JPH11211791A - Lsi tester - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an LSI tester capable of exact measurement by making exact impedance matching in the power source system of a measuring circuit. SOLUTION: A DC power source 2 of the LSI tester and a power source terminal 11 of a DUT 1 are connected through a coil 3, and the power source terminal 11 and a ground terminal 12 are connected through a resistor 4. The resistor 4 is set sufficiently lower than the impedance of the coil 3. Namely, impedance matching is performed by the resistor 4 and the coil 3, and no capacitor having a frequency dependent impedance is not used in the circuit. Thus, the frequency dependency of the characteristic impedance is eliminated, reflections are prevented and the exact measurement of a high frequency current can be performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an LSI tester, and in particular, applies a predetermined signal to a signal input terminal while supplying DC power from a DC power supply to a power supply terminal of an LSI to be measured and appears at a signal output terminal. The present invention relates to an LSI tester that tests the LSI by using a signal.

[0002]

2. Description of the Related Art In an electronic circuit, it is necessary to perform impedance matching. In a circuit that does not perform impedance matching, signal reflection occurs and the circuit may not operate normally. In particular, since the power supply system is involved in the operation of all signal systems, careful impedance matching is required.

FIG. 5 schematically shows an example of a circuit for such impedance matching. An impedance matching circuit of an LSI tester having a function of performing impedance matching of a power supply system of an LSI operating at a high frequency and accurately testing the LSI. This is an example.

In FIG. 5, a power supply terminal 1 of a DUT (DEVICE UNDER TESTING) 1 as an LSI to be measured is shown.
1 and the ground terminal 12, an impedance element (Z1
) 8 and a voltage dividing circuit of the impedance element (Z2) 9 to supply a DC voltage from the DC power supply 2. Reference numeral 5 denotes a power supply line. Where DUT
It is desirable that the impedance seen from one side be sufficiently smaller than the impedance seen from the power source 2 side.

[0005] Therefore, as shown in FIG.
The capacitor 7 is used as the impedance element (Z1) 8 and the solenoid coil 3 is used as the impedance element (Z2) 9 to achieve impedance matching.

[0006]

What matters here is the frequency characteristic of the capacitor 7. A capacitor generally has a frequency characteristic as shown in FIG. Here, since currents of various frequencies usually flow through the power supply line 5, even if one decoupling capacitor 7 is inserted, it is not possible to cope with all frequencies and impedance matching cannot be achieved. .

Therefore, generally, curves 71 to 74 in FIG.
Although there is a method of connecting capacitors having different frequency characteristics from each other in parallel to make the impedance substantially constant, in practice, it is not possible to obtain the ideal characteristic shown by the one-dot chain line 76 in FIG. Impossible. This is because the number of capacitors that can be connected in parallel is limited,
This is because the characteristics shown in FIG.

[0008] Further, the frequency characteristics of the capacitor are not constant due to variations at the time of manufacture, and therefore, there may be a case where matching cannot be accurately performed even at a target frequency. For the above reasons, the impedance matching of the measurement circuit in the LSI tester cannot be accurately performed.

An object of the present invention is to provide an LSI tester capable of performing accurate measurement with accurate impedance matching in a power supply system of a measurement circuit.

[0010]

According to the present invention, a predetermined signal is applied to a signal input terminal while supplying DC power from a DC power supply to a power supply terminal of an LSI to be measured and appears at a signal output terminal. LS that tests the LSI with a signal
An I tester, wherein an impedance element provided between a power supply terminal of the LSI and a supply terminal of the DC power supply is compared with an impedance of the impedance element provided between a power supply terminal and a ground terminal of the LSI. Characterized by having a resistance element having a sufficiently small value.
An I tester is obtained.

Further, according to the present invention, a predetermined signal is supplied to a signal input terminal while a DC power from a DC power supply is supplied to a power supply terminal of an LSI to be measured, and a signal appearing at a signal output terminal is used for the LSI. An LSI tester for performing the test described above, wherein a voltage drop due to an alternating current flowing through the LSI is provided between a power supply terminal of the LSI and a supply terminal of the DC power supply, as compared with a DC voltage supplied to the LSI. An impedance element having a sufficiently large value;
I provided between a power terminal and a ground terminal of the I.
And a resistance element having a value such that a voltage drop caused by an alternating current flowing through the resistor is sufficiently smaller than a DC voltage supplied to the LSI.

The impedance element is a choke coil, and the impedance element is a resistance element.

Further, the resistance element provided between the power supply terminal and the ground terminal comprises a coaxial cable having a predetermined specific impedance and terminated with a terminating resistor equal to the specific impedance. The coaxial cable is characterized by having a plurality of parallel connection configurations, and furthermore, a resistance element provided between the power supply terminal and the supply terminal of the DC power supply has a predetermined intrinsic impedance. It is characterized by comprising a coaxial cable terminated with a terminating resistor equal to the intrinsic impedance.

The operation of the present invention will be described. By adopting a configuration in which impedance matching is realized not by a capacitor having a frequency characteristic but by a resistance element, the frequency dependence of impedance is reduced and impedance matching can be performed at any frequency. By setting the impedance to a value sufficiently smaller than the impedance of the impedance element connected between the power supply terminal of the LSI and the supply terminal of the DC power supply, the circuit operation becomes more ideal. It should be noted that the current consumption increases by reducing the resistance value of the resistance element, but the problem of the current consumption is negligible because of the LSI tester.

[0015]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a circuit diagram of an embodiment of the present invention, which is an impedance matching circuit of a power supply system of an LSI tester. In FIG. 1, the same parts as those in FIGS. 5 and 6 are denoted by the same reference numerals. Power is supplied from the DC power supply 2 to the DUT 1 to be inspected. In this case, impedance matching of the power supply system is performed by the solenoid coil 3 and the resistance element 4. That is, the resistance element 4 is connected between the power supply terminal 11 and the ground terminal 12 of the DUT 1, and the power supply terminal 1
The coil 3 is connected between the power supply 1 and the supply terminal of the DC power supply 2. The ground terminal 12 of the DUT 1 and the negative side of the DC power supply 2 are common.

In this case, the resistance value of the resistance element 4 is set sufficiently smaller than the impedance of the coil 3. For example, the impedance is preferably set to 1/100 or less of the impedance of the coil 3. In other words, the resistor 4 is connected between the power supply terminal 11 and the ground terminal 12 of the DUT 1 such that the voltage drop due to the alternating current flowing through the DUT 1 is sufficiently smaller than the DC voltage supplied to the DUT 1. On the other hand, between the power supply terminal 11 and the supply terminal of the DC power supply 2, the coil 3 having an impedance value such that the voltage drop due to the AC flowing through the DUT 1 is sufficiently larger than the DC voltage supplied to the DUT 1.
Are connected.

Since the impedance of the resistor 4 does not have such a large frequency dependence as a capacitor, the dashed line 7 in FIG.
As shown in FIG. 6, almost ideal frequency characteristics are exhibited. At this time, the power consumption is larger than that of the conventional example, but in the case of an LSI tester, the magnitude of the power consumption does not matter so much, and the effect of the application of the present invention is large.

In FIG. 1, a DUT 1 operating at a high speed
The impedance viewed from the side is only the resistance value of the resistor 4. As described above, the impedance of the resistor 4 has an extremely small frequency dependency as compared with the capacitor, and the impedance of the resistor 4 is sufficiently smaller than that of the coil 3. Close to characteristics. Therefore, impedance matching can be performed for all frequencies, and the measurement of a high-frequency current can be accurately performed while suppressing signal reflection.

FIG. 2 is a diagram showing another embodiment of the present invention, and the same parts as those in FIG. 1 are denoted by the same reference numerals. In this example, a plurality of coaxial cables 41 are used as the resistor 4 in FIG.
44 and the terminating resistors 45-48. These coaxial cables 41 to 44 have predetermined specific impedances, and each has a terminating resistor 45 to 48 equivalent to the specific impedance for impedance matching.

One end of each core wire of the coaxial cables 41 to 44 is commonly connected to the power supply terminal 11 of the DUT 1, and the other end of each core wire is grounded via terminating resistors 45 to 48, respectively.
It is assumed that the respective coated wires of the coaxial cables 41 to 44 are grounded.

As a result, a plurality of coaxial cables are connected in parallel, and the impedance between the power supply and the ground (Z1 in FIG. 5) viewed from the DUT 1 is changed to the impedance (Z2 in FIG. 5) inserted into the power supply line 5. Can be made sufficiently smaller than. For example, by terminating a coaxial cable having a specific impedance of 50Ω with a resistor of 50Ω and connecting 100 of them, the impedance viewed from the DUT 1 side becomes 50Ω / 100 = 0.5Ω.

The impedance Z1 can be finely adjusted by changing the number of the coaxial cables.

An advantage of using a coaxial cable is that it is easy to design considering impedance. In other words, when designing the impedance matching circuit with the circuit configuration of FIG. 1, it is necessary to design in consideration of the parasitic inductance of the lead wire added to both ends of the resistance element.
On the other hand, in the circuit shown in FIG. 2, since impedance matching is performed by terminating the coaxial cable, it is only necessary to design in consideration of only the impedance of the terminating resistor.

In the above example, the impedance element inserted between the power supply terminal 11 and the supply terminal of the DC power supply 2 (power supply line 5) is the solenoid coil 3, but may be a resistance element. An example is shown in FIG. 3, and the same parts as those in FIG. In FIG. 3, a resistor 6 is used in place of the coil 3 of FIG. 1, and the other configuration is the same as that of FIG.

In this case, the impedance of the resistor 4 is set sufficiently smaller than that of the resistor 6. Further, since the voltage applied to the power supply terminal 11 of the DUT 1 is smaller than the voltage of the power supply 2, the voltage of the power supply 2 needs to be set higher.
Assuming that the operating voltage of the DUT 1 is 2 V, the resistance 6 is 50Ω, and the resistance 4 is 0.5Ω, the voltage applied to both ends of the DUT 1 is 1/100 of the voltage of the DC power supply 2. It is necessary to set to 200V.

Further, the coil 3 shown in FIG. 2 can be constituted by a resistor, and this resistor can be constituted by a coaxial cable and a terminating resistor. FIG. 4 shows a circuit in this case (in the case of being constituted by a coaxial cable and a terminating resistor), and the same parts as those in FIG. 2 are denoted by the same reference numerals. In FIG. 4, a resistive element, which is an impedance element inserted between the power supply terminal 11 and the supply terminal of the DC power supply 2 (power supply line 5), is constituted by a coaxial cable 61 and a terminating resistor 62.

That is, one end of the core wire of the coaxial cable 61 is connected to the supply terminal of the power supply 2, and the other end is connected to the terminating resistor 62.
And the power supply line 5 (the power supply terminal 11 of the DUT 1) via the coated wire. Of course, the terminating resistor 62 has a resistance value equivalent to the intrinsic impedance of the coaxial cable 61. The specific impedance of the coaxial cable 61 is set sufficiently larger than those of the coaxial cables 41 to 44 connected between the power supply line 5 and the ground.

When a coaxial cable 61 having a specific impedance of 50Ω is used, a terminating resistor 62 having the same resistance value is used. Further, since the voltage applied to the power supply terminal 11 of the DUT 1 is smaller than the voltage of the power supply 2, the voltage of the power supply 2 needs to be set higher, as in the previous example.

[0030]

As described above, according to the present invention, since the resistance element is used instead of the capacitor having the frequency characteristic for impedance matching, the frequency dependency is reduced, and Since the impedance of the power supply seen from the DUT side is small, there is an effect that the impedance of the power supply system in the tester can be accurately matched for all operating frequencies.

[Brief description of the drawings]

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

FIG. 2 is a circuit diagram of another embodiment of the present invention.

FIG. 3 is a circuit diagram of still another embodiment of the present invention.

FIG. 4 is a circuit diagram of another embodiment of the present invention.

FIG. 5 is a schematic diagram of an impedance matching circuit.

FIG. 6 is a diagram illustrating an example of a conventional impedance matching circuit.

FIG. 7 is a diagram illustrating an example of a characteristic of frequency versus impedance of a capacitor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 DUT (LSI) 2 DC power supply 3 Solenoid coil (choke coil) 4,6 Resistance element 5 Power supply line 7 Capacitor 11 Power supply terminal 12 Ground terminal 41-44,61 Coaxial cable 45-48,62 Terminating resistance

Claims (8)

[Claims] 1. A method according to claim 1, wherein a predetermined signal is supplied to a signal input terminal while a DC power from a DC power supply is supplied to a power supply terminal of an LSI to be measured, and a signal appearing at a signal output terminal is applied to the LSI.
An LSI tester for testing an SI, comprising: an impedance element provided between a power supply terminal of the LSI and a supply terminal of the DC power supply; and an impedance element provided between a power supply terminal and a ground terminal of the LSI. An LSI tester having a resistance element having a value sufficiently smaller than the impedance of the element. 2. A method according to claim 1, wherein a predetermined signal is supplied to a signal input terminal while supplying DC power from a DC power supply to a power supply terminal of an LSI to be measured and a signal appearing at a signal output terminal is used to control the LSI.
An LSI tester for performing an SI test, wherein a voltage drop caused by an alternating current flowing through the LSI is provided between a power supply terminal of the LSI and a supply terminal of the DC power supply, compared with a DC voltage supplied to the LSI. An impedance element having a value that is sufficiently large and provided between a power supply terminal and a ground terminal of the LSI, and a voltage drop caused by an alternating current flowing through the LSI.
And a resistance element having a value sufficiently smaller than a DC voltage supplied to the LSI tester. 3. The LS according to claim 1, wherein the impedance element is a choke coil.
I tester. 4. The LSI tester according to claim 1, wherein said impedance element is a resistance element. 5. The LSI tester according to claim 1, wherein a resistance value of the resistance element provided between the power supply terminal and the ground terminal is variable. 6. A resistive element provided between the power supply terminal and the ground terminal comprises a coaxial cable having a predetermined specific impedance and terminated with a terminating resistor equal to the specific impedance. An LSI tester according to claim 1. 7. The LSI tester according to claim 6, wherein said coaxial cable has a plurality of parallel connection configurations. 8. A resistive element provided between the power supply terminal and the supply terminal of the DC power supply is formed of a coaxial cable having a predetermined specific impedance and terminated with a terminal resistance equal to the specific impedance. The LSI tester according to claim 4, wherein: