JPH116860A - Semiconductor testing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize power source current/voltage conversion capable of dividing voltage by the relation of specific voltage division ratio with the rage switching of large current measurement range, by providing a control switch inserted and connected in series to a resistor through which power source current always flows. SOLUTION: The large current measuring part 100 of a programmable power source is constituted of resistors R1 and R2 for current detection, control switches SW1 and SW2, a potential difference detector 50 and an AD converter 60. To the resistor R1 through which power source current always flows, the control switch SW1 is connected. That is, a luminous diode D1 of a switch controller 300 is always driven. Therefore, the corresponding control switch SW1 is always in ON state. By making the control switch SW1 always in ON state, it is balanced with the ON resistance value of other control switch SW2 for ON/OFF control and so fluctuation of current division ratio due to scattering of parts and fluctuation of temperature is cancelled. By this, the accuracy of current division is current measurement range switching is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply current measuring circuit of a programmable power supply used for supplying power to a device under test in a semiconductor test apparatus.

[0002]

2. Description of the Related Art A prior art example will be described below with reference to FIG. The programmable power supply supplies a desired power supply voltage to the device under test, and the maximum current to be supplied to the DUT is 1
It can supply up to near A. This programmable power supply has a built-in functional circuit for measuring the power supply current of the DUT. On the other hand, the power supply current of the DUT is several μA to 1 depending on the type.
A and extremely wide. Therefore, in order to measure the power supply current of the DUT, it is necessary to measure the current by switching a plurality of ranges.

An example of a circuit configuration of a main part of a programmable power supply is as follows.
As shown in FIG. 4, the DA converter 20 and the resistors R11 and R11
12, a differential power amplifier 30, and a buffer amplifier 40
, A large current measuring section 100, a small current measuring section 200, and a switch control section 300. The small current measuring unit 200 in this configuration measures a small DUT power supply current that cannot be measured by the large current measuring unit 100 side. When this small current measuring unit is not used, the control is closed between the input and output terminals by a control switch so as to prevent unnecessary voltage drop. Since the small current measuring section 200 is not directly related to the present problem, the internal configuration and the description thereof are omitted.

In order to test a DUT, the voltage at the power supply terminal must be constantly stabilized at a predetermined voltage regardless of fluctuations in the power supply current. For this purpose, the power supply cable (Fo
rce), a separate return cable (Sence) is used for voltage sensing. The voltage at the power supply terminal point of the DUT is received by the feedback cable line, buffered by the buffer amplifier 40, and then fed back to the negative input terminal of the differential power amplifier 30 via the feedback resistor R12. As a result, the DUT is not affected by the voltage drop at the large current measuring unit 100, the small current measuring unit 200, and the power supply cable, and the predetermined voltage is always DUT.
Applied to the power supply terminal point.

[0005] The large current measuring unit 100 measures a large current of the DUT power supply current. As an example of the internal configuration, current detection resistors R1 and R2 and a control switch SW
1, a potential difference detector 50, and an AD converter 60.
The control switch SW2 and the corresponding light emitting diode D2 of the switch control section 300 form a pair of photo MOS relays and are electrically insulated electronic switches. Here, the ON resistance value of the control switch SW2 is r2
And The resistors R1 and R2 convert a power supply current into a voltage. It is assumed that the resistor R1 is a resistor that constantly supplies a power supply current, the resistor R2 is a shunt resistor for expanding the measurement range, and that both resistors use the same low resistance value Ra. To switch the current measurement range, use the control switch SW.
For example, 0.8 A / 0.
Switched and used as 4A range. Potential difference detector 50
Receives the voltage signal at both ends of the resistor R1, amplifies the difference voltage between the two voltages by a factor of 1 or a predetermined factor, and
Supply to Then, the AD converter 60 converts the analog input voltage into digital data and outputs the digital data to the outside as measurement data of the power supply current.

[0006]

However, the large current measuring section 100 having the above configuration has a drawback that an error in current measurement occurs. That is, the photo MOS relay is not an ideal switch but has an ON resistance value r2 of about several tens of milliohms. As a result, the shunt ratio by the measurement range switching is Ra: (Ra +
r2). This does not result in a target ratio relationship of 1: 1. On the other hand, there is a method of changing the resistance values of the resistors R1 and R2 so that the shunt ratio has a relation of 1: 1. In this case, the photo MOS relay, which is a semiconductor switch, is turned ON due to component variations and temperature changes. The resistance value r2 differs individually. For this reason, a desired split ratio is not always obtained, which is an error factor. DUT in any of these
The power supply current measurement in the large current measurement range described above is not preferable because it causes an error factor, and has a practical difficulty.

Accordingly, an object of the present invention is to provide a semiconductor test for realizing a power supply current / voltage conversion capable of dividing a voltage with a predetermined voltage dividing ratio in a range switching of a large current measurement range in a power supply current measurement of a DUT. It is to provide a programmable power supply for the device.

[0008]

FIG. 1 shows a solution according to the present invention. First, in order to solve the above-mentioned problem, in the configuration of the present invention, at least a first power supply current / voltage conversion resistor R1 and a second power supply, which are connected in parallel to flow a power supply current of a device under test. A second control switch SW2, which has a current / voltage conversion resistor R2, always supplies a power supply current to the first resistor R1, and connects in series to the second resistor R2 to control the opening / closing of the power supply current. A semiconductor test for supplying power to the DUT and measuring a power supply current flowing through the DUT by a programmable power supply having a built-in power supply current measurement range switching means based on the configuration of at least the first and second resistors R1 and R2. The apparatus includes a first control switch SW1 connected in series to a first resistor R1 that constantly supplies a power supply current, and a unit that drives the first control switch SW1 to be always on. A structural unit having a more programmable power supply. As described above, a programmable power supply of a semiconductor test apparatus that realizes power supply current / voltage conversion capable of dividing a voltage with a predetermined voltage division ratio in a range switching of a large current measurement range in a power supply current measurement of a DUT can be realized.

FIG. 3 shows a solution according to the present invention. Secondly, in order to solve the above-mentioned problem, in the configuration of the present invention, at least a first power supply current / voltage conversion resistor R1 and a second power supply, which are connected in parallel to supply a power supply current of a device under test, A current / voltage conversion resistor R2 is provided. A power supply current always flows through the first resistor R1, and the second resistor R2
Has a second control switch SW2 connected in series to control the opening and closing of the shunting of the power supply current, and incorporates a power supply current measurement range switching means constituted by at least the first and second resistors R1 and R2 described above. DU by programmable power supply
In a semiconductor test apparatus for supplying power to T and measuring a power supply current flowing through a DUT, receiving a voltage signal from a load terminal of a first resistor R1 and receiving a voltage signal from a load terminal of a second resistor R2 A changeover switch 55 for selecting and outputting any one of the voltage signals, and a signal path for supplying a voltage signal from the voltage signal selection and output means to one input terminal of the potential difference detector 50. There is a configuration means that includes a signal path for supplying the common connection terminal of the first resistor R1 and the second resistor R2 to the other input terminal of the potential difference detector 50, and the above-described configuration is provided in a programmable power supply.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings together with embodiments.

The present invention will be described below with reference to the circuit diagram of the main part of the programmable power supply shown in FIG. Elements corresponding to the conventional configuration are denoted by the same reference numerals.

An example of the internal configuration of the large current measuring section 100 of the programmable power supply according to the present invention includes resistors R1 and R2 for detecting current.
, Control switches SW1 and SW2, potential difference detector 50
And an AD converter 60. Other components are the same as the conventional one. The present invention provides a control switch SW
1 is added. Of course, since the control switch SW1 is a photo MOS relay, it has a driving light emitting diode D1 corresponding to the switch control unit 300. The control switches SW1 and SW2 select and use parts of the same type having the same characteristics.

Light emitting diode D of switch controller 300
1 is constantly driven. Therefore, the corresponding control switch S
W1 is always on. Here, the current detection resistor R
1 and R2 are assumed to be Ra having the same resistance value. On the other hand, assuming that the ON resistance values of the control switches SW1 and SW2 are r1 and r2, the relationship of r1 = r2 is substantially satisfied because the components have uniform characteristics.

As a result, when the control switch SW1 is OFF, the resistance value between the input and output of the large current measuring unit 100 = Ra +
r1. When the control switch SW1 is ON, the resistance between the input and output is the parallel resistance of both. R1 = r2 described above
成立 (Ra + r1) from the establishment of the relationship. As a result, the relationship of 1: (1/2) is always established without being affected by the fluctuation of the ON resistance of the control switch SW1. That is, by using a configuration in which control switches having the same characteristics are connected in series to both resistors, there is obtained an advantage that variations in ON resistance between the two control switches can be offset.

According to the configuration of the present invention described above, one power supply current /
A control switch SW having the same characteristics as the ON / OFF control switch SW2 connected in series to the voltage conversion resistor R1
1 is connected in series to the other current / voltage conversion resistor R1 and the control switch SW1 is always in the ON state, so that the ON / OFF control switch SW2 is turned on. As a result of always achieving a predetermined shunt ratio relationship in balance with the resistance value, there is obtained an advantage of offsetting variations in the shunt ratio due to component variations and temperature variations.

In the description of the above-described embodiment, the description has been made of the case where the resistance ratios for the power supply current / voltage conversion are 1: 1 and the same resistance value. However, for example, when the resistance ratio is different from 1: 3. 2A, the control switches SW1a to SW1c of the photo moss relay, which are always on, are inserted in the same manner as shown in the circuit configuration example of FIG. The advantage is obtained that the ratio fluctuation due to the component fluctuation and the temperature fluctuation can be eliminated.

In the description of the above embodiment, an example of a two-range switching configuration has been described. Similarly, in a three-range or more switching configuration, the configuration shown in FIG. Obviously, it is feasible.

Although the above embodiment has been described with reference to a circuit configuration in which both resistance ratios for measuring the power supply current are kept constant, as shown in the circuit configuration example of FIG.
There is a configuration example in which a changeover switch 55 is provided between one input terminal of 0 and the load terminals of both resistors, each current is individually switched and measured, and a value obtained by adding both current values is used as a power supply current. In this case, since the current flowing to the input terminal of the potential difference detector 50 is very small, the ON resistance of the changeover switch 55 can be almost ignored, and does not become an error factor. In the case of this circuit configuration, an advantage is obtained that is not affected by the ON resistance of the control switch SW2.

[0019]

According to the present invention, the following effects can be obtained from the above description. According to the above-described configuration, the control switches SW1 having the same characteristics are connected to the current / voltage conversion resistor R1.
And the control switch SW1 is always turned on.
By adding a circuit configuration that sets the state to N, other ON
As a result of being balanced with the ON resistance value of the control switch SW2 for / OFF control, the advantage of canceling the variation of the shunt ratio due to the component variation and the temperature variation is obtained, and the shunt accuracy of the current measurement range switching can be improved.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a main part of a programmable power supply according to the present invention.

FIG. 2 is another configuration example of the large current measuring unit of the programmable power supply according to the present invention.

FIG. 3 is another circuit configuration example of the programmable power supply according to the present invention.

FIG. 4 is a circuit diagram of a main part of a conventional programmable power supply.

[Explanation of symbols]

 D1, D2 Light emitting diode R1, R2 Power supply current / voltage conversion resistance SW1, SW2, SW1a to SW1c Control switch r2 ON resistance R11, R12 Resistance 20 DA converter 30 Differential power amplifier 40 Buffer amplifier 50 Potential difference detector 55 Switching Switch 60 AD converter 100 Large current measuring unit 200 Small current measuring unit 300 Switch control unit

Claims (3)

[Claims] At least a first power supply current / voltage conversion resistor and a second power supply current / voltage conversion resistor are connected in parallel to flow a power supply current of a device under test (DUT). A power supply current always flows through the first resistor, and a second control switch connected in series with the second resistor to control opening and closing of the branch of the power supply current. A programmable power supply incorporating a power supply current measurement range switching means based on the configuration of the first and second resistors,
A semiconductor test apparatus for supplying power to a UT and measuring a power supply current flowing through the DUT, comprising: a first control switch inserted in series with and connected to the first resistor that always supplies a power supply current; A semiconductor test apparatus comprising: means for constantly driving a control switch to an ON state; and a programmable power supply having the above. 2. The first control switch uses a photo MOS relay having the same characteristics as the second control switch.
The semiconductor test apparatus according to the above. 3. A power supply current / voltage conversion resistance and a second power supply current / voltage conversion resistance of at least a first power supply current / voltage conversion resistance and a second power supply current / voltage conversion resistance in a parallel connection configuration for flowing a power supply current of a device under test (DUT). A power supply current always flows through the first resistor, and a second control switch connected in series with the second resistor to control opening and closing of the branch of the power supply current. A programmable power supply incorporating a power supply current measurement range switching means based on the configuration of the first and second resistors,
In a semiconductor test apparatus for supplying power to a UT and measuring a power supply current flowing through the DUT, a voltage signal from a load terminal of the first resistor is received, and a voltage signal from a load terminal of the second resistor is received. Means for selecting and outputting any voltage signal; a signal path for supplying a voltage signal from the voltage signal selection and output means to one input terminal of a potential difference detector; A semiconductor test apparatus comprising: a signal path for supplying a common connection terminal of a second resistor to another input terminal of a potential difference detector;