Period Signal Generation Circuit for DRAM Refresh
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Solution Overview
Problem
Conventional DRAM devices face challenges in maintaining data retention time due to varying leakage currents influenced by internal temperature, requiring a refresh circuit that adjusts refresh cycle time based on temperature to ensure operational stability and minimize power consumption.
Innovation Solution
A period signal generation circuit that includes a control node, a period signal generator, a discharge controller, and a tester, which alternately charges and discharges the control node to generate a period signal, with discharge currents varying according to internal temperature, allowing for adaptive refresh cycle time adjustment without the need for multiple oscillators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the refresh cycle time is reduced to ensure successful operations as internal temperature increases, then data retention reliability is improved, but power consumption increases
Solution Approach 1:
The refresh cycle time is made dynamic rather than fixed, allowing it to adjust automatically based on internal temperature conditions. The period signal generation circuit generates temperature-dependent period signals that shorten the refresh cycle when temperature rises (improving reliability) and lengthen it when temperature decreases (reducing power consumption), thus resolving the contradiction between reliability and energy usage.
Solution Approach 2:
The invention changes the parameter of refresh cycle time based on temperature conditions. By using a period signal generation circuit that outputs different period signals according to internal temperature, the system optimizes the balance between data retention reliability and power consumption by adjusting the refresh frequency parameter dynamically.
2Adaptability or versatility
If multiple oscillators are used to generate different oscillation signals for temperature-based refresh control, then adaptability to temperature variations is improved, but device complexity increases
Solution Approach 1:
A single period signal generation circuit is designed to perform multiple functions: it generates period signals with different periods based on internal temperature conditions, eliminating the need for separate oscillators for different temperature ranges. This multi-functional approach maintains temperature adaptability while reducing circuit complexity.
Solution Approach 2:
The invention merges the functions of multiple temperature-dependent oscillators into a single period signal generation circuit. This circuit integrates the temperature sensing and period signal generation capabilities, producing appropriate period signals for different temperature conditions without requiring separate oscillator circuits, thus reducing overall device complexity.
Data Source
AI summary
A period signal generation circuit includes a period signal generator configured to alternately charge and discharge a control node according to a level of the control node to generate a period signal, a discharge controller configured to discharge a first current having a constant value from the control node in response to a temperature signal and discharge a second current varying according to an internal temperature thereof from the control node in response to the temperature signal, and a tester configured to control a charging speed and a discharging speed of the control node.