JPH09243715A - Method of measuring voltage of integrated circuit device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the influence by GND connection resistance and VCC connecting resistance which are common impedances, and perform a precise inspection. SOLUTION: A voltage measuring equipment 12 and a first current source 13 are connected to the first terminal 5 of an integrated circuit device 1, a second current source 14 is connected to a second terminal. 6 of the integrated circuit device 1, and the total sum of current values of the first and second current sources 13, 14 are set constant to measure the voltage of the first terminal 5. Thus, the error voltage generated in a common impedance 9 or 10 is constant, the error voltage before and after input or load current change can be ignored, and a precise inspection can be performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voltage measuring method capable of highly accurately measuring the electrical characteristics of an integrated circuit device having a large current output terminal for a SCSI terminator or the like, and particularly the output impedance.

[0002]

2. Description of the Related Art In recent years, electrical characteristic tests of integrated circuit devices have been
It has come to be implemented in automatic measuring instruments equipped with a controlling computer. Hereinafter, a conventional voltage measuring method for an integrated circuit device will be described.

FIG. 3 is a circuit diagram showing a measuring device of an integrated circuit device. In FIG. 3, reference numeral 1 is a semiconductor integrated circuit to be measured (hereinafter referred to as “device to be measured”). Reference numeral 2 is a ground terminal of the device under test 1 (hereinafter referred to as "ground terminal"). 3
Is the power terminal of the device under test 1 (hereinafter referred to as "power terminal")
It is. Reference numeral 4 is an input terminal of the device under test 1. Reference numerals 5 and 6 are output terminals of the device under test 1, which usually have a current driving capability up to about several tens of mA and have substantially the same electrical characteristics. Reference numeral 7 is a ground of the measuring device (hereinafter referred to as "ground"). Although not shown, 8 is a power supply terminal (hereinafter, referred to as “power supply”) that supplies electric power for operating the device under test 1. Reference numeral 9 denotes a resistance distributed and attached to the ground connection line, which connects the ground terminal of the device under test 1 and the ground 7. Reference numeral 10 denotes a resistor distributed and attached to the power supply connection line, which connects the power supply terminal 3 of the device under test 1 and the power supply 8. Reference numeral 11 denotes a variable voltage source that generates a voltage with the ground as a reference potential, and is connected to the input terminal 4 of the device under test 1. Reference numeral 12 is a voltage measuring device that measures a voltage with the ground being a reference potential, and is connected to the output terminal 5 of the device under test 1. Reference numeral 13 is a variable current source that generates a current with reference to the ground, and is connected to the output terminal 5 of the device under test 1.

FIG. 4 is an SCS for concrete explanation.
It is a circuit diagram of the output part of the semiconductor integrated circuit for I terminators. Normally, it has two or more output terminals, but for convenience of description, two output terminals will be described.

When the transistor 30 is not operating,
A current path is formed from the power supply terminal 3 to the terminal 5 via the transistor 21 and the resistor 16. Similarly, when the transistor 31 is not operating, a current path is formed from the power supply terminal 3 to the terminal 6 via the transistor 22 and the resistor 17. The values of the resistors 16 and 17 are set to around 110Ω. Further, resistors 18 and 19 having a relatively high value of about several KΩ are connected in parallel to the resistors 16 and 17 for the purpose of lowering the impedance when viewed from the power source side from the terminals 5 and 6. By setting the value of the variable voltage source 11 near the power supply voltage and operating the transistors 30 and 31, the resistance 1
It is possible to pass a current through 8 and 19 to lower the impedance when the power supply terminal 3 side is viewed from the terminal 5 or 6.

A voltage measuring method for the semiconductor integrated circuit configured as described above will be described. Device under test 1 is SCS
A semiconductor integrated circuit that drives a large current, such as an I terminator, and the case of measuring the output impedance of the output terminal 5 will be described.

For concrete description, it is assumed that the output impedance of the terminals 5 and 6 is designed to be 100Ω. As an example, currents of 5 mA and 15 mA are drawn from the terminal 5, the voltage for each current value is measured by the voltage measuring device 12, and the output impedance is obtained by performing arithmetic processing with the changed voltage and current value. Here, in the case of drawing a current and measuring a voltage, first, the variable current source 13
To draw a current of 5 mA and measure the voltage of the terminal 5.
Next, a current of 15 mA is drawn from the terminal 5 and the voltage of the terminal 5 is measured. The output impedance of terminal 5 is
It is given by dividing the voltage fluctuation value of 1 by the current fluctuation value of the terminal 5.

[0008] Here, it is desired that the manufacturing variation of the impedance as viewed from the side of the power source terminal 3 from the terminal 5 or 6 is about 5% or less, and in the measurement of the impedance, the variation can be accurately measured. Required.

[0009]

However, in the above-mentioned conventional configuration, voltage fluctuations occur in the ground connection resistance 9 and the power supply connection resistance 10, which are common impedances, in response to changes in the amount of current supplied from the variable current source 13. There is a problem that voltage fluctuations occur in the ground connection resistance 9 and the power supply connection resistance 10, which are common impedances, and the generated voltage gives an error voltage to the terminal 5, so that highly accurate voltage measurement cannot be performed. Specifically, when a current is drawn from the output terminal 5, a voltage fluctuation occurs in the power supply terminal 3 due to the product of the resistance value of the power supply connection resistor 10 and the current value drawn from the output terminal 5. Current value drawn from terminal 5 is 5 m
A and 15 mA, assuming that the resistance value of the power supply connection resistor 10 is 10 Ω, the difference in the amount of current drawn is 10 mA and the resistance value 1
From the product of 0Ω, a voltage difference of 100 mV occurs at the power supply terminal 3 before and after the current value changes. The voltage difference generated at the power supply terminal 3 becomes a voltage error in the measurement at the output terminal 5. The output impedance of the terminal 5 is 100Ω, and the product 100 mV of 10Ω and 10 mA with respect to the product 1000 mV of the difference in the amount of current drawn and 100Ω causes a 10% error in the measurement of the voltage of the output terminal 5.

On the contrary, when a current is applied to the output terminal 5 to measure the output impedance, a voltage rise occurs in the ground connection resistance 9 or the power supply connection resistance 10.

The variable voltage source 1 supplied from the input terminal 4
When the input voltage of 1 changes, the amount of current generated inside the semiconductor integrated circuit 1 to be measured changes, so that voltage fluctuations occur in the ground connection resistor 9 and the power supply connection resistor 10, which are common impedances, Since the generated voltage gives an error voltage to the terminal 5, there is a problem that highly accurate measurement cannot be performed.

The resistance value of the power supply connection resistance or the ground connection resistance that determines the measurement accuracy is not fixed, but may have a higher impedance due to equipment routing, etc., and under such equipment, a larger measurement error may occur. May occur.

The present invention solves the above-mentioned conventional problems, and provides a voltage measuring method of a semiconductor integrated circuit which corrects an error voltage generated in a connection resistance and enables accurate voltage measurement of a terminal to be measured. The purpose is to provide.

[0014]

In order to achieve this object, a voltage measuring method for an integrated circuit device according to claim 1 of the present invention comprises a voltage measuring device and a voltage measuring device at a first terminal of an integrated circuit device to be measured. One current source is connected, a second current source is connected to the second terminal of the integrated circuit device, the sum of the first and second current values is made constant, and the voltage of the first terminal is It has a measuring method.

According to a second aspect of the present invention, there is provided a voltage measuring method for an integrated circuit device comprising: a first transistor of a differential amplifier circuit in which a current source is connected to a common emitter at a first terminal of the integrated circuit device to be measured. And a voltage measuring device are connected, and a collector of a second transistor of the differential amplifier circuit is connected to a second terminal of the integrated circuit device, and the first and second
The method has a method of measuring the voltage of the first terminal by changing the base voltage of the transistor of.

According to a third aspect of the present invention, in a voltage measuring method for an integrated circuit device, a first transistor of a differential amplifier circuit in which a current source is connected to a common source is connected to a first terminal of the integrated circuit device to be measured. Connected to the drain of the second transistor of the differential amplifier circuit to the second terminal of the integrated circuit device, and the gate voltages of the first and second transistors are made different. , A method of measuring the voltage at the first terminal.

According to a fourth aspect of the present invention, in a voltage measuring method for an integrated circuit device, a voltage measuring device and a first current source are connected to a first terminal of the integrated circuit device, and a second terminal of the integrated circuit device is connected. A second current source connected to the second current source to store the current value of the power supply terminal or the ground terminal due to the circuit operation inside the integrated circuit device; and the step of calculating the difference current between the stored current value and the first current value. And a step of supplying from a second current source, the first
And a method of measuring the voltage at the first terminal with the sum of the current values of the second current source being a constant value.

According to the method of the present invention, the sum of the currents flowing in the common impedance is always kept constant with respect to the change in the current applied to the measurement terminal of the integrated circuit device or the change in the current generated inside the integrated circuit device. The error voltage generated at the measurement terminal can be made constant, and the output impedance value obtained by calculating from the voltage value measured before and after the input voltage or the current flowing at the measurement terminal changes and the changed current value. It can be measured with high accuracy.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a circuit diagram showing a voltage measuring method for an integrated circuit device. In FIG. 1, 1 to 13 are the same as conventional ones. Further, 14 is a variable current source for generating a constant current with reference to the ground, and the device under test 1
Connected to the output terminal 6 of the variable current source 13 and increasing the current of the variable current source 13 with respect to a predetermined reference current value, a current obtained by subtracting the increased amount is generated and the current of the variable current source 13 is decreased. , Generates a current with a decrement added. A voltage measuring method for the integrated circuit device configured as described above will be described.

In the case of drawing a current and measuring the voltage, first, a current of 5 mA is drawn from the variable current source 13 and the voltage of the terminal 5 is measured. At the same time as drawing the current from the terminal 5, a current of 15 mA is drawn from the terminal 6. next,
A current of 15 mA is drawn from the terminal 5 and the voltage of the terminal 5 is measured. At the same time as drawing current from terminal 5, draw 5 mA from terminal 6. The output impedance of terminal 5 is given by dividing the voltage fluctuation value of terminal 5 by the current fluctuation value of terminal 5. Here, the sum of the current values of the terminals 5 and 6 contributes to the sum of the current values flowing through the power supply connection resistor 10, and the sum of the current values is constant at each voltage measurement. From the above, the voltage value of the power supply terminal 3 is constant without being influenced by the resistance value of the power supply connection resistance, and the voltage of the terminal 5 is measured under the constant power supply voltage value.

Next, in the case of applying a current to measure the voltage, first, a current of 5 mA is applied from the variable current source 13 and the voltage of the terminal 5 is measured. A current is applied from the terminal 5 and at the same time, a current of 15 mA is applied from the terminal 6. Next, terminal 5
15 mA current is applied to measure the voltage at terminal 5.
A current of 5 mA is applied from the terminal 6 at the same time as the current is applied from the terminal 5. The output impedance of terminal 5 is given by dividing the voltage fluctuation value of terminal 5 by the current fluctuation value of terminal 5. Here, the sum of the current values of the terminals 5 and 6 contributes to the sum of the current values flowing through the ground connection resistance 9, and the sum of the current values is constant at each voltage measurement. From the above, the voltage value of the terminal 2 is constant without being affected by the resistance value of the ground connection resistance, and the voltage of the terminal 5 is measured under the constant ground terminal voltage value.

Further, the current value of the power supply 8 for each voltage applied to the input terminal 4 of the device under test 1 is stored, and the current value supplied from the power supply 8 is always constant with reference to a predetermined current value. By drawing the current from 6, the voltage of the power supply terminal 3 is always constant. Next, the voltage of the terminal 5 is measured while keeping the sum of the current value drawn from the terminal 5 and the current value drawn from the terminal 6 constant. Even in this state, the voltage value of the power supply terminal 3 remains constant. Terminal 5 in the above measurement
The output impedance of the terminal 5 can be obtained from the ratio between the voltage fluctuation value and the current fluctuation value of.

As described above, according to the present embodiment, the current of the current source is varied while keeping the total amount of output current supplied to the integrated circuit device constant, and the ground connection resistance 9 which is a common impedance, and Since the error voltage due to the power supply connection resistor 10 becomes constant, highly accurate voltage measurement can be performed.

FIG. 2 is a circuit diagram showing a measuring device and a voltage measuring method for an integrated circuit device according to the second embodiment.

In FIG. 2, 1 to 12 are the same as those in FIG. Reference numeral 15 denotes a differential amplifier circuit, which is the device under test 1
Connected to the output terminals 5 and 6 of the constant current source 18, the output current of which the total current amount is constant is changed by the voltage sources 19 and 20 and applied to the output terminals 5 and 6. The difference from the configuration of FIG. 1 is that the variable current sources 13 and 14 are connected to the differential amplifier circuit 15.
To the output transistor 1 of the differential amplifier circuit 15.
That is, the collectors 6, 17 are connected to the output terminals 5, 6 of the device under test 1. Here, the bipolar transistor may be replaced with a MOS transistor.

A method of measuring the voltage of the integrated circuit device configured as described above will be described. First, power is supplied from the power supply 8 to the device under test 1. Next, a signal voltage is applied from the variable voltage source 11 to the input terminal 4. Next, the result is output to the output terminal 5 according to the input signal given from the variable voltage source 11. An output current is applied to the output terminals 5 and 6 from the differential amplifier circuit 15 according to the output situation. Next, the electrical characteristics are measured by the voltage measuring device 12. Next, the voltage sources 19 and 20 inside the differential amplifier circuit 15 are varied to increase or decrease the current supplied to the output terminals 5 and 6. Next, the electrical characteristic is measured by the voltage measuring device 12, and the electrical characteristic is measured by calculating the measurement result before the variation and the measurement result after the variation of the differential amplifier circuit 15.

As described above, according to the present embodiment, the total amount of output current supplied to the integrated circuit device is made constant by the constant current source 18 of the differential amplifier circuit 15, and the current of the current source is varied. As a result, the error voltage due to the ground connection resistance 9 and the power supply connection resistance 10, which are common impedances, becomes constant, and the error voltage can be corrected by calculating the measured values before and after the output current change, and the accurate electrical characteristics can be obtained. Can be measured.

In the first embodiment, two variable current sources provided to the integrated circuit device to be measured are used for description, but the total current amount supplied to the integrated circuit device is kept constant while the current is kept constant. If the current of the source is variable, three or more may be used.

Further, in the second embodiment, the variable voltage sources 19 and 20 of the differential amplifier circuit 15 are described as the DC signal source, but they are replaced with the AC signal source and the transistor 1 is used.
The circuit configuration may be such that the phases of the outputs of 6 and 17 are inverted and the total current amount is constant, and even if a combination of three or more sets of differential amplifier circuits is used, when the phase differences are combined, the total If the circuit configuration is such that the amount of current is constant, the same action and effect can be produced.

[0031]

As described above, according to the present invention, the voltage measuring device and the first current source are connected to the first terminal of the integrated circuit device,
A second current source is connected to a second terminal of the integrated circuit device, a total sum of current values of the first and second current sources is made constant, and further, a power supply by a circuit operation inside the integrated circuit device. A step of storing a current value of the terminal or the ground terminal; and a step of supplying a difference current between the stored current value and the first current value from a second current source, the first and second currents An excellent voltage measuring method for an integrated circuit device capable of stabilizing the voltage of the power supply terminal or the ground terminal and accurately measuring the voltage of the first terminal by setting the sum of the current values of the sources to a constant value. It can be realized.

[Brief description of drawings]

FIG. 1 is a diagram showing a voltage measuring method for an integrated circuit device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a voltage measuring method for an integrated circuit device according to a second embodiment of the present invention.

FIG. 3 is a diagram showing a voltage measuring method of a conventional integrated circuit device.

FIG. 4 is a circuit diagram of a semiconductor integrated circuit output unit for a SCSI terminator.

[Explanation of symbols]

 1 device under test (integrated circuit device for device under test) 2 ground terminal (ground terminal for device under test 1) 3 power supply terminal (power supply terminal for device under test 1) 4 input terminal for device under test 5, 6 Output terminal of device 1 7 Ground (ground of measurement device) 8 Power supply 9 Ground connection resistance 10 Power supply connection resistance 11 Variable voltage source 12 Voltage measuring instrument 13 Variable current source 14 Variable current source 15 Differential amplifier circuit

Claims (4)

[Claims] 1. A voltage measuring device and a first current source are connected to a first terminal of the integrated circuit device, and a second terminal of the integrated circuit device is connected.
A voltage of the integrated circuit device is characterized in that a second current source is connected to a terminal of the integrated circuit device, the sum of current values of the first and second current sources is made constant, and the voltage of the first terminal is measured. Measuring method. 2. The first terminal of the integrated circuit device is connected with the collector of the first transistor of the differential amplifier circuit in which the current source is connected to the common emitter and the voltage measuring device, and the second terminal of the integrated circuit device is connected. An integrated circuit characterized in that the collector of a second transistor of the differential amplifier circuit is connected to a terminal, the base voltages of the first and second transistors are made different, and the voltage of the first terminal is measured. Method of measuring voltage of equipment. 3. The first terminal of the integrated circuit device is connected to the drain and the voltage measuring device of the first transistor of the differential amplifier circuit in which the current source is connected to the common source, and the second terminal of the integrated circuit device is connected. An integrated circuit characterized in that the drain of the second transistor of the differential amplifier circuit is connected to a terminal, the gate voltages of the first and second transistors are made different, and the voltage of the first terminal is measured. Method of measuring voltage of equipment. 4. A voltage measuring device and a first current source are connected to a first terminal of the integrated circuit device, and a second terminal of the integrated circuit device is connected.
Connecting a second current source to the terminal of the integrated circuit device to store the current value of the power supply terminal or the ground terminal by the circuit operation inside the integrated circuit device; and a difference current between the stored current value and the first current value. Is supplied from a second current source, and the total voltage value of the first and second current sources is set to a constant value, and the voltage at the first terminal is measured. Method of measuring voltage of equipment.