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US 5,640,350 AGranted
Multi-bit dynamic random access memory cell storage
OwnerAdam Sempa Igainventor
Life of this patent
Estimating the term…
Abstract
A single transistor capacitor stacked memory cell utilizing precharge voltage and spacial format to miximize storage per unit of area.
Claims7
A one transistor multi-bit dynamic memory cell comprising:
- (a) a switching transistor means for switching on said one transistor multi-bit dynamic memory cell;
- (b) a data storage capacitor means constructed in such a way that said data storage capacitor means has a wafer-surface stacked structure in combination with a deep wafer substrate trenched structure, said wafer-surface stacked structure and said deep wafer substrate trenched structure both comprising in uniform combination a storage node plate of appropriate material, or cell node plate that is pre-charged to a reference ground voltage level and an insulator or dielectric layer that is constructed in between said storage node plate and said cell node plate, said storage node plate, said cell node plate and said insulator or dielectric layer being capable of being stacked in several layers on the surface of the wafer of said multi-bit one transistor cell and above a row address word line, in order to increase the effective surface area of said data storage capacitor for the purpose of multi-bit storage without increasing the overall wafer surface area occupied by said data storage capacitor, whereby said storage node plate is further insulated from signal leakage in the trenched structure areas by first depositing an appropriately doped layer of field oxide or preferably an "N" type doped layer;
- (c) a bit line means whose first end is connected to said storage node plate of said data storage capacitor and whose length is connected to a source terminal of said switching transistor and a drain terminal of said switching transistor in such a way that an applied signal on said bit line means when said switching transistor is appropriately turned on can either flow from source to drain so as to charge said data storage capacitor during the process of data storage or data writing or flow from drain to source so as to provide the stored data signal to a sense amplifier circuit during the process of data writing;
- (d) a decoder driven row address word line connected to a gate terminal of said switching transistor of said multi-bit one transistor dynamic cell for turning on said switching transistor during the process of data writing, data reading and data restoration.
1 more element
A method of reading data stored in a multi-bit one transistor dynamic cell comprising the steps of:
- (a) building a dynamic cell array composed of a predetermined number of rows and columns of said multi-bit one transistor dynamic cells;
- (b) splitting said array into two equal halves in a left to right manner or a north to south manner and connecting a balanced differential sense amplified between the left half and the right half of said array or between the north half and the south half of said array;
- (c) connecting all gate terminals of said multi-bit one transistor dynamic cells of said dynamic cell array to a new address decoder driver lines and all connecting all gate terminals of said multi-bit one transistor dynamic cells belonging to either half of said dynamic cell array to a new address decoder driver and all column bit lines belonging to one half of said dynamic cell array to a corresponding side of said balanced differential sense amplifier;
- a buffer memory and a data conversion circuit means;
- (d) providing a predetermined supply voltage signal to said balanced differential sense amplifier and to said dynamic cell array;
- (e) applying a first predetermined voltage signal to set all voltage and all column lines near said supply voltage provided to said balanced differential sense amplifier and to set all dummy cells of said balanced differential sense amplifier to a predetermined reference voltage;
- (f) selecting one row either in the left half side or the right half side of said dynamic cell array and applying thereon a second predetermined voltage signal using said row address decoder driver circuit means and;
- (g) simultaneously providing a third predetermined voltage signal to the dummy cell on the opposite side of said balanced differential sense amplifier so as to cause said dummy cell on the opposite of said balanced differential sense amplifier to be selected;
- (h) letting the column voltage of the side of said dynamic cell array connected to said dummy cell drop to a predetermined reference level as the column charge is shared with the capacitor of said dummy cell;
- (i) letting the column voltage of said selected side connected to said selected multi-bit one transistor dynamic cell drop to a predetermined level, said predetermined level representing the amount of charge stored on a data storage capacitor of said multi-bit one transistor dynamic cell, whereby the drop in said predetermined level of said column voltage is maximum for said data storage capacitor without any charge or data stored thereon, and is minimum for said data storage capacitor filled with the maximum amount of charge or maximum amount of data in terms of binary bits stored thereon;
- (j) Enabling a buffer memory or register to receive said column voltage of said selected side connected to said selected multi-bit one transistor dynamic cell and said reference dummy cell column voltage;
- (k) enabling a data conversion circuit means to access said buffer memory to receive both said column voltage of said selected side connected to said selected multi-bit one transistor dynamic cell and said reference dummy cell column voltage;
- (l) letting said data conversion circuit calculate the difference between said column voltage of said selected side connected to said selected multi-bit one transistor dynamic cell and said reference dummy cell column voltage so as to obtain an amount of voltage level that represents the amount of data stored in said selected multi-bit one transistor dynamic cell;
- (m) using said data conversion circuit means to compare said amount of voltage level that represents the amount of data stored in said selected multi-bit one transistor dynamic cell to a set of reference voltage levels stored in said data conversion circuit means to obtain an actual count of the number of bits or the amount of data stored in said selected multi-bit one transistor dynamic cell;
- (n) adjusting said amount of voltage that represents the amount of data in total bits stored in said selected multi-bit one transistor dynamic cell to be equal to the next higher level of reference voltage within said set of reference voltages stored in said data conversion circuit in the unique case that said amount of data stored in said selected multi-bit one transistor dynamic cell falls in between two referent voltage ranges due to data distortion or storage capacitor discharge, the first of said two reference voltage levels between the immediate next lower level reference voltage and the second of said two reference voltage levels being said immediate next higher level reference voltage;
- (o) using the correct adjusted read voltage that represents the actual number of bits of data stored in said selected multi-bit one transistor dynamic cell to refresh said selected multi-bit one transistor dynamic cell by applying an appropriate voltage signal to said column bit line of said selected multi-bit one transistor dynamic cell so as to restore the actual charge that represents the actual number of bits presently stored in said selected multi-bit one transistor dynamic cell.
13 more elements
Dependencies are inferred from the claim text.