Miscellaneous active electrical nonlinear devices – circuits – and – Specific identifiable device – circuit – or system – With specific source of supply or bias voltage
Reexamination Certificate
1998-07-30
2004-10-26
Ton, My-Trang Nu (Department: 2816)
Miscellaneous active electrical nonlinear devices, circuits, and
Specific identifiable device, circuit, or system
With specific source of supply or bias voltage
C327S546000
Reexamination Certificate
active
06809576
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a semiconductor integrated circuit device having internal power supply voltage down-converting circuits for down-converting an external power supply voltage and generating internal power supply voltages, and more particularly, it relates to a semiconductor integrated circuit device having at least one voltage-dividing type internal power supply voltage down-converting circuit and at least one direct feedback type internal power supply voltage down-converting circuit. More specifically, the present invention relates to a structure for equalizing internal power supply voltages generated by the voltage-dividing type and the direct feedback type internal power supply voltage down-converting circuits with each other in temperature dependency.
2. Description of the Prior Art
As a semiconductor integrated circuit device is improved in degree of integration, MOS transistors (insulated gate field-effect transistors) as the components thereof are refined in response. In order to guarantee a breakdown voltage of the refined transistors, operating power supply voltages must be reduced. However, an integrated circuit device such as a semiconductor memory device must be further refined as compared with an integrated circuit such as a processor or a logic circuit, in order to implement a large storage capacity. Further, it is necessary to keep compatibility with semiconductor memory devices of old generations. Therefore, the overall system power supply voltage cannot be reduced, and a high voltage of 3.3 V, for example, is employed as the system power supply voltage in consideration of compatibility with processors and logic circuits or devices of old generations, so that the integrated circuit device such as a semiconductor memory device down-converts this external power supply voltage to 2.5 V, for example, in its interior for generating the operating power supply voltages.
FIG. 11
illustrates an exemplary structure of a conventional internal power supply voltage down-converting circuit VDCa. Referring to
FIG. 11
, the internal power supply voltage down-converting circuit (hereinafter simply referred to as a voltage down-converting circuit) VDCa includes a comparator CMPa for comparing a voltage VIN
1
on an internal power supply line VLa with a reference voltage Vref
1
and outputting a signal indicating the result of the comparison, and a current drive transistor DRa formed by a p-channel MOS transistor and connected between a power supply node ENa receiving an external power supply voltage VEX and the internal power supply line VLa for supplying a current from the power supply node ENa to the internal power supply line VLa in accordance with the signal outputted from the comparator CMPa. The comparator CMPa receives the reference voltage Vref
1
at its negative input, while receiving the internal power supply voltage VIN
1
on the internal power supply line VLa at its positive input. The operation is now briefly described.
When the reference voltage Vref
1
is higher than the internal power supply voltage VIN
1
, the output signal from the comparator CMPa goes low to increase the conductance of the current drive transistor Dra, for supplying the current from the power supply node ENa to the internal power supply line VLa and increasing the level of the internal power supply voltage VIN
1
. When the reference voltage Vref
1
is lower than the internal power supply voltage VIN
1
, the output signal from the comparator CMPa goes high to bring the current drive transistor DRa into an OFF state, for cutting off the current path between the power supply node ENa and the internal power supply line VLa. Namely, when the internal power supply voltage VIN
1
is lower than the reference voltage Vref
1
, the conductance of the current drive transistor DRa is adjusted in response to the voltage difference for supplying the current from the power supply node ENa to the internal power supply line VLa. Thus, the internal power supply voltage VIN
1
is held substantially at the level of the reference voltage Vref
1
.
FIG. 12
illustrates another exemplary structure of a conventional voltage down-converting circuit VDCb. Referring to
FIG. 12
, the voltage down-converting circuit VDCb includes a resistive element RE connected between an internal power supply line VLb and a node ND, a constant current source IS connected between the node ND and a ground node supplying a ground voltage VSS which is a basic voltage, a comparator CMPb for comparing the voltage on the node ND with a reference voltage Vref
2
, and a current drive transistor DRb formed by a p-channel MOS transistor which is connected between a power supply node ENb receiving an external power supply voltage VEX and the internal power supply line VLb for supplying a current from the power supply node ENb to the internal power supply line VLb in accordance with an output signal of the comparator CMPb. The operation of the voltage down-converting circuit VDCb shown in
FIG. 12
is now briefly described.
The comparator CMPb compares the voltage on the node ND with the reference voltage Vref
2
. Similarly to the voltage down-converting circuit VDCa shown in
FIG. 11
, the conductance of the current drive transistor DRb is adjusted in accordance with the output signal of the comparator CMPb, for substantially equalizing the voltage level on the node ND with the reference voltage Vref
2
. In this case, therefore, an internal power supply voltage VIN
2
on the internal power supply line VLb is given by V(ND)+I·R, where V(ND) represents the voltage on the node ND, and I and R represent the current supplied by the constant current source IS and the resistance value of the resistive element RE respectively. The internal power supply voltage VIN
2
is reduced through the resistive element RE to be compared with the reference voltage Vref
2
, thereby driving the comparator CMPb in its most sensitive region and recovering the internal power supply voltage VIN
2
to a prescribed level at a high speed upon its fluctuation.
It is possible to supply the internal power supply voltages VIN
1
and VIN
2
of a constant voltage level as operating power supply voltages for internal circuits by down-converting the external power supply voltage VEN through the voltage down-converting circuits VDCa and VDCb shown in
FIGS. 11 and 12
.
FIG. 13
schematically illustrates the overall structure of a conventional semiconductor integrated circuit device IC. Referring to
FIG. 13
, the semiconductor integrated circuit IC includes an internal circuit #A receiving the internal power supply voltage VIN
1
from the voltage down-converting circuit VDCa shown in
FIG. 11
as an operating power supply voltage, and an internal circuit #B receiving the internal power supply voltage VIN
2
from the voltage down-converting circuit VDCb shown in
FIG. 12
as an operating power supply voltage. No high-speed operation is required to the internal circuit #A, which in turn consumes a relatively large current. On the other hand, a high-speed operation is required to the internal circuit #B, which in turn consumes a relatively small current.
The semiconductor integrated circuit IC employs the voltage down-converting circuit VDCa which can supply a large current but is not required of high-speed response and the voltage down-converting circuit VDCb which is responsive to fluctuation of the internal power supply voltage VIN
2
at a high speed while supplying a relatively small current, independently of each other depending on the operational characteristics of the internal circuits #A and #B respectively.
Particularly, when the internal circuit #A consumes a large current to fluctuate the internal power supply voltage VIN
1
, the semiconductor integrated circuit device IC can prevent the internal power supply voltage VIN
2
for the internal circuit #B from an adverse influence by the fluctuation of the internal power supply voltage VIN
1
(the voltage down-converting circu
McDermott Will & Emery LLP
Nu Ton My-Trang
Renesas Technology Corp.
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