Semiconductor Memory Hold-Margin Control Using Programmable RC Delays
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Solution Overview
Problem
Conventional semiconductor memory devices face performance limitations due to high variability in logic gate delays across Process, Voltage, and Temperature (PVT) corners, leading to excessive number of delay logics required, which hampers performance and results in inefficient use of resources, especially in smaller instances where unnecessary delays occur.
Innovation Solution
A method and system that control the hold-margin by inducing delays in the clock and data paths using a combination of logic circuits, wires, and programmable RC networks across columns and rows of the semiconductor memory device, allowing for dynamic adjustment based on device size and PVT conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the number of delay logics is increased to satisfy the hold margin across PVT range, then the hold margin reliability is improved, but the device complexity and area usage increase significantly
Solution Approach 1:
The patent changes the parameter from discrete logic gate delays to continuous RC network delays. By using resistor-capacitor networks with adjustable resistance values, the delay can be precisely tuned to meet hold margin requirements without requiring multiple discrete delay logic circuits. This reduces device complexity while maintaining reliability across PVT corners.
Solution Approach 2:
The patent replaces the mechanical/logic gate-based delay system with an electrical RC network system. Instead of using multiple logic gates to create delay, the invention uses resistor-capacitor networks that provide smoother, more predictable delay characteristics and can be adjusted without changing the physical structure, thereby reducing complexity.
2Reliability
If the same number of delay logics is placed for all memory device sizes, then the hold margin is satisfied for the biggest instance, but the performance of smaller instances is hampered due to unnecessary delays
Solution Approach 1:
The patent introduces dynamic adjustability to the delay system. The RC networks can be configured with different resistance values to provide different delay amounts based on the specific memory device size and performance requirements. This allows the system to adapt to different instances rather than using a fixed one-size-fits-all approach, thereby improving productivity for smaller instances while maintaining hold margin for larger instances.
Solution Approach 2:
The patent applies different delay characteristics to different parts of the system based on local requirements. Instead of uniformly applying the same delay logic to all memory sizes, the RC networks can be locally tuned to provide appropriate delay amounts for each specific instance, optimizing performance for both small and large memory devices.
3Reliability
If more delay logics are used to account for logic gate delay variability, then the hold margin across PVT corners is improved, but the area usage and design cost increase
Solution Approach 1:
The patent transitions from discrete logic gate delays to continuous RC network delays, allowing for precise parameter adjustment. By varying the resistance values in the RC networks, the delay can be optimized for different PVT corners without requiring additional logic gates, thereby maintaining hold margin reliability while reducing area usage.
Solution Approach 2:
The RC network structure serves multiple functions: it provides delay, it can be tuned for different PVT corners, and it reduces area compared to multiple logic gates. This multi-functional approach allows a single RC network configuration to handle what would otherwise require multiple separate delay logic circuits, reducing both area and complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces the number of logic gates needed, improves performance by 2% to 6% based on memory size, and reduces system design costs by optimizing area usage and logic gate variation, effectively managing parasitic delays across PVT corners.
Implementation Method 1
A delay associated with the clock path is induced using a combination of a logic circuit and a wire placed across at least one of a column and a row of the semiconductor memory device. Further, the delay associated with a data path is induced using a combination of at least one delay logic circuit and at least one load cell and a wire placed across at least one of a column and a row of the semiconductor memory device.
Data Source
AI summary
A system for controlling a hold-margin in a semiconductor memory device includes a programmable RC network communicatively coupled to a delay logic circuit, a latch clock generator and a latch circuit. A delay associated with a clock path is induced using a combination of a logic circuit and a wire placed across at least one of a column and a row of the semiconductor memory device. A delay associated with the data path is induced using a combination of the delay logic circuit and at least one of the load cell and a wire routed across at least one of a column and a row of the semiconductor memory device. The system controls the hold-margin based on the delay associated with the data path and the delay associated with the clock path.