Miscellaneous active electrical nonlinear devices – circuits – and – Specific identifiable device – circuit – or system – With specific source of supply or bias voltage
Reexamination Certificate
2001-01-08
2002-03-05
Zweizig, Jeffrey (Department: 2816)
Miscellaneous active electrical nonlinear devices, circuits, and
Specific identifiable device, circuit, or system
With specific source of supply or bias voltage
C327S143000
Reexamination Certificate
active
06353355
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a semiconductor device, and in particular to a semiconductor device that incorporates a voltage generating circuit, converting an external power-supply potential supplied from an external power-supply into an internal power-supply potential which is to be used for driving an internal circuit.
2. Description of the Background Art
In a device including a group of internal circuits driven at various potential levels, such as a semiconductor device, a voltage generating circuit is used, for converting an external power-supply potential supplied from an external power-supply into an internal power-supply potential of a desired potential level. Such a voltage generating circuit includes a socalled VDC (Voltage Down Converter) or the like.
FIG. 14
is a schematic block diagram showing a configuration of a voltage generating circuit
500
commonly used for generation of an internal power potential within a semiconductor device.
Referring to
FIG. 14
, voltage generating circuit
500
includes a VREF generating circuit
510
receiving an external power-supply potential VDD from an external power-supply line
505
to generate a reference potential signal VREF corresponding to a set value of the internal power-supply potential, and a VDC
520
generating an internal power-supply potential Vcc to an internal power-supply line
525
.
VDC
520
compares a potential level of internal power-supply line
525
to that of reference potential signal VREF, and if the potential level of internal power-supply line
525
is lower than that of reference potential signal VREF, VDC
520
supplies current from external power-supply line
505
to internal power-supply line
525
in an attempt to hold internal power-supply potential Vcc at a target level.
Therefore, when an external power-supply is turned on and external power-supply potential rises at external power-supply line
505
, the potential level of reference potential signal VREF rises, and then internal power-supply potential Vcc is controlled by VDC
520
based on reference potential signal VREF.
Thus, in voltage generating circuit
500
, when the external power-supply is turned on, the external power-supply potential, reference potential signal VREF and internal power-supply potential Vcc are activated in this order. Setting accuracy of internal power-supply potential Vcc, which is controlled by voltage generating circuit
500
, is greatly affected by the setting accuracy of reference potential signal VREF, so that a configuration in which reference potential signal VREF is generated stepwise is also used, in order to avoid transient overshoot and so forth and to more stably generate internal power-supply potential Vcc.
However, in a semiconductor device, time period from activation of the external power-supply to actual operation of an internal circuit must satisfy a standard value defined by a specification. Thus, when the external power-supply is turned on (hereinafter also referred to as “at the time of power on”), at which transient variation in potential tends to occur, stable generation of reference potential signal VREF is required, while speed-up of rising of internal power-supply potential Vcc is also required.
Monitoring potential level of the internal power-supply line, if the potential level of internal power-supply potential Vcc is not higher than a predetermined value, an operational speed of VDC may possibly be increased to be higher than usual. However, at an initial state, i.e., at the time of power on, the potential level of each internal node is in a transient state. Therefore, there arises a problem that which internal node is to be compared, for its potential level, with internal power-supply potential Vcc, to switch the operational speed of VDC.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a configuration of a semiconductor device, in which an internal power-supply potential used in an internal circuit can be generated at a high speed at the time of power on.
It is another object of the present invention to provide a configuration of a semiconductor device, in which rising speed of an internal power-supply potential at the time of power on can be easily selected in a manufacturing process.
According to one aspect of the present invention, a semiconductor device, supplied, for operation, with a first external power-supply potential from a first external power-supply, includes an external power-supply line, a voltage generating circuit and an internal circuit. The external power-supply line transmits the first external power-supply potential. The voltage generating circuit converts the first external power-supply potential received from the external power-supply line into an internal power-supply potential to be supplied to an internal power-supply line. The internal circuit receives the internal power-supply potential from the internal power-supply line, for operation. The voltage generating circuit includes a reference potential generating unit receiving the first external power-supply potential from the external power-supply line to generate a reference potential signal in accordance with a set potential level of the internal power-supply potential at an intermediate node, a voltage converting circuit supplying current, in accordance with a difference between potential levels of the internal power-supply line and the first intermediate node, from the external power-supply line to the internal power-supply line, a first current supply circuit supplying a first operational current to the voltage converting circuit during an activation period of a first control signal, and a first activation control circuit activating the first control signal for the period from activation of the first external power-supply until the potential level of the internal power-supply line reaches a predetermined level. The first activation control circuit detects the activation of the first external power-supply by comparing potential level of a first reference node transmitting a first potential with that of the internal power-supply line. The first reference node is electrically separated from a node affecting a potential level of the reference potential signal.
According to another aspect of the present invention, a semiconductor device, supplied with a first external power-supply potential from a first external power-supply for operation, includes an external power-supply line, a plurality of voltage generating circuits and a plurality of internal circuits. The external power-supply line supplies the first external power-supply potential. The plurality of voltage generating circuits convert the first external power-supply potential received from the external power-supply line into a plurality of internal power-supply potentials respectively. The plurality of internal circuits respectively receive the plurality of internal power-supply potentials from the plurality of voltage generating circuits. Each of the voltage generating circuits includes an internal power-supply line outputting a corresponding one of the plurality of internal power-supply potentials, a reference potential generating unit receiving the first external power-supply potential from the external power-supply line, to generate a reference potential signal in accordance with a set potential level of the corresponding one of internal power-supply potentials, a voltage converting circuit supplying current in accordance with a difference between potential levels of the internal power-supply line and a first intermediate node from the external power-supply line to the internal power-supply line, a voltage converting circuit supplying current in accordance with a difference between potential levels of the internal power-supply line and the first intermediate node, and a first current-supply circuit supplying a first operational current to the voltage converting circuit in response to an activation of a first control signal. One of the plurality of voltage generati
McDermott & Will & Emery
Mitsubishi Denki & Kabushiki Kaisha
Zweizig Jeffrey
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