Sense Amplifier Cross-Coupling to Preserve Memory Read Margin
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Solution Overview
Problem
In some memory circuits, direct and indirect coupling between data inputs and reference inputs in sense amplifiers reduces the read margin, leading to incorrect data reading and reduced memory reliability.
Innovation Solution
The sense amplifier design includes cross-coupled capacitors that provide positive coupling effects on data and reference inputs, offsetting negative indirect coupling effects from internal nodes, thereby maintaining or improving the read margin.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the reference input QB is directly coupled to the data input Q, then the sense amplifier can be simplified, but the read margin is reduced
Solution Approach 1:
The patent divides the sense amplifier into separate differential pairs: one for data input (Q) and one for reference input (QB). This segmentation prevents direct coupling between data and reference inputs, eliminating the harmful voltage level changes on QB while maintaining the simplified amplifier structure through systematic design.
Solution Approach 2:
The patent introduces intermediate nodes and separate differential pairs as mediators between the data input and reference input. These intermediaries prevent direct coupling while allowing the sense amplifier to function, thus preserving read margin without significantly increasing overall complexity.
2Device complexity
If the data input Q is in-directly coupled to an internal node, then the sense amplifier can share internal nodes, but the voltage level on Q changes during operation, reducing read margin
Solution Approach 1:
The patent segments the sense amplifier into distinct differential pairs with separate internal nodes for data and reference operations. This prevents indirect coupling that would cause voltage level changes on the data input Q during sense amplifier operation, thereby maintaining read margin while preserving structural efficiency.
3Device complexity
If the reference input QB is in-directly coupled to an internal node, then the sense amplifier can share internal nodes, but the voltage level on QB changes during operation, reducing read margin
Solution Approach 1:
The patent divides the sense amplifier into separate differential pairs, assigning dedicated internal nodes to the reference input QB path. This segmentation prevents indirect coupling that would cause voltage level fluctuations on QB during operation, maintaining read margin while preserving the efficiency of node sharing where applicable.
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 design effectively reduces direct and indirect coupling effects, enhancing the read margin and memory reliability, with improvements greater than 80% in indirect coupling reduction.
Implementation Method 1
The first input transistor includes an internal coupling capacitor from its gate to the drain/source connection with the first latch transistor, and the second input transistor includes an internal coupling capacitor from its gate to the drain/source connection with the second latch transistor
Data Source
AI summary
A sense amplifier including a first input transistor having a first input gate and a first drain/source terminal, a second input transistor having a second input gate and a second drain/source terminal, a latch circuit, and a first capacitor. The latch circuit includes a first latch transistor having a third drain/source terminal connected to the first drain/source terminal and a second latch transistor having a fourth drain/source terminal connected to the second drain/source terminal. The first capacitor is connected on one side to the first input gate and on another side to the fourth drain/source terminal to reduce a coupling effect in the sense amplifier.