Miscellaneous active electrical nonlinear devices – circuits – and – Specific identifiable device – circuit – or system – With specific source of supply or bias voltage
Reexamination Certificate
2001-08-30
2003-09-16
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
Reexamination Certificate
active
06621326
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to integrated circuits and, in particular, to pump circuits used in integrated circuits.
2. Description of the Related Art
In some integrated circuits, it is desirable to have a circuit that provides a high negative voltage. This is particularly true for integrated circuits that include memory devices, such as, for example, electrically erasable programmable read-only-memory (EEPROM) devices. The high negative voltage is applied to control gates of memory cells during erasure to erase the data stored in the memory cells.
An example of a pump circuit that provides a negative voltage is described in U.S. Pat. No. 5,406,517. Some P-channel negative charge pumps, such as that of U.S. Pat. No. 5,406,517, operate with a power supply voltage V
CC
of 5 volts. However, at lower power supply voltages, such as 3 volts or lower, these charge pumps are made impractical due to source bias and large body-effect coefficients, unless clock signals themselves are pumped to a higher voltage than the power supply voltage V
CC
.
As a result, there has been a need for a charge pump circuit that is practical at lower power supply voltages.
SUMMARY OF THE INVENTION
The present invention encompasses a charge pump circuit. In one embodiment, the charge pump circuit of the present invention includes: a first pumping stage including a first switch and a second switch coupled to the first switch; and at least a second pumping stage coupled to the first pumping stage, where the second pumping stage includes a third switch and a fourth switch coupled to the third switch; where the first and second switches are in opposite states, further where immediately prior to the first switch transitioning from an off state to an on state, the second switch and the fourth switch are on.
In one embodiment, the third and fourth switches are in opposite states, and immediately prior to the third switch transitioning from an off state to an on state, the second switch and the fourth switch are on.
REFERENCES:
patent: 5406517 (1995-04-01), Chang et al.
patent: 5973979 (1999-10-01), Chang et al.
patent: 6097161 (2000-08-01), Takano et al.
patent: 6130572 (2000-10-01), Ghilardelli et al.
patent: 6137344 (2000-10-01), Miki
patent: 6157242 (2000-12-01), Fukui
patent: 6198342 (2001-03-01), Kawai
patent: 6459328 (2002-10-01), Sato
Altera Corporation
Cunningham Terry D.
Tra Quan
LandOfFree
P-channel negative pumps does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with P-channel negative pumps, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and P-channel negative pumps will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3065903