Electricity: measuring and testing – Measuring – testing – or sensing electricity – per se – With rotor
Reexamination Certificate
2003-01-10
2004-08-24
Tang, Minh N. (Department: 2829)
Electricity: measuring and testing
Measuring, testing, or sensing electricity, per se
With rotor
C324S765010
Reexamination Certificate
active
06781364
ABSTRACT:
This patent application claims priority based on a Japanese patent application, 2000-222926 filed on Jul. 24, 2000, the contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a testing apparatus for testing an electron device. More particularly, the present invention relates to a testing apparatus, which has an apparatus for a high current testing, and an apparatus for a low current testing.
2. Description of the Related Art
FIG. 1
shows a conventional testing apparatus
100
. The testing apparatus
100
comprises a direct-current testing apparatus
10
for a high current and one or more direct-current testing apparatus
20
a
. . .
20
n
for a low current. The direct-current testing apparatus
10
is an apparatus, which supplies higher current than the direct-current testing apparatus
20
a
. . .
20
n
. The electron device
30
to be tested has a plurality of electrodes, each of which is connected to corresponding switches
12
-
1
. . .
12
-
n
, switches
14
-
1
. . .
14
-
n
, switches
16
-
1
. . .
16
-
n
, switches
18
-
1
. . .
18
-
n
. Switches
12
-
1
. . .
12
-
n
and
18
-
1
. . .
18
-
n
are each connected to a sense line
22
and a force line
26
of the direct-current testing apparatus
10
. As shown in
FIG. 1
, switches
14
-
1
. . .
14
-
n
are each connected to corresponding sense lines
28
a
. . .
28
n
of the direct-current testing apparatus
20
a
. . .
20
n
and switches
16
-
1
. . .
16
-
n
are each connected to corresponding force lines
30
a
. . .
30
n
of the direct-current testing apparatus
20
a
. . .
20
n
. Further, the testing apparatus
100
has a measure line
24
selectively connecting the direct-current testing apparatus
10
and direct-current testing apparatus
20
a
. . .
20
n.
The testing apparatus
100
performs a voltage applying current measuring test, which applies predetermined voltage on an electron device
30
to measure a current supplied to the electron device
30
, or performing an electric current applying voltage measuring test, which supplies predetermined electric current to the electron device
30
to measure a voltage applied on the electron device
30
.
The testing apparatus
100
will be explained below using a voltage applying current measuring test as an example. When a high current must be supplied to the electron device
30
, the direct-current testing apparatus
10
applies voltage to the electron device
30
through the force line
26
. The voltage applied to the electron device
30
is fed back to the direct-current testing apparatus
10
through the sense line
22
. The direct-current testing apparatus
10
adjusts the voltage applied to the electron device
30
to the predetermined voltage based on the fed-back voltage. Moreover, the direct-current testing apparatus
10
detects the current supplied to the electron device
30
when predetermined voltage is applied to the electron device
30
. The testing apparatus
100
judges the quality of an electron device
30
based on the detected current.
When a low current must be supplied to the electron device
30
, the direct-current testing apparatus
20
a
. . .
20
n
applies voltage to the electron device
30
. The voltage applied to the electron device
30
is fed back to the direct-current testing apparatus
20
a
. . .
20
n
. The direct-current testing apparatus
20
a
. . .
20
n
adjusts the voltage applied to the electron device
30
to predetermined voltage based on the fed-back voltage. Moreover, the direct-current testing apparatus
20
a
. . .
20
n
detects the current supplied to the electron device
30
when predetermined voltage is applied to the electron device
30
. The testing apparatus
100
judges the quality of an electron device
30
based on the detected current.
When the testing is performed by applying voltage to the electron device
30
from the direct-current testing apparatus
10
, the corresponding switches
12
-
1
. . .
12
-
n
and
18
-
1
. . .
18
-
n
are switched-on, and the switches
14
-
1
. . .
14
-
n
and
16
-
1
. . .
16
-
n
are switched-off. When the testing is performed by applying voltage to the electron device
30
from the direct-current testing apparatus
20
a
. . .
20
n
, the corresponding switches
14
-
1
. . .
14
-
n
and
16
-
1
. . .
16
-
n
are switched-on and the switches
12
-
1
. . .
12
-
n
and
18
-
1
. . .
18
-
n
are switched-off.
The electron device
30
has a plurality of electrodes to be tested, and the testing apparatus
100
has the direct-current testing apparatuses
20
for each electrode. The testing apparatus
100
performs testing by choosing the desired electrodes using the switches
12
-
1
to
12
-
n
, the switches
14
-
1
to
14
-
n
, the switches
16
-
1
to
16
-
n
, and the switches
18
-
1
to
18
-
n
, which are provided for each plurality of electrodes. Moreover, the testing apparatuses that perform other tests are also connected to the plurality of the electrodes of the electron device
30
.
The testing apparatus
100
mentioned above switches-off switches
12
-
1
. . .
12
-n, when the testing apparatus
100
is separated from the electron device
30
. Each of the switches has a floating capacity, called off capacity. Since the off capacity is large, the value measured by the testing apparatus that performs other test is affected when the switches
12
-
1
. . .
12
-
n
,
14
-
1
. . .
12
-
n
,
16
-
1
. . .
12
-
n
and
18
-
1
. . .
12
-
n
are switched-off. Thus, it was difficult to test the electron device
30
with sufficient accuracy. Therefore, it was desired to reduce the off capacity of the switch that separates the testing apparatus
100
and the electron device
30
.
SUMMARY OF THE INVENTION
Therefore, it is an object of the present invention to provide a testing apparatus which overcomes the above issues in the related art. This object is achieved by combinations described in the independent claims. The dependent claims define further advantageous and exemplary combinations of the present invention.
To solve the above issues, according to the first aspect of the present invention, a testing apparatus for testing an electron device comprises a first supply unit that supplies a first current to the electron device; a first feedback circuit which feeds back voltage applied to the electron device to the first supply unit; a first switch which switches to whether or not connect electrically the electron device to the first feedback circuit; and a second supply unit that supplies a second current to the electron device, the second supply unit being separated from the electron device by the first switch.
In the first aspect of the present invention, the first supply unit may adjust a voltage or a current to be supplied to the electron device based on the voltage, which is fed back by the first feedback circuit. Moreover, the testing apparatus may further comprise a second switch that switches to whether or not connect electrically the first supply unit to the electron device. The testing apparatus may further comprise: a third switch that selects to whether or not connect electrically the first feedback circuit to the first supply unit; and a fourth switch that selects to whether or not connect electrically the second supply unit to the electron device via the first switch. The second current may be lower than the first current.
The first feedback circuit may have a voltage follower circuit that outputs a voltage substantially equal to an input voltage, and the input impedance of the voltage follower circuit is higher than the output impedance of the voltage follower circuit. The second supply unit may have a supply source that supplies the second current to the electron device and a feedback path that feeds back the voltage applied to the electron device to the supply source; and the supply source adjusts the voltage or current to be output to the electron device based on the voltage fed back by the feedback path.
The electron device may have
Hashimoto Yoshihiro
Kawasaki Yoshitaka
Tanaka Hironori
Advantest Corporation
Osha & May L.L.P.
Tang Minh N.
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