DRAM Refresh Control Circuit Temperature Sensor Verification
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Solution Overview
Problem
Dynamic random access memory (DRAM) devices require frequent refresh operations to prevent data loss, which is sensitive to temperature variations, necessitating temperature-controlled operation conditions that existing technologies struggle to manage effectively.
Innovation Solution
A semiconductor device and system that includes a temperature sensor, register, and refresh control circuit to generate sensing codes and refresh signals with controlled pulse cycles, allowing for independent refresh cycle time management regardless of internal temperature, enabling normal or abnormal temperature sensor verification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If temperature-controlled refresh operations are implemented in DRAM devices, then data retention reliability is improved, but device complexity increases due to additional temperature sensors and control circuits
Solution Approach 1:
The temperature sensor and refresh control circuit are integrated within the DRAM device itself, allowing the device to autonomously monitor its own temperature and adjust refresh operations without requiring external control. This self-service approach improves data retention reliability while minimizing the increase in device complexity by using internal resources rather than adding separate external control systems.
Solution Approach 2:
The temperature sensor serves multiple functions: it monitors temperature for refresh control, provides temperature information for mode register set (MRS) operations, and enables temperature-dependent parameter adjustments. This multi-functionality allows a single component to address multiple requirements, improving reliability without proportionally increasing device complexity.
2Duration of action of stationary object
If refresh cycle time is adjusted according to temperature variations, then data retention time is improved, but operation control complexity increases
Solution Approach 1:
The refresh cycle time is made dynamic rather than fixed, allowing it to be automatically adjusted based on real-time temperature measurements. The refresh control circuit continuously monitors temperature and modifies refresh timing parameters accordingly, enabling the system to adapt to changing thermal conditions without manual intervention. This dynamic adjustment improves data retention time while keeping operation control simple through automated temperature-based feedback.
Solution Approach 2:
The system changes operational parameters (refresh cycle time, retention time) based on temperature conditions. By automatically modifying these parameters in response to temperature sensor readings, the system optimizes data retention without requiring complex manual control procedures. The parameter changes are driven by temperature thresholds and predefined refresh policies, simplifying the control logic.
3Reliability
If multiple sensing codes are generated for temperature verification, then temperature sensor reliability is improved, but measurement and control difficulty increases
Solution Approach 1:
The temperature sensing function is divided into multiple independent sensing codes (first through Nth sensing codes), each representing different temperature measurement instances or aspects. This segmentation allows the system to verify temperature sensor reliability by comparing multiple independent measurements rather than relying on a single reading. The segmented approach improves reliability while keeping each individual measurement simple and manageable.
Solution Approach 2:
The system implements feedback verification by comparing multiple sensing codes against expected temperature values stored in the mode register set. The refresh control circuit uses this feedback mechanism to detect temperature sensor abnormalities and adjust refresh operations accordingly. This feedback-based verification improves temperature sensor reliability while maintaining simple control logic through automated comparison and decision-making.
Data Source
AI summary
A semiconductor system includes a first semiconductor device and a second semiconductor device. The first semiconductor device outputs first to (M+1)th command/address signals (wherein, “M” denotes a natural number which is equal to or greater than two) and receives a detection signal to detect a normality/abnormality of a temperature sensor. The second semiconductor device enters a test mode in response to the (M+1)th command/address signal and compare first to Nth sensing codes (wherein, “N” denotes a natural number which is equal to or greater than two) generated by the temperature sensor with the first to Mth command/address signals to generate the detection signal. The second semiconductor device also executes a refresh operation in response to a refresh signal including a plurality of pulses whose cycle time is controlled by the first to Mth command/address signals.