Semiconductor Device Timing Adjust Circuit
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Solution Overview
Problem
In semiconductor devices with memory units, such as SRAM, variations in MOS transistors due to finer geometries lead to challenges in optimizing the start-up timing of sense amplifiers, as dummy memory cells used for timing design suffer from process fluctuations, resulting in inconsistent driving timing across dummy bit lines.
Innovation Solution
A semiconductor device with a timing adjusting circuit that includes a sense amplifier circuit, a control circuit, and a timing adjusting circuit with a dual dummy bit line configuration and load circuits to stabilize the start-up timing of the sense amplifier by using a fixed load capacitance and distributing column direction load circuits across both dummy bit lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If dummy memory cells are used for timing design, then the start-up timing of sense amplifier can be set, but process fluctuations cause variations in driving timing across dummy bit lines
Solution Approach 1:
The invention divides the timing adjustment function into multiple independent dummy bit lines (first dummy bit line and second dummy bit line) with separate load circuits. This segmentation allows each dummy bit line to be independently optimized and controlled, reducing the impact of process fluctuations on overall timing consistency.
Solution Approach 2:
The invention changes the capacitance parameters of load circuits connected to different dummy bit lines to compensate for process fluctuations. By adjusting the capacitance values, the driving timing of each dummy bit line can be tuned to achieve consistent start-up timing across all dummy bit lines despite manufacturing variations.
2Adaptability or versatility
If dummy memory cells are formed by the same processing size as proper memory cells, then they reflect proper memory cell characteristics, but process fluctuation occurs leading to timing variations
Solution Approach 1:
The invention introduces load circuits as intermediary elements between the dummy memory cells and the dummy bit lines. These load circuits act as mediators that can be independently adjusted to compensate for process fluctuations, allowing the dummy memory cells to maintain their representative characteristics while achieving timing consistency through the intermediary load adjustment.
3Device complexity
If a single dummy bit line is used, then the circuit complexity is low, but the start-up timing optimization is insufficient due to process fluctuation
Solution Approach 1:
The invention segments the single dummy bit line into multiple dummy bit lines (first and second dummy bit lines), each with its own load circuit. This segmentation increases timing optimization precision by allowing independent adjustment of each segment, while the overall complexity increase is managed through systematic design of the segmented structure.
Data Source
AI summary
A semiconductor device with a memory unit of which the variations in the operation timing are reduced is provided. For example, the semiconductor device is provided with dummy bit lines which are arranged collaterally with a proper bit line, and column direction load circuits which are sequentially coupled to the dummy bit lines. Each column direction load circuit is provided with plural NMOS transistors fixed to an off state, predetermined ones of which have the source and the drain suitably coupled to any of the dummy bit lines. Load capacitance accompanying diffusion layer capacitance of the predetermined NMOS transistors is added to the dummy bit lines, and corresponding to the load capacitance, the delay time from a decode activation signal to a dummy bit line signal is set up. The dummy bit line signal is employed when setting the start-up timing of a sense amplifier.