Miscellaneous active electrical nonlinear devices – circuits – and – Specific identifiable device – circuit – or system – With specific source of supply or bias voltage
Reexamination Certificate
1996-11-25
2004-12-14
Cunningham, Terry D. (Department: 2816)
Miscellaneous active electrical nonlinear devices, circuits, and
Specific identifiable device, circuit, or system
With specific source of supply or bias voltage
C327S540000, C327S566000
Reexamination Certificate
active
06831502
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an internal power-source potential supply circuit for supplying an internal power-source potential to a predetermined load.
2. Description of the Background Art
FIG. 98
is a circuit diagram of a conventional internal power-source potential supply circuit for use in a semiconductor device. As shown, an external power-source potential VCE is applied as an internal power-source potential VCI to a load
11
through a PMOS transistor Ql. A comparator
1
has a negative input receiving a reference potential Vref and a positive input receiving the internal power-source potential VCI as a feedback signal, and provides a control signal S
1
based on the result of comparison between the reference potential Vref and the internal power-source potential VCI to the gate of the PMOS transistor Q
1
.
In such an arrangement, if the internal power-source potential VCI is lower than the reference potential Vref, the control signal S
1
from the comparator
1
has a lower potential to cause the PMOS transistor Q
1
to conduct heavily. This increases the current supply capability from the external power-source potential VCE. Then, the circuit acts to raise the lowered internal power-source potential VCI. Conversely, if the internal power-source potential VCI is higher than the reference potential Vref, the control signal S
1
from the comparator
1
has a higher potential to cause the PMOS transistor Q
1
to conduct lightly. This stops the current supply capability from the external power-source potential VCE. Then, the circuit prevents further increase in raised internal power-source potential VCI. The comparator
1
may include a differential amplifier having a current mirror circuit or the like. In this manner, the internal power-source potential supply circuit may supply the internal power-source potential VCI equal to the reference potential Vref.
FIG. 99
is a circuit diagram of another conventional internal power-source potential supply circuit for use in a semiconductor device. As shown, the external power-source potential VCE is applied as the internal power-source potential VCI to the load
11
through the PMOS transistor Q
1
. The comparator
1
has a negative input receiving the reference potential Vref and a positive input receiving a divided internal power-source potential DVCI as a feedback signal.
The drain of the PMOS transistor Q
1
is grounded through a resistor R
11
and a resistor R
12
. The internal power-source potential VCI divided by the resistors R
11
and R
12
is applied as the divided internal power-source potential DVCI to the positive input of the comparator
1
.
The circuit of
FIG. 99
is advantageous in that the operating point of the comparator
1
may be freely selected, allowing the characteristics of the comparator
1
to be held satisfactory independently of the conditions set for the internal power-source potential VCI and external power-source potential VCE. In the arrangement of
FIG. 98
, a small difference between the external power-source potential VCE and the internal power-source potential VCI deteriorates the characteristics of the comparator
1
, resulting in a delay in operation and a large amount of temporary reduction in internal power-source potential VCI.
The arrangement of
FIG. 99
may supply the internal power-source potential VCI in a stable manner when the reference potential Vref is constant.
FIG. 100
is a graph indicating a drawback of the circuit of FIG.
99
. In
FIG. 100
, (R
11
+R
12
)/R
12
=3/2. As shown in
FIG. 100
, a time interval T
11
is defined during which the reference potential Vref rises to follow the varying external power-source potential VCE. During the time interval T
11
, the internal power-source potential VCI also rises to follow the varying external power-source potential VCE, but has a tendency to provide access to the external power-source potential VCE as the external power-source potential VCE increases. The internal power-source potential VCI grows higher than required, resulting in dangers of an increase in current consumption and a lower degree of reliability.
Additionally, the resistors R
11
and R
12
have fixed resistances, resulting in the fixed internal power-source potential VCI.
In this manner, the conventional internal power-source potential supply circuits are disadvantageous in that variations in the external power-source potential may cause decreased performance of the circuit, finding difficulties in supplying the internal power-source potential with high accuracy.
SUMMARY OF THE INVENTION
A first aspect of the present invention is intended for an internal power-source potential supply circuit for supplying an internal power-source potential to a predetermined load. According to the present invention, the internal power-source potential supply circuit comprises: internal power-source potential applying means having a first end receiving an external power-source potential, and a second end for applying the internal power-source potential to the predetermined load in response to a control signal; a resistor element having a first end connected to the second end of the internal power-source potential applying means; current supply means for supplying a predetermined current to between a second end of the resistor element and a fixed potential; and a comparator circuit for receiving a divided internal power-source potential from the second end of the resistor element and a reference potential to output the control signal on the basis of a comparison result between the divided internal power-source potential and the reference potential.
Preferably, according to a second aspect of the present invention, the resistor element receives a resistor control signal and has a resistance varied in response to the resistor control signal.
Preferably, according to a third aspect of the present invention, the internal power-source potential supply circuit further comprises: a control circuit for outputting the resistor control signal on the basis of an environmental condition including temperature change.
Preferably, according to a fourth aspect of the present invention, the resistor element comprises a plurality of partial resistive elements connected in series between the first and second ends of the resistor element, and the internal power-source potential supply circuit further comprises: resistor selecting means provided in at least one of the plurality of partial resistive elements for selecting enablement/disablement of the at least one partial resistive element.
Preferably, according to a fifth aspect of the present invention, the current supply means comprises first partial current supply means for supplying a first partial current to between the second end of the resistor element and the fixed potential, and second partial current supply means for supplying a second partial current to between the second end of the resistor element and the fixed potential when being active, the second partial current supply means receiving a current control signal, the second partial current supply means being active/inactive in response to the current control signal.
Preferably, according to an sixth aspect of the present invention, the current supply means comprises first partial current supply means for supplying a first partial current to between the second end of the resistor element and the fixed potential, and second partial current supply means for supplying a second partial current to between the external power-source potential and the second end of the resistor element when being active, the second partial current supply means receiving a current control signal, the second partial current supply means being active/inactive in response to the current control signal.
Preferably, according to a seventh aspect of the present invention, the comparator circuit is active/inactive in response to a circuit control signal indicative of an active/inactive state, and the internal power-source potential supply circuit furth
Cunningham Terry D.
McDermott Will & Emery LLP
Renesas Technology Corp.
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