JPH10221402A - Power source current measuring circuit for ic tester - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power source current measuring circuit for IC tester wherein expansion of circuit's scale is suppressed even with increase in the number of parallel measurement of DUT(device under test), with less dispersion in measurement. SOLUTION: Plural DUT power sources 41-4n are connected to DUTs 31-3n in series, while the plural DUTs 31-n applied with power source voltage, respectively. Plural switches 51-5n turn on/off connection to the DUT power sources 41-4n corresponding to each DUT. A DUT power source 11 provided with a current measuring circuit branches/connects into plural DUTs 31-3n, while each DUT applied with a power source, for measuring a power source current IDD. Plural switches 21-2n turns on/off the branch connection of the DUT power source 11 corresponding to each DUT. While plural switches 51-5n are turned on at the same time to parallel-measure plural DUTs 31-3n, plural switches 51-5n and plural second switches 21-2n are switched sequentially, so that the power source current IDD of plural DUTs 31-3n are measured.

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 for an IC tester. In particular, the present invention relates to a circuit for measuring the power supply current I _DD when measuring the electrical characteristics of a plurality of DUTs (Device Under Test) with an IC tester.

[0002]

2. Description of the Related Art Next, the configuration of a conventional power supply current measuring circuit for an IC tester will be described with reference to FIG. 11 in FIG.
1 to 1n are DUT power supplies with a current measuring circuit for measuring the power supply current I _DD of the DUT (hereinafter referred to as DPS / IDD), 21
２2n are switches, and 31１〜３3n are DUTs.

In FIG. 4, a plurality of DPS / IDDs 11 to 1
n and a plurality of DUTs 31 to 3n are connected one to one. The switches 21 to 2n are connected in series. When the switches 21 to 2n are turned on, a power supply voltage is applied to each of the plurality of DUTs 31 to 3n,
The power supply current I _{DD of} T31 to Tn is measured. The switches 21 to 2n are turned on and off according to a command from a CPU (not shown).

Next, the configuration of the DPS / IDD 11 is shown in a circuit diagram of FIG. 5, 111 is a D / A converter, 112 and 113 are resistors, 114 and 115 are operational amplifiers, 116
The current amplifier circuit, 117 I _DD measurement circuit, 117A resistors, 117B are current measuring circuit, 117C is A / D converter, 21A and 21B are switches.

Next, the operation of FIG. 4 will be described with reference to a time chart of FIG. In FIG. 6, T indicates the time during which the power supply voltage is supplied to the DUT, that is, the measurement time of one DUT. In addition, t indicates the measurement time of the power supply current I _DD .

In the configuration shown in FIG. 4, as shown in FIG. 6, the switches 21 to 2n operate basically simultaneously to reduce the power supply voltage to DU.
Supply to T31 ~ 3n. All DPS / IDD11-
Since 1n has a built-in function of measuring the power supply current I _DD ,
All switches 21~2n supply current I _DD also during the measurement remains turned on, it measures the power supply current I _DD of the plurality of DUT31~3n simultaneously.

[0007]

Conventionally, all DPS
/ IDDs 11 to 1n have a built-in function of measuring the power supply current I _DD , so that when the number of parallel measurement of a plurality of DUTs increases, the circuit scale of the measurement of the power supply current I _DD increases,
There is a problem that the tester becomes large. There is also a problem that the current consumption increases. In addition, multiple DPS / I
Variations in DD11~1n there is a problem that affects the supply current I _DD measurement accuracy of the DUT.

According to the present invention, a plurality of first DUT power supplies are connected one-to-one to a plurality of DUTs, and a second DUT power supply with a current measuring circuit for measuring a power supply current I _DD is branch-connected to each of the DUTs. Within the time to measure multiple DUTs in parallel, the second
Of by sequentially measuring the power supply current I _DD of the plurality of DUT in DUT power supply, be increased parallel number of measurements of the DUT can suppress an increase in circuit scale, a small variation power supply current measuring IC tester measurement The purpose is to provide a circuit.

[0009]

In order to achieve this object, the present invention provides a plurality of DUT power supplies 41 to 4n connected in series to a plurality of DUTs 31 to 3n and applying a power supply voltage to each of the plurality of DUTs 31 to 3n. A plurality of switches 51 to 5n for turning on and off the connection to each of the DUT power supplies 41 to 4n corresponding to each of the DUTs; and a branch connection to the plurality of DUTs 31 to 3n; DUT power supply 11 with current measurement circuit for measuring current I _DD
And a plurality of switches 21 to 2n for turning on and off the branch connection of the DUT power supply 11 corresponding to each of the DUTs.
In the time for measuring 1 to 3n in parallel, a plurality of switches 51 to
5n and the plurality of second switches 21 to 2n are sequentially switched,
The power supply current I _DD of the plurality of DUTs 31 to 3n is measured.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment according to the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of a power supply current measuring circuit for an IC tester according to an embodiment of the present invention, and corresponds to FIG. 4 of the related art. In the following, components having the same reference numerals have the same functions, and duplicate descriptions will be omitted unless otherwise required.

In FIG. 1, reference numerals 41 to 4n denote DUT power supplies (hereinafter, DUT power supplies).
The switches 51 to 5n are the same as those in FIG.

In FIG. 1, a plurality of DPSs 41 to 4n are connected in series to a plurality of DUTs 31 to 3n, and a plurality of DUTs 31
To 3n, respectively. Multiple switches 5
1 to 5n indicate DUT power supplies 41 to 41 corresponding to the respective DUTs.
4n is turned on / off. The DPS / IDD 11 is branched and connected to a plurality of DUTs 31 to 3n. Multiple switches 2
1 to 2n are DPS / IDDs 11 corresponding to the respective DUTs.
Turn on / off the branch connection of

FIG. 2 is a circuit diagram showing one embodiment of the DPS 41 in FIG. In FIG. 2, 411 is a D / A converter, 412 and 413 are resistors, 414 and 415 are operational amplifiers, 416 is a current amplifier circuit, and 51A and 51B are switches. The DPS / IDD 11 is as shown in FIG.

Next, the operation of FIG. 1 will be described with reference to the time chart of FIG. First, switch 51~5n is turned on during measurement other than I _DD measurement, DUT 3 from DPS11~1n
A power supply voltage is supplied to 1 to 3n.

[0015] Then, at the I _DD measurement, first, DUT3
Starting from 1, the switch 21 is turned on, the switch 51 is turned off, the power supply voltage is supplied from the DPS / IDD 11 to the DUT 31, and I _DD is measured. And I _DD measurements DUT31 ends switch 51 is turned on, switch 21 is turned off.

Furthermore, switches 22-2n and switches 52-
5n are sequentially operated in the same manner, so that DUTs 31 to 3n
The _ID measurement of n DUTs up to n is completed. FIG.
Is switched by a CPU (not shown).

In the circuit configuration of FIG. 1, DPS / IDD is 1
Therefore, the IDD measurement time of n DUTs requires n times as long as the _ID measurement time t of one DUT.
However, usually, as shown in FIG.
Since t is extremely short with respect to the entire measurement time of T, there is no problem. In FIG. 1, DPS / IDD
Is one, but a plurality may be prepared.

[0018]

According to the present invention, if there is at least one DUT power supply having a built-in power supply current _IDD measurement function, the other plurality of DUT power supplies do not need the power supply current _IDD measurement function. Therefore, it is possible to suppress an increase in the circuit scale even if the number of parallel measurements of the DUT increases, thereby suppressing an increase in the size of the IC tester and an increase in current consumption. Further, when the number of DUT power supplies having the power supply current I _DD measurement function is one, the variation in the measurement of the power supply current I _DD for a plurality of DUTs is smaller than in the related art.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an embodiment of a power supply voltage measuring circuit for an IC tester according to the present invention.

FIG. 2 is a circuit diagram showing an embodiment of the DPS of FIG. 1;

FIG. 3 is a time chart showing the operation of FIG.

FIG. 4 is a circuit diagram of a power supply voltage measuring circuit for an IC tester according to the related art.

FIG. 5 is a DPS / IDD circuit diagram of FIG. 4;

FIG. 6 is a time chart illustrating the operation of FIG. 4;

[Explanation of symbols]

DUT power supply with a built-in 11 to 1n I _DD measurement function (D
PS / IDD) 21-2n switch 31-3n Device under test (DUT) 41-4n DUT power supply (DPS) 51-5n switch

Claims (2)

[Claims] 1. A plurality of DUTs (31-3n) connected in series,
A plurality of first DUT power supplies (41 to 4n) for applying a power supply voltage to each of the plurality of DUTs (31 to 3n); and a plurality of on / off connections for connecting the first DUT power supplies corresponding to the respective DUTs. A first switch (51 to 5n) and a second DUT with a current measuring circuit that is branched and connected to a plurality of DUTs (31 to 3n) and applies a power supply voltage to each of the DUTs to measure a power supply current I _DD A power supply (11); and a plurality of second switches (21 to 2n) for turning on and off a branch connection of the second DUT power supply (11) corresponding to each of the DUTs. (51-5n) are turned on at the same time and the plurality of first switches (51-5n) and the plurality of second switches (21-2n) are within the time for measuring the plurality of DUTs (31-3n) in parallel. ) Is sequentially switched to measure a power supply current I _DD of a plurality of DUTs (31 to 3n). 2. A power supply current measuring circuit for an IC tester according to claim 1, comprising a plurality of second DUT power supplies.