Miscellaneous active electrical nonlinear devices – circuits – and – Specific identifiable device – circuit – or system – With specific source of supply or bias voltage
Reexamination Certificate
2000-04-28
2004-10-05
Wells, Kenneth B. (Department: 2816)
Miscellaneous active electrical nonlinear devices, circuits, and
Specific identifiable device, circuit, or system
With specific source of supply or bias voltage
C363S060000
Reexamination Certificate
active
06801076
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to semiconductor integrated circuits. More particularly, it pertains to charge pumps.
BACKGROUND OF THE INVENTION
System designs are routinely constrained by a limited number of readily available power supply voltages (V
cc
). For example, consider a portable computer system powered by a conventional battery having a limited power supply voltage. For proper operation, different components of the system, such as display, processor, and memory components employ diverse technologies which require power to be supplied at various operating voltages. Components often require operating voltages of a greater magnitude than the power supply voltage and, in other cases, a voltage of reverse polarity. The design of a system, therefore, includes power conversion circuitry to efficiently develop the required operating voltages. One such power conversion circuit is known as a charge pump. Charge pumps have been used as on-chip voltage generators capable of providing a voltage more positive than the most positive external supply or more negative than the most negative external supply. The demand for highly efficient and reliable charge pump circuits has increased with the increasing number of applications utilizing battery powered systems, such as notebook computers, portable telephones, security devices, battery-backed data storage devices remote controls, instrumentation, and patient monitors, to name a few.
Inefficiencies in conventional charge pumps lead to reduced system capability and lower system performance in both battery and non-battery operated systems. Inefficiency can adversely affect system capabilities e.g., limited battery life, excess heat generation and high operating costs. Examples of lower system performance include low speed operation, excessive operating delays, loss of data, limited communication range, and inability to operate over wide variations in ambient conditions including ambient light level and temperature.
In addition to constraints on the number of power supply voltages available for system design, there is increasing demand for reducing magnitudes of the power supply voltages due to shrinking die size and also to save power. The demand in diverse application areas requires highly efficient charge pumps that operate from a supply voltage of around one volt.
Thus, there is a need for a low voltage charge pump that can operate at supply voltages less than one volt while reducing the die area and increasing the power efficiency.
SUMMARY OF THE INVENTION
These and other embodiments, aspects, advantages, and features of the present invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art by reference to the following description of the invention and referenced drawings or by practice of the invention. The aspects, advantages, and features of the invention are realized and attained by means of the instrumentalities, procedures, and combinations particularly pointed out in the appended claims and their equivalents.
Other aspects of the invention will be apparent on reading the following detailed description of the invention and viewing the drawings that form a part thereof.
The charge pump of the present invention provides, among other things, a high output high efficiency low voltage charge pump. According to one embodiment, it has two staggered phase generators which act together with a delay to produce non-overlapping signals required to drive charge and precharge capacitors to work around a supply voltage of 1.0 Volts (V
cc
), to provide a higher output voltage and superior current per unit area.
An illustrative embodiment includes a charge pump circuit. The charge pump circuit includes an oscillator to generate an oscillating signal. The charge pump circuit further includes a primary phase generator, which receives the oscillating signal and generates a first and a second phase signals that are non-overlapping and crossing around their high points. The primary phase generator further generates a third and fourth phase signals that are non-overlapping and crossing around their low points. The charge pump circuit further includes a secondary phase generator, which receives the first and second phase signals from the primary phase generator, and generates a fifth and sixth phase signals that are similar to the first and second phase signals and having a predetermined delay from the first and second phase signals. The charge circuit further includes a first and second pre-boot precharge capacitors, which receive the third and fourth phase signals from the primary phase generator. The charge pump circuit further includes a first and second pre-boot capacitors, which receive the first and second phase signals from the primary phase generator, and is further precharged by the first and second pre-boot precharge capacitors during a first phase and a second phase respectively to a first pre-determined level. The charge pump further includes a first and second main pump precharge capacitors, which receive the first and second phase signals during the first and second phases. The charge pump circuit further includes a first and second main pump capacitors for outputting the charge. The first and second man pump precharge capacitors precharge the first and second main pump capacitors to a second pre-determined level respectively. According to one embodiment, the charge pump is generally prebooting one of the main pump capacitors to a predetermined boot level, while it is outputting the charge from the other main pump capacitor when it receives the one of the phase signals from the secondary phase generator which boots the main pump cap to a third predetermined level. As a result, the pre-boot time is hidden during a charge out This enables the charge pump to run at a faster cycle time which can result in a higher output. This also enables the charge pump to produce more charge for a given size of a capacitor. Other aspects of the invention will be apparent on reading the following detailed description of the invention and viewing the drawings that form a part thereof.
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Micro)n Technology, Inc.
Schwegman Lundberg Woessner & Kluth P.A.
Wells Kenneth B.
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