Sense Amplifier Isolation for Non-Volatile Memory Read Speed
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Solution Overview
Problem
Bit line load impacts the sensing operation of sense amplifiers in non-volatile memory, leading to longer read access times, increased power consumption, and reduced sensing margins, which can result in higher read error rates due to process variations and temperature effects.
Innovation Solution
A sense amplifier design incorporating a first and second sample and hold circuit, a latch-type amplifier, and a feedback circuit, which isolates the sense amplifier from the bit line and reference bit line during the evaluation phase to reduce load impact and enhance sensing margin, utilizing capacitors and transistors to store and compare data during pre-charge and evaluation phases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the sense amplifier is directly connected to the bit line during evaluation phase, then the sensing operation can be performed, but the bit line load causes longer read access time and increased power consumption
Solution Approach 1:
The sensing operation is divided into two distinct phases: pre-charge phase where the sense amplifier is isolated from the bit line, and evaluation phase where the sense amplifier compares the stored data with reference data. This segmentation allows the bit line to be charged separately without continuously loading the sense amplifier, reducing both read access time and power consumption.
Solution Approach 2:
The sense amplifier is isolated from the bit line during the pre-charge phase to perform preliminary charging of the bit line without the load of the sense amplifier. This preliminary action prepares the bit line for subsequent evaluation while minimizing power consumption and time penalties.
2Reliability
If the sense amplifier is directly connected to the bit line, then sensing operation is enabled, but the sensing margin becomes too small leading to larger read error rate
Solution Approach 1:
The sensing operation is segmented into pre-charge phase (isolation) and evaluation phase (comparison). During the pre-charge phase, the sense amplifier is isolated from the bit line, allowing the bit line to be charged without the sense amplifier's load. This segmentation enables the sense amplifier to maintain a larger sensing margin during evaluation, improving reliability and reducing read error rates.
Solution Approach 2:
The sense amplifier uses feedback mechanisms to compare the data stored in the first sample and hold circuit with the reference data in the second sample and hold circuit during the evaluation phase. This feedback-based comparison enhances the sensing margin, making the sensing operation more robust against process variations and temperature effects, thereby reducing read error rates.
Data Source
AI summary
A sense amplifier includes a first sample and hold circuit, a second sample and hold circuit, a latch-type amplifier. The first sample and hold circuit is coupled to a bit line and configured to sample and hold memory cell data during a pre-charge phase of a sensing operation. The second sample and hold circuit is coupled to a reference bit line and configured to sample and hold data of a reference memory cell data during the pre-charge phase of the sensing operation. The latch-type amplifier, coupled to the first sample and hold circuit and the second sample and hold circuit, and configured to compare the memory cell data and the reference cell data during an evaluation phase of the sensing operation to output a sensing signal. The sense amplifier is isolated from the bit line and the reference bit line during the evaluation phase of the sensing operation. A sensing method adapted to a sense amplifier and a non-volatile memory include a sense amplifier are also introduced.