JP2006214827A - Test system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a test system which suppresses degradation of accuracy in a temporal measurement of an object to be tested, having a high-voltage output. <P>SOLUTION: The test system which is realized by improving a system used for testing the object to be tested outputting a high-voltage pulse signal, comprises a determining section which inputs the pulse signal of the object to be tested and determines its high level and low level, based on high-level and low-level threshold voltages; a transformer into which the determination result of the determining section is input; and a time-measuring section which inputs the output of this transformer and carries out the temporal measurement by using a low-voltage signal. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a test system for testing an object to be tested that outputs a high-voltage pulse signal, such as an IC or LSI, and relates to a test system that can suppress deterioration in accuracy of time measurement in the object to be tested having a high-voltage output. Is.

  The IC tester applies a test signal to an object to be tested (hereinafter abbreviated as DUT), for example, IC, LSI, etc., measures the output signal of the DUT, for example, measures time, and determines the quality of the DUT. Such an apparatus is described in, for example, Patent Document 1 and the like.

JP 2003-139817 A

In recent years, digital amplifiers used in audio equipment and the like have been integrated into ICs. In audio equipment and the like, a large audio amplitude is generated by a digital amplifier and a speaker is driven.
By the way, when testing such a digital amplifier with an IC, it is difficult to perform a continuous large-amplitude test with an IC tester. Therefore, for example, it is conceivable that an offset voltage of about 0 to 120 V is given as a common voltage, and a test pulse signal is superimposed on the offset voltage to perform a test.
However, the signal in which the test pulse signal is superimposed on the offset voltage in this way becomes an excessive voltage in the time measuring unit of the IC tester, and time measurement cannot be performed.

  Therefore, it is also conceivable to remove the offset voltage via a capacitor and measure only the pulse signal component. However, paying attention to the DC level of the output of the DUT, it is unstable that changes as the duty of the pulse signal changes, and it is difficult to accurately measure the time when measuring the time from the output of the capacitor. is there.

  The present invention solves such problems, and an object of the present invention is to realize a test system capable of suppressing deterioration of time measurement accuracy in a test object having a high voltage output.

In order to achieve such a problem, the invention according to claim 1 of the present invention is:
In a test system for testing an object to be tested that outputs a high voltage pulse signal,
A determination unit that receives the pulse signal to be tested and determines a high level and a low level based on a threshold voltage of a high level and a low level;
A transformer to which the determination result of the determination unit is input;
The output of the transformer is input, and a time measuring unit that measures time by a low voltage signal is provided.

The invention according to claim 2 is the invention according to claim 1,
The judgment part
A first comparator that compares the divided voltage between the output of the test object and the high-level threshold voltage and the common voltage, and outputs the result to the transformer;
A second comparator for comparing the divided voltage between the output of the device under test and the low level threshold voltage with the common voltage and outputting the same to the transformer is provided.

The invention according to claim 3 is the invention according to claim 1 or 2,
A threshold voltage generator for outputting high and low level threshold voltages;
An insulation amplifier that supplies the threshold voltage of the threshold voltage generation unit to the determination unit is provided.

The invention according to claim 4 is the invention according to any one of claims 1 to 3,
An offset voltage generator for outputting an offset voltage is provided as a common voltage of the object to be tested, the determination unit, and the primary winding of the transformer.

The invention according to claim 5 is the invention according to any one of claims 1 to 4,
The object to be tested is a digital amplifier.

The invention according to claim 6 is the invention according to any one of claims 1 to 5,
A DC / DC converter is provided as a power source of the determination unit.

  According to the present invention, the determination unit performs the determination of the high level and the low level of the object to be tested, and gives the determination result to the time measurement unit via the transformer. Therefore, the time measurement can be performed at a low voltage. Accordingly, it is possible to suppress deterioration in accuracy in time measurement.

  According to the fourth aspect, since the common voltage of the primary winding of the test object, the determination unit, and the transformer is given by the offset voltage of the offset voltage generation unit, the determination unit performs the determination based on the low voltage small signal. be able to. In other words, the internal circuit of the determination unit can be configured so as to be able to operate at high speed, and the test can be performed even when the object under test is output at high speed.

  Furthermore, according to the sixth aspect, by providing a DC / DC converter as a power source of the determination unit, the determination unit can be insulated from other circuit parts, and work safety can be ensured. By superimposing an offset voltage on the output system of the DC / DC converter, the signal in the determination unit can be handled as a low voltage small signal, and a high-speed device can be used as a device constituting the determination unit.

  Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the present invention.

  In FIG. 1, DUT 1 is a digital amplifier, for example, and outputs a high voltage pulse signal. A pulse signal of DUT 1 is input to the determination unit 2, and the high level and the low level are determined based on the threshold voltages of the high level and the low level.

  The determination unit 2 includes buffers 21 to 23, comparators 24 and 25, resistors R1 to R4, and silicon diodes D1 to D4. The buffer 21 receives the output of DUT1. The buffers 22 and 23 are inputted with high level and low level threshold voltages, respectively. One end of the resistor R <b> 1 is connected to the output end of the buffer 22. One ends of the resistors R2 and R3 are connected to the output end of the buffer 21. One end of the resistor R <b> 4 is connected to the output end of the buffer 23. The comparator 24 has an inverting input terminal connected to the common voltage, and a non-inverting input terminal connected to the other ends of the resistors R1 and R2. The comparator 25 has an inverting input terminal connected to the common voltage and a non-inverting input terminal connected to the other ends of the resistors R3 and R4. Here, the resistors R1 to R4 have the same resistance value. The silicon diode D1 has an anode connected to the common voltage and a cathode connected to the non-inverting input terminal of the comparator 24. The silicon diode D2 has an anode connected to the non-inverting input terminal of the comparator 24 and a cathode connected to the common voltage. The silicon diode D3 has an anode connected to the common voltage and a cathode connected to the non-inverting input terminal of the comparator 25. The silicon diode D4 has an anode connected to the non-inverting input terminal of the comparator 25 and a cathode connected to the common voltage.

  The transformer 3 is input with the determination result of the determination unit 2 and includes pulse transformers 31 and 32. The output terminals of the comparators 24 and 25 are connected to the primary windings of the pulse transformers 31 and 32, respectively.

  The IC tester 4 includes a time measurement unit 41, threshold voltage generation units 42 and 43, an offset voltage generation unit 44, and the like, and receives the output of the transformer 3. The time measuring unit 41 is connected to the secondary windings of the pulse transformers 31 and 32 and performs time measurement with a low voltage signal. The threshold voltage generators 42 and 43 output high level and low level threshold voltages, respectively. The offset voltage generator 44 provides an offset voltage as a common voltage for the primary windings of the DUT 1, the determination unit 2, and the transformer 3. The isolation amplifiers 5 and 6 receive the outputs of the threshold voltage generators 42 and 43, respectively, and output them to the buffers 22 and 23. As a result, they are insulated as indicated by a dashed line.

  The operation of such an apparatus will be described with reference to FIG. The offset voltage generator 44 applies an offset voltage of 0 to 120 V as a common voltage. The threshold voltage generators 42 and 43 generate voltages having opposite polarities with respect to the determination level of high level or low level. This voltage is output to the determination unit 2 via the insulation amplifiers 5 and 6. The buffers 22 and 23 of the determination unit 2 receive the voltages of the insulation amplifiers 5 and 6 to be constant with respect to load fluctuations, and output them to the comparators 24 and 25 via the resistors R1 and R4, respectively.

  The DUT 1 superimposes the offset voltage when the common voltage is pushed up by the offset voltage of the offset voltage generator 44, and outputs a high voltage pulse signal as shown in FIG. This output is input to the buffer 21 of the determination unit 2, is made constant with respect to the load fluctuation, and is output to the resistors R2 and R3. The voltage at the midpoint between the high-level threshold voltage and the output voltage of DUT 1 is input to the comparator 24 by voltage division of the resistors R 1 and R 2. Similarly, a voltage at the midpoint between the low level threshold voltage and the output voltage of DUT 1 is input to the comparator 25 by voltage division of the resistors R 3 and R 4.

  Each of the comparators 24 and 25 compares with the common voltage, and outputs a high level and low level timing signal to the transformer 3 as shown in FIGS. The pulse transformers 31 and 32 of the transformer 3 input the outputs of the comparators 24 and 25 to the primary side winding and output them to the time measuring unit 41 from the secondary side winding. The time measuring unit 41 measures the time difference between the rise of the output of the comparator 25 and the rise of the output of the comparator 24. Then, the time measuring unit 41 measures the time difference between the fall of the output of the comparator 24 and the fall of the output of the comparator 25. Based on the result of this time measurement, the quality of the DUT 1 is determined.

  In this way, the determination unit 2 determines the high level and low level of the DUT 1 and gives the determination result to the time measurement unit 41 via the transformer 3, so that the determination can be made with a high voltage, and the time measurement can be made with a low voltage. Can be measured. Therefore, accuracy degradation in time measurement can be suppressed. That is, it is possible to accurately determine whether the DUT 1 is good or bad.

  Further, since the common voltage of the primary windings of the DUT 1, the determination unit 2, and the transformer 3 is given by the offset voltage of the offset voltage generation unit 44, the determination unit 2 can perform the determination based on the low voltage small signal. . That is, the internal circuit of the determination unit 2 can be configured to be able to operate at high speed, and the test can be performed even when the DUT 1 outputs a high-speed signal.

  Further, the diodes D1 to D4 are provided to constitute a diode clamp, and the input level to the comparators 24 and 25 can be limited, so that fluctuations in the input signal can be suppressed and the delay time can be suppressed. Therefore, degradation of measurement accuracy can be suppressed.

  Further, the determination unit 2 is mounted on a performance board, a DUT board, or the like outside the IC tester 4 and is exposed to the outside, but since it is insulated, work safety can be ensured.

  In the embodiment, the offset voltage generator 44 is insulated in the IC tester 4, but the present invention is not limited to this. For example, a DC / DC converter may be provided outside the IC tester 4 to generate an offset voltage. The DC / DC converter is configured to simultaneously apply the power supply voltage to the buffers 21 to 23 and the comparators 24 and 25 that constitute the determination unit 2.

  With this configuration, the determination unit can be insulated from other circuit parts, ensuring work safety, and determining by superimposing an offset voltage on the output system of the DC / DC converter. The signal in the unit can be handled as a low voltage small signal, and a high-speed device can be used as a device constituting the determination unit.

It is the block diagram which showed one Example of this invention. 2 is a timing chart showing the operation of the apparatus shown in FIG.

Explanation of symbols

1 DUT
2 Determination unit 24, 25 Comparator 3 Transformer 41 Time measurement unit 42, 43 Threshold voltage generation unit 44 Offset voltage generation unit 5, 6 Insulation amplifier

Claims (6)

In a test system for testing an object to be tested that outputs a high voltage pulse signal,
A determination unit that receives the pulse signal to be tested and determines a high level and a low level based on a threshold voltage of a high level and a low level;
A transformer to which the determination result of the determination unit is input;
A test system comprising: a time measuring unit which receives the output of the transformer and performs time measurement using a low voltage signal. The judgment part
A first comparator that compares the divided voltage between the output of the test object and the high-level threshold voltage and the common voltage, and outputs the result to the transformer;
2. The test system according to claim 1, further comprising: a second comparator that compares a divided voltage of the output of the test target with a low-level threshold voltage and a common voltage and outputs the result to a transformer. A threshold voltage generator for outputting high and low level threshold voltages;
The test system according to claim 1, further comprising: an insulation amplifier that supplies the threshold voltage of the threshold voltage generation unit to the determination unit.   The test system according to any one of claims 1 to 3, further comprising an offset voltage generation unit that outputs an offset voltage as a common voltage of the test target, the determination unit, and the primary winding of the transformer.   The test system according to claim 1, wherein the object to be tested is a digital amplifier. The test system according to claim 1, wherein a DC / DC converter is provided as a power source of the determination unit.

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