Semiconductor Memory Voltage Control for Leakage Reduction
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Solution Overview
Problem
Semiconductor memory devices face increased power consumption due to the use of the same substrate voltage in both normal and self-refresh modes, leading to unnecessary leakage current and reduced self-refresh periods.
Innovation Solution
A semiconductor memory device that varies voltage levels of the substrate voltage and reference voltage between normal and self-refresh modes, using a voltage level selection unit and reference voltage generator to output different voltage levels, thereby optimizing power consumption by extending the self-refresh period.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the same substrate voltage is used in both normal mode and self-refresh mode, then the device operation is simplified, but power consumption increases due to unnecessary leakage current
Solution Approach 1:
The patent applies parameter changes by varying the substrate voltage level according to operational mode. In self-refresh mode, the substrate voltage is adjusted to a level that minimizes leakage current in memory cells, while in normal mode, a different voltage level is used to ensure proper transistor operation. This dynamic parameter adjustment reduces unnecessary leakage current during self-refresh without compromising device functionality.
Solution Approach 2:
The invention implements dynamics by making the substrate voltage adjustable and mode-dependent rather than fixed. The substrate voltage generator responds to mode signals (normal mode or self-refresh mode) and dynamically changes the substrate voltage level accordingly. This dynamic adaptation allows the device to optimize power consumption based on operational requirements while maintaining proper transistor operation.
2Reliability
If the substrate voltage is optimized for normal mode, then transistor operation is improved, but the self-refresh period is reduced due to increased leakage current
Solution Approach 1:
The patent changes the substrate voltage parameter based on operational mode. During self-refresh mode, the substrate voltage is adjusted to a level that extends the self-refresh period by reducing leakage current, while during normal mode, the voltage is optimized for reliable transistor operation. This parameter adaptation resolves the contradiction between reliable operation and extended self-refresh duration.
3Reliability
If higher substrate voltage is used to ensure proper transistor operation, then device reliability is improved, but leakage current increases and self-refresh period decreases
Solution Approach 1:
The invention changes the substrate voltage parameter according to operational mode. In self-refresh mode, a lower substrate voltage is applied to reduce leakage current and extend the self-refresh period, while in normal mode, a higher voltage is used to ensure reliable transistor operation. This mode-dependent parameter adjustment simultaneously optimizes both reliability and energy efficiency.
Data Source
AI summary
A semiconductor memory device includes a voltage level selection unit configured to output a plurality of voltage level selection signals according to a fuse program in response to a self-refresh command signal and a reference voltage generator configured to receive a reference voltage and output a target reference voltage having a different voltage level depending on a normal mode or a self-refresh mode in response to the voltage level selection signals.