I/O Pad Delay Matching for Semiconductor Timing Closure
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Solution Overview
Problem
Existing techniques face challenges in achieving timing closure in semiconductor devices due to variations in process, voltage, and temperature, which affect the sampling of signals across different semiconductor devices, particularly in NAND Flash storage systems, where ensuring proper signal sampling within a guaranteed window is crucial.
Innovation Solution
Incorporating a read enable signal with I/O pad delay to facilitate easier timing closure by using I/O pads to introduce necessary delays, rather than relying solely on internal buffers, and configuring the system to account for variations in process, voltage, and temperature across different chips.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If internal buffers are used to delay signals for timing closure, then timing constraints can be met, but device complexity increases and manufacturing precision becomes more difficult to achieve across process corners
Solution Approach 1:
The patent extracts the delay function from internal buffers and relocates it to external I/O pads. By using the I/O pad's inherent delay characteristics rather than adding internal buffer stages, the solution reduces internal device complexity while achieving the required timing closure. The I/O pad delay is utilized as a resource rather than treated as a nuisance to be compensated for.
2Reliability
If timing constraints are enforced across multiple semiconductor devices from different suppliers, then proper signal sampling is ensured, but manufacturing precision varies due to process, voltage, and temperature variations
Solution Approach 1:
The patent changes the approach from trying to control internal timing parameters to utilizing external I/O pad delay characteristics. By measuring and accounting for the actual I/O pad delay under different process, voltage, and temperature conditions, the system adapts to manufacturing variations rather than fighting against them. This allows timing closure to be achieved across all process corners without requiring ultra-precise manufacturing control.
Solution Approach 2:
The patent implements a feedback mechanism where the I/O pad delay is measured and used to adjust the timing of read operations. By continuously monitoring the actual delay introduced by the I/O pad and using this information to synchronize read enable signals with data arrival, the system compensates for PVT variations and maintains reliable signal sampling across different operating conditions.
3Ease of manufacture
If I/O pad delay is used for timing closure, then ease of manufacture improves, but the system must account for variations in delay across different chips and operating conditions
Solution Approach 1:
The patent introduces dynamic adaptation by measuring the I/O pad delay under actual operating conditions and adjusting the read timing accordingly. Rather than using fixed timing parameters, the system dynamically adapts to the specific delay characteristics of each chip and operating condition, making the manufacturing process easier while handling delay variations through measurement and adjustment rather than rigid specification control.
Data Source
AI summary
A data signal is sampled by generating a read enable signal at a first semiconductor device which is intended for a second semiconductor device. A read enable signal with at least some I/O pad delay included is obtained, including by passing the read enable signal intended for the second semiconductor device at least partially through an input/output (I/O) pad on the first semiconductor device. At the first semiconductor device, a data signal from the second semiconductor is sampled using the read enable signal with at least some I/O pad delay included.