Low-Noise Power Conversion with Linear Ripple Suppression
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Solution Overview
Problem
Existing power conversion systems for noise-sensitive loads face challenges in achieving high efficiency while minimizing switching noise, particularly in applications requiring both high efficiency and low noise, such as RF transmitters and receivers.
Innovation Solution
A low noise power supply system comprising a current-mode switcher and a linear amplifier, with sourcing and sinking power converters configured to reduce ripple current components, utilizing various power converter topologies like buck, boost, and switched-capacitor converters to manage voltage rails and minimize power losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a switching mode power supply is used to convert input voltage, then conversion efficiency is improved, but switching noise (ripple current components) is generated at the output
Solution Approach 1:
The power conversion system is segmented into multiple functional stages: a switching mode power converter for efficient voltage conversion, followed by a noise reduction circuit (linear amplifier) to eliminate ripple components. This segmentation allows each stage to perform its specialized function optimally - the switching converter handles efficiency while the linear stage handles noise reduction.
Solution Approach 2:
A linear amplifier is introduced as an intermediary component between the switching mode power converter and the noise-sensitive load. This intermediary reduces the switching noise generated by the efficient converter while maintaining the benefits of high-efficiency power conversion, effectively mediating between the conflicting requirements of efficiency and noise reduction.
2Object-generated harmful factors
If an LDO is used as a downstream regulator to reduce noise, then noise is reduced, but efficiency decreases when output voltage is far from input voltage
Solution Approach 1:
The system dynamically adjusts the operating point of the LDO by using the switching mode power converter to pre-regulate the input voltage to the LDO. This dynamic voltage adjustment ensures that the LDO operates in its most efficient region (where Vin is close to Vout) while still providing effective noise reduction, resolving the efficiency-performance tradeoff.
3Object-generated harmful factors
If additional efforts are made to reduce switching noise in high efficiency converters, then noise is reduced, but device complexity increases
Solution Approach 1:
Rather than making the switching converter itself more complex with additional noise reduction circuitry, the system segments the noise reduction function into a separate, simpler linear amplifier stage. This segmentation maintains the simplicity of the high-efficiency switching converter while adding dedicated noise reduction capability.
Data Source
AI summary
A system includes a current-mode switcher configured to provide a direct current (DC) voltage for a noise sensitive load, and a linear amplifier connected to an output of the current-mode switcher, the linear amplifier configured to draw a reduced supply voltage through at least one power conversion device that is coupled between a power source and the linear amplifier.