Miscellaneous active electrical nonlinear devices – circuits – and – Specific identifiable device – circuit – or system – With specific source of supply or bias voltage
Reexamination Certificate
1999-09-21
2001-11-06
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, C323S316000
Reexamination Certificate
active
06313694
ABSTRACT:
This application claims priority from Korean patent application No. 98-39751 filed Sep. 24, 1998 in the name of Samsung Electronics Co., Ltd., which is herein incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to internal power voltage generating circuits for semiconductor devices, and more particularly, to an internal power voltage generating circuit that uses a single drive transistor to reduce power consumption during stand-by mode and to reduce the transition time from stand-by mode to active mode.
2. Description of the Related Art
An internal power voltage generating circuit in a semiconductor memory device generates an internal power voltage which remains constant regardless of changes in the external power supply voltage. Considerable current flows through the internal power voltage generating circuit in order to supply a stable voltage to the semiconductor memory device.
When a semiconductor memory device operates in an active mode in which read and write operations are performed, it consumes significantly more current than in a standby mode during which it simply stores cell data. Continuous efforts have been made to reduce current consumption during standby mode.
A conventional internal power voltage generating circuit has separate output drivers and comparison circuits for standby and active modes. An additional circuit is required to turn the output driver for active mode completely off during standby mode. For example, the conventional internal power voltage generating circuit shown in
FIG. 1
, which will be described more thoroughly below, includes an additional transistor
20
which turns the active mode output driver
14
completely off during standby mode.
A problem with the conventional circuit of
FIG. 1
, however, is that the additional transistor
20
creates a current path through comparison circuit
10
during standby mode, thereby causing unnecessary current consumption during standby mode, Because the comparison circuit
10
is constructed with large transistors, a considerable amount of current flows through the comparison circuit
10
during standby mode.
An additional problem with the circuit of
FIG. 1
is that it cannot switch quickly from standby mode to active mode because the output driver is turned completely off during standby mode.
FIG. 3
shows a conventional internal power voltage generating circuit having a PMOS output driver
34
and an additional transistor
38
for turning the output driver completely off during standby mode. As with the circuit of
FIG. 1
, the circuit of
FIG. 3
cannot switch quickly from standby mode to active mode because the output driver
34
is turned completely off during standby mode.
Therefore, the conventional internal power voltage generating circuits of
FIGS. 1 and 3
are not suitable for use in high-speed semiconductor memory devices.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to reduce current consumption in an internal power voltage generating circuit during standby mode.
Another object of the present invention is to provide an internal power voltage generating circuit which can switch rapidly from standby mode to active mode.
To achieve these and other objects, an internal power voltage generating circuit in accordance with the present invention uses a single output driver for both standby mode and active mode.
The output driver is coupled to both an active mode comparison circuit which is disabled during stand-by-mode, and to a stand-by mode comparison circuit which is enabled during stand-by mode. The active mode comparison circuit is fabricated from large transistors and generates a first output signal having a high current capacity to turn the output driver completely on. The stand-by mode comparison circuit is fabricated from small transistors and generates a second output signal having a low current capacity which only turns the output driver partially on. The output driver can switch quickly from stand-by mode to active mode because it is not turned completely off during stand-by mode. This also eliminates the need for an additional circuit for turning the driver completely off. The stand-by mode comparison circuit can by left on during active mode without influencing the output driver because the current capacity of its output signal is small compared to that of the active mode comparison circuit.
REFERENCES:
patent: 5254883 (1993-10-01), Horowitz et al.
patent: 5307315 (1994-04-01), Oowaki et al.
patent: 5317254 (1994-05-01), Olson
patent: 5335203 (1994-08-01), Ishii et al.
patent: 5493234 (1996-02-01), Oh
patent: 5506541 (1996-04-01), Herndon
Cunningham Terry D.
Marger & Johnson & McCollom, P.C.
Samsung Electronics Co,. Ltd.
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