Multi-Story Cross-Point Read/Write Circuits With Shared Sense Amplifiers
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Solution Overview
Problem
Accessing memory cells in multi-story cross-point memory arrays requires dedicated sense amplifiers for each story, leading to increased space occupation and design constraints.
Innovation Solution
Implementing control circuits that enable a common sense amplifier to connect to either a bit line or a word line based on the memory cell's location, allowing the same sense amplifier to be used for multiple stories, thereby reducing the number of required sense amplifiers and space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If dedicated sense amplifiers are provided for each story in multi-story cross-point memory, then reading memory cells in different stories can be performed simultaneously, but the area occupied by sense amplifiers increases significantly
Solution Approach 1:
The patent makes sense amplifiers universal by enabling them to serve multiple stories through dynamic connection switching. The sense amplifier can be connected to different word lines and bit lines depending on which story is being accessed, allowing one sense amplifier to replace multiple dedicated sense amplifiers. This multi-functionality resolves the contradiction by maintaining simultaneous read capability across stories while reducing the total number of sense amplifiers needed.
Solution Approach 2:
The patent introduces dynamic connection switching mechanisms that allow sense amplifiers to change their connections between different word lines and bit lines based on the active story. This dynamic reconfiguration enables a single sense amplifier to access memory cells in different stories at different times, achieving the functionality of multiple dedicated sense amplifiers with fewer physical components, thus reducing area while maintaining productivity.
2Area of stationary object
If the number of sense amplifiers is reduced to decrease area occupation, then area efficiency improves, but the capability to access multiple stories simultaneously may be compromised
Solution Approach 1:
The patent adds the dimension of time to the sense amplifier operation by implementing dynamic switching between different stories. Instead of having spatially distributed dedicated sense amplifiers for each story, the system uses temporally multiplexed access where a single sense amplifier sequentially serves multiple stories. This dimensional transition from spatial parallelism to temporal parallelism maintains multi-story access capability while reducing area occupation.
Solution Approach 2:
The sense amplifier is designed as a universal component that can interface with any word line and bit line combination across different stories through controlled switching. This universality allows the system to maintain full multi-story access capability with a reduced number of sense amplifiers, as each sense amplifier can be dynamically assigned to serve any story as needed.
Data Source
AI summary
An apparatus includes one or more control circuits to connect to a multi-story memory structure. The multi-story memory structure includes nonvolatile memory cells each having a programmable resistive element. The control circuits are configured to receive addresses of selected cells and for each selected cell determine a story in which the selected cell is located from stories including a first story between a first word line layer and a bit line layer and a second story between the bit line layer and a second word line layer. The control circuits are further configured to connect a sense amplifier to a first selected nonvolatile memory cell in the first story through a bit line of the bit line layer and connect the sense amplifier to a second selected nonvolatile memory cell in the second story through a second word line of the second word line layer.