US 2003/0111682 A1Published application

Nonvolatile memory and processing system

AssigneeHitachi, Ltd.

InventorsHitoshi Tanaka, Masanori Isoda, Takayuki Kawahara

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Abstract

It is an object of the present invention to allow a voltage generating section which produces a high voltage to efficiently produce a high voltage, and to reduce a layout area of a semiconductor chip. An intermediate voltage charge pump circuit is provided in a voltage producing section of a flash memory. The intermediate voltage charge pump circuit comprises switching elements, a first charge pump circuit comprising capacitors, a second charge pump circuit comprising switching elements, capacitors and an equalizer comprising switching elements. These elements are driven by driving signals. A period during which all of one contacts of parasitic capacities Capacitor are brought into floating state temporarily is formed. After corresponding parasitic capacities are short-circuited by the switching elements, nodes thereof are electrically charged or discharged, and a high voltage is produced while reusing electric charge while using electric charge discharged to a reference potential by next cycle.

Claims10

Dependent claims

A nonvolatile semiconductor memory device comprising a memory array having a plurality of nonvolatile memory cells;

a control section;
and a voltage producing section for supplying a predetermined voltage to be supplied to said nonvolatile memory cell, wherein
said memory array can store predetermined information in each of said nonvolatile memory cells;
said control section controls a writing operation for storing information in said nonvolatile memory cell, a reading-out operation for reading out the information stored in said nonvolatile memory cell, and an erasing operation for erasing the information stored in said nonvolatile memory cell;
said voltage producing section comprises an operation signal producing section for producing a predetermined voltage to be applied to the memory cells in each of said operations in accordance with control from said control section;
and a plurality of voltage generating sections;
said operation signal producing section produces various operation signals to be supplied to said plurality of voltage generating sections;
said voltage generating section comprises:
a serial type first charge pump circuit for producing a boosted voltage based on a first operation signal;
a serial type second charge pump circuit for producing a boosted voltage based on a second operation signal;
and
an equalizer for short-circuiting parasitic capacities of said first and second charge pump circuits based on a third operation signal during a floating state of the corresponding parasitic capacities parasitized to the boosted capacities of said first and second charge pump circuits when the boosted voltage produced by said first or second charge pump circuit is output.

9 more elements

A nonvolatile semiconductor memory device comprising a memory array having a plurality of nonvolatile memory cells;

a control section;
and a voltage producing section for supplying a predetermined voltage to be supplied to said nonvolatile memory cell, wherein
said memory array can store predetermined information in each of said nonvolatile memory cells;
said control section controls a writing operation for storing information in said nonvolatile memory cell, a reading-out operation for reading out the information stored in said nonvolatile memory cell, and an erasing operation for erasing the information stored in said nonvolatile memory cell;
said voltage producing section comprises an operation signal producing section for producing a predetermined voltage to be applied to the memory cells in each of said operations in accordance with control from said control section;
and a plurality of voltage generating sections;
said operation signal producing section produces various operation signals to be supplied to said plurality of voltage generating sections;
said voltage generating section comprises:
a third charge pump circuit having a parallel parasitic capacitance provided at its preceding stage and a plurality of serial pump circuits connected to its following stage, said third charge pump circuit producing a boosted voltage based on the first operation signal;
a fourth charge pump circuit having a parallel parasitic capacitance provided at its preceding stage and a plurality of serial pump circuits connected to its following stage, said fourth charge pump circuit producing a boosted voltage based on the second operation signal;
and
an equalizer for short-circuiting parasitic capacities of said third and fourth charge pump circuits based on a third operation signal during a floating state of the corresponding parasitic capacities parasitized to the boosted capacities of said first and second charge pump circuits when the boosted voltage produced by said third or fourth charge pump circuit is output.

9 more elements

A processing system comprising a nonvolatile memory section and a central processing unit, in which an operation voltage is supplied from outside, said central processing unit can carry out a predetermined processing and can give operation instructions to said nonvolatile memory section, wherein:

said nonvolatile memory section comprises a plurality of nonvolatile memory cells for storing information, and a voltage producing section, said nonvolatile memory section accesses said plurality of nonvolatile memory cells in accordance with operation instructions from said central processing unit to store and read out information, said nonvolatile memory section gives instructions to said voltage producing section to produce a predetermined voltage in accordance with storing operation instructions of the information from said central processing unit;
said voltage producing section comprises an operation signal producing section and a plurality of voltage generating sections;
said operation signal producing section produces an operation signal to be supplied to said plurality of voltage generating sections;
said voltage generating section comprises:
a third charge pump circuit having a parallel parasitic capacitance provided at its preceding stage and a plurality of serial pump circuits connected to its following stage, said third charge pump circuit producing a boosted voltage based on the first operation signal;
a fourth charge pump circuit having a serial parasitic capacitance provided at its preceding stage and a plurality of parallel pump circuits connected to its following stage, said fourth charge pump circuit producing a boosted voltage based on the second operation signal;
and
an equalizer for short-circuiting parasitic capacities of said third and fourth charge pump circuits based on a third operation signal during a floating state of the corresponding parasitic capacities parasitized to the boosted capacities of said first and second charge pump circuits when the boosted voltage produced by said third or fourth charge pump circuit is output.

5 more elements

Dependencies are inferred from the claim text.