JPH06235752A - Characteristic measuring method - Google Patents

Abstract

PURPOSE:To make possible quick and accurate measurement of the characteristics of an element over a wide range from microcurrent to high current by switching the waveform of current or voltage to be fed to the element to be measured from stepped waveform to pulsating waveform depending on a predetermined current value or voltage value. CONSTITUTION:A predetermined current value or a voltage value is previously inputted from a keyboard or the like to a CPU 10. The CPU 10 sets a stepped output voltage mode according to a program stored in a memory 12. An I/O control 14 increases the amplitude of voltage and begins to output a stepped voltage from a voltage source 16. The CPU 10 then makes a decision whether the current value measured for an element 22 or the supply voltage value exceeded a predetermined level. When the predetermined level is not exceeded, the element 22 is measured continuously otherwise a switching is made to pulsating output voltage mode. The voltage source 16 feeds a pulsating waveform to the element 22 through a range setting section 20 and a current measuring section 18 measures the current flowing through the element 22. This method allows wide range measurement of the characteristics of the element 22 by only one time measurement.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a characteristic measuring method capable of accurately measuring the characteristic of a device in a wide current range from a very small current to a large current.

[0002]

2. Description of the Related Art When measuring the characteristics of a device under test, the voltage or current waveform supplied to the device under test is usually a stepped waveform 30 as shown in FIG. 6 or a pulsed waveform as shown in FIG. Waveform 32 is used. Then, the current value or voltage value at each supply voltage or supply current is measured. Only one of the stepped waveform 30 and the pulsed waveform 32 is supplied as the voltage waveform or the current waveform in one measurement.

[0003]

However, taking the characteristic measurement of the diode as an example, when the stepwise waveform 30 is used for the measurement in a large current region, the device under test generates heat and the measurement can be performed accurately. Absent. Further, when the pulse-shaped waveform 32 is used, the thermal influence in the large current region is reduced, but the influence of the charging current to the equivalent parallel capacitance 36 as shown in FIG. Equally accurate measurements cannot be made. It should be noted that the charging current to the equivalent parallel capacitance 36 can be neglected in the measurement in the large current region because the current to the diode 34 becomes relatively large. Therefore, conventionally, there has been a troublesome matter that the measurement with the step-shaped waveform 30 and the measurement with the pulse-shaped waveform 32 have to be performed, and then the two measurement results have to be combined and analyzed. FIG. 9 shows an example of VI characteristics. The characteristic curve 38 is the measurement result in the step mode, and the characteristic curve 40 is the measurement result in the pulse mode. During the measurement with the pulse-shaped voltage waveform 32, the current measured in the minute current region is shifted to the larger side due to an error due to the charging current to the equivalent parallel capacitance. Further, in the measurement with the step-shaped waveform voltage 30, the current measured in the large current region is shifted to the larger side due to the thermal effect.

Therefore, an object of the present invention is to provide a characteristic measuring method capable of quickly and accurately measuring a wide current region from a small current to a large current by one measurement.

[0005]

According to the present invention, in order to solve the above problems, an arbitrary current value or voltage value is determined in advance by an input device such as a keyboard or a CPU. A stepwise voltage or current is output in a region smaller than a predetermined value, and a pulsed voltage or current is output in a region exceeding the predetermined value, so that a single measurement can be performed in a wide current range. Can be accurately measured.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, a characteristic measuring apparatus using the characteristic measuring method of the present invention will be described with reference to FIG. The CPU 10 is connected to a host computer, a keyboard or the like (not shown in the figure). A program for performing measurement is stored in the memory 12. The input / output control 14 includes a voltage source 16, a current measuring unit 18, and a range setting unit 2
They are connected to 0 respectively. The voltage source 16 is the device under test 2
2 is connected in series to generate a voltage to be supplied to the device under test 22. The current measuring unit 18 is connected in series with the device under test 22 and measures the current flowing through the device under test 22. The range setting unit 20 sets the current range of the current measuring unit.

FIG. 1 is a flow chart illustrating the present invention. Each step is controlled or processed by the CPU 10 according to a program stored in the memory 12. Figure 1 below
Referring to FIG. 3 together with FIG.
The CPU 10 receives an instruction from the host computer, keyboard or the like, and sets the output to the step voltage mode according to the program stored in the memory 12. In step 51, the voltage amplitude is increased and the output of the stepped voltage is started from the voltage source 16 through the input / output control 14. In step 52, the current value flowing from the current measuring unit 18 to the device under test is sent to the CPU. In step 54, the measured current value or the supply voltage value is previously set to CP.
It is determined whether the value is less than or exceeds the value calculated by U or the value input from the keyboard. If not, the process returns to step 51 and the output voltage waveform from the voltage source 16 is as shown in FIG.
The waveform becomes step-like as shown in, and if it exceeds,
Proceeding to step 56, the output is set to pulsed voltage mode. In step 57, the voltage amplitude is increased, and the voltage source 16 outputs the pulsed waveform 32 as shown in FIG. In step 58, the current measuring section 16 measures the current flowing through the device under test. In step 59, it is judged whether or not the supply voltage value or the measured current value exceeds the measurement range. If it does not exceed the measurement range, the process returns to step 57, and if it exceeds, the measurement ends. Therefore, the entire output waveform of the voltage source 16 is stepwise below a predetermined supply voltage value or measured current value as shown in FIG. 5, and continuous in a pulsed state above a predetermined supply voltage value or measured current value. The waveform 42 is obtained.

FIG. 4 is a block diagram of the current output / voltage measurement of the characteristic measuring method of the present invention. The same parts are designated by the same reference numerals. Operation will now be described in conjunction with the flow chart of the present invention of FIG. 2, in step 60 the output is set to step current mode. In step 61, the current amplitude is increased, and the current source 26 starts outputting the step-shaped current waveform 30. In step 62, the voltage measuring unit 28 measures the voltage value. In step 64, when the output current value of the current source 26 or the voltage value measured by the measuring unit 28 is less than or equal to a predetermined value, the process returns to step 61 again, and the stepwise current waveform 30 as shown in FIG. 6 is output. When the output current value or the measured voltage value exceeds a predetermined value, the process proceeds to step 66 and the pulse current mode is set. In step 67, the voltage amplitude is increased and a pulsed output current waveform 32 as shown in FIG. 7 is output. In step 69, it is judged whether or not the supplied current value or the measured voltage value exceeds the measurement range. If not exceeded, the process returns to step 67, and if exceeded, the measurement ends. Therefore, the entire output waveform of the current source 26 is a step-like pattern below a predetermined output current value or a measured voltage value as shown in FIG. 5, and a pulse-like continuous waveform above a predetermined output current value or a measured voltage value. The waveform 42 is obtained.

In the above embodiment, the control may be performed not by the CPU 10 but by the hardware sequencer. The device under test may be a passive device or an active device. Further, needless to say, in measurement from a large current to a minute current or a large voltage to a minute voltage, it is clear that the supply waveform changes from a pulse waveform to a step waveform.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the embodiments described herein, and various modifications and changes can be made as necessary without departing from the gist of the present invention. It will be apparent to those skilled in the art that changes can be made.

[0011]

According to the characteristic measuring method of the present invention, since the waveform supplied to the device under test is switched from the step-like waveform to the pulse-like waveform, a small current (small voltage) to a large current (large voltage). It is possible to measure quickly and accurately in a wide area.

[Brief description of drawings]

FIG. 1 is a flow chart according to the present invention.

FIG. 2 is a flow chart according to the present invention.

FIG. 3 is a configuration block diagram showing an embodiment of a characteristic measuring apparatus using the characteristic measuring method of the present invention.

FIG. 4 is a configuration block diagram of another embodiment of the characteristic measuring apparatus using the characteristic measuring method of the present invention.

FIG. 5 is an output waveform diagram of a voltage source or a current source according to the characteristic measuring method of the present invention.

FIG. 6 is a waveform diagram of a step-like waveform.

FIG. 7 is a waveform chart of a pulse-like waveform.

FIG. 8 is an equivalent circuit diagram of a diode as an example of a device under test.

FIG. 9 is a diagram showing an example of a measurement result based on a step waveform and a measurement result based on a pulse waveform.

[Explanation of symbols]

 10 CPU 12 memory 14 input / output control 16 voltage source 18 current measuring unit 20 range setting unit 22 device under test

Claims (2)

[Claims] 1. In a characteristic measuring method of supplying a voltage to a device under test and measuring a current flowing through the device under test, the voltage supplied to the device under test or the current flowing through the device under test is predetermined. A characteristic measuring method characterized in that a step-like voltage is supplied when the value is equal to or less than the predetermined value, and a pulse-like voltage is supplied when the value exceeds the predetermined value. 2. In a characteristic measuring method of supplying a current to a device under test and measuring a voltage generated in the device under test, the current supplied to the device under test or the voltage generated across the device under test is A characteristic measuring method characterized in that a stepwise current is supplied when the value is a predetermined value or less, and a pulsed current is supplied when the value exceeds the predetermined value.