DRAM Wordline Control With Temperature-Dependent Precharge Delay
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Solution Overview
Problem
Semiconductor memory devices face reliability issues due to temperature-dependent timing variations, which can cause signals to operate out of sequence, particularly at low temperatures, leading to potential data loss and reduced device reliability.
Innovation Solution
A delay circuit is introduced in the command path of the semiconductor memory device, with a temperature-dependent delay that increases at lower temperatures and decreases at higher temperatures, ensuring proper sequencing of operations across a wide range of temperatures by adjusting the timing of precharge commands relative to wordline deactivation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If temperature decreases, then write recovery time increases dramatically, but precharge time remains relatively constant, causing timing mismatch and reduced reliability
Solution Approach 1:
The patent introduces a temperature-dependent delay circuit that dynamically adjusts the precharge command timing based on temperature conditions. At low temperatures, the delay circuit adds extra delay to the precharge command to compensate for the increased write recovery time, ensuring proper timing alignment between write completion and precharge operations across varying temperature conditions.
2Reliability
If no temperature compensation is applied, then device complexity remains low, but timing sequencing fails at low temperatures leading to data loss
Solution Approach 1:
The patent introduces a delay circuit as an intermediary component between the precharge command generator and the memory array. This delay circuit acts as a mediator that adjusts the timing of precharge commands based on temperature conditions, ensuring proper sequencing without requiring fundamental changes to the memory architecture or control logic.
3Reliability
If standard timing is used across all temperatures, then ease of operation is maintained, but hot carrier degradation increases at low temperatures
Solution Approach 1:
The patent implements a dynamic timing control mechanism where the delay circuit automatically adjusts precharge command timing based on real-time temperature conditions. This dynamic adjustment prevents hot carrier degradation at low temperatures by ensuring adequate write recovery time, while maintaining ease of operation through automatic temperature sensing and compensation without requiring manual intervention.
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 solution enhances the reliability of semiconductor memory devices by ensuring that write operations are completed before precharge operations, mitigating the effects of temperature variations and reducing hot carrier degradation, thereby maintaining consistent performance across varying environmental conditions.
Implementation Method 1
A delay circuit is introduced in the command path of the semiconductor memory device, with a temperature-dependent delay that increases at lower temperatures and decreases at higher temperatures
Data Source
AI summary
Apparatuses and methods for a temperature dependent delay between a wordline off signal and deactivating the wordline are disclosed. Memory devices may have reduced reliability when operating at relatively cold temperatures, which may be due in part to an increase in the write recovery time while the timing for a wordline to deactivate remains relatively unaffected. In some embodiments of the present disclosure, a delay circuit is used to insert a temperature dependent delay between a wordline off command being issued and the wordline being deactivated. The delay circuit may increase the length of temperature dependent delay at relatively cold temperatures, and decrease the length of the delay at relatively warm temperatures.