Memory Controller Programmable Delay Unit Read Timing
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Solution Overview
Problem
Memory controllers face challenges in managing varying access times between processors and memory devices, leading to unpredictable propagation delays and potential read errors due to differences in memory access latencies.
Innovation Solution
A memory controller with a digitally programmable delay unit that adjusts the read-enable signal delay time in multiples of the clock signal period, using a multi-tap delay block and switch unit to synchronize data output with the enable signal, preventing read errors by compensating for dynamic access time variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a simple delay line is used to control timing, then the device complexity is reduced, but the reliability deteriorates due to unpredictable propagation delay and access time variations
Solution Approach 1:
The patent implements a dynamically adjustable delay line where the delay amount can be programmatically controlled. The delay line includes multiple tap points with different delay values, and a selector circuit chooses the appropriate delay amount based on real-time access time requirements. This dynamic adjustment capability allows the system to adapt to varying memory access latencies while maintaining reliable synchronized data reading.
2Device complexity
If the delay time is fixed, then the device complexity is reduced, but the adaptability deteriorates because it cannot compensate for dynamic access time variations
Solution Approach 1:
The delay line is segmented into multiple sections with different delay values (first delay line section, second delay line section, etc.). Each section provides a specific delay amount, and a selector circuit chooses the appropriate section based on the required access time compensation. This segmentation allows the system to adapt to different memory access latencies by selecting the suitable delay segment.
Solution Approach 2:
The delay control mechanism is made dynamic through programmable control. The controller can adjust the delay amount in real-time based on detected access time variations, enabling the system to adapt to changing memory performance characteristics while maintaining synchronized data reading.
3Ease of operation
If no delay adjustment is implemented, then the ease of operation is improved, but the productivity deteriorates due to read errors and performance loss
Solution Approach 1:
The delay control system operates autonomously by detecting access time variations and automatically adjusting the delay amount without requiring manual intervention. The controller monitors the timing between read command issuance and data availability, then programmatically selects the appropriate delay setting to compensate for access time variations, ensuring continuous optimal performance.
Data Source
AI summary
A memory controller includes an digitally programmable delay unit having a selectable delay time receiving a read-enable signal and outputting a delayed read-enable signal. The delay time is selected in response to an externally applied delay-control signal. A sampling unit in the memory controller outputs data received from a separate memory, in synchronization with the delayed enable signal. The delay time may be a multiple of the period of a clock signal.