Flash Memory Pad Serial Output Circuit Logic Read Timing
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Solution Overview
Problem
Higher frequency operations in Flash memory devices are bottlenecked by delays in command decode and logic circuit operations during logic read operations, leading to insufficient timing margins and reduced performance.
Innovation Solution
Implementing instruction pre-decoding and data pre-fetching techniques in the pad serial output circuit, allowing for early generation of pre-command signals and pre-fetching of logic data, which are then resolved on the last clock of the command input sequence to bypass sequential logic and internal signal line delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If traditional command decode and logic circuit operations are used in Flash memory, then the device can perform logic read operations, but delays occur that prevent high-frequency operation and reduce performance
Solution Approach 1:
The patent applies preliminary action by pre-decoding the command in the pad serial output circuit before the traditional logic circuit processes it. The pad serial output circuit generates pre-command signals in advance during the command input sequence, allowing the data register to prepare and output logic data earlier than the conventional half-cycle timing margin would permit. This preliminary decoding eliminates sequential logic delays and enables high-frequency operation.
2Reliability
If traditional sequential logic decoding is used, then command processing follows standard protocols, but internal signal line delays and sequential logic delays prevent timely output
Solution Approach 1:
The patent extracts the command decoding function from the traditional logic circuit and relocates it to the pad serial output circuit. This separation allows the decoding operation to occur in parallel with data register operations, removing the sequential dependency that causes internal signal line delays. The pre-command signal is generated independently in the pad serial output circuit, bypassing the delayed signal paths of conventional logic circuits while maintaining accurate command processing.
3Manufacturing precision
If the half-cycle timing margin is maintained for traditional logic read operations, then timing requirements are met, but high-frequency operation cannot be achieved
Solution Approach 1:
The patent uses preliminary action to pre-generate the pre-command signal during the command input sequence itself, rather than waiting for the traditional half-cycle timing margin to elapse. The data register is enabled to output logic data earlier in the cycle, effectively reducing the required timing margin while maintaining compliance. This allows the system to operate at higher frequencies by performing the decoding and data preparation actions before the traditional timing deadline.
Data Source
AI summary
The timing of logic read operations in a Flash memory device may be improved by a pad serial output circuit which receives a pre-decoded instruction signal and pre-fetched logic data prior to the last command clock, and which performs a fast resolution of the command in the pad serial output circuit on the last clock of the command input sequence. In one illustratively implementation, instruction pre-decode and data pre-fetch may be done on the seventh clock during command input. In another illustrative implementation, a first instruction pre-decode and data pre-fetch may be done on the fourth clock during command input, and a second instruction pre-decode may be done on the seventh clock during command input. Both serial protocol interface, including dual and quad I/O SPI, and quad peripheral interface are supported.