Cross-Feedback Dual-Path Charge Pump Against Body Effect
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Solution Overview
Problem
Prior art charge pumps face inefficiencies due to the body effect increasing the threshold voltages of transistors, which limits the ability to generate high voltages effectively.
Innovation Solution
A dual-path charge pump design with cross-feedback between stages, utilizing native NMOS transistors and applying higher voltages to transistor gates through cross-feedback, mitigates the body effect and enhances boosting efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional charge pump stages are used to boost voltage across subsequent stages, then voltage multiplication is achieved, but the body effect increases threshold voltages of transistors making it difficult to fully turn them on
Solution Approach 1:
The charge pump is divided into two separate paths (first path with first stage and second stage, second path with third stage and fourth stage) that operate independently and out of phase with each other. This segmentation allows each path to handle voltage boosting separately, reducing the cumulative body effect impact on any single transistor while maintaining overall voltage multiplication efficiency.
Solution Approach 2:
The two paths are operated out of phase, with clock signals alternately enabling each path. The first path operates during one phase while the second path operates during the opposite phase. This periodic action ensures that at least one path is always active for voltage boosting, maintaining continuous high voltage generation while allowing transistors in inactive paths to recover from body effect accumulation.
2Ease of operation
If higher gate voltages are applied to overcome the body effect, then transistors can be fully turned on, but process-temperature variation increases
Solution Approach 1:
Cross-feedback is implemented where the output of the first path feeds back to control elements in the second path, and vice versa. This feedback mechanism allows the circuit to automatically adjust operating parameters based on actual conditions, compensating for temperature and process variations without requiring excessive gate voltage swings, thereby maintaining stable transistor switching across varying conditions.
3Productivity
If dual-path topology with cross-feedback is implemented, then voltage boosting efficiency is enhanced, but device complexity increases
Solution Approach 1:
Each path in the dual-path topology is designed with identical circuit structures that can perform multiple functions: voltage boosting, body effect compensation, and temperature stabilization. The first path and second path are universal modules that can independently execute the complete charge pump operation, allowing the system to maintain high efficiency while managing complexity through modular design.
Data Source
AI summary
Examples of improved charge pumps are disclosed. In one example, a system comprises a first charge path comprising a first stage to boost an input voltage and a second stage to boost a voltage received from the first stage of the first charge path; and a second charge path comprising a first stage to boost an input voltage and a second stage to boost a voltage received from the first stage of the second charge path; wherein an output of the second stage of the first charge path is coupled to the first stage of the second charge path and an output of the second stage of the second charge path is coupled to the first stage of the first charge path.