Source Synchronous Strobe Receiver Lockout Using DLL Timing
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Solution Overview
Problem
Conventional receiver lockout techniques for source synchronous strobe signals in microprocessor systems are inadequate as they do not account for variations in bus clock frequency, voltage, temperature, and fabrication processes, leading to substandard error correction and increased system costs due to worst-case scenario design.
Innovation Solution
A dynamic lockout mechanism using a delay-locked loop (DLL) that continuously updates the lockout time period based on bus clock frequency, voltage, and temperature variations, employing a 64-tap delay element and a select vector signal to determine the optimal lockout time, ensuring accurate reception of source synchronous strobe signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If fixed logic mechanisms are used for receiver lockout, then device complexity is reduced, but manufacturing precision deteriorates due to inability to compensate for process variations
Solution Approach 1:
The patent implements a dynamic lockout time adjustment mechanism that continuously adapts the lockout duration based on detected strobe signal characteristics and environmental conditions. The system transitions from static fixed-duration lockout to dynamic adaptive lockout, allowing the lockout time to be modified in real-time to compensate for manufacturing variations and environmental changes without increasing fundamental device complexity.
Solution Approach 2:
The system changes the lockout time parameter dynamically based on detected conditions including strobe signal timing, bus clock frequency variations, voltage levels, and temperature. By making the lockout time a variable parameter rather than a fixed value, the system achieves high manufacturing precision across different process conditions while maintaining relatively simple device architecture.
2Reliability
If worst-case scenario design is employed, then reliability is improved, but device complexity increases due to overspecification
Solution Approach 1:
The patent implements a feedback mechanism that continuously monitors strobe signal transitions and bus operating conditions, then adjusts the lockout time accordingly. This closed-loop approach allows the system to achieve high reliability by adapting to actual operating conditions rather than relying on worst-case overspecification, thereby reducing device complexity while maintaining or improving error correction capability.
Solution Approach 2:
The system transitions from static worst-case lockout design to dynamic condition-based lockout adjustment. By continuously adapting the lockout duration to match actual operating conditions, the system achieves reliable error correction without the overhead of overspecified fixed mechanisms, reducing overall device complexity.
3Ease of manufacture
If fixed lockout time is used, then ease of manufacture is improved, but adaptability deteriorates due to inability to compensate for environmental variations
Solution Approach 1:
The system implements dynamic parameter adjustment for lockout time based on environmental conditions including temperature, voltage, and bus clock frequency. This allows a single manufactured device to adapt to varying environmental conditions without requiring different manufacturing specifications, combining ease of manufacture with high adaptability.
Solution Approach 2:
The lockout mechanism performs self-adjustment based on detected environmental and operational conditions. The system automatically modifies its own lockout time parameter without external intervention, enabling a single manufacturing specification to serve multiple environmental conditions and thereby improving both ease of manufacture and adaptability.
4Reliability
If longer lockout time is used, then reliability is improved by filtering more noise, but loss of time increases
Solution Approach 1:
The patent implements dynamic lockout time adjustment that extends the lockout duration only when and where bus noise is detected, rather than using a uniformly long lockout time. This allows the system to achieve reliable noise filtering selectively, minimizing time loss during clean operating conditions while providing enhanced protection when noise is present.
Solution Approach 2:
The system applies extended lockout protection locally and selectively based on detected noise conditions rather than globally and uniformly. By making the lockout duration conditional and location-specific, the system achieves reliable noise filtering only where and when needed, thereby reducing overall time loss while maintaining reliability.
Data Source
AI summary
An apparatus for locking out a source synchronous strobe receiver, including a delay-locked loop (DLL) and one or more receivers. The DLL receives a reference clock, and generates a select vector and an encoded select vector that both indicate a lockout time. The select vector is employed to select a delayed version of the reference clock that lags the reference clock by the lockout time. The lockout time is slightly less than a number of cycles of the reference clock. The one or more receivers are each coupled to the delay-locked loop. Each of the one or more receivers receives the encoded select vector and a corresponding strobe, and locks out reception of the corresponding strobe for the lockout time following transition of the corresponding strobe. The encoded select vector is employed to determine the lockout time by selecting a delayed version of the corresponding strobe.