JPH06109810A - Device and method for inspecting device - Google Patents

Abstract

PURPOSE:To judge whether the difference signal obtained by differentially comparing a reference signal of an arbitary level subjected to time sharing in synchronous relation to a clock with the output signal of a device to be inspected is within a standard range in a dyamic state synchronous to the clock within a real time with relative accuracy by an N-value comparator. CONSTITUTION:A device 1 to be inspected, an arbitrary waveform generator 5 and an N-value comparator 3 are synchronously driven through a clock generator 6 and a reference signal is applied to the device to be inspected from the arbitrary waveform generator 5. The output value of the device 1 to be inspected and the reference signal of the arbitrary waveform generator 5 are differentially compared and the obtained difference signal is applied to an N- value comparator 3 and it is judged whether the difference signal is within a specific standard range.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inspection apparatus and inspection method for devices such as IC and LSI.

[0002]

2. Description of the Related Art In recent years, inspection devices for ICs, LSIs, etc.
Along with the progress of high speed, large scale, and high precision of C / LSI, an inspection method that can inspect accurately, in a short time, and at low cost is desired. In particular, for an active matrix analog operational amplifier type liquid crystal display (LCD) driver LSI having a sample and hold circuit, a technique for measuring and inspecting an output voltage level with high accuracy in a short time has become important.

The LCD of the conventional LCD driver LSI of the analog operational amplifier type for active matrix is described below.
A device inspection device and inspection method will be described by taking a case where a drive output voltage test is performed as an example.

FIG. 3 shows an L for an active matrix LCD.
It is a block diagram of the conventional inspection apparatus of SI. 1 is a device to be inspected, 3 is a three-valued comparator of H, L, Z, 6 is a clock generator, and 7 is a DC level source (reference voltage source).

FIG. 4 is a circuit diagram showing a conventional inspection state. 1 is a device to be inspected, 10 to 12 are sample and hold circuits corresponding to outputs of Y ₁ to Y _m in the device,
101, 111, 121 are analog switches, 102,
112 and 122 are holding capacitors, 103 and 11
Reference numerals 3 and 123 denote output buffer circuits, 13 denotes a level shifter circuit, 9 denotes a main body of an automatic inspection apparatus, 3 denotes an entire three-valued comparator of H, L and Z, and 30 to 32 are 3 corresponding to respective device outputs. A value comparator, 6 is a clock generator, 7 is a DC reference voltage source, 8 is a DC level measuring device, and 14 and 15 are signal line changeover switches.

The operation of the device inspection method performed by the device inspection apparatus configured as described above will be described below.

In FIG. 4, in the LCD driver LSI ₁ , gradation signals for color display or analog signals of RGB signals are input to C _{1 to} C _n . When a clock signal is input to CLK, a high level pulse is sequentially applied from the level shifter circuit 13 to each of the sample and hold circuits 10 to 12, and the analog signal at that time is held,
Generating a LCD driving voltage from the output Y ₁ to Y _m. The automatic inspection device 9 is a general automatic inspection device for digital LSI (digital tester), in which a device clock is generated from a clock generator 6 and a DC voltage corresponding to an analog signal is generated by a DC level source 7. When driving output Y ₁ from the inspection device 1 to Y _m is input to the automatic inspection device 9 are inputted to each of the three value comparator 30-32, it is determined whether the voltage level of the test standard range. Although omitted in the figure, when the Y output voltage is a high voltage output of several tens of volts and exceeds the input range of the ternary input, the input of the ternary comparator is input by the attenuator before inputting to the ternary comparator 3. Reduce the voltage level to the voltage range. In addition, in order to perform an output current test and an output leak test for measuring the voltage level with high accuracy and for checking the drive capability of the output buffer circuit, the relay switch 15 is connected to the DC measuring device 8 to provide high accuracy. Can be measured and inspected.

[0008]

However, in the above-mentioned conventional inspection method, the voltage of the LCD drive Y output or the like is measured by 3 times.
This is a method of directly measuring with a value comparator, and since the absolute accuracy of the ternary comparator determines the inspection accuracy, a highly accurate ternary comparator is required for each measurement channel. Further, in order to measure a plurality of voltage levels of the LCD drive Y output, it is necessary to change the voltage level of the DC level source 7 every time and also the measurement level of the ternary comparator 3 is changed. Error and variation in the setting time increase the test time. Further, in the method of using a DC measuring device, each measuring channel is switched by a relay switch to measure with the DC measuring device, which requires a long measuring time, which makes it difficult to measure with a device having a short analog signal hold time. Even if it is possible to measure the total amount of time, the entire measurement time is required, the test time is extended, and the test cost is increased. Further, in order to measure with a DC measuring device in a short time, a DC measuring device is required for each measurement channel, so that there is a drawback that it can be measured only with an expensive tester.

Therefore, the present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide a device inspection method and an inspection apparatus capable of performing highly accurate measurement in a short time at a relatively low cost. .

[0010]

To achieve this object, a device inspection apparatus according to the present invention comprises an arbitrary waveform generator for applying a time-divided reference signal to a device under test in synchronization with a clock, and the device under test. A differential comparator that receives the output of the device and the reference signal, and an N-value comparator (an integer of N ≧ 3) that receives the output of the differential comparator and makes a determination in synchronization with the clock. is doing.

Also, the device inspection method of the present invention applies a time-divided reference signal to an inspected device from an arbitrary waveform generator synchronized with a clock, and differentially outputs the output signal of the inspected device and the reference signal. An N-value comparator (an integer of N ≧ 3) that is input to the comparator and is synchronized with the clock determines whether the output value of the differential comparator is within a specified standard range. This is an inspection method for determining a defect.

[0012]

According to this method and structure, the reference signal of an arbitrary level which is time-divided in synchronism with the clock is differentially compared with the output signal of the device under test, and the difference signal is an N-value comparator (N ≧ 3). In a dynamic state synchronized with a clock (integer), it is possible to perform inspection with high accuracy and in a short time in order to determine in real time whether or not it is within the standard range with relative accuracy.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a device inspection apparatus according to the first embodiment of the present invention. In FIG. 1, 1 is a device under test, 2 is a differential comparator, 5 is an arbitrary waveform generator synchronized with a clock, 3 is a ternary comparator synchronized with the clock, and 6 is a clock generator.

FIG. 2 is a circuit diagram of an embodiment of the present invention. 1
Is a device to be inspected, Y ₁ to Y _m are LCD drive Y outputs, C ₁
To C _n are input terminals for color display gradation signals or analog signals of RGB signals, CLK is a clock input terminal,
10-12 are sample and hold circuits, 101, 11
1, 121 are analog switches, 102, 112, 12
Reference numeral 2 is a holding capacitor, 103, 113 and 123 are output buffer circuits, and 13 is a level shifter circuit. Four
Is an automatic inspection device (digital tester), 2 is the whole differential comparator, and 20 to 22 are the differential comparators for each channel. Reference numeral 3 denotes the entire ternary comparator, and reference numerals 30 to 32 denote ternary comparators for each channel. 41 to 43 are relay switches for switching between the differential comparator output signal and the direct input signal of 2, 5 is an arbitrary waveform generator synchronized with a clock, 6 is a clock generator, 8 is a DC level measuring device, 14, 15 Is a signal line changeover switch.

Regarding the device inspection apparatus and inspection method configured as described above, the LCD of the LCD driver LSI
The inspection of the drive output voltage will be described as an example.

In FIG. 2, the device under test 1 operates in the same manner as that described with reference to FIG. 4, and outputs Y _{1 to} Y _m to L
Generate a CD drive voltage. The automatic inspection device (digital tester) 4 supplies a clock from the clock generator 6 to the device and also supplies a clock to the arbitrary waveform generator 5 and the ternary comparators 30 to 32. Device under test 1
When the drive outputs Y ₁ to Y _m are input to the automatic inspection device 4 from the drive output voltage Y ₁ to the differential comparators 20 to 22, respectively.
~ Y _m are applied, and at the same time, the analog reference signal of the same voltage level supplied to the device under test is supplied to the arbitrary waveform generator 5.
Supplied from The differential comparators 20 to 22 use the voltage change of the sample and hold circuits 10 to 12 of the device as a signal of the difference from the reference signal, and pass through the relay switches 41 to 43, the three-value comparator 30 of H, L, and Z. To 32. Three
The value comparators 30 to 32 are set values between a high level and a low level whose inputs are preset, that is, an expected value "Z".
Whether or not it is within the range can be determined and inspected in the dynamic state at the timing synchronized with the clock.

Further, a DC test such as an output current test or an output leak test for measuring the voltage level with high accuracy or for inspecting the driving capability of the output buffer circuit is performed through the relay switch 15 and the DC measuring device 8 is used. Can measure with high accuracy.

As described above, according to this embodiment, the drive output voltage measurement of the LCD driver LSI 1 is converted by the differential comparator 2 into the voltage difference from the reference analog signal voltage, and the difference voltage is compared in three values. Since the measurement accuracy can be handled with relative accuracy by measuring with a measuring instrument, high-accuracy measurement can be easily realized.
Further, the configuration is such that the voltage of the difference is measured, the clock of the device under test, the arbitrary waveform generator, the differential comparator, and 3
By synchronizing with the value comparator, the judgment standard of the ternary comparator can be made common in all voltage ranges to be measured, and real-time inspection in a dynamic state becomes possible, which is significantly larger than the conventional method. The test time can be shortened. As a result, it is possible to inspect an LCD driver LSI having a short hold time.

In this embodiment, the differential comparators 20-2 are used.
No. 2 does not specifically discuss the presence or absence of an amplification function, but it may have an amplification function in order to measure a smaller difference signal.
Further, in the present embodiment, the LCD drive outputs Y _{1 to} Y _m are directly connected to the differential comparators 20 to 22, but the output voltage level of the device under test is high, and the differential comparator or the automatic inspection apparatus itself. If the input voltage level of 1 is exceeded, an attenuator may be added in order to reduce the voltage to an appropriate voltage level and enable measurement.

Further, in this embodiment, the differential comparison result is judged by the "Z" comparison by the ternary comparator, but a comparator having a ternary level or more may be used. Although the differential comparator is not synchronized with the clock in this embodiment, the differential comparator may have a structure synchronized with the clock when a considerably high-speed clock is used. In this embodiment, the LCD device LSI of the analog operational amplifier type for active matrix is used as the device to be measured. However, not only other devices having a sample and hold circuit, but also a D / A converter and other analogs are provided. It goes without saying that the present invention is also applicable to devices that generate outputs.

[0022]

As described above, the present invention provides a differential comparator,
By providing an arbitrary waveform generator synchronized with the clock supplied to the device and an N-value comparator (an integer of N ≧ 3), the reference signal and the device under test are real-time in a state close to the actual operation of the device. By performing the differential comparison with the output signal, it is possible to realize an excellent device inspection apparatus and inspection method capable of performing highly accurate device inspection in a short time.

[Brief description of drawings]

FIG. 1 is a block diagram of a device inspection apparatus according to an embodiment of the present invention.

FIG. 2 is a block diagram of a detailed device inspection apparatus according to an embodiment of the present invention.

FIG. 3 is a block diagram of a conventional device inspection apparatus.

FIG. 4 is a diagram of a conventional detailed device inspection apparatus.

[Explanation of symbols]

 1 device to be inspected 2 differential comparator 3 3 value comparator 4 automatic inspection device (tester) 5 arbitrary waveform generator 6 clock generator 7 DC level source 8 DC level measuring device 9 conventional automatic inspection device 10-12 samples Hold circuit 13 Level shifter circuit 14, 15 Switch 20-22 Differential comparator 30-32 N-value comparator 41-43 Changeover switch 101, 111, 121 Analog switch 102, 112, 122 Hold capacitor 103, 113, 123 Buffer circuit

Claims (2)

[Claims] 1. An arbitrary waveform generator that applies a time-divided reference signal to a device under test in synchronization with a clock, a differential comparator that receives an output of the device under test and the reference signal, and the difference. A device inspection apparatus having an N-value comparator (an integer of N ≧ 3) that receives an output of a dynamic comparator and makes a determination in synchronization with the clock. 2. A clock-synchronized arbitrary waveform generator applies a time-division reference signal to a device under test, inputs the output signal of the device under test and the reference signal to a differential comparator, and outputs the clock. A device inspection method for determining whether the device under test is good or defective by an N-value comparator (an integer of N ≧ 3) synchronized with the above, depending on whether or not the output value of the differential comparator is within a specific standard range.