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US 7,116,155 B2Granted
High voltage ripple reduction and substrate protection
AssigneeSanDisk Corporation
InventorFeng Pan
Life of this patent
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AssigneeSanDisk Corporation
InventorFeng Pan
Estimating the term…
In a non-volatile memory, charge pumps are used to provide high voltages needed for programming memory cells that have floating gate structures. Charge pumps have a series of voltage multiplier stages in series to boost voltage. These charge pumps must rapidly charge a load to a high voltage and then maintain a voltage with a high degree of stability. Techniques for achieving both of these goals are presented. In one aspect, a charge pump has two operating states, one to charge a load rapidly and a second to maintain a voltage on a charged load with high stability. These states are achieved by changing the current output-from a high current during charging to a low current to maintain the voltage. This is done by changing the capacitance used in the individual voltage multiplier stages. In another aspect, two different current levels are produced by changing the voltage used to charge the capacitors of the voltage multiplier stages.
A wordline voltage control system for raising a voltage of a wordline to a predetermined voltage and maintaining the voltage of the wordline at the predetermined voltage, comprising:
A charge pump connected to a wordline of a nonvolatile memory array to deliver current to the wordline, comprising:
A charge pump connected to a nonvolatile memory array, comprising:
Dependencies are inferred from the claim text.