Data Input Clock Training for Setup/Hold Margin in Semiconductor I/O
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Solution Overview
Problem
In semiconductor device design, the buffer clock tree structure increases chip size due to additional buffers, which are necessary for high-performance clock characteristics, but can lead to insufficient setup/hold time margins in data sampling, affecting operation reliability.
Innovation Solution
A semiconductor device with a clock selection block, clock generation circuit, data input circuit, and training circuit that selects a reference clock based on phase detection signals, generates sampling clocks, and aligns input data to ensure sufficient setup/hold time margins by adjusting clock tree delay values during training and normal operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a buffer clock tree structure is used to achieve high-performance clock characteristics, then clock signal quality is improved, but chip size increases due to additional buffers
Solution Approach 1:
The clock tree is divided into multiple paths with different delay characteristics. Instead of using a single buffer clock tree for all clock paths, the invention segments the clock distribution into multiple independent paths, each with optimized delay properties, eliminating the need for additional buffers while maintaining clock signal quality.
Solution Approach 2:
The invention dynamically selects between different clock paths based on real-time delay measurements. The system determines which clock path has the appropriate delay range and uses that path for data sampling, making the clock selection adaptive rather than static, thereby avoiding the need for fixed buffer insertion.
2Speed
If clock tree delay is reduced to improve data sampling speed, then operation speed is improved, but setup/hold time margins become insufficient, affecting operation reliability
Solution Approach 1:
The system measures the actual delay of each clock path and uses this feedback information to determine the most appropriate clock path for data sampling. By continuously monitoring delay characteristics and adjusting clock path selection accordingly, the system ensures that setup/hold time margins are maintained while achieving optimal sampling speed.
Solution Approach 2:
The invention changes the selection criteria for clock paths based on delay parameters. Instead of using a fixed clock path, the system evaluates delay values and selects the clock path whose delay falls within a predetermined appropriate range, thereby optimizing both speed and reliability based on actual measured parameters.
Data Source
AI summary
A semiconductor device includes a clock selection block selecting a first or a second input clock as a reference clock based on a phase detection signal; a clock generation circuit outputting first to Nth sampling clocks by distributing the reference clock to first to Nth clock paths, and outputting a first training signal by delaying a test pulse through one clock path during a training operation; a data input circuit sampling input data based on the first and second input clocks and one sampling clock outputted through the same clock path as the first training signal among the first to Nth sampling clocks; and a training circuit delaying the test pulse by a reference delay value to output a second training signal, and comparing a phase of the first training signal with a phase of the second training signal to generate the phase detection signal, during the training operation.