Hybrid Sampling Circuit for Dynamic Row Hammer Refresh Control
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Solution Overview
Problem
Conventional static Row-Hammer refresh rate control fails to prevent bit errors caused by Row Hammer effects, which can occur at various timings due to different causes, necessitating a dynamic control mechanism for DRAM memory devices.
Innovation Solution
A hybrid sampling circuit with a time-based and command-based sampling mechanism, incorporating a sampling timing generator circuit and RHR state-control circuit, dynamically adjusts the Row Hammer refresh rate by generating randomized trigger signals for sampling, optimizing the steal rate and probability of Row Hammer refresh operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If static Row-Hammer refresh rate control is used, then device complexity is reduced, but reliability deteriorates due to inability to prevent bit errors at various timings
Solution Approach 1:
The patent implements dynamic Row Hammer refresh rate control by adjusting the refresh frequency based on detected access patterns. The system monitors row access timing and dynamically modifies the RHR interval to match actual usage conditions, transitioning from a fixed static rate to an adaptive dynamic rate that responds to real-time memory access behavior.
Solution Approach 2:
The patent incorporates feedback mechanisms that monitor row access patterns and timing information, then use this data to adjust the Row Hammer refresh rate. The system detects when rows are accessed frequently or at specific intervals and feeds this information back to the refresh controller, which then modifies the refresh timing accordingly to prevent bit errors while avoiding unnecessary refresh operations.
2Reliability
If dynamic Row Hammer refresh rate control is implemented, then reliability improves by preventing bit errors, but device complexity increases
Solution Approach 1:
The patent divides the refresh control function into separate sampling circuits: a time-based sampling circuit that monitors row access timing and a command-based sampling circuit that detects refresh commands. This segmentation allows each circuit to specialize in detecting specific aspects of row access patterns, simplifying the overall detection logic while improving reliability through comprehensive monitoring.
Solution Approach 2:
The patent creates a universal sampling mechanism that can detect both time-based patterns (intervals between row accesses) and command-based patterns (refresh command timing) using a unified hybrid sampling circuit. This multi-functional approach allows the system to monitor multiple aspects of row access behavior through a single integrated structure, reducing overall system complexity.
3Measurement precision
If hybrid sampling mechanism is used, then measurement precision of row access patterns improves, but device complexity increases
Solution Approach 1:
The patent merges the time-based sampling circuit and command-based sampling circuit into a unified hybrid sampling circuit. The time-based sampler detects intervals between row accesses, while the command-based sampler detects refresh command timing. By combining these two sampling mechanisms into a single integrated circuit, the system achieves comprehensive row access pattern detection with improved measurement precision while avoiding the complexity of completely separate monitoring systems.
Data Source
AI summary
Apparatuses and methods for triggering row hammer address sampling are described. An example apparatus includes an oscillator circuit configured to provide a clock signal, and a filter circuit. The filter circuit includes a control circuit configured to receive pulses of the clock signal and provide an output signal that represents a count number by counting a number of pulses of the clock signal and control a probability of enabling the output signal based on the count number. The filter circuit further includes a logic gate configured to pass one of the pulses of the clock signal responsive to the output signal from the control circuit being enabled and filter another of the pulses responsive to the output signal from the control circuit being not enabled.