in a second coordinate system based on the pulling phase
V _cur And the 90 ° component of
Both voltages V in the coordinate system _pot And V _cur Each 0 °
Component and 90 ° component to each component at the same rotation coordinates
By performing correction for conversion, both voltages V _pot And V _cur
Find the vector voltage ratio with A vector voltage ratio measuring device, characterized in that: 5. The switching device according to claim 1, wherein the switch is one-fourth of the measurement signal period.
Each of the two voltages V _pot And V _cur
5. The method according to claim 4, wherein sampling is performed.
Vector voltage ratio measuring device. 6. The switching device according to claim 1, wherein the switch is one-half of the measurement signal period.
6. The device according to claim 4, wherein the device operates in a cycle of eight.
2. The vector voltage ratio measuring device according to 1.