JPH0634705Y2 - IC test equipment - Google Patents

Description

[Detailed Description of the Invention] "Industrial Application Field" This invention relates to an IC tester for testing the DC characteristics of a semiconductor integrated circuit (hereinafter referred to as an IC).

"Prior art" For the DC characteristics test of IC, voltage applied current measurement to test whether a predetermined current flows to a terminal with a known voltage applied, and with a known current applied to the terminal, There are current applied current measurement that tests whether a predetermined voltage is generated at that terminal, and voltage measurement test that tests whether the voltage output from the output terminal of the IC under test has a normal level. .

Conventionally, only one test device for performing these DC tests is provided in one IC test system, and the DC characteristics of the terminal pins are measured one by one while being switched and connected to each terminal pin. Therefore, in the case of an IC with a large number of terminal pins, there is a drawback that the DC characteristic test takes time.

Therefore, it is considered that a simple type DC characteristic test device is provided for each of the terminal pins of the IC, and the DC characteristics of the IC terminal pins are tested at once.

FIG. 2 shows a conventional type direct current characteristic testing device. The simplified DC characteristics test device has two measurement modes, a voltage applied current measurement mode and a voltage measurement mode for measuring the voltage output from the IC under test 1.

In the voltage applied current measurement mode, set the mode selector switches K ₁ and K ₆ to OFF, and select the other mode selector switches K ₂ , K ₃ ,
All the K _7, K ₈ is set to ON.

Under this condition, a known voltage V _i is applied from the DC voltage source 2 to the non-inverting input terminal of the operational amplifier 3, and the output terminal of the operational amplifier 3 is passed through the current detecting resistor 4 and the mode changeover switch K ₃ to detect the IC 1 under test. It gives the voltage V _o to the test pin 1A. This voltage V
_o is fed back to the inverting input terminal of the operational amplifier 3 through the feedback circuit composed of the mode changeover switch K ₂ , the resistor 5 and the mode changeover switch K _8, and even if there is a voltage drop in the current detection resistor 4, V _i = V _The operational amplifier 3 is operated so that it becomes _o, and a known voltage V _o is applied to the pin under test 1A.

In a state in which given a known voltage V _o to the terminal pin 1A of the test IC1, voltage extraction circuit 6 is a current detecting resistor 4
The voltage generated at is taken out and this voltage signal is input to the AD converter 8 through the mode changeover switch K ₇ and the buffer 7.
Current I flowing through IC1 under test with voltage V _o applied
_The structure is such that the value corresponding to _o can be obtained as a digital value.

On the other hand, in the voltage measurement mode, the mode selector switches K ₁ , K ₂ ,
The K ₆ set on and set off the mode selector switch _{K 3, K 7, K 8} . The range changeover switches K ₄ and K ₅ constitute a voltage measurement range changeover switch, and one of them is set to ON.

Terminal pins 1A of the test IC1 in this state acts as example the output terminal, and outputs a voltage V _x, provided to the inverting input terminal of the operational amplifier 9 and the voltage V _x of the mode selector switch K ₂ through a resistor 5 The operational amplifier 9 amplifies the level of the voltage signal to a level at which AD conversion can be performed, and the amplified voltage signal is passed through the mode selector switch K ₆ and the buffer 7 to the AD converter 8
And the voltage measurement value can be obtained as a digital value.

In the DC characteristic test apparatus shown in "Problems to be devised to resolve" Figure 2, the resolution of I connexion voltage measurements made range switching circuit by the operational amplifier 9 and range selector switch K _4, K ₅ Decided. That is, when the maximum measurable voltage value is set to a large value, the voltage measurement resolution becomes poor. That is, there is an inconvenience that a small change in voltage cannot be measured with high resolution.

Mode All changeover switch _{K 1, K 2, K 3} , K 6, K 7, K 8 even conventional shape due to the use of reed relays some drawbacks becomes large.

"Means for solving problems" In this invention, the IC to be tested is measured in the current applied voltage measurement mode.
Connect the series circuit of the buffer and the resistor to the feedback circuit that feeds back the voltage generated at the terminal of the operational amplifier to the inverting input terminal of the operational amplifier, and connect the output terminal of the operational amplifier and the voltage extraction circuit in series via the mode changeover switch. The structure is such that a plurality of connected resistors are connected and the connection point of each resistor connected in series is connected to the inverting input terminal of the operational amplifier through the range change switch.

According to the structure of the present invention, the voltage V _x generated from the IC under test is applied to one end of the resistor connected to the feedback circuit, and the voltage V _i applied from the DC voltage source is applied to the other end.
This is the result that this resistor is given a potential difference (V _x -V _i), the current I _M flows determined by the resistance value of the potential difference (V _x -V _i) and the resistor.

This current I _M flows into the output terminal of the operational amplifier through the range change switch and the resistor connected in series.

Since the resistance value of each resistor is known, the voltage V _x output to the terminal of the IC under test can be known by measuring the voltage value generated in the series circuit of the resistors.

According to this invention, the current I _M flowing in the series circuit of the resistors connected to the output side of the operational amplifier is the resistance value of the resistor connected to the feedback circuit and the potential difference (V _x −V _i ). Therefore, even if the range change switch has an ON resistance, the current I _M does not change due to the ON resistance, and as a result, the range change switch can be replaced with a semiconductor switch.

In this device, a current proportional to the potential difference (V _x −V _i ) applied across the resistor connected to the feedback circuit is passed through a known resistor, the voltage is read, and the voltage output from the IC under test is read. potential by setting from the structure to obtain the V _x be a relatively large value the voltage V _x the value of the voltage V _i which gives a DC voltage source to a voltage close to the expected value of V _x (V _x -V _i )
The value of can be small.

As a result, the voltage capture circuit captures voltage in the high sensitivity range,
Since the voltage can be given to the AD converter, the change in the voltage V _x can be measured in a high sensitivity range. Therefore, the change in the voltage V _x can be measured with high resolution.

"Embodiment" FIG. 1 shows an embodiment of the present invention. The parts corresponding to those in FIG. 2 are designated by the same reference numerals.

In the circuit structure shown in FIG. 1, which operates in the voltage applied current measurement mode, the switch K ₇ is installed on the input side of the voltage extracting circuit 6, the buffer 7 is removed, and the inverting input terminal of the operational amplifier 3 is provided. The circuit structure is exactly the same as that of FIG. 1 except that the buffer 11 is inserted in the feedback circuit for feeding back the voltage of the pin under test 1A.

Therefore, the IC to be tested is fed from the DC voltage source 2 through the operational amplifier 3.
The voltage V _o applied to this terminal 1A
Is fed back to the inverting input terminal of the operational amplifier 3 through the feedback circuit composed of the mode changeover switch K ₂ -buffer 11 -resistor 5, and the voltage V _o given to the terminal 1A by this feedback operation.
_{Operates so} that V _o = V _i , a known voltage is applied to the terminal 1A of the IC under test 1, and the voltage generated in the current detection resistor 4 in this state is taken out via the mode selector switch K _7. AD
The operation in the voltage applied current measurement mode for converting and measuring the value of the current flowing through the terminal 1A is also the same as the conventional one.

Configuration, wherein the invention is in that a analog subtraction circuit 12 for taking out a difference between the output voltage V _x and the voltage V _i of the DC voltage source 2 to be tested IC1 (V _x -V _i). This analog subtraction circuit
12 is an operational amplifier 3 and an output terminal of the operational amplifier 3,
Resistors 13 and 14 connected in series between the voltage extracting circuit 6 and
Resistors 13 and range selector switch K ₄ which connects the connection point 14 to the inverting input terminal of the operational amplifier 3, the resistor 14 and the operational connection points of the switch K ₆ is set to the voltage measurement mode amplifier 3
The switch K ₅ connected to the inverting input terminal of the operational amplifier 3 and the resistor 5 for applying the voltage V _x output from the buffer 11 to the inverting input terminal of the operational amplifier 3.

The analog subtraction circuit 12 operates as follows. The voltage V _x output from the terminal 1A of the IC under test 1 is applied to one end of the resistor 5 through the buffer 11.

The voltage V _i applied to the non-inverting input terminal of the operational amplifier 3 is applied to the other end of the resistor 5. Therefore, the resistor 5 has V _x
A potential difference of −V _i is given. Assuming that the resistance value of the resistor ₅ is R 5, the current will flow through the resistor 5 based on the potential difference (V _x −V _i ).
I _M = (V _x −V _i ) / R ₅ flows.

This current I _M flows into the output terminal of the operational amplifier 3 through the range changeover switch K ₄ or K ₅ . That is, when the range selector switch K ₅ is on, the resist selector switch K ₅ and the resistor
Flows into the output terminal of the operational amplifier 3 is current I _M flowing through 14-13. When the range switch K ₄ is on, the current I _M flows in the order of resistor 5-range switch K ₄ -resistor 13-output terminal of operational amplifier 3.

Here, the current I _M is the potential difference V _x − given to both ends of the resistor 5.
It is determined by V _i and the resistance value R 5 of the resistor ₅ , and the value of the current I _M remains unchanged regardless of which of the range changeover switches K ₄ and K ₅ is turned on.

The voltage extracting circuit 6 extracts the voltage generated at both ends of the resistor 13 or the series circuit of the resistors 13 and 14 by setting the switch K ₆ to ON, and supplies the voltage to the AD converter 8.

The voltage extracted by the voltage extraction circuit 6 is V _M , and the resistor 13
If the resistance values of 14 and 14 are R ₁₃ , R ₁₄ , and the range selector switch K ₄ is on, V _M = − (V _x −V _i ) · R ₁₃ / R ₅ · n where n is the voltage extraction circuit 6 It is the value of the gain.

K ₅ of the range selector switch is in the case of on-V _M = - a _{(V x -V i) · (} R 13 + R 14) / R 5 · n.

V _i is known because it is provided from the DC voltage source 2, and the resistance values R ₅ , R ₁₃ and R ₁₄ of the resistors ₅ , ₁₃ and ₁₄ are also known values. Therefore, the value of the voltage V _x output from the IC under test 1 can be known from the measured voltage value V _M.

Here, even if the range changeover switches K ₄ and K ₅ have ON resistance, the current I _M does not change regardless of which of the range changeover switches K ₄ or K ₅ is turned on.
Thus since it is not the voltage V _M that is affected by the on-resistance of the range selector switch K _4, K ₅ drawn by voltage extraction circuit 6, the range selector switch K ₄ and K ₅ is the ON resistance relatively large semiconductor switches Can be used.

Also, since the switches K ₂ , K ₆ , and K ₇ are also inserted in the circuit in which almost no current flows, even if there is an on-resistance, it does not give an error. Therefore, the switches K ₂ , K ₆ , and K ₇ can be replaced with semiconductor switches.

Furthermore, in the voltage applied current measurement mode, the switch K ₃ is inserted in the circuit through which the current I _o flows, but even if the switch K ₃ has an on resistance, the voltage drop due to this on resistance is
The voltage V _o fed back to the inverting input terminal of the operational amplifier 3 through K ₂ , the buffer 11 and the resistor 5 and applied to the terminal 1A is V _o =
_Operate to become V _i . Therefore, the switch K ₃ can also be replaced with a semiconductor switch having an on-resistance.

“Effect of Device” As described above, according to this device, the voltage V _x output from the IC under test 1 can be measured in addition to the voltage applied current measurement mode. In particular the voltage V _M to be fetched by the voltage extraction circuit 6 in the measurement state of voltage V _x is taken in proportion to (V _x -V _i). Therefore range selector switch in the output voltage V _x is greater value by setting the center value of the expected value of the output voltage V _x of the current voltage V _i which gives a direct voltage source 2 high set to turn on the K ₅ It can be set to the sensitivity range.

As a result, even when the output voltage V _x has a relatively large value, it is possible to measure with high resolution using the high sensitivity range.

Further, since the range changeover switches K ₄ and K ₅ can be replaced with semiconductor switches, all the switches can be replaced with semiconductor switches. Also, the number of switches is
According to the present invention, there were ₇ of K _{1 to} K ₇ , though there were ₈ of K _{1 to} K _8.
Individuals are all right. Therefore, the direct-current characteristic test device can be made compact, and the entire shape can be made compact even if the number of terminals of the IC under test 1 is provided.

In addition, although the example in which the resistors 13 and 14 are provided for the range switching is described above, the number of the resistors is not limited to two, and a larger number of resistors are connected in series to increase the range switching number. Good.

[Brief description of drawings]

FIG. 1 is a connection diagram showing an embodiment of the present invention, and FIG. 2 is a connection diagram for explaining a conventional technique. 1: IC under test, 2: DC voltage source, 3: operational amplifier, 4: current detection resistor, 5: resistor, 6: voltage extraction circuit, 8: AD converter,
_{K 1, K 2, K 3} , K 6, K 7: mode switch, K _4, K _5: Range selector switch, 11: buffer, 12: analog subtraction circuit, 13 and 14: resistors connected in series.

Claims (1)

[Scope of utility model registration request] 1. A DC voltage source for applying a known DC voltage to a non-inverting input terminal of an operational amplifier, and B. A DC voltage source connected in series between the output terminal of the operational amplifier and a terminal pin of the IC under test, A current detection resistor that detects the current flowing from the amplifier to the terminal pin of the IC under test, and C. The voltage applied to the terminal pin of the IC under test is fed back to the inverting input terminal of the operational amplifier and consists of a buffer and a resistor. A feedback circuit composed of a series circuit, D. A voltage extraction circuit that extracts the voltage generated in the current detection resistor via the mode switch and gives it to the AD converter, E. Output terminal of the operational amplifier A plurality of resistors connected in series via the mode selector switch between the input terminals of the voltage extraction circuit, and F. A range in which the connection point of these resistors is selectively connected to the inverting input terminal of the operational amplifier. Switching switch IC test equipment consisting of