Adaptive Word-Line Voltage Control for Memory Stability
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Solution Overview
Problem
The operation stability of memory devices is compromised due to dynamic changes in power supply voltages, leading to potential read and write errors, especially when the power supply voltage for the memory cell array is lower than that for the peripheral circuit, causing an imbalance in operation speed and voltage levels.
Innovation Solution
A voltage generation circuit that adaptively adjusts the word-line driving voltage based on the difference between the power supply voltages provided to the memory cell array and the peripheral circuit, maintaining or adjusting the voltage level to ensure stable operation by activating or deactivating assist operations accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the power supply voltage for the memory cell array is lowered to reduce power consumption, then energy efficiency is improved, but operation stability deteriorates due to voltage imbalance with the peripheral circuit
Solution Approach 1:
The voltage generation circuit dynamically adjusts the word-line driving voltage based on the difference between the first power supply voltage (VDD1) and the second power supply voltage (VDD2). When VDD1 is lower than VDD2, the circuit activates assist operations to boost the word-line voltage, thereby maintaining operation stability while allowing the memory cell array to operate at lower power consumption voltages.
Solution Approach 2:
The patent changes the word-line driving voltage parameter adaptively based on the power supply voltage difference. The voltage generation circuit monitors the voltage levels and adjusts the word-line voltage accordingly, switching between normal operation mode and assist operation mode to resolve the contradiction between low power consumption and stable operation.
2Reliability
If the word-line driving voltage is increased to maintain operation stability, then reliability is improved, but power consumption increases
Solution Approach 1:
The system dynamically adjusts the word-line driving voltage only when necessary (when VDD1 < VDD2 and assist operation is activated). During normal operation when voltage levels are balanced, the system operates at standard voltage levels, minimizing power consumption while maintaining stability only when required.
Solution Approach 2:
The word-line driving voltage parameter is changed adaptively based on the power supply voltage difference. The voltage generation circuit increases the word-line voltage above the normal level only during assist operations, rather than maintaining a consistently high voltage level, thereby resolving the contradiction between reliability and power consumption.
3Reliability
If assist operations are activated to maintain write margin, then write reliability is improved, but device complexity increases
Solution Approach 1:
The voltage generation circuit acts as an intermediary component that automatically manages the assist operation. It monitors the power supply voltage difference and controls the word-line voltage adjustment without requiring complex external control logic, thereby improving write reliability while adding minimal circuit complexity.
Solution Approach 2:
The voltage generation circuit performs self-service by automatically detecting the voltage imbalance condition and activating assist operations without external intervention. The circuit monitors its own operating conditions and adjusts the word-line voltage accordingly, simplifying the overall control architecture while maintaining write margin.
Data Source
AI summary
A memory device includes a memory cell array and a peripheral circuit. The memory cell array receives a first power supply voltage and includes a plurality of bit cells that store data based on the first power supply voltage. The peripheral circuit is receives a second power supply voltage and controls the memory cell array based on the second power supply voltage. The peripheral circuit includes a voltage generation circuit that receives the first power supply voltage and the second power supply voltage. The voltage generation circuit adaptively adjusts a word-line driving voltage directly or indirectly based on a difference between the first power supply voltage and the second power supply voltage during a memory operation on the plurality of bit cells, and applies the word-line driving voltage to a first word-line coupled to first bit cells selected from the bit cells.