JP2003057270A - Voltage-applied current measuring apparatus and semiconductor tester - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a voltage-applied current measuring apparatus realizable by a cheaper circuit arrangement and a semiconductor tester using the same. SOLUTION: The current-measuring apparatus has a floating type current measuring unit 300, having a floating form insulated from a circuit ground GND. The unit 300 is mainly composed of a floating power source, a current detecting resistance, a gain-regulating resistance, an operational amplifier(OPAMP), an DC converter, a series output unit and a photocoupler. The floating power source intended to feed circuits used for the measuring unit 300 with DC powers is an insulated DC power source floating from the circuit ground and is composed of, e.g., light-emitting elements and solar cells.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voltage application current measuring circuit for measuring a current flowing to a load by applying a predetermined voltage to the load. In particular, the present invention relates to a voltage applied current measuring circuit which is applied to a semiconductor test apparatus and supplies a device under test (DUT) with a constant voltage of a predetermined high voltage to measure a load current.

[0002]

2. Description of the Related Art FIG. 1 is an example of a block diagram of a voltage applied current measuring apparatus applied to a semiconductor test apparatus. Here, since the semiconductor test apparatus is publicly known and well known in the art, other signals and constituent elements, and detailed description thereof will be omitted except for the main part of the present application. As the voltage applied current measuring device applied in the semiconductor test device, a programmable power supply, a voltage applied current measurement of a DC test device,
There are others. In order to improve the throughput of device test, these are equipped with a large number of channels, for example, 64 channels, and current measurement is performed in parallel at the same time.

A main component of FIG. 1 is a DA converter 11
A power operational amplifier A1, an operational amplifier A2, a current measuring unit 200, and a station cable CB1. The load device in the semiconductor test apparatus is a device under test (DUT), which is placed on the test head in a predetermined manner via the station cable CB1 and is connected to the IC pin for signal of the DUT or the IC pin for power supply to supply current. The measurement is taken. At this time, the station cable CB1 is provided with two independent lines of the force line CBf and the sense line CBs so that the DUT end voltage of the IC pin becomes a predetermined constant voltage without being affected by the load current. The circuit configuration is such that feedback control is performed by the line CBs so that the voltage at the DUT end becomes constant.

The DA converter 11 receives desired setting data D11 from the outside and receives a corresponding DC reference voltage 11s.
To occur. This is supplied to the negative input terminal of the operational amplifier A1 via the resistor Ra.

The operational amplifier A1 is an operational amplifier for power corresponding to a high voltage, receives the reference voltage 11s,
Feedback control is performed based on the resistors Ra and Rb so that the DUT end voltage Vd becomes a predetermined constant DC voltage. The output voltage V1 is applied to the DUT via the current measuring unit 200. The DUT end voltage Vd needs to be able to apply a high voltage of, for example, 40 V or more. The positive input terminal of the operational amplifier A1 is connected to the circuit ground GND.

The operational amplifier A2 is a high-impedance 1: 1 voltage buffer that receives the DUT end voltage V.
The sense line CBs, which is a feedback line, receives d and outputs the buffered feedback voltage V2, which is supplied to the negative input terminal of the operational amplifier A1 via the resistor Rb.

The current measuring section 200 is a measuring section for measuring the load current of the DUT, in which a relatively small resistance corresponding to the load current is inserted in series, and the amount of current flowing through this resistance is converted into a voltage. The potential difference V9 at both ends is measured, converted into digital code data 200s, and output to the outside. An example of the internal principle circuit configuration will be described with reference to FIG.

FIG. 2 is a circuit diagram of the internal principle of the current measuring unit 200, the main components of which are a current detection resistor Rm and
Operational amplifiers (OPAMP) A3, A4, first voltage dividing resistors Rc1, Rd1, second voltage dividing resistors Rc2, Rd2, A
And a D converter 80. Although not shown, the current detection resistor Rm is provided with a current measurement range switching means by a plurality of resistors Rm1 to Rmn and a switching relay, and corresponds to a load current, for example, a measurement range of several tens to several hundred millivolts. A resistor is applied and the potential difference V9 based on this is output.

The operational amplifier A3 is a 1: 1 voltage buffer that receives a high impedance so as not to affect the load current. Here, since a high voltage of 40 V or more is applied, it is necessary to apply a high breakdown voltage operational amplifier. The high breakdown voltage type operational amplifier is extremely expensive, and as a result, there is a problem that the cost becomes high.

The first voltage dividing resistors Rc1 and Rd1 are resistors that divide the operational amplifier A4 so that the amplification degree of the operational amplifier A4 is, for example, 10 times. For example, the voltage dividing resistor Rc1 is 10 KΩ and the voltage dividing resistor Rd1 is 100 KΩ. As a result, one load side voltage V8 is supplied to the negative input terminal of the operational amplifier A4.

The second voltage dividing resistors Rc2 and Rd2 are the first
The voltage divider resistors Rc1 and Rd1 are resistors having a voltage division ratio that exactly matches, for example, 1/10, and the other output side voltage V1 is supplied to the positive input terminal of the operational amplifier A4. By the way, the potential difference V9 to be amplified is a small voltage of, for example, several tens to several hundreds of millivolts, and the high voltage applied to the other DUT is 40 V or more. Therefore, the first voltage dividing resistor R
If the voltage division ratios of c1, Rd1 and the second voltage dividing resistors Rc2, Rd2 are not exactly matched (matching), the CMR (common mode noise removal capability) will deteriorate. That is, 40v applied
The offset variation occurs due to the above high voltage.
Therefore, in order to maintain a predetermined measurement accuracy, these four resistance values use, for example, resistors with a component variation of ± 0.1% or less, and a highly stable resistance with a temperature coefficient of resistance of 10 PPM or less. It is necessary to use a device. Therefore, a dedicated set resistor may be applied in some cases. As a result, the cost of the four resistors is also high.

A specific numerical example will be described. For example, let us calculate the measurement error assuming that there is 0.1% error in the voltage division ratio due to the voltage dividing resistance. Applied voltage 40v is 1
If it is divided into / 10, it should be 4v (4000mv)
However, due to the partial pressure error of 0.1%, 4
An offset error voltage of 000 mv × 0.1% = 4 mv is generated. On the other hand, assuming that the potential difference V9 of the measurement target is 100 millivolts, 4 mv causes a measurement error of 4%. It can be seen that this measurement error of 4% is a large error and cannot be practically applied. Therefore, it is necessary to use a highly accurate resistive element and a resistive element with a small temperature coefficient, which are specially considered so that the voltage dividing ratios of the voltage dividing resistors on the positive input side and the negative input side match.

The operational amplifier A4 is provided with the divided voltage A4i.
1 and A4i2, the amplified voltage A4s is output as a result of amplifying the potential difference V9 across the current detection resistor Rm by 10 times. Here, since a high voltage of 40 V or more is applied to the input terminal, it is necessary to apply a high breakdown voltage operational amplifier. In this case as well, it is necessary to use an extremely expensive IC element which is a high breakdown voltage type operational amplifier, and there is a drawback that the cost becomes high.

The AD converter 80 is, for example, an AD converter having a resolution of 12 to 16 bits, receives the amplified voltage A4s, converts it into digital code data 200s, and outputs it to the outside.

According to the above conventional configuration, the operational amplifier A3,
Since a high voltage of 40 V or more is applied to the input terminal of A4, it is necessary to apply a high breakdown voltage operational amplifier. This high voltage type operational amplifier is extremely expensive as compared with other parts. Further, it is necessary to use expensive resistance elements for the first voltage dividing resistors Rc1 and Rd1 and the second voltage dividing resistors Rc2 and Rd2. As a result, the cost of the entire circuit is high.

[0016]

In the semiconductor test apparatus, it is necessary to provide a large number of channels for the voltage application current measuring apparatus. As described above, in the conventional technique, the current measuring unit 200 uses the high breakdown voltage operational amplifier corresponding to the high voltage of 40 V or more applied to the DUT. Further, it is necessary to use expensive resistance elements for the first voltage dividing resistors Rc1 and Rd1 and the second voltage dividing resistors Rc2 and Rd2. Along with these, there is a practical problem that the voltage applied current measuring device becomes expensive. Therefore, the problem to be solved by the present invention is to provide a voltage applied current measuring device which can be realized with a cheaper circuit configuration, and a semiconductor test device using the same.

[0017]

A first solution will be described.
In order to solve the above-mentioned problems, in a voltage application current measurement device, a load current measurement means for measuring a load current in a state of being floated from a circuit ground GND of the voltage application current measurement device is provided. It is a current measuring device. According to the above invention, it is possible to realize a voltage applied current measuring device that supplies a high voltage and that can be realized with a cheaper circuit configuration.

Next, the second solving means will be shown. In order to solve the above-mentioned problem, in the voltage applied current measuring device, the load current measuring means for measuring the load current flowing from the voltage applied current measuring device to the load device is in a state of floating from the circuit ground GND of the voltage applied current measuring device. Floating power supply 5
There is a voltage applied current measuring device characterized in that 0 is applied.

Next, a third solving means will be shown. As one mode of the load current measuring means, a current flowing through the load is converted into a voltage by inserting a resistor in series, the converted voltage is received across the resistor, and the floating state is floated from the circuit ground GND. There is the above-mentioned voltage application current measuring device characterized by performing predetermined amplification by the operational amplification means (for example, the gain defining resistors Rc3 and Rd3 and the operational amplifier A5).

Next, a fourth solving means will be shown. As one mode of the above-mentioned load current measuring means, there is the above-mentioned voltage application current measuring device, which is the floating type current measuring unit 300.

Next, the fifth solving means will be described. The fourth here
The figure shows the solution according to the invention. One mode of the floating type current measuring unit 300 includes a floating power source 50 that supplies a DC power source used in the floating type current measuring unit, and a current detecting unit (for example, a current detecting resistor Rm) that detects a load current. Then, it receives the voltage signal from the current detection resistor Rm, amplifies the signal in a predetermined state in a floating state with the circuit ground GND of the voltage application current measuring device, and outputs the power signal. (OPAMP) A5
The power supply includes an AD converter 85 which receives the amplified signal from the operational amplifier A5 and converts it into digital code data and outputs the digital code data. The circuit ground of the voltage applied current measuring device is provided. The GND is provided with a photocoupler PC3 for transmitting the digital code data in a floating state to the circuit ground GND side of the voltage applied current measuring apparatus, and the above voltage applied current measuring apparatus is provided with the above.

Next, a sixth solving means will be described. As one mode of the floating power source 50, a DC power source insulated based on the light emitting element D1 and the solar cell C2 is supplied.
There is the above-mentioned voltage application current measuring device characterized by the above.

Next, the seventh means for solving the problems will be described. The third here
The figure shows the solution according to the invention. One mode of the above-mentioned voltage applied current measuring device includes a DA converter 11 that generates a corresponding DC reference voltage 11s based on a predetermined setting data D11 from the outside, and a predetermined output voltage based on the reference voltage 11s. And a sense line CBs for detecting the voltage at the connection end on the side of the load device. The force line CBf is provided with a power operational amplifier A1 for generating a current and supplies the current to the load device. The above-mentioned voltage application current measuring device comprising: a line; and an operational amplifier A2 for current-buffering a voltage signal from the sense line CBs and feeding back to the operational amplifier A1. is there.

Next, the eighth solving means will be described. There is the above-mentioned voltage applied current measuring device characterized in that the voltage supplied from the above voltage applied current measuring device to the load device is applied to the voltage applied current measuring device configured to supply a high voltage that cannot be applied to a general operational amplifier. .

Next, the ninth solving means will be described. There is a semiconductor test apparatus characterized in that the voltage applied current measuring apparatus described above is applied to measure the current of a device under test.

Next, the tenth solving means will be described. There is a semiconductor test apparatus characterized in that a predetermined plurality of channels of the voltage applied current measuring apparatus described above are provided to measure the current of a device under test.

If desired, the means of the present invention may be appropriately combined with the respective element means of the above-mentioned solving means to form other practical means. Further, although the reference numerals given to the above respective elements correspond to the reference numerals shown in the embodiments of the present invention and the like, the present invention is not limited to this, and constituent means to which other practical equivalents are applied. Also good.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION An example of an embodiment to which the present invention is applied will be described below with reference to the drawings. Further, the scope of the claims is not limited by the description content of the following embodiments, and the elements and connection relationships described in the embodiments are not necessarily essential to the solving means.
Furthermore, the forms / forms of the elements and connection relationships described in the embodiments are examples, and the form / form contents are not limited to these.

The present invention will be described below with reference to FIGS. 3 and 4. The elements corresponding to those of the conventional configuration are designated by the same reference numerals, and the description of the overlapping portions will be omitted.

FIG. 3 is an example of a block diagram of a voltage applied current measuring device applied to a semiconductor testing device. This essential component has a configuration in which a floating type current measuring unit 300 is provided instead of the current measuring unit 200 of the conventional component. The floating type current measuring unit 300 is a floating type current measuring unit that is insulated from the circuit ground GND. An example of the internal principle circuit configuration will be described with reference to FIG.

The floating type current measuring unit 300 of FIG.
The main components of the above are the floating power supply 50, the current detection resistor Rm, the gain regulating resistors Rc3 and Rd3, the operational amplifier (OPAMP) A5, the AD converter 85, the serial output unit 60, and the photocoupler PC3. With.
The floating type current measuring unit 300 is about a fraction of the cost as compared with a high breakdown voltage type operational amplifier.

The floating power supply 50 supplies a DC power of several tens of milliwatts to each circuit used in the floating type current measuring section 300, and the circuit ground is an insulated DC power supply in a floating state. As an example, it is composed of a light emitting element D1 and a solar cell C2.
The light emitting element D1 is, for example, a light emitting diode in which a plurality of light emitting diodes are connected in series, and a predetermined current is applied to the light emitting diode to emit light, which is received by a solar cell C2 in which a plurality of light emitting elements are connected in series, and a positive power source + Vf of, for example, about 10v is supplied. Negative power supply -Vf is output. The middle point of the solar cell C2 is output as the common terminal COM. Here, although not shown, both power supplies and the common terminal COM
A bypass capacitor is provided between them. If desired, as shown in FIG. 5, a constant voltage IC may be inserted to supply a constant DC voltage.

Since the current detection resistor Rm is the same as the conventional one, its explanation is omitted. However, the common terminal COM is connected to the terminal corresponding to the output side voltage V1 of the current detection resistor Rm.

The gain defining resistors Rc3 and Rd3 are resistors that define the amplification degree of the operational amplifier A5. For example, 10
To give a doubled resistance value, the gain regulating resistor Rc3
Is 10 KΩ and Rd3 is 90 KΩ. The voltage signal A5i2 at the midpoint of both resistors is supplied to the negative input terminal of the operational amplifier A5. According to this connection configuration, the voltage signal A5i2 at the midpoint between the gain regulating resistors Rc3 and Rd3 is the DUT.
The high voltage of 40 V applied to is not divided. That is,
The advantage that these variations in resistance value can be caused only by the variation factor of the amplification degree is obtained. That is, although the variation in the resistance value causes a large measurement error due to the division of the applied voltage 40v as in the conventional case, this has been resolved. Therefore, the variation of the resistance value is only the variation of the amplification degree, and therefore, there is an advantage that a general inexpensive resistance of about 0.1% can be applied.

As the operational amplifier A5, a general operational amplifier can be applied instead of the high breakdown voltage type. A low power consumption type is desirable. The positive power source + Vf and the negative power source -Vf are used as this power source. Then, the load side voltage V8 is supplied to the positive input end, the voltage signal A5i2 is supplied to the negative input end, and the amplified signal A5 obtained by amplifying the potential difference V9 by 10 times is supplied.
Output s. According to this, the voltage signal input to the operational amplifier A5 is about several hundred millivolts based on the COM level standard. Therefore, there is an advantage that an inexpensive general operational amplifier can be applied.

As the AD converter 85, for example, a serial output type having a resolution of 12 to 16 bits is applied. The power source is a positive power source + Vf. The amplified signal A5s is received, converted into serial digital code data 85s at a built-in clock cycle, and output.

The serial output section 60 is a buffer which receives the serial digital code data 85s and drives the photocoupler PC3 in a predetermined manner.

The photocoupler PC3 is an electrically insulated signal transmission means for converting a serial signal in a floating state into a serial signal based on the circuit ground GND. The serial digital code data 85s is received at the input end side via the serial output section 60 and converted into an optical signal, and at the output end side is converted into an electric signal by a phototransistor, and the original serial digital code data 300 is obtained.
Output s to the outside. The photo coupler PC3 is inexpensive.

According to the configuration of the above-mentioned invention, the floating type current measuring section 300 can be applied with one general operational amplifier A5. As a result, two expensive high withstand voltage operational amplifiers as in the prior art are not required. You can Therefore, there is a great advantage that a significantly cheaper voltage applied current measuring device can be realized. Furthermore, since the variations in the resistance values of the gain defining resistors Rc3 and Rd3 are only variations in the amplification degree, there is an advantage that a general inexpensive resistor can be applied.

The technical idea of the present invention is not limited to the specific configuration examples and connection mode examples of the above-described embodiment. Furthermore, based on the technical idea of the present invention, the above-described embodiments may be appropriately modified and widely applied. For example, in the above-described embodiment, the light source is applied as the floating power supply 50 to electrically insulate it. However, an insulating transformer configuration using a high frequency oscillation power supply and a coil may be applied, and the power supply current is small. In that case, a piezoelectric transformer may be applied.

If the serial output section 60 can directly drive the photocoupler PC3 with the output signal of the AD converter 85, the serial output section 60 may be omitted.

If a DC reference voltage is received from the outside, the DA converter 11 may be omitted.

A serial / parallel conversion means for converting into parallel code data may be provided at the subsequent stage of the photocoupler PC3.

[0044]

The present invention has the following effects based on the above description. As described above, according to the present invention, by providing the means for measuring the load current while floating from the circuit ground GND, an expensive high withstand voltage operational amplifier can be eliminated. Therefore, particularly in a semiconductor test apparatus having a large number of channels, a great advantage that an inexpensive voltage applied current measuring apparatus can be realized can be obtained. Further, the variation in the resistance value of the resistors used affects only the amplification degree, so that there is an advantage that practical measurement accuracy can be obtained even if a general inexpensive resistor is applied. Therefore, the technical effect of the present invention is great, and the economic effect in industry is also great.

[Brief description of drawings]

FIG. 1 is an example of a block diagram of a conventional voltage applied current measuring apparatus applied to a semiconductor test apparatus.

FIG. 2 shows a conventional internal principle circuit configuration of a current measuring unit.

FIG. 3 is an example of a block diagram of a voltage application current measurement device applied to a semiconductor test device according to the present invention.

FIG. 4 is an internal principle circuit configuration of a current measuring unit according to the present invention.

FIG. 5 is a configuration example in which a constant voltage IC is provided on the output side of a floating power supply according to the present invention.

[Explanation of symbols]

A1, A2, A3, A4, A5 Operational amplifier (OPAM
P) CB1 Station cable D1 Light emitting element Rc1, Rd1 First voltage dividing resistor Ra, Rb Resistor C2 Solar cell Rc2, Rd2 Second voltage dividing resistor PC3 Photo coupler Rc3, Rd3 Gain regulating resistor 11 DA converter 50 Floating power source 60 Serial Output unit 80, 85 AD converter 200 Current measuring unit 300 Floating type current measuring unit COM Common terminal DUT Device under test GND Circuit ground Rm Current detection resistor

Claims (10)

[Claims] 1. A voltage applied current measuring device, comprising: a load current measuring means for measuring a load current in a state of being floated from a circuit ground of the voltage applied current measuring device. 2. In the voltage applied current measuring device, the load current measuring means for measuring the load current flowing from the voltage applied current measuring device to the load device is a floating power source floating above the circuit ground of the voltage applied current measuring device. A voltage applied current measuring device characterized by being applied. 3. The load current measuring means converts a current flowing through a load into a voltage by inserting a resistor in series, receives the converted voltage across the resistor, and floats from a circuit ground in a floating state. 3. The voltage applied current measuring device according to claim 1, wherein the operational amplification means is used for predetermined amplification. 4. The load current measuring means is a floating type current measuring unit.
The voltage applied current measuring device described. 5. The floating type current measuring unit supplies a DC power source used in the floating type current measuring unit, a floating power source for detecting a load current, and a voltage signal from the current detecting resistor. In the floating state with respect to the circuit ground of the voltage applied current measuring device, it is amplified and output in a predetermined manner, and the power source is an operational amplifier to which the floating power source is applied and a digital code which receives the amplified signal from the operational amplifier. The digital code data is converted into data and output, and the power supply is an AD converter that applies the floating power supply and the circuit ground of the voltage application current measurement device. 5. A voltage applied current measurement according to claim 4, further comprising: apparatus. 6. The voltage applied current measuring apparatus according to claim 5, wherein the floating power source supplies a direct current power source insulated based on the light emitting element and the solar cell. 7. The voltage applied current measuring device generates a corresponding DC reference voltage based on predetermined setting data from the outside, and a predetermined output voltage based on the reference voltage. Two lines, an operational amplifier that supplies current to the load device, a force line that supplies current to the load device, and a sense line that detects the voltage at the connection end on the load device side, and a voltage signal from the sense line. 3. An operational amplifier according to claim 1, further comprising: an operational amplifier that current-buffers the current and feeds it back to the operational amplifier. 8. The voltage applied current measuring device applies to a voltage applied current measuring device having a structure for supplying a high voltage which is not applicable to a general operational amplifier, to a load device.
The voltage applied current measuring device according to claim 1, wherein 9. A semiconductor test apparatus to which the voltage applied current measuring apparatus according to claim 1 is applied. 10. A semiconductor test apparatus comprising the voltage application current measuring apparatus according to claim 1 provided in a predetermined plurality of channels to measure the current of a device under test.