Noise suppression in memory device sensing
First Claim
1. A method of sensing a target memory cell, comprising:
- applying a first potential to first variable-potential nodes associated with switching a first latch;
switching the first latch to a state indicative of a data value of the target memory cell while the first variable-potential nodes have their first potential;
applying a second potential to the first variable-potential nodes while holding the first latch in its state indicative of the data value;
applying a first potential to second variable-potential nodes associated with switching a second latch;
switching the second latch to a state indicative of the state of the first latch and of the data value while the second variable-potential nodes have their first potential and while the first variable-potential nodes have their second potential; and
applying a second potential to the second variable-potential nodes while holding the second latch in its state indicative of the data value.
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Accused Products
Abstract
Methods of sensing a programmed state of a nonvolatile memory cell, as well as apparatus for carrying out the methods, are useful in memory devices. Latches in sensing devices are selectively coupled to a variable-potential node to receive a first potential to switch the latch, i.e., presetting, setting or resetting the latch. After switching, the variable-potential node may be set to an intermediate potential to increase noise immunity to the latch while holding the data value. In NAND sensing devices having a data latch and a cache latch, the variable-potential nodes of the data latch and the variable-potential nodes of the cache latch are coupled to separate ground control circuits. By independently varying the potentials applied to the variable-potential nodes of the data latch and cache latch, determined by whether the individual latch is switching or holding data, noise immunity in the data path is increased.
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Citations
34 Claims
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1. A method of sensing a target memory cell, comprising:
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applying a first potential to first variable-potential nodes associated with switching a first latch;
switching the first latch to a state indicative of a data value of the target memory cell while the first variable-potential nodes have their first potential;
applying a second potential to the first variable-potential nodes while holding the first latch in its state indicative of the data value;
applying a first potential to second variable-potential nodes associated with switching a second latch;
switching the second latch to a state indicative of the state of the first latch and of the data value while the second variable-potential nodes have their first potential and while the first variable-potential nodes have their second potential; and
applying a second potential to the second variable-potential nodes while holding the second latch in its state indicative of the data value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method of writing to a target memory cell, comprising:
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applying a first potential to first variable-potential nodes associated with switching a first latch;
switching the first latch to a state indicative of a data value to be written to the target memory cell while the first variable-potential nodes have their first potential;
applying a second potential to the first variable-potential nodes while holding the first latch in its state indicative of the data value;
applying a first potential to second variable-potential nodes associated with switching a second latch;
switching the second latch to a state indicative of the state of the first latch and of the data value while the second variable-potential nodes have their first potential and while the first variable-potential nodes have their second potential;
applying a second potential to the second variable-potential nodes while holding the second latch in its state indicative of the data value; and
coupling the second latch to a bit line coupled to the target memory cell while applying the second potential to the second variable-potential nodes. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19)
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20. A method of passing data between latches in a sensing device of a memory device, the method comprising:
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applying a first potential to first nodes associated with switching a first latch of the sensing device during a switching period of the first latch;
applying a second potential to the first nodes during a holding period of the first latch, wherein the second potential of the first nodes is greater than the first potential of the first nodes and less than a supply potential; and
passing a state of the first latch to a second latch of the sensing device during the holding period of the first latch. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27)
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28. A sensing device, comprising:
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a first latch for providing a first signal at a first node of the first latch and having a logic level indicative of a data value of a target memory cell, wherein the first latch is selectively coupled to one or more first variable-potential nodes for switching the first latch; and
a second latch for providing a second signal at a first node of the second latch and having a logic level indicative of the data value, wherein the second latch is selectively coupled to one or more second variable-potential nodes for switching the second latch;
a first ground control circuit coupled to receive a first control signal and to provide a variable potential to the first variable-potential nodes responsive to the first control signal; and
a second ground control circuit coupled to receive a second control signal and to provide a variable potential to the second variable-potential nodes responsive to the second control signal. - View Dependent Claims (29, 30, 31)
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32. A memory device, comprising:
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an array of memory cells; and
a sensing device for sensing a data value of a target memory cell of the array of memory cells, the sensing device comprising;
a first latch for providing a first signal at a first node of the first latch and having a logic level indicative of the data value of the target memory cell, wherein the first latch is selectively coupled to one or more first variable-potential nodes for switching the first latch; and
a second latch for providing a second signal at a first node of the second latch and having a logic level indicative of the data value, wherein the second latch is selectively coupled to one or more second variable-potential nodes for switching the second latch;
a first ground control circuit coupled to receive a first control signal and to provide a variable potential to the first variable-potential nodes responsive to the first control signal; and
a second ground control circuit coupled to receive a second control signal and to provide a variable potential to the second variable-potential nodes responsive to the second control signal;
wherein the first ground control circuit and the second ground control circuit are adapted to provide either a ground potential or an intermediate potential greater than the ground potential and less than a supply potential; and
wherein the first ground control circuit and the second ground control circuit are further adapted to provide their ground potentials or intermediate potentials independently of each other. - View Dependent Claims (33)
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34. An electronic device, comprising:
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a processor; and
a memory device coupled to the processor, wherein the memory device comprises;
an array of memory cells; and
a sensing device for sensing a data value of a target memory cell of the array of memory cells, the sensing device comprising;
a first latch for providing a first signal at a first node of the first latch and having a logic level indicative of the data value of the target memory cell, wherein the first latch is selectively coupled to one or more first variable-potential nodes for switching the first latch; and
a second latch for providing a second signal at a first node of the second latch and having a logic level indicative of the data value, wherein the second latch is selectively coupled to one or more second variable-potential nodes for switching the second latch;
a first ground control circuit coupled to receive a first control signal and to provide a variable potential to the first variable-potential nodes responsive to the first control signal; and
a second ground control circuit coupled to receive a second control signal and to provide a variable potential to the second variable-potential nodes responsive to the second control signal;
wherein the first ground control circuit and the second ground control circuit are adapted to provide either a ground potential or an intermediate potential approximately one Vt less than a supply potential; and
wherein the first ground control circuit and the second ground control circuit are further adapted to provide their ground potentials or intermediate potentials independently of each other.
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Specification