Memory Controller Continuous Read Latency
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Solution Overview
Problem
NAND flash devices experience significant read latency, making them slower than other memory types for certain operations due to the time gap between issuing a read command and data availability, which is not effectively addressed by existing continuous read command sequences.
Innovation Solution
A memory device architecture with a controller that manages continuous read operations by loading data segments from a memory array to a data register and caching them, allowing for flexible throughput control, including random access and termination of operations based on host availability, using a combination of page and cache read commands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If continuous read command sequence is used to reduce read latency, then data availability time is improved, but the host device cannot control the data flow rate to match its processing capacity
Solution Approach 1:
The patent introduces a controller as an intermediary component between the memory array and the host device. This controller manages the continuous read operations by receiving commands from the host and controlling the data flow from the memory array, thereby mediating between the fast data retrieval capability and the host's processing capacity to enable flexible throughput control.
Solution Approach 2:
The patent implements dynamic control of data flow by allowing the host to issue multiple cache read commands during a continuous read operation. The controller dynamically adjusts the data transfer rate by stalling or continuing data movement based on host availability, transforming a static continuous read operation into a dynamically adaptable process.
2Productivity
If data is continuously transferred from memory array to cache at high speed, then productivity is improved, but the host interface buffer may overflow due to mismatched data rates
Solution Approach 1:
The patent implements a feedback mechanism where the host device can issue cache read commands in response to data becoming available in the cache. The controller monitors host availability and adjusts the continuous read operation accordingly, creating a feedback loop that prevents buffer overflow by synchronizing data transfer with host processing capacity.
Solution Approach 2:
The patent allows the controller to pre-load data from the memory array into the cache before the host is fully ready to process it. This preliminary action of loading data into the cache buffer enables the system to maintain high data transfer rates while giving the host time to prepare its processing operations, thereby preventing synchronization issues.
3Adaptability or versatility
If the memory device supports random cache read operations during continuous read, then adaptability is improved, but device complexity increases
Solution Approach 1:
The patent makes the controller universal by enabling it to handle both sequential continuous read operations and random cache read operations through the same interface and control logic. The controller can process cache read commands with arbitrary addresses while simultaneously managing the continuous data flow from the memory array, providing multi-functional capability without requiring separate dedicated circuits for each operation type.
Data Source
AI summary
A memory device includes a data register operatively coupled to the memory array, a cache operatively coupled to the data register, and an input/output interface operatively coupled to the cache. A controller executes a continuous page read operation to sequentially load pages to the data register and move the pages to the cache, in response to a page read command, executes the cache read operation in response to a cache read command to move data from the cache to the input/output interface, and to stall moving of the data from the cache until a next cache read command, and terminates the continuous page read operation in response to a terminate command.