Trimmable Sense Amplifier for Memory Mismatch Compensation
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Solution Overview
Problem
Existing sense amplifiers in non-volatile semiconductor memory devices face performance issues due to transistor mismatching, which can occur during operation, leading to inaccurate data reading, as there is no mechanism to correct for this mismatching in real-time.
Innovation Solution
A trimmable sense amplifier design that allows for on-the-fly trimming during operation by testing each sense amplifier for mismatch and injecting the necessary current compensation, using an extra sense amplifier and mismatch compensation circuit to maintain accurate readings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If transistor mismatching occurs during operation due to thermal changes, then sense amplifier performance degrades and data reading accuracy decreases, but adding trimming mechanisms increases device complexity
Solution Approach 1:
The patent applies preliminary action by performing trimming operations before normal read operations. The sense amplifier is trimmed during a preliminary phase where memory cells are not accessed, allowing mismatch compensation to be established in advance. This ensures the sense amplifier is calibrated for accurate operation before actual data reading begins, resolving the contradiction by preparing the system beforehand rather than adding continuous complexity during operation.
Solution Approach 2:
The patent implements self-service through self-trimming mechanisms where the sense amplifier automatically compensates for its own transistor mismatching. The trimming circuitry uses internal reference cells and feedback mechanisms to detect and correct mismatch errors without requiring external intervention or complex external control systems. This reduces device complexity while maintaining reliability through autonomous error correction.
2Measurement precision
If trimming is performed during memory operation, then mismatch compensation can be applied in real-time, but it disrupts normal memory access and reduces productivity
Solution Approach 1:
The patent resolves this contradiction by performing all trimming operations during preliminary phases before normal memory access begins. The trimming process establishes mismatch compensation values in advance, and once trimming is complete, the sense amplifier operates at full speed without interruption. This separates the precision-improving trimming function from the productivity-critical read operations, eliminating the trade-off between accuracy and speed.
Solution Approach 2:
The patent implements periodic trimming where the sense amplifier is recalibrated at scheduled intervals rather than continuously. Trimming is performed periodically during idle periods or at predetermined time intervals, allowing the system to maintain high productivity during normal operation while still applying mismatch compensation when needed. This periodic approach balances measurement precision with productivity by limiting disruption to specific time windows.
3Duration of action of stationary object
If an extra sense amplifier is added for trimming operations, then continuous memory operation during trimming is enabled, but device complexity and area increase
Solution Approach 1:
The patent applies universality by designing the extra sense amplifier to serve multiple functions: it acts as a functional duplicate during normal read operations and as an active trimming workstation during calibration phases. This multi-functionality allows the same hardware resource to support both continuous operation requirements and trimming operations without requiring separate dedicated circuits for each function, thereby reducing the overall area impact.
Solution Approach 2:
The patent implements discarding and recovering by temporarily assigning the extra sense amplifier to trimming operations during calibration phases, then recovering it for normal read operations afterward. This dynamic resource allocation allows the system to utilize the extra amplifier only when needed for trimming, minimizing its impact on chip area while still enabling continuous memory operation during trimming through temporary resource dedication.
Data Source
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AI summary
A trimmable sense amplifier for use in a memory device is disclosed.