Dual reference cell sensing scheme for non-volatile memory
First Claim
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1. A high speed non-volatile memory device, comprising:
- at least one memory cell;
a first reference cell;
a second reference cell;
a first sense amplifier coupled to the first reference cell and the memory cell for determining a voltage difference between the first reference cell and the memory cell;
a second sense amplifier coupled to the second reference cell and the memory cell for determining a voltage difference between the second reference cell and the memory cell; and
a third sense amplifier coupled to the first sense amplifier and the second sense amplifier for determining a status of the memory cell according to the voltage differences of the first sense amplifier and the second sense amplifier.
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Abstract
The present invention provides a dual reference cell sensing scheme for non-volatile memory. A high voltage reference cell and a low voltage reference cell are individually coupled to two sense amplifiers for providing two distinct reference voltages for comparison against the memory cell voltage. The output of the two sense amplifiers is further connected to a second stage sense amplifier to determine the status of the memory. The dual reference cell sensing scheme provides an increased sensing window which increases performance under low voltage application. The dual reference cell sensing scheme can be implemented by either voltage-based, current-based, or ground.
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Citations
20 Claims
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1. A high speed non-volatile memory device, comprising:
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at least one memory cell;
a first reference cell;
a second reference cell;
a first sense amplifier coupled to the first reference cell and the memory cell for determining a voltage difference between the first reference cell and the memory cell;
a second sense amplifier coupled to the second reference cell and the memory cell for determining a voltage difference between the second reference cell and the memory cell; and
a third sense amplifier coupled to the first sense amplifier and the second sense amplifier for determining a status of the memory cell according to the voltage differences of the first sense amplifier and the second sense amplifier. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A high speed non-volatile memory device, comprising:
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at least one memory cell;
a first reference cell comprising a current source and a capacitor;
a second reference cell comprising a current source and a capacitor;
a first sense amplifier coupled to the first reference cell and the memory cell for determining a voltage difference between the first reference cell and the memory cell;
a second sense amplifier coupled to the second reference cell and the memory cell for determining a voltage difference between the second reference cell and the memory cell; and
a third sense amplifier coupled to the first sense amplifier and the second sense amplifier for determining a status of the memory cell according to the voltage differences of the first sense amplifier and the second sense amplifier. - View Dependent Claims (9, 10)
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11. A high speed non-volatile memory device, comprising:
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at least one memory cell;
a first reference cell comprising a current source and a resistor connected to VDD;
a second reference cell comprising a current source and a resistor connected to VDD;
a first sense amplifier coupled to the first reference cell and the memory cell for determining a voltage difference between the first reference cell and the memory cell;
a second sense amplifier coupled to the second reference cell and the memory cell for determining a voltage difference between the second reference cell and the memory cell; and
a third sense amplifier coupled to the first sense amplifier and the second sense amplifier for determining a status of the memory cell according to the voltage differences of the first sense amplifier and the second sense amplifier. - View Dependent Claims (12)
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13. A high speed non-volatile memory device, comprising:
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at least one memory cell;
a first reference cell coupled to ground;
a second reference cell comprising a current source and a resistor connected to VDD;
a first sense amplifier coupled to the first reference cell and the memory cell for determining a voltage difference between the first reference cell and the memory cell;
a second sense amplifier coupled to the second reference cell and the memory cell for determining a voltage difference between the second reference cell and the memory cell; and
a third sense amplifier coupled to the first sense amplifier and the second sense amplifier for determining a status of the memory cell according to the voltage differences of the first sense amplifier and the second sense amplifier. - View Dependent Claims (14)
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15. A method for sensing a non-volatile memory with dual reference cells, comprising:
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providing first sense amplifier, a second sense amplifier, and a third sense amplifier, wherein each of the sense amplifiers has a first polarity input terminal and a second polarity input terminal;
applying a first voltage reference signal to the first polarity input terminal of the first sense amplifier, and a second voltage reference signal to the second polarity input terminal of the second sense amplifier;
applying a cell reference signal, which is to be sensed, to the second polarity input terminal of the first sense amplifier and the first polarity input terminal of the second sense amplifier, and leading outputs of the first sense amplifier and the second sense amplifier to the third sense amplifier. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification