JPH04242179A - Dc characteristic measuring apparatus - Google Patents

Abstract

PURPOSE:To enable the shortening of testing time by inserting an arithmetic logic between an analog/digital comparator and a judging logic with a register and a subtraction logic cascade connected. CONSTITUTION:This DC characteristic measuring apparatus has an analog/ digital comparator 2 which inputs a characteristic detection value of a semiconductor integrated circuit to perform a digital comparison and a judging logic 8 which inputs a digital conversion signal of the analog/digital comparator 2 to judge the acceptance thereof. An arithmetic logic 4 which has a cascade circuit of a register 5 to record a digital conversion signal in a range setting a timing of an analog/digital conversion set and a subtraction logic 6 which performs a subtraction between the digital conversion signal at a specified timing and an output signal of the register 5 before a specified time to output the digital conversion signal by a differentiation judgment when a subtraction value is below a specified value is inserted between an analog/digital comparator 2 and a judging logic 8. The DC characteristic measuring apparatus thus obtained advances the final judging time automatically thereby enabling the shortening of testing time.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC characteristic measuring instrument.

0002

[Prior Art] As shown in FIG. 3, the determining section of a conventional DC characteristic measuring instrument that measures DC characteristics that take time to stabilize, such as that of an IC, is based on an analog signal measured by a measuring unit. The DC voltage that stabilizes after changing is converted into a digital value by an analog-digital comparator (hereinafter referred to as ADC) 2 after the detection value S1 has passed a set determination time, and the digital value S2 and the limit value S9 are converted into a digital value by the determination logic 8. A pass/fail signal P/F is output.

As shown in FIG. 4, the determination time T at this time is generally set at a time ts at which the detected value S1 becomes stable, based on circuit design and experimental data. In the case of the example shown in FIG. 4, the determination time T is 8 ms, at which point AD conversion is performed by the ADC 2, and the resulting detected value of 4.0 V is subject to pass/fail determination. Although voltage is used as an example here, the DC characteristic I
The same applies when C is the current characteristic.

0004

[Problems to be Solved by the Invention] Conventional DC characteristic measuring instruments have a sufficient judgment timing so that, for example, when measuring the DC characteristics of an IC, the judgment can be made at a point where the detected value, which changes in an analog manner, is sufficiently stable. Since the waiting time is set as a condition and occupies a large proportion of the overall test time, there is a problem in that it takes time to measure the IC.

[0005]

[Means for Solving the Problems] The DC characteristic measuring device of the present invention includes an analog-to-digital comparator that inputs a detected DC characteristic value of a semiconductor integrated circuit and performs a digital comparison, and a digital conversion device for the analog-to-digital comparator. In a DC characteristic measuring instrument that has a judgment logic that inputs a signal and makes a pass/fail judgment, there is a register that records the digital conversion signal within a range in which the timing of analog-to-digital conversion is set, and a register that records the digital conversion signal at a predetermined timing and a predetermined value. The analog-to-digital comparator includes an arithmetic logic having a cascade circuit with a subtraction logic that subtracts the output signal of the register from the previous time and performs a differential judgment to output the digital conversion signal when the subtracted value is less than or equal to a predetermined value. It is configured by inserting it between the and judgment logic.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be explained with reference to the drawings. FIG. 1 is a block diagram of a measurement unit according to an embodiment of the present invention, and FIG. 2 shows a determination timing chart for explaining the operation of the block. An arithmetic logic 4 in which a register 5 and a subtraction logic 6 are connected in cascade is inserted between the ADC 2 and the determination logic 8 of the conventional measurement unit shown in FIG.

Next, the operation of the block will be explained. For example, at a judgment time of 3 ms after the start of the test, the detected value S1 = 3.8
V is input to ADC2, S2=3.8V is taken into register 5 of arithmetic logic 4, and then at a predetermined timing of 1 m.
AD convert S1 = 4.0V 4ms after s, and convert S2 value 4.0V at that time to 1m held in register 5.
When 0.2V, which is the difference between S2 = 3.8V before s, is smaller than 0.1V of the calculation limit S7, it is not detected as a saturation value, and the next 1ms later, when S1 = 4.0V for 5ms, the previous value is Since the difference between the
is saturated, input S1 = 4.0V to the logic 8 as the calculation output S6 = 4.0V, and compare it with, for example, the judgment limit S9 of 5.0V to determine the DC detection value S1.
Pass/fail is performed as digital judgment P/F. Then move on to the next measurement item.

That is, here, 1m of the DC detection value S1
Logic 4 calculates the saturation state as the change amount for s decreases.
The detected value S1 at the time when saturation is determined by differential determination by
has been selected for pass/fail judgment.

[0009]

Effects of the Invention As explained above, the DC characteristic measuring device of the present invention automatically advances the final judgment time, which is different from the conventional DC characteristic measuring device.
Test time can be reduced compared to C characteristic measuring instruments.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of one embodiment of the present invention.

FIG. 2 is a determination timing chart for explaining the operation of the blocks in FIG. 1;

FIG. 3 is a block diagram of an example of a conventional DC voltage measuring device.

FIG. 4 is a determination timing chart for explaining the operation of the blocks in FIG. 3;

[Explanation of symbols]

S1 DC voltage measurement detector 2 ADC 4 Arithmetic logic 5 Register 6. Subtraction logic 8 Judgment logic S3 ADC trigger S7 Calculation limit S9 Judgment limit

Claims (1)

[Claims] 1. An analog/digital comparator that inputs a DC characteristic detection value of a semiconductor integrated circuit and performs a digital comparison, and a judgment logic that inputs a digital conversion signal of the analog/digital comparator and makes a pass/fail determination. In the DC characteristic measuring device, a register records the digital conversion signal within a set range of analog-to-digital conversion timing, and subtracts the digital conversion signal at a predetermined timing and the output signal of the register a predetermined time ago. A DC characterized in that an arithmetic logic having a cascade circuit with a subtraction logic that performs differential judgment and outputs the digital conversion signal when the subtraction value is less than a predetermined value is inserted between the analog-digital comparator and the judgment logic. Characteristic measuring instrument.