Word line drivers having a low pass filter circuit in non-volatile memory device

• US 7,609,559 B2
• Filed: 01/12/2007
• Issued: 10/27/2009
• Est. Priority Date: 01/12/2007
• Status: Active Grant

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Micron Technology, Inc.
• Inventors: Yamada, Shigekazu
• Primary Examiner(s): Nguyen; Tuan T.
• Application Number:
  US11/652,817
• Publication Number:
  US 20080170433A1
• Time in Patent Office: 1,019 Days
• Field of Search: 365/185.23, 365/185.18, 365/185.05
• US Class Current: 365/185.23
• CPC Class Codes: G11C 16/08 Address circuits; Decoders; Word-line control circuits
• CPC Class Codes: G11C 8/08 Word line control circuits, e.g. drivers, boosters, pull-up circuits, pull-down circuits, precharging circuits, for word lines

Abstract

A word line driver system that utilizes a voltage selection circuit to supply one of several voltages to an output node coupled to a plurality of word line control circuits. Each word line control circuit is coupled to a respective word line in an array of non-volatile memory cells. The voltage selection circuit may include selectable low pass filters for filtering the supplied voltage supplied to the word lines in the array of memory cells without significantly increasing the overall die-size of the device.

Claims

1. A word line driver system coupled to an array of non volatile memory cells arranged in rows, each row of cells coupled by a word line, the word line driver system comprising:

a voltage driver circuit operable to select and drive one of at least two voltages;

a low pass filter circuit coupled to the voltage driver circuit and having an output node, the low pass filter circuit operable to receive the selected voltage from the voltage driver circuit and to generate a filtered voltage at the output node; and

a plurality of word line control circuits coupled to the output node of the low pass filter circuit, each of the word line control circuits coupled to a respective word line in the array of the non-volatile memory cells and being operable to selectively couple the filtered voltage at the output node to the respective word line.

2. The word line driver system of claim 1 wherein the word line control circuits are operable to couple the filtered voltage at the output node to the respective word lines responsive to a received address.

3. The word line driver system of claim 1 wherein the voltage driver circuit is operable to supply to the low pass filter circuit a programming voltage during a programming operation, one of at least two bias voltages during a read operation, and one of at least two enable voltages depending upon whether the memory device is performing a read operation or a programming operation.

4. The word line driver system of claim 1 wherein the bias voltages correspond to one of a plurality of charge levels being read from the memory cells.

5. The word line driver system of claim 1 wherein the low pass filter circuit is operable to provide a delay time for reducing word line-to-word line coupling during a programming operation.

6. The word line driver system of claim 1 wherein the low pass filter circuit comprises at least two low-pass filters coupled in a parallel configuration, each low-pass filter comprising a capacitor coupled in series with a transistor, and wherein each of the transistors are selectively enabled such that a combination of low-pass filters are selectively activated to filter the received voltage from the voltage driver circuit.

7. The word line driver system of claim 1 further comprising a voltage discharging circuit coupled to the output node.

8. The word line driver system of claim 1 further comprising a circuit operable to disable the respective word line in the array of the non-volatile memory cells.

9. A processor-based system comprising:

a processor operable to process data and to provide memory commands and addresses;

an input device coupled to the processor;

an output device coupled to the processor; and

a non-volatile memory device having a word line driver system coupled to an array of non-volatile memory cells arranged in rows, each row of cells coupled by a word line, the word line driver system comprising;

a voltage driver circuit operable to select and drive one of at least two voltages;

a low pass filter circuit coupled to the voltage driver circuit and having an output node, the low pass filter circuit operable to receive the selected voltage from the voltage driver circuit and to generate a filtered voltage at the output node; and

a plurality of word line control circuits coupled to the output node of the low pass filter circuit, each of the word line control circuits coupled to a respective word line in the array of the non-volatile memory cells and being operable to selectively couple the filtered voltage at the output node to the respective word line.

10. The processor-based system of claim 9 wherein the word line control circuits are operable to couple the filtered voltage at the output node to the respective word lines responsive to an address provided by the processor.

11. The processor-based system of claim 9 wherein the voltage driver circuit is operable to supply to the low pass filter circuit a programming voltage responsive to a programming command provided by the processor, one of at least two bias voltages during a read command provided by the processor, and one of at least two enable voltages depending upon whether the processor is providing a read command or a programming command.

12. The processor-based system of claim 9 wherein the bias voltages correspond to one of a plurality of charge levels being read from the memory cells.

13. The processor-based system of claim 9 wherein the low pass filter circuit is operable to provide a delay time for reducing word line-to-word line coupling responsive to a programming command provided by the processor.

14. The processor-based system of claim 9 wherein the low pass filter circuit comprises at least two low-pass filters coupled in a parallel configuration, each low-pass filter comprising a capacitor coupled in series with a transistor, and wherein each of the transistors are selectively enabled such that a combination of low-pass filters are selectively activated to filter the received voltage from the voltage driver circuit.

15. The processor-based system of claim 9 further comprising a voltage discharging circuit coupled to the output node.

16. The processor-based system of claim 9 further comprising a circuit operable to disable the respective word line in the array of the non-volatile memory cells.