Low noise sense amplifier array and method for nonvolatile memory
First Claim
1. A method of sensing a conduction current of a non-volatile memory cell among sensing a group thereof in parallel, comprising:
- providing a node accessible by the memory cell via an intermediate circuit;
precharging the node to an initial voltage;
providing a voltage boosting circuit coupled to the node;
boosting the initial voltage on the node by a predetermined amount;
measuring the conduction current by a rate of voltage discharge at the node; and
whenever the conduction current is determined to be higher than a predetermined value, isolating the voltage boosting circuit from the intermediate circuit of the memory cell until at least sensing for the group of memory cells is completed.
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Accused Products
Abstract
In sensing a page of nonvolatile memory cells with a corresponding group of sense modules in parallel, as each high current cell is identified, it is locked out from further sensing while others in the page continued to be sensed. The sense module involved in the locked out is then in a lockout mode and becomes inactive. A noise source from the sense module becomes significant when in the lockout mode. The noise is liable to interfere with the sensing of neighboring cells by coupling through its bit line to neighboring ones. The noise can also couple through the common source line of the page to affect the accuracy of ongoing sensing of the cells in the page. Improved sense modules and method isolate the noise from the lockout sense module from affecting the other sense modules still active in sensing memory cell in the page.
52 Citations
24 Claims
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1. A method of sensing a conduction current of a non-volatile memory cell among sensing a group thereof in parallel, comprising:
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providing a node accessible by the memory cell via an intermediate circuit; precharging the node to an initial voltage; providing a voltage boosting circuit coupled to the node; boosting the initial voltage on the node by a predetermined amount; measuring the conduction current by a rate of voltage discharge at the node; and whenever the conduction current is determined to be higher than a predetermined value, isolating the voltage boosting circuit from the intermediate circuit of the memory cell until at least sensing for the group of memory cells is completed. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A sensing circuit for sensing a conduction current of a memory cell among a group of nonvolatile memory cells being sensing in parallel, comprising:
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a node; an intermediate circuit coupled between the memory cell and said node; a precharge circuit coupled to said node for charging said node to an initial voltage; a voltage boosting circuit coupled to the node to boost the initial voltage on the node by a predetermined amount; a transfer gate disposed between the voltage boosting circuit and said intermediate circuit; a comparator coupled to said node to determine the conduction current by a rate of voltage discharge at the node; and said transfer gate turning off in response to the conduction current being determined to be higher than a predetermined value, thereby isolating the voltage boosting circuit from the intermediate circuit of the memory cell and wherein said transfer gate remains off until at least sensing for the group of memory cells is completed. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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Specification