Multivalue Memory Cell With Dual Gating Transistors
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Solution Overview
Problem
Concurrent sensing of multivalue bits in digital memory devices requires complex implementation and manufacturing of four sense amplifiers with different reference voltages, imposing latency and complexity compared to sequential sensing methods.
Innovation Solution
A multivalue memory cell with two gating transistors and a storage element, such as a capacitor, is configured to use two or three sense amplifiers with distinct or shared reference voltages, where the gating transistors activate based on threshold voltages to act as part of the sensing logic, allowing for efficient determination of stored voltage levels corresponding to four discrete binary values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If four sense amplifiers with different reference voltages are used for concurrent sensing of multivalue bits, then sensing accuracy is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent combines the sensing function for multiple voltage levels into a single sense amplifier by integrating threshold detection logic directly into the sense amplifier circuit. This allows one sense amplifier to perform the work of four separate amplifiers by using internal threshold comparisons to determine which voltage level range the stored value falls into, thereby reducing device complexity while maintaining sensing accuracy
Solution Approach 2:
The sense amplifier is designed with multi-functionality to handle concurrent sensing of multivalue bits across different voltage levels. By incorporating multiple threshold detection capabilities within a single amplifier circuit, the design achieves universal sensing capability that eliminates the need for multiple specialized sense amplifiers with different reference voltages
2Adaptability or versatility
If four sense amplifiers with different reference voltages are used for concurrent sensing, then sensing capability is improved, but manufacturing complexity increases
Solution Approach 1:
The patent merges the functionality of four separate sense amplifiers into one unified circuit structure. This consolidation reduces the number of components that need to be manufactured and assembled, simplifying the manufacturing process while preserving the full sensing capability to detect all four voltage levels corresponding to two bits of data
3Device complexity
If sequential sensing is used to reduce sense amplifier count, then device complexity is reduced, but latency increases
Solution Approach 1:
The patent enables continuous useful action by allowing concurrent sensing of both voltage levels simultaneously within a single sense amplifier cycle. The internal threshold detection mechanism processes multiple voltage level comparisons in parallel, eliminating the sequential waiting time between sensing operations while maintaining simplicity in the sense amplifier configuration
Data Source
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AI summary
Digital memory devices and systems, as well as methods of operating digital memory devices, that include a multivalue memory cell (111) with a first (101) and a second (103) gating transistor arranged in parallel, having a first and a second node, respectively, coupled to a storage element (105), and sensing circuitry (113, 115) coupled to a third and a fourth node of the first and second gating transistors, respectively, to sense a stored voltage of the memory cell (111). In embodiments, the first and second gating transistors (101, 103) are configured to activate at different threshold voltage levels.