DLL-Based Strobe Lockout Timing for Source Synchronous Receivers
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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 process variations, leading to substandard error compensation and increased system costs.
Innovation Solution
A dynamic lockout mechanism using a delay-locked loop (DLL) that continually adjusts the lockout time by generating successively delayed versions of the reference clock signal and strobe signal, allowing the receiver to lock out reception for a period updated based on bus and core voltage variations, temperature changes, and fabrication process differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional fixed logic mechanisms are used to calculate lockout time, then the implementation is simple, but the lockout time is adversely affected by operating parameter changes such as bus clock frequency variations, temperature variations, voltage variations, and fabrication process variations
Solution Approach 1:
The patent implements a dynamic lockout time adjustment mechanism using a delay-locked loop (DLL) that continuously adapts the lockout time based on actual operating conditions. The DLL dynamically adjusts delay values in response to changes in bus clock frequency, temperature, voltage, and fabrication process variations, replacing static fixed logic with a self-adjusting dynamic system that maintains accurate lockout timing under varying conditions
Solution Approach 2:
The patent employs feedback mechanisms where the DLL monitors operating parameters and adjusts the lockout time accordingly. The system uses feedback from clock signals and delay elements to continuously refine the lockout duration, ensuring it remains accurate despite changes in operating conditions. This closed-loop approach allows the system to self-correct timing deviations caused by environmental and manufacturing variations
2Reliability
If worst-case scenarios are employed in conventional techniques, then the system can handle all variations, but error is introduced into the computer system design and manufacturing costs increase
Solution Approach 1:
The patent changes the parameter of lockout time from a fixed worst-case value to a dynamically adjusted value based on actual operating conditions. By using a DLL to continuously adapt the lockout time to match real-time clock frequency, temperature, and voltage conditions, the system achieves reliable error handling without the performance penalties and cost overhead of worst-case design margins
3Ease of operation
If fixed lockout time is used, then the receiver can be locked out for a predetermined period, but the lockout time does not account for variations in bus clock frequency, voltage, temperature, and fabrication process
Solution Approach 1:
The system transitions from a static fixed lockout time to a dynamic adaptively-adjusted lockout time using a delay-locked loop. The DLL continuously modifies the lockout duration based on real-time measurements of clock frequency, temperature, voltage, and process variations, enabling the receiver to maintain accurate timing synchronization across diverse operating conditions without manual reconfiguration
Solution Approach 2:
The delay-locked loop implements a self-service mechanism where the system automatically adjusts its own lockout timing without external intervention. The DLL monitors its own operating conditions and self-corrects timing deviations by adjusting delay elements internally, eliminating the need for external calibration or manual adjustment across different operating conditions
Data Source
AI summary
An apparatus for adjusting a lockout time in a source synchronous strobe receiver, including a delay-locked loop (DLL) and receivers. The DLL receives a reference clock and generates adjusted and encoded vectors, both indicating a first time period. A select vector is employed to select a delayed version of the reference clock that lags the reference clock by a second time period, which is slightly less than a number of reference clock cycles. The select vector is reduced in value to generate the adjusted vector. The receivers are coupled to the delay-locked loop. Each of the one or more receivers receives the encoded vector and a corresponding strobe, and locks out reception of the corresponding strobe for the first time period following transition of the corresponding strobe. The encoded vector is employed to determine the first time period by selecting a delayed version of the corresponding strobe.