Sensing amplifier for floating gate memory devices
First Claim
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1. An amplifier for sensing the binary state of a first MOS floating gate memory device comprising:
- a line coupled to said first device;
a first biasing means coupled to said line for charging said line to a first potential when said first device is in one binary state and for preventing said line from dropping below a second potential when said first device is in its other binary state;
a second floating gate memory device substantially identical to said first device for providing a reference load;
a biasing circuit coupled to said second device for biasing said second device at a predetermined level;
a second biasing means coupled to said second device for providing a reference potential;
comparator means for comparing potentials, said comparator means coupled to said line and coupled to receive said reference potential;
whereby said amplifier senses said binary state of said first device and is quickly able to again sense the binary state of said first device since said line is prevented from discharging by said first biasing means.
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Abstract
An MOS sensing amplifier for sensing the binary state of floating gate memory devices in a read-only memory is disclosed. The potentials on the column lines in the memory are held to a narrow voltage swing. A pair of "zero" threshold voltage transistors having slightly different threshold voltages are used to maintain the potentials on these lines. A potential developed from the column line is compared with a reference potential developed with a "dummy" biasing network and a "dummy" floating gate memory device.
75 Citations
15 Claims
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1. An amplifier for sensing the binary state of a first MOS floating gate memory device comprising:
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a line coupled to said first device; a first biasing means coupled to said line for charging said line to a first potential when said first device is in one binary state and for preventing said line from dropping below a second potential when said first device is in its other binary state; a second floating gate memory device substantially identical to said first device for providing a reference load; a biasing circuit coupled to said second device for biasing said second device at a predetermined level; a second biasing means coupled to said second device for providing a reference potential; comparator means for comparing potentials, said comparator means coupled to said line and coupled to receive said reference potential; whereby said amplifier senses said binary state of said first device and is quickly able to again sense the binary state of said first device since said line is prevented from discharging by said first biasing means. - View Dependent Claims (2, 3, 4, 5, 6)
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7. In a read-only memory which includes a plurality of floating gate memory devices which are selectively coupled to a line in said memory, a sensing amplifier coupled to said line for detecting the binary state of said memory devices comprising:
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a first biasing means coupled to said line for charging said line to a first potential when a selected one of said memory devices is in one binary state and for preventing said line from dropping below a second potential when said selected one of said memory devices is in its other binary state; an additional floating gate device substantially identical to said memory devices for providing a reference load; a biasing circuit coupled to the control gate of said additional device for biasing said additional device such that said additional device conducts; a second biasing means substantially identical to said first biasing means for providing a reference potential, said second biasing means coupled to said additional device; comparator means for comparing two potentials, said comparator means coupled to said line and coupled to receive said reference potential; whereby said amplifier quickly senses said binary states of said devices since said line is prevented from discharging. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15)
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Specification