JPS6126630B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a circuit for rapidly measuring minute currents such as leakage currents of electronic components.

Measuring how much current flows by applying a constant voltage to an electronic component is often done at the inspection stage of the electronic component manufacturing process, but when the current is a very small value, such as a leakage current, from several nA to several μA. In this case, the resistance for current detection becomes a high resistance of several 100KΩ to several 10MΩ, and the capacitance of the wiring and electronic components is not charged quickly, so the voltage applied to the electronic components does not reach the above-mentioned constant voltage. It takes time to complete the test, making rapid testing impossible. The present invention aims to enable rapid charging by quickly performing tests, and to enable current conduction measurements of a large number of electronic components to be carried out in a short period of time. The electronic component current measuring device of the present invention includes a digital-to-analog converter that receives a digital setting value that commands the voltage applied to the electronic component and outputs a corresponding analog voltage, and a digital-to-analog converter that amplifies the output voltage of the converter with a high resistance. and an amplifier that applies voltage to the electronic component through wiring, a measurement unit that measures the voltage drop across the high resistance and measures the current flowing into the electronic component, and is connected in parallel to the high resistance to insert and remove it. relay contacts and
The device is characterized by comprising a comparator that compares the output voltage of the converter and the voltage applied to the electronic component and opens the relay contact when the latter becomes equal to the former and generates a measurement command to the measuring section. , which will now be explained in detail with reference to examples.

In the drawings, DUT is an electronic component whose current is to be measured, such as an integrated circuit transistor, diode, etc.
A DAC is a digital-to-analog converter that receives a set value _S1 that numerically commands the voltage to be applied to electronic components, and outputs a corresponding analog voltage _V1 . This voltage of V ₁ is applied to the amplifier AMP.
AMP is an amplifier for impedance conversion,
It receives the voltage V ₁ and outputs the voltage V ₂ so that the voltage V ₃ applied to the electronic component in a steady state becomes equal to V ₁ .

₁ is a force line for supplying current, and ₂ is a sense line for applying feedback to the amplifier AMP. R _M is a high resistor inserted into the face line ₁ for current detection, and V ₃ (= V ₁ ) is applied to the electronic component DUT by these resistors, and the current flowing at that time is accelerated as a voltage drop across the high resistor R _M. , the voltage drop is measured by a measuring section (ADC). R _y2 is the electronic component DUT to be tested (only one is shown in the drawing, but in reality there are many)
The distance from this relay contact to the electronic component DUT is short in the drawing, but in reality it is usually quite long. Therefore, the wiring capacitance (C) of the long force line ₁ , the sense line ₂ , and the capacitance (Cd) of the electronic components are charged through the high resistance R _M when voltage is applied, and the rise of the voltage V ₃ applied to the electronic components is Become slow. It is necessary to wait until the voltage V ₃ reaches the set value S ₁ to measure the current i flowing through the electronic component, which takes time.

The present invention aims to improve this point, and includes a relay contact _Ry1 such as a reed relay that short-circuits the high resistance _R. Set up a container COMP. One input terminal of the comparator COMP is connected to the output terminal of the converter DAC, and the other input terminal is connected to the electronic component via the comparator sense line ₃ .
Connect to the sense line terminal of the DUT.

In this circuit, when the set value _S1 is not applied, the output voltage of each part is zero, as is the output of the comparator COMP, and the relay contact _Ry1 is closed. Therefore, the high resistance R _M is short-circuited, and in this state, when a set value S ₁ is given and the converter DAC outputs a voltage V ₁ obtained by digital-to-analog conversion of the set value, the amplifier AMP receives this and outputs a voltage V 1 . ₂ and the voltage V ₂
is the force line ₁ via the relay contact R _y1
Furthermore, electronic components DUT and
₂ and ₃ . Therefore, due to this voltage V ₂ and the low resistance of the supply path, the force line ₁
and the capacity of the electronic component DUT is rapidly charged. On the other hand, the comparator COMP is the applied voltage of electronic components V ₃
and the output voltage V ₁ of the converter DAC, and the voltage V ₃
When equals V ₁ , it generates a signal S ₂ and opens the relay contact R _y1 . This signal _S2 also serves as a measurement start command to the measurement unit ADC. Relay contact R _y1
When is opened, a high resistance R _M is inserted into the force line ₁ , and the measuring section ADC starts measurement in a stable state. That is, the voltage drop across the high resistance R _M is measured, and the leakage current i is measured from that voltage and the resistance value of the resistance R _M.

According to this current measurement method, during the test, a predetermined voltage is first applied directly to the force line and electronic components through the relay contact without passing through a high resistance, so the ground capacity of the line and electronic components is rapidly charged. The voltage applied to the electronic circuit can be quickly increased to a predetermined value. Additionally, when the voltage applied to the electronic component increases to the measurement voltage specified by the set value _S1 , the comparator operates, the relay contact opens, and a high resistance is inserted, making it possible to measure the current flowing to the electronic component. In this way, it becomes possible to quickly measure minute currents such as leakage currents.

[Brief explanation of the drawing]

The drawing is a circuit diagram showing an embodiment of the present invention. In the figure, DUT is an electronic component, DAC is a digital-to-analog converter, AMP is an amplifier, ADC is an analog-to-digital converter and measurement section, _Ry1 is a relay contact,
COMP is a comparator.

Claims (1)

[Claims] 1 A digital-to-analog converter that receives a digital setting value that commands the voltage applied to electronic components and outputs the corresponding analog voltage, and a digital-analog converter that amplifies the output voltage of the converter and applies the voltage to the electronic components through high resistance and wiring. an amplifier for applying voltage, a measurement unit that measures the voltage drop across the high resistance to measure the current flowing into the electronic component, a relay contact that is connected in parallel to the high resistance to insert and remove it, and the converter. A comparator that compares an output voltage and an applied voltage to the electronic component and opens the relay contact when the latter becomes equal to the former and generates a measurement command to the measuring section. measuring device.