Electric power conversion systems – Current conversion – With voltage multiplication means
Reexamination Certificate
2000-08-23
2001-06-19
Berhane, Adolf Deneke (Department: 2838)
Electric power conversion systems
Current conversion
With voltage multiplication means
Reexamination Certificate
active
06249446
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to the field of electronic circuits, and, more particularly, to charge pump circuits and related methods.
BACKGROUND OF THE INVENTION
Integrated circuits are typically supplied by one or more direct current (DC) power sources. Certain applications may require that an operating voltage which is higher or lower than the available supply voltages also be provided to the integrated circuit. For example, memory devices such as FLASH electrically erasable programmable read-only memories (EEPROMs) typically require such an operating voltage to perform read and write operations. Another example is a digital wristwatch, which needs a high voltage in order to drive the segments in its output display. Yet, in many instances it is not feasible to add an additional power source to provide the higher voltage.
An alternative to providing an additional, external power source is to use a charge pump circuit to generate a local-use supply voltage. A typical charge pump circuit includes one or more pumping capacitors that are selectively charged and discharged through a series of switches to boost the supply voltage and thereby provide the higher reference voltage. The switches are often driven by control signals having non-overlapping phases that are provided by an oscillator. Furthermore, the number of stages of switches and capacitors may be increased or cascaded to correspondingly increase the voltage boost by a desired multiple.
One example of a charge pump circuit providing a multiple voltage boost is U.S. Pat. No. 5,635,776 to Imi entitled “Charge Pump Voltage Converter.” This charge pump circuit can generate a 4× or an 8× voltage boost and includes two pumping capacitors that are alternatingly controlled by a series of switches. The switches are each driven by respective phase signals that are generated using an oscillator and a frequency divider. While such a configuration does provide a significant voltage boost, it may not be feasible in applications where very little supply current is available because too much supply current may be consumed during the generation of the switch control signals. For the same reason, other prior art charge pump circuits that use multiple oscillators or other clock sources to provide the timing signals may also be inadequate where low current consumption is desirable, such as in portable battery powered devices.
SUMMARY OF THE INVENTION
In view of the foregoing background, it is therefore an object of the invention to provide a charge pump circuit that may be used in applications where low current consumption is desired.
This and other objects, features, and advantages in accordance with the present invention are provided by a charge pump circuit that includes at least one pumping capacitor (also known as a flying capacitor), a plurality of switches connected to the at least one pumping capacitor, and a controller for generating first and second sets of switch control signals for controlling the switches so that the at least one pumping capacitor generates an increased output voltage. More particularly, the controller preferably includes a clock having first outputs for the first set of switch control signals, a transient clamp network having second outputs for the second set of switch control signals, and a respective level shifting capacitor connected between each first output and a corresponding second output. The level shifting capacitors cooperate with the transient clamp network so that the second set of signals are level shifted from the first set. As a result, the second set of signals is produced with substantially no current consumption, which allows the charge pump circuit to be used in applications where low power consumption is desired.
The first set of switch control signals may include a first pair of control signals having opposite relative phases and a second pair of control signals also having phases opposite one another. The first set of control signals is driven into respective level shifting capacitors. The transient clamp network DC references its side of the capacitors to either an input or an output supply during an idling or off switch phase. The transient clamp network may include a plurality of MOS transistors, and each of the switches may be a MOS transistor as well.
A method for providing an increased output voltage according to the present invention preferably includes providing at least one pumping capacitor and a plurality of switches connected thereto, generating a first set of switch control signals, generating a second set of switch control signals by level shifting the first set of switch control signals, and controlling the plurality of switches based upon the first and second sets of switch control signals to generate the increased output voltage.
REFERENCES:
patent: 5397928 (1995-03-01), Chan et al.
patent: 5581455 (1996-12-01), Rossi et al.
patent: 5635776 (1997-06-01), Imi
patent: 5650671 (1997-07-01), Pascucci et al.
patent: 5680300 (1997-10-01), Szepesi et al.
patent: 5774348 (1998-06-01), Druce et al.
patent: 5808883 (1998-09-01), Hawkes
patent: 5926059 (1999-07-01), Brani et al.
patent: 5939866 (1999-08-01), Bjorkengren
patent: 6160723 (2000-12-01), Liu
patent: 6169444 (2001-01-01), Thurber, Jr.
Isham Robert Haynes
Shearon William Brandes
Vulih Salomon
Allen Dyer Doppelt Milbrath & Gilchrist, P.A.
Berhane Adolf Deneke
Intersil America's Inc.
LandOfFree
Cascadable, high efficiency charge pump circuit and related... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Cascadable, high efficiency charge pump circuit and related..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Cascadable, high efficiency charge pump circuit and related... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2545982