Semiconductor memory device having floating gate transistors and data holding means
First Claim
1. A semiconductor memory device comprising:
- a first floating gate transistor and a second floating gate transistor each storing charges, the amount of the charges stored in the first floating gate transistor being made different from that stored in the second floating gate transistor;
at least one control means for generating a voltage difference in accordance with respective threshold voltages of the first and second floating gate transistors, and for then turning off the first and second floating gate transistors; and
at least one data holding means for holding the voltage difference as a binary dataand wherein the control means detects completion of sensing operation of the data holding means, and turns off the first and second floating gate transistors after the detection.
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Abstract
In a semiconductor memory device, a data holding unit is disposed separately from the first and second floating gate transistors. A voltage difference is generated by the difference between the threshold voltages of the first and second floating gate transistors, and the voltage difference is stored in the form of a binary data. Thereafter, the first and second floating gate transistors are turned off. Thus, a minute current which always flows through the first and second floating gate transistors in the conventional technique is prevented from being generated so that the power consumption is reduced. In addition, data is fetched from the data holding unit while the bias voltage generating units are turned off. Thus, the time period of operating the bias voltage generating units is eliminated so that the memory device can operate at a high speed.
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Citations
5 Claims
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1. A semiconductor memory device comprising:
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a first floating gate transistor and a second floating gate transistor each storing charges, the amount of the charges stored in the first floating gate transistor being made different from that stored in the second floating gate transistor; at least one control means for generating a voltage difference in accordance with respective threshold voltages of the first and second floating gate transistors, and for then turning off the first and second floating gate transistors; and at least one data holding means for holding the voltage difference as a binary data and wherein the control means detects completion of sensing operation of the data holding means, and turns off the first and second floating gate transistors after the detection. - View Dependent Claims (2, 3, 4, 5)
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Specification