JPH06300813A - Device for measuring element characteristic - Google Patents

Abstract

PURPOSE:To instantaneously respond to modification at the time when amplitude of a test signal of current and voltage for applying on an element to be measured is modified in a device for measuring an element characteristic. CONSTITUTION:A digital waveform data are supplied to DCA 20 from a digital waveform data storing means 100 and a serrate waveform test signal is generated. When the maximum values of current and voltage for applying on an element to be measured 50 are modified on an operation panel 11, the serrate waveform test signal is amplified or attenuated with a multiplier 110 and the digital waveform data responding to a plurality of measuring points need not be calculated again respectively because the amplitude is regulated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an element characteristic measuring apparatus, and more particularly to an element characteristic measuring apparatus capable of observing and measuring without destroying the element even when the characteristic of the element changes sharply.

[0002]

2. Description of the Related Art FIG. 4 is a block diagram of a conventional device characteristic measuring apparatus (parameter analyzer) for measuring a current flowing through a device 50 to be measured when a voltage is applied to the device under test 50. The microprocessor (CPU) 10 puts the digital waveform data which meets the setting conditions according to the measurement item on the bus 5 and sequentially processes the digital-analog converter (DA).
C) Send to 20. The operation panel 11 is used to set the measurement items, and the setting conditions are random access memory (RA
M) 12 is stored. Read Only Memory (RO
M) 13 stores programs and the like processed by the CPU 10. The DAC 20 converts the digital waveform data from the CPU 10 into an analog signal. Amplifier 30
Amplifies this analog signal and applies it to the device under test 50 via the current and voltage detection circuit 40.

In the current / voltage detection circuit 40, the buffer 41 is provided to accurately detect the voltage generated in the device under test 50. The voltage detection analog-digital converter (ADC) 42 converts the signal from the buffer 41 into digital data and sends it to the CPU 10. This digital data corresponds to the voltage value of the device under test 50. The current detection resistor 43 is provided to detect the current flowing through the device under test 50. The current detection amplifier 44 detects the voltage across the current detection resistor 43, and detects the current detection analog-digital converter (ADC) 4
Send to 5. The current detection ADC 45 converts the signal from the current detection amplifier 44 into digital data to convert the signal to the CPU 1.
Send to 0. Since the resistance value of the current detecting resistor 43 is known, the CPU 10 measures the digital value corresponding to the voltage across the resistor 43 and the resistance value data of the resistor 43 using Ohm's law. The current value of the element 50 can be calculated. The resistance value data of the current detection resistor 43 may be stored in the RAM 12 or the ROM 13. By repeating these operations, the CPU 10
Collects all parameter curves. The obtained data may be stored in the RAM 12 and then displayed on the display 60.

FIG. 5 is a block diagram of a conventional device characteristic measuring apparatus for measuring the voltage generated in the device 50 when a predetermined current is passed through the device under test 50. This is because the output voltage of the current detection amplifier 44, which is the voltage across the current detection resistor 43, is input to the inverting input terminal of the operational amplifier 46, while the output voltage of the DAC 20 is input to the non-inverting input terminal of the operational amplifier 46. And the output of the operational amplifier 46 is input to the non-inverting input terminal of the amplifier 30. According to this, D
By controlling the output voltage of the AC 20, the voltage across the current detecting resistor 43 can be controlled. That is, the current flowing through the non-measurement element 50 can be controlled. For example, if the voltage across the current detecting resistor 43 increases, the output voltage of the operational amplifier 46 decreases, and the voltage across the current detecting resistor 43 decreases. On the contrary, if the voltage across the current detecting resistor 43 becomes low, the current detecting resistor 4
It works to increase the voltage between both ends of 3. The current / voltage detection circuit 40 detects the current value and the voltage value of the device under test 50 as described above.

As shown in FIG. 6, the test signal supplied from the DAC 20 to the device under test 50 is preferably a sawtooth waveform having a plurality of steps and a macroscopically predetermined inclination. . This is to collect all parameter curves of the device under test 50. However, the test signal may be a sine wave or other waveforms in some cases. Each stair (step) corresponds to a measurement point, and the device under test 50
The current value and voltage value of are measured. When the amplitude of the sawtooth waveform test signal is set on the operation panel 11, the CPU 10
Is its amplitude (that is, the maximum value of the sawtooth test signal)
Recalculate the values of multiple measurement points according to the
The analog sawtooth waveform test signal output by 20 is changed. Therefore, if the amplitude is changed, the slope of the sawtooth waveform is also changed. CPU10, at each measurement point,
Device under test 5 by digital data from ADC45
The value of the current flowing to 0 is calculated. The number of measurement points may be set arbitrarily.

A semiconductor element having a pn junction such as a diode or a transistor causes a breakdown phenomenon when a certain voltage is reached when the reverse voltage is increased,
The flowing current increases rapidly. FIG. 7 shows that when the collector current Ic of the transistor and the collector-base voltage Vcb reach the voltage Vx, the current value sharply increases and a breakdown phenomenon occurs. Conventionally, when measuring the breakdown voltage of a semiconductor device with a curve tracer, the operator increases the voltage on the operation panel while observing the display, and when the breakdown phenomenon appears, the operation panel is operated to perform the measurement. The maximum voltage (amplitude) applied to the device was reduced. The reason why the maximum voltage is lowered is to prevent destruction of the device under test. In this operation, the curve tracer generates the voltage to be applied to the element to be measured in an analog manner, so that the applied voltage is reduced in response to the operation of the operation panel instantaneously.

[0007]

As described above, the device characteristic measuring apparatus shown in FIG. 4 sends digital waveform data to the DAC 20 and converts the digital waveform data into digital-analog to generate a test signal. ing. Therefore,
When the amplitude is changed by the operation panel, all the measurement points (steps) are calculated and changed. Therefore, when measuring characteristics such as breakdown voltage of a semiconductor device that changes rapidly, unlike a curve tracer, even if the amplitude is changed, the signal applied to the device under test can be instantly changed in response to an operation. could not. Therefore, in the conventional device characteristic measuring device, the current or voltage supplied to the device under test unexpectedly increases, and the device may be destroyed.

Therefore, an object of the present invention is to provide an element characteristic measuring device using a digital circuit, which has a good response to the change when the setting of the current value or voltage value applied to the element to be measured is changed. It is to provide a measuring device. Another object of the present invention is to provide an element characteristic measuring apparatus capable of instantaneously changing the amplitude of a current value or a voltage value applied to a measured element. Still another object of the present invention is to provide an element characteristic measuring device capable of observing and measuring the current value or voltage value applied to the element to be measured in real time.

[0009]

A device characteristic measuring apparatus according to the present invention comprises a storage means 1 for storing digital waveform data of a test signal of voltage or current supplied to a device under test.
00, a digital-analog converter 20 for receiving a digital waveform data and outputting a voltage or current test signal, and a setting means 11 for setting the amplitude of the voltage or current test signal.
And a detection means 40 for detecting the current value or voltage value of the device under test when a test signal of voltage or current is supplied, respectively,
In an element characteristic measuring device having a display device for displaying the characteristic of the device under test, an amplitude adjusting means for adjusting the amplitude of the voltage or current test signal output from the digital-analog converter 20 according to the setting of the setting means 11. It has 110. Thus, the amplitude of the voltage or current test signal can be adjusted according to the setting of the setting unit 11 without changing the digital waveform data stored in the storage unit 100.

The test signal output from the DAC 20 may be applied to the device under test 50 via the amplifier 30 functioning as a buffer. Although the digital waveform data output from the storage means 100 corresponds to a plurality of measurement points, according to the present invention, even when the maximum value of the current value or the voltage value is changed by the setting means 11, the amplitude adjusting means 110 causes the test signal to change. Since the amplitude (maximum value) of is adjusted, it is not necessary to change the digital waveform data corresponding to the plurality of measurement points. Therefore, the maximum value of the test signal applied to the device under test 50 can be changed at high speed.

[0011]

1 shows a block diagram of one preferred embodiment of the device characteristic measuring apparatus of the present invention. The blocks corresponding to those in FIG. 4 are denoted by the same reference numerals. The present invention can be easily applied to the circuit shown in FIG. Therefore,
In the following description, the case where the circuit of FIG. 4 is improved by using the present invention will be mainly described.

Compared with FIG. 4, one of the present invention shown in FIG.
In the preferred embodiment, a digital waveform data storage means 100 and a multiplier (amplitude adjusting means) 110 are newly provided. The digital waveform data storage means 100 includes a DAC 20.
Generates digital waveform data for generating a stepped analog sawtooth waveform test signal. However, the waveform of the test signal is not limited to the sawtooth waveform. A memory (storage means) may be used as the digital waveform data storage means 100, and when the CPU 10 supplies an address, the corresponding digital waveform data may be output. The operation panel (setting means) 11 is a device under test 50.
It is used to set the amplitude (maximum value) of the current or voltage of the test signal applied to the. The multiplier 110 is the CPU 10
Under the control of, the amplitude of the sawtooth waveform test signal from the DAC 20 is amplified or attenuated so that the amplitude of the sawtooth waveform test signal matches the maximum value (amplitude of the test signal) set on the operation panel 11, It is adjusted and supplied to the amplifier 30. The detection circuit (detection means) 40 detects a current value and a voltage value of the device under test 50. The measurement point (step) mentioned here corresponds to each step of the output waveform (test signal) of the DAC 20 shown in FIG. 6, that is, each step.

According to the device characteristic measuring apparatus of the present invention, DA
The digital waveform data for the C20 to output the test signal may be at least one type. When the setting of the maximum value of the current value or the voltage value applied to the device under test 50 is changed, the digital waveform data storage means does not change the digital waveform data supplied to the DAC 20, but the multiplier 1
The amplitude of the test signal is adjusted by amplifying or attenuating the test signal at 10. According to this, it is not necessary for the CPU 10 to calculate the digital waveform data respectively corresponding to the plurality of measurement points each time the maximum value of the test signal is changed, and the amplification or multiplication of the multiplier 110 is simply performed based on the setting of the operation panel. All you have to do is control the damping ratio. This allows the maximum value to be changed quickly. The amplification or attenuation ratio can be easily calculated by comparing the set maximum value with the amplitude of the current test signal.

FIG. 2 shows another embodiment of the present invention. The DAC 20 uses a digital-analog converter such as a ladder resistance circuit (R-2R ladder circuit or the like) that can obtain an analog signal output by multiplying a reference voltage and digital data. The multiplication circuit 110 uses the reference voltages Vr and C
Multiplies the digital data supplied by PU10 and
The reference voltage Vr ′ supplied to 20 is amplified or attenuated with respect to the reference voltage Vr. In proportion to the reference voltage Vr ', the DAC
The amplitude of the sawtooth waveform test signal output by 20 changes.
Therefore, as in the case of FIG. 1, even if the maximum value of the current value or the voltage value applied to the device under test 50 is changed, it is not necessary to change the digital waveform data stored in the digital waveform data storage means 100. . That is, since it is not necessary for the CPU 10 to recalculate the digital waveform data corresponding to a plurality of measurement points, a quick response can be made even when the set value is changed.

FIG. 3 shows still another embodiment of the present invention. This is because a multiplier 110 is arranged between the DAC 20 and the digital waveform data storage means 100, and digital waveform data supplied to the DAC 20 is multiplied,
The amplitude of the sawtooth waveform test signal output from the DAC 20 is adjusted. Also in this case, similarly to the above, it is not necessary to change the digital waveform data stored in the digital waveform data storage means 100. The multiplier 110 used here is different from that shown in FIGS. 1 and 2 only in that the multiplication is performed digitally, and the multiplier 110 amplifies or attenuates the sawtooth waveform test signal output from the DAC 20. Is the same.

Although the device characteristic measuring apparatus of the present invention has been described above, it is easy to apply the present invention to the conventional circuit shown in FIG. For example, considering a circuit corresponding to FIG.
The digital waveform data storage means 100 may be arranged between the CPU 10 and the DAC 20, and the multiplier 110 may be arranged between the operational amplifier circuit 46 and the DAC 20. The same applies to the circuits corresponding to FIGS. 3 and 4. The device under test that can be measured by the device of the present invention is not limited to the semiconductor device. For example, it may be a resistor or a capacitor. Since the device of the present invention has good responsiveness to the setting value changing operation, there is substantially no time lag with respect to the setting value changing operation using the operation panel. Therefore, the electrical characteristics of various elements can be observed and measured in real time.

[0017]

The device characteristic measuring apparatus of the present invention can change the digital / analog converter (DA) when the set value of the maximum value of the current value or the voltage value applied to the measured element is changed.
It is not necessary to recalculate the digital waveform data corresponding to the plurality of measurement points of the test signal output by C), and the amplitude of the test signal output by the DAC is adjusted using the amplitude adjusting means (multiplier). Therefore, even when the setting value is changed on the operation panel, it is possible to respond to the changing operation at high speed. As a result, when measuring the characteristics of the device under test, there is virtually no time lag with respect to the operation of changing the set value.Therefore, although it is a device that uses digital processing, it can be used like an analog curve tracer. It is possible to observe and measure the characteristics of the device under test in real time. Therefore, even when the characteristics change sharply, it is possible to avoid destruction of the element.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of an element characteristic measuring device of the present invention.

FIG. 2 is a block diagram showing another embodiment of the device characteristic measuring apparatus of the present invention.

FIG. 3 is a block diagram showing still another embodiment of the device characteristic measuring apparatus of the present invention.

FIG. 4 is a block diagram of a conventional example of an element characteristic measuring device.

FIG. 5 is a block diagram of another conventional example of the device characteristic measuring apparatus.

FIG. 6 is a diagram showing a waveform of a test signal output from a DAC.

FIG. 7 is a diagram showing an example of characteristics of a semiconductor element.

[Explanation of symbols]

 10 CPU 11 Operation Panel (Setting Means) 12 Random Access Memory 13 Read Only Memory 20 Digital-Analog Converter 30 Amplifier 40 Characteristic Detection Circuit (Detection Means) 50 Measured Element 60 Display Device 100 Storage Means 110 Amplitude Adjustment means

Claims (1)

[Claims] 1. Storage means for storing digital waveform data of a voltage or current test signal supplied to a device under test, and a digital-analog converter for receiving the digital waveform data and outputting the voltage or current test signal. A setting means for setting the amplitude of the voltage or current test signal, a detecting means for detecting the current value or the voltage value of the device under test when the voltage or current test signal is supplied, and the detecting means. An element characteristic measuring device having a display device for displaying the characteristic of the measuring element, wherein an amplitude adjusting means for adjusting the amplitude of the test signal of the voltage or current output from the digital-analog converter according to the setting of the setting means. The test signal of the voltage or current according to the setting of the setting means without changing the digital waveform data stored in the storage means. Element characteristic measuring device, wherein the width adjustable to.