Charge Pump Stage Frequency Split for Memory Area Reduction
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Solution Overview
Problem
The increasing number of memory cells in semiconductor memory devices leads to increased loading on charge pumps, occupying significant chip area and requiring efficient area minimization as die-size decreases.
Innovation Solution
Implementing a stage-based frequency optimization for charge pumps, where different stages operate at their best possible frequency simultaneously, rather than a single common frequency, to achieve higher area efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the number of memory cells is increased to improve storage capacity, then the loading on charge pumps increases, but the chip area occupied by charge pumps becomes significant and area efficiency decreases
Solution Approach 1:
The charge pump is divided into multiple stages, with each stage operating at a different frequency optimized for its specific function. This segmentation allows each stage to be sized efficiently, reducing the total area required while handling the increased loading from higher density memory cells.
Solution Approach 2:
Different stages of the charge pump operate at different frequency parameters rather than a single common frequency. This parameter optimization allows each stage to achieve maximum efficiency at its operating point, reducing the overall size required for the charge pump circuit while supporting increased memory cell density.
2Device complexity
If a single common frequency is used for all charge pump stages, then the circuit design is simplified, but area efficiency and output strength are reduced
Solution Approach 1:
The charge pump is segmented into multiple stages with different frequency characteristics. This segmentation enables area-efficient design by matching each stage's frequency to its optimal operating point, improving overall area efficiency despite the increased design complexity.
Solution Approach 2:
The system transitions from a single-frequency operation to multi-frequency operation across different stages. This parameter change optimizes the area efficiency and output strength by allowing each stage to operate at its best frequency, accepting that the design complexity increases accordingly.
Data Source
AI summary
A stage-based frequency optimization for a charge pump achieves a higher area efficiency by operating different stages of the charge pump at their optimized frequency simultaneously, instead of single common frequency, to obtain greater output strength. A first set of stages uses triple well devices as transfer switches and operates at a first, higher frequency. The first stages supply a second set of stages using high voltage devices as transfer switches and operates at a second, lower frequency. The two set of stages are connected through a frequency transition circuit.