JPH01262483A - Testing device for semiconductor integrated circuit - Google Patents

Abstract

PURPOSE:To decide whether a tested IC is normal or not correctly by converting a detected voltage which is converted from the source current of the IC into a digital signal, sampling this output with time and calculating its mean value, and deciding whether or not the mean value is within a reference range. CONSTITUTION:The power circuit of an IC tester consists of a D/A converter 12 and a current voltage amplifying circuit 13 and sends out a digital signal to the converter 12 under the control of a control part 11. The converter 12 converts the digital signal into an analog signal, which is amplified by the circuit 13 to apply a prescribed voltage to the power terminal of the IC 14 to be tested. The source current of the IC 14 is nearly equal to a current which flows through a resistance for current detection and the resistance for current detection converts this current into a voltage. An operational amplifier 19 detects this voltage, which is converted by a D/A converter 16 into the digital signal at the timing of a strobe signal and sent out to a digital signal processing processor DSP 17. The control part 11 judges whether or not the power source mean current is within the reference range for a DSP 17 within a constant time.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a test bag for semiconductor integrated circuits (IC).
In particular, it relates to a power source rIL style test device.

[Conventional technology]

Used for testing semiconductor integrated circuits (IC). General I
When testing power supply current with a C tester, a DC voltage of a predetermined magnitude is applied from the power supply circuit of the IC tester to the power supply terminal of the IC, the power supply current is passed through the current detection resistor, and the voltage between the resistor terminals is Is voltage the basis for judgment? F! By comparing the voltage with an analog comparator, it was determined whether the IC power supply current was within the standard or outside the standard.

By the way, when measuring the power consumption of a 0MO5IC, a pulse is applied to the gate, so the power supply current is not a constant direct current, but fluctuates periodically. Therefore, the power supply current is normally smoothed in a pseudo manner using a smoothing capacitor, and this smoothed current is measured as the power supply average current.

An overview of the above test apparatus and method will be explained with reference to FIGS. 5 to 7.

FIG. 5 is a block diagram of a test device for measuring the power supply average current using an IC tester, and FIGS. 6 and 7 are specific circuits of the main parts enclosed by dotted lines in FIG. 5. In Figure 6,
Combine capacitor GO in parallel with current detection resistor R5,
't! The current flowing through the iL detection resistor Rs is smoothed to give a pseudo average current. In FIG. 7, a resistor R1 and a capacitor C1 are provided on the output side of a voltage detection circuit 5' for smoothing. Both have the same effect on smoothing the power supply current. The conventional example will be explained below with reference to the case shown in FIG. 6.

When testing the average current of the power supply current of the IC under test 4 (hereinafter referred to as the power supply f average current), the control unit 1 first sends a digital signal to the D/A converter 2 (hereinafter referred to as DAC), and
AC2 converts the digital signal into an analog signal and outputs it.
The current is amplified by the current/voltage amplification circuit 3 and applied to the power supply terminal of the IC under test 4. In order to obtain the average power supply current flowing through the IC under test 4, in the current-voltage conversion circuit 30 connected to the output of the operational amplifier 8 in the current-voltage amplification circuit 3, the current ro flowing through the current detection resistor Rs is connected to the smoothing capacitor CO. The current Io is smoothed by the operational amplifier 9 in the voltage detection circuit 5.
The voltage across the current detection resistor R5 generated by the current detection resistor R5 is detected.

Next, the determination circuit 6 uses an analog comparator (not shown) included in this circuit to convert the detected voltage value and the voltage value generated under the control of the control unit 1 as a reference for determination into a strobe signal STB. Compare the IC under test at the timing of
It is determined whether Tj and source average current of No. 4 are within or outside the standard, and the result is sent to the control unit l.

[Problem to be solved by the invention]

Figure 8 shows an example of measuring the average power supply current of an IC using the device shown above. Figure 8 shows the actual power supply current flowing through the TC4 under test and the smoothed current ( (measured as the power supply average current) is compared with a reference value in the 0 judgment circuit 6 shown in the figure.
When the actual power supply current increases rapidly, the smoothing capacity of the smoothing capacitor CO is not strong enough to keep up with it, and as a result, when the smoothed current exceeds the reference value at time t1, the judgment circuit 6 starts smoothing at this one time t1. It was determined that the current was larger than the reference value, and the result of the determination was sent to the control unit 1, and the control unit 1 received the result and deemed the average power supply current of the IC 4 under test to be defective.

Smoothing by CR is difficult to select the time constant of CR, and C
If R is increased, it will be less likely that the current will be determined to be larger than the above-mentioned reference value, but only a value smaller than the true power supply average current ix will be obtained.

The purpose of the invention is to provide a test device that determines the pass/fail of an IC under test by calculating the average power supply current from the actual power supply current using arithmetic means, rather than calculating the average power supply current by smoothing. It is about providing.

[Means to solve the problem]

The test device of the present invention includes a current-voltage conversion circuit that converts the power supply current of an IC into a voltage using a current detection resistor, a voltage detection circuit that outputs the voltage as a detection voltage, and an A that converts the detection voltage into a digital signal. /D converter and the A/D converter;
A digital signal processing processor that samples the output of the D converter over time and calculates an average value from the sampled values; and a digital signal processing processor that receives the calculated data of the digital signal processing processor and determines whether the average power supply current of the IC is within a standard. It has a control section that makes a pass/fail judgment based on whether or not it is acceptable.

[Effect]

The current-voltage conversion circuit uses only a current detection resistor and converts the current as a voltage drop across the resistor, so there is no time lag.

Since the output of the voltage detection circuit is sampled and each sampled value is integrated and averaged by a high-speed digital signal processor, the true average power supply current can always be obtained.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of a first embodiment of the present invention, and a second embodiment of the present invention.
゛The figure shows the specific circuit of the part surrounded by the dotted line in Figure 1.
11 is a control unit, 12 is a D/A converter (DAC), and 12 is a D/A converter (DAC).
), 13 is a current/voltage amplification circuit, 14 is an IC under test, 15
is a voltage detection circuit, 16 is a D/A converter (ADC), 17
is a digital signal processing processor (DSr), 3OA is a current-voltage conversion circuit, 18.19 in FIG. 2 is an operational amplifier, and Rs is a 'y current detection resistor. That is, the current-voltage conversion circuit 3OA does not perform smoothing but only performs current-voltage conversion. Further, the voltage detection circuit 15 is also the same as the voltage detection circuit 5 in FIG. 5, and does not perform smoothing.

The power supply circuit of the IC tester is composed of a DAC 12 and a current/voltage amplification circuit 13, and under the control of the control section 11, the DAC
12, the DAC 12 converts the digital signal into an analog signal, and sends it to the current/voltage amplification circuit 13. The current/voltage amplification circuit 13 converts the digital signal to an operational amplifier 18.
The analog signal is amplified and a predetermined voltage is applied to the power supply terminal of the IC 4 under test. The power supply current of the IC under test is approximately equal to the current I flowing through the current detection resistor R5 connected to the output of the operational amplifier 18 in the current/voltage amplification circuit 13.
The current detection resistor R5 converts this current ■ into a voltage, and
The operational amplifier 19 in the rL pressure detection circuit 15 detects the voltage, and the ADC 16 converts the analog signal representing the voltage value into a digital signal at the timing of the strobe signal.
Send to DSP17. The DSP 17 converts the digital signal into a strobe signal, takes it in, and performs arithmetic processing such as integration of the digital signal. The control unit 11 requests the DSP 17 to send out the power supply average current value after a certain period of time. The DSP 17 divides the data calculated by a by the number of samples, calculates the power supply average current, and sends it to the control unit 11.
The control unit 11 determines whether the power supply average current is within the standard.

3 and 4 are configuration diagrams of a second embodiment of the present invention,
16' in Fig. 3 is the A/D conversion unit 1-n group (ADCI-
n), 20 is Memo 1) Circuit 1-n group, A-DC
i, memory circuit i, and strobe signal i form one set i (i=1 to n).

FIG. 4 shows the timing relationship of strobe signals 1-n. The processing up to the voltage detection circuit 15 is the same as in the first embodiment, and to explain the processing content for one set i, the ADCi converts the analog signal at time point i into a digital signal at the timing of the strobe signal i, and converts it into a digital signal in the memory circuit. i
The memory circuit i stores the digital signal one by one. The same process is performed for the other set i. D
The SP 17 receives the request signal for the power supply average current sent from the control unit 11, integrates all the data in the memory circuits 1-n group 20, takes the quotient by all the sampling numbers of the strobe signals 1 to n, and calculates the power supply average. The current value is determined and sent to the control unit 11, and the control unit 11 determines the current value and sends it to the control unit 11. Source average current value power (judge whether it is within the standard or not.

The first embodiment described above is a method for roughly determining the power supply average current in terms of relative accuracy, whereas the second embodiment shows a method for determining the power supply average current with high accuracy.

〔Effect of the invention〕

As explained above, the test device of the present invention can obtain the fluctuating average current value of the power supply without using CR like the conventional test device.
Smooth the power supply current that fluctuates depending on the circuit and use the smoothed current as the power supply average! Instead of converting the actual power supply current into voltage with a current detection resistor, the voltage detection circuit detects the voltage, and after the A/D change, samples it and uses a high-speed digital signal processing processor. By integrating the sampling values over time and dividing them,
This measures the true average current value of the power supply.

Therefore, regardless of the type of variation in the power supply current, this measurement has the effect of correctly determining whether the IC is good or defective.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of the first embodiment of the present invention, Fig. 2 is the main part of Fig. 1, Fig. 3 is a block diagram of the second embodiment, and Fig. 4 is the timing of the strobe signal in Fig. 3. FIG. 5 is a waveform diagram and a configuration diagram of a conventional example. FIG. 6: JS7 is the main part of FIG. 5, and FIG. 8 is a diagram for explaining problems when testing the average current of the power supply according to the conventional example. 11... Control unit, 12... D/A converter,
13... Current voltage amplification circuit. 14... IC under test115... Voltage detection circuit, 16
... A/D converter, 16'... A/D converter group, 17... Digital signal processing processor, 20...
Memory circuit group. 3OA...Current voltage conversion circuit. Patent applicant: NEC Corporation Agent Susumu Uchihara, patent attorney Figure 1 Figure 2 Figure 2 λ-n group Figure 4 Strobe buoy f4 -'-m-'--l--1-1'L
--"-strophe (mago strike O-)i"JLf'm- and-JLL (++2
+=+. ) ='1flfL-i-111fL
L-1 diagram 5 for i-j

Claims (1)

[Claims] In measuring the average power supply current of a semiconductor integrated circuit (IC) when the power supply current fluctuates periodically, a current-voltage conversion circuit converts the IC power supply current into a voltage using a current detection resistor, and the voltage is used as a detection voltage. A voltage detection circuit that outputs and an A/D converter that converts the detected voltage into a digital signal.
a D converter; a digital signal processor that samples the output of the A/D converter over time and calculates an average value from the sampled values; and a digital signal processor that receives the calculated data of the digital signal processor; 1. A test device comprising: a control section that determines pass/fail based on whether the average current is within a standard.