Programmable Synchronous Strobe Advance for Phase Alignment
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Solution Overview
Problem
Source synchronous systems face errors due to inaccuracies in clock generation circuits and uneven distribution of strobe signals, leading to misalignment of data and strobe signals on the bus, which affects reception conditions.
Innovation Solution
An apparatus comprising a JTAG interface, synchronous bus optimizer, core clocks generator, and synchronous strobe driver is used to receive control information and advance the data strobe clock, ensuring phase alignment of data and strobe signals on the synchronous bus, thereby compensating for misalignment and optimizing reception conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If data strobe and data signals are routed along equal propagation paths on the system board, then propagation timing is synchronized, but additional propagation lengths required to route the strobe to various receivers add delay over the data signals, skewing the phase of the synchronous transmission
Solution Approach 1:
The patent applies preliminary action by advancing the data strobe signal before it is distributed to receivers. The strobe signal is提前 advanced by a programmable amount (0-90 degrees) to compensate for the delay that will occur during distribution to various receivers. This pre-adjustment ensures that when the strobe reaches the receivers, it arrives at the correct phase relative to the data signals, eliminating the need for post-distribution delay compensation.
2Productivity
If clock generation circuits are used to gate data signals and switch strobes, then data transmission is enabled, but inaccuracies in clock generation circuits cause misalignment of data and strobe signals
Solution Approach 1:
The patent implements feedback by allowing the system to measure the actual phase alignment between data and strobe signals and then adjust the strobe advance amount accordingly. The JTAG interface enables programming of the strobe advance value based on measured performance, creating a closed-loop system that continuously optimizes signal alignment while maintaining high transmission speeds.
Solution Approach 2:
The patent applies parameter changes by making the strobe advance amount programmable and adjustable. The system can modify the phase advance parameter (from 0 to 90 degrees) to compensate for variations in clock generation circuit accuracy, fabrication tolerances, and environmental factors. This dynamic parameter adjustment restores optimal signal alignment without reducing transmission speed.
3Adaptability or versatility
If the strobe signal is distributed to all internal synchronous receivers, then all receivers can process data, but the additional propagation lengths required add delay and skew the phase
Solution Approach 1:
The patent applies preliminary action by advancing the strobe signal at the source before distribution to multiple receivers. This pre-advancement compensates for the varying propagation delays that different receivers will experience. Each receiver receives the strobe at a different time due to varying path lengths, but the initial advance ensures that all receivers see the strobe at the correct phase relative to their respective data signals.
Data Source
AI summary
An apparatus includes a Joint Test Action Group (JTAG) interface, a synchronous bus optimizer, a core clocks generator, and a synchronous strobe driver. The JTAG interface is configured to receive control information over a standard JTAG bus, where the control information indicates an amount to advance a synchronous data strobe associated with a data group. The synchronous bus optimizer is configured to receive the control information, and is configured to develop a value on a ratio bus that indicates the amount. The core clocks generator is coupled to the ratio bus and is configured to advance a data strobe clock by the amount. The synchronous strobe driver is configured to receive the data strobe clock, and is configured to employ the data strobe clock to generate the synchronous data strobe, where the synchronous data strobe, when enabled, is advanced also by the amount.