JPH076544Y2 - Difference signal measuring instrument - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to a means for measuring a difference signal between a large number of channels required by an LSI tester or the like with high accuracy, low cost and a simple configuration.

[Conventional technology]

LSI has many output terminal pins, but in order to judge the quality of this LSI, between the signals output from each output terminal of the LSI to be inspected (hereinafter referred to as DUT. DUT: Device Uuder Test) For example, checking the voltage difference may be useful for determining the quality.

FIG. 3 is a diagram showing a configuration example of a difference signal measuring device used in a conventional LSI tester. In the figure, the DUT 1 outputs signals of a plurality of channels (ch1, ch2, ...). To measure the voltage difference between arbitrary channel signals, two sets of scanners 10 and 11 and a differential amplifier 12 are conventionally used as shown in FIG.
Was needed.

The reason will be described with reference to FIG. In general, common mode noise N _C is superimposed on each channel signal of the LSI as shown in FIG. Therefore, if only one set of scanners is provided, for example, the ch3 signal and the ch4 signal cannot be sampled at the same time. That is, the sampling is performed alternately. If it is not possible to sample at the same time, the voltage level of the common mode noise component N _C contained in each measured value changes every moment, so even if the difference calculation is performed on the data for each sampling, the correct difference voltage is obtained. I didn't ask for it. Referring to FIG. 2,
The difference between the ch3 signal data D31 and the ch4 signal data D41 is
The correct difference voltage V _A shown in the figure is not obtained.

For the above reasons, conventionally, two scanners and a differential amplifier were provided. Each of the two scanners 10 and 11 has a switch element connected to each signal line, and selects a voltage of any one signal line by a control signal from a control device (not shown) to extract the differential amplifier 12. Can be led to one of the input terminals. Therefore, for example, when trying to obtain the voltage difference between ch1 and ch2, it is necessary to control so that the predetermined switch elements of the scanners 10 and 11 are turned on.
The signals output from the same time can be taken into the differential amplifier 12. After that, it is converted into digital data by the AD converter 3 and transferred to various data processing circuits (not shown).

[Problems to be solved by the device]

The conventional difference signal measuring device as described above requires two sets of scanners and a differential amplifier, and has a problem that the number of parts is large and the cost is high.

An object of the present invention is to provide a difference signal measuring device which does not require one scanner and a differential amplifier as compared with the conventional example.

[Means for Solving the Problems]

In order to solve the above-mentioned problems, the present invention introduces a plurality of signal lines and measures the difference in the amount of electricity between the signal lines. A scanner capable of alternately repeating and sampling the electric quantities of the two signal lines, and a digital signal data (D31, D41,
D32, D42, ...), and an AD converter for storing the data of the AD converter, and a controller for calculating the average value of the difference between the electric quantities of the two signal lines from the data. It was done.

[Action]

In the present invention, the data based on the electric quantity alternately sampled by using one scanner is temporarily stored, and the difference calculation of the data is performed a plurality of times, and the plurality of values obtained as a result are further averaged. And a controller for calculating the average of the difference in the amount of electricity. Therefore, a differential amplifier is not required and only one scanner is required.

〔Example〕

 Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a diagram showing an embodiment of a difference signal measuring device according to the present invention, and FIG. 2 is a diagram showing a state of channel signals in the apparatus of FIG.

In FIG. 1, reference numeral 1 denotes a DUT, which outputs a plurality of signals (ch1, ch2, ...) As described with reference to FIG.

Reference numeral 2 denotes a scanner, which has switch elements (SW1, SW2, ...) Connected to the signal lines from the DUT. Then, for example, under the control of a controller described later, the electric quantities of two arbitrary signal lines can be alternately repeated and sampled and taken out to the next stage.

Reference numeral 3 denotes an AD converter, which converts the output of the scanner 2 into digital signal data (D31, D41, D32, D42, ...).

A controller 4 stores the output data of the AD converter 3, and calculates the average value of the difference between the electric quantities of the two signal lines from this data. There are several means for calculating the average value of the difference in the amount of electricity. For example, the difference calculation of the data of the AD converter 3 based on the alternately sampled amount of electricity is performed a plurality of times, and the obtained plurality of values are obtained. There is a method of further calculating the average of the individual values and calculating the average of the differences in the electric quantities. In this case, the controller 4 has a memory for temporarily storing the data introduced from the AD converter 3 and the value obtained by the difference calculation, the difference calculation section, and the average calculation section. Of course, the controller 4 may have any configuration as long as the average value of the differences can be obtained.

The operation of the apparatus of FIG. 1 configured as described above will be described with reference to FIG.

For example, an operation of obtaining a difference voltage (not limited to the voltage) between the ch3 signal and the ch4 signal will be described. Common mode noise N _C is superimposed on the signals of ch3 and ch4 as shown in FIG. The scanner 2 is controlled by the controller 4.
The switching elements SW3 and SW4 are alternately turned on and off n times. Therefore, the digital data D31 → D41 → D32 → D42 → D33 → ... → D3n → D4n are sequentially output from the AD converter 3 as shown in FIG. And these digital data D31,
D41, D32, D42, D33, ..., D3n, D4n are temporarily stored in the memory built in the controller 4.

After that, the controller 4 performs the calculation shown in the equation (1) or the equation (2), and the average value V _A of the difference voltage between the two signals ch3 and ch4.
To get

In the method of the equation (1), the sum of the data of ch3 and ch4 (see FIG. 2) is respectively obtained, the difference between them is obtained, and this is divided by the number of repetitions n.

According to the method of the formula (2), the difference calculation of the data of the AD converter based on the alternately sampled electric quantity is performed n times, and the n values obtained as a result are further averaged to obtain V _A. It was done like this.

In the above description, a difference voltage is used as the difference in the amount of electricity,
Not limited to this, any signal may be used as long as it can be captured as an electric signal and AD-converted (for example, current value, resistance value, frequency value, etc.).

Further, the difference between the measurement points can be calculated by performing sequential measurement at a larger number of points without being limited to between the two channels.

[Effect of the present invention]

As described above, according to the present invention, the difference signal can be measured without requiring one scanner and one differential amplifier as compared with the conventional means, and the difference signal measurement with the inexpensive and simple structure is possible. Can be realized.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of a difference signal measuring device according to the present invention, FIG. 2 is a diagram showing a state of channel signals in the device shown in FIG. 1, and FIG. 3 is a diagram showing a conventional configuration example. . 1 ... DUT, 2 ... scanner, 3 ... AD converter, 4 ...
controller.

Claims (1)

[Scope of utility model registration request] 1. An apparatus for introducing a plurality of signal lines and measuring a difference in the amount of electricity between the signal lines, wherein each device has a switch element connected to each of the signal lines. A scanner capable of alternately repeating and sampling the electric quantity, and the output of the scanner is digital signal data (D31, D41,
D32, D42, ...), and a controller that stores the data of the AD converter and calculates the average value of the difference between the electric quantities of the two signal lines from the data. A difference signal measuring instrument characterized by.