Electric power conversion systems – Current conversion – With condition responsive means to control the output...
Reexamination Certificate
2000-08-16
2001-12-25
Patel, Rajnikant B (Department: 2838)
Electric power conversion systems
Current conversion
With condition responsive means to control the output...
C323S313000, C327S537000
Reexamination Certificate
active
06333864
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to power supply adjusting circuits and semiconductor devices using these circuits, and more particularly to a power supply adjusting circuit and a semiconductor device using a power supply adjusting circuit generating a plurality of internal power supplies based on an external power supply.
2. Description of the Related Art
In recent years, semiconductor devices such as Dynamic Random Access Memories (DRAMs) and the like have been manufactured with high density and high speed. In order to support this trend, parts used therein such as transistors, diodes, resistances, condensers and so on are required to be scaled down and operating voltages applied thereon are required to be lower.
For example, a DRAM semiconductor device causes a power supply adjusting circuit thereof to generate an internal step-down voltage Vii (for example, Vii=2.5V) based on an external voltage VDD (for example, VDD=3.3V) and supplies the internal step-down voltage Vii to internal circuits therein. The internal step-down voltage Vii is, however, subject to deviation from a design voltage due to dispersion of element characteristics caused during the manufacturing of the semiconductor device. The power supply adjusting circuit usually corrects such deviation by adjusting fuse boxes thereof.
FIG. 1
is a diagram showing a configuration of a conventional power supply adjusting circuit.
As shown in this diagram, the conventional power supply adjusting circuit includes a plurality of fuse boxes
10
, a test register
11
, a switch circuit
12
, an internal reference power supply circuit
13
, an internal step-down power supply circuit
14
, and an internal step-up or boosted voltage generating circuit
20
generating an internal step-up voltage VPP.
The internal step-up voltage generating circuit
20
further includes a reference voltage generating circuit
21
, a voltage dividing circuit
22
, a comparator
23
, an internal step-up voltage control circuit
24
, and a charge pump
25
.
The fuse boxes
10
and the test register
11
are connected to the internal reference power supply circuit
13
via the switch circuit
12
. The switch circuit
12
switches between being connected to the fuse boxes
10
in a normal mode and being connected to the test register
11
in a test mode. The switch circuit
12
receives setting signals “a” from the fuse boxes
10
in the normal mode or setting signals “b” from the test register
11
in the test mode, and sends them to the internal reference power supply circuit
13
.
According to the setting signals “a” or “b”, the internal reference power supply circuit
13
generates an internal reference voltage Vrf from an external voltage VDD and supplies the internal reference voltage Vrf to the internal step-down power supply circuit
14
.
According to the internal reference voltage Vrf, the internal step-down power supply circuit
14
generates an internal step-down voltage Vii, which is adjusted by adjusting the internal reference voltage Vrf.
First, the internal step-down voltage Vii is adjusted in the test mode such that the setting signals “b” are supplied to the internal reference power supply circuit
13
from the test register
11
and are adjusted by adjusting a setting of the test register
11
until the internal step-down voltage Vii reaches an optimum value. At this time, if the fuse boxes
10
are adjusted so as to correspond to the setting of the test register
11
, the internal step-down voltage Vii can be adjusted to reach an optimum value in the normal mode. As a result, the internal step-down voltage Vii is thus adjusted to reach its optimum value.
In general, a semiconductor device generates other internal voltages besides the above-mentioned internal step-down voltage Vii. For example, the internal step-up voltage generating circuit
20
receives the internal reference voltage Vrf and generates the internal step-up voltage VPP.
Specifically, when receiving the internal reference voltage Vrf, the reference voltage generating circuit
21
generates an internal reference voltage Vpref
1
and supplies it to the comparator
23
. The comparator
23
compares the internal reference voltage Vpref
1
to a divided voltage VPP′ obtained by dividing the internal step-up voltage VPP in the voltage dividing circuit
22
so as to send a comparison result VPPSZ to the internal step-up voltage control circuit
24
. The VPP control circuit
24
controls the charge pump
25
according to the comparison result VPPSZ so as to make the internal step-up voltage VPP reach its optimum value.
In addition, configurations of the voltage dividing circuit
22
and the comparator
23
can be understood from FIG.
2
.
The conventional power supply adjusting circuit generates, however, the internal step-down voltage Vii and the internal step-up voltage VPP based on the one internal reference voltage Vrf. In other words, since the internal step-down voltage Vii and the internal step-up voltage VPP are varied according to the internal reference voltage Vrf, a problem occurs in that relative adjustment between the internal step-down voltage Vii and the internal step-up voltage VPP cannot be made.
For example, in the case of correcting the voltage deviation caused by the dispersion of the element characteristics in the semiconductor device manufacturing, it is impossible for the internal step-down voltage Vii and the internal step-up voltage VPP to be adjusted independently.
SUMMARY OF THE INVENTION
It is a general object of the present invention to provide a power supply adjusting circuit and a semiconductor device including the same, in which the above problem can be eliminated.
Another and a more specific object of the present invention is to provide a power supply adjusting circuit and a semiconductor device including such a power supply adjusting circuit, which is capable of separately adjusting and optimizing a plurality of internal power supplies generated from an external power supply.
The above objects and other objects of the present invention are achieved by a power supply adjusting circuit comprising a reference voltage supplying part generating a reference voltage based on an external voltage, a plurality of internal voltage generating parts generating a plurality of respective internal voltages based on the reference voltage, and a plurality of control parts corresponding to the internal voltage generating parts, respectively, so as to be able to separately control the internal voltages.
The above objects and other objects of the present invention are achieved by a power supply adjusting circuit comprising a first internal voltage generating part generating a first internal voltage based on an external voltage, a second internal voltage generating part generating a second internal voltage based on the first internal voltage, a third internal voltage generating part generating a third internal voltage based on the first internal voltage, a first control part controlling the first internal voltage, and a second control part controlling the third internal voltage.
The above objects and other objects of the present invention are achieved by a semiconductor device comprising a power supply adjusting circuit, the power supply adjusting circuit including a reference voltage supplying part generating a reference voltage based on an external voltage, a plurality of internal voltage generating parts generating a plurality of respective internal voltages based on the reference voltage, and a plurality of control parts corresponding to the internal voltage generating parts, respectively, so as to be able to separately control the internal voltages, wherein at least one of the internal voltage generating parts generates an internal step-up power supply voltage.
Other objects, features and advantages of the present invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings.
REFERENCES:
patent: 5086238 (199
Nishimura Koichi
Uchida Toshiya
Arent Fox Kintner & Plotkin & Kahn, PLLC
Fujitsu Limited
Patel Rajnikant B
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