Linear Regulator Isolation Circuit for Switching Supply Noise
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Solution Overview
Problem
Switching power supplies generate noise that can be transmitted to linear voltage regulation circuits, affecting the performance and efficiency of connected loads, particularly those sensitive to noise like radio frequency signal circuits.
Innovation Solution
The electronic circuit design incorporates a linear voltage regulation circuit with multiple output stages and switches to isolate noise from the switching power supply, ensuring that noise is not transmitted to the substrate of transistors, thereby preventing current leaks and maintaining capacitor charge during different operating modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a switching power supply is used to power loads, then power efficiency is improved, but noise is generated that can be transmitted to linear voltage regulation circuits
Solution Approach 1:
The patent introduces an intermediary isolation circuit between the switching power supply and the linear voltage regulation circuit. This intermediary circuit includes a first transistor whose substrate is connected to the switching power supply output, and whose source/drain connects to the regulator input. This intermediary structure blocks noise transmission while allowing power transfer, resolving the contradiction between maintaining power efficiency and preventing noise generation.
Solution Approach 2:
The patent segments the power supply system into distinct isolated sections: the switching power supply section, the isolation circuit section, and the linear regulation section. By dividing the system and inserting isolation elements (transistors with specific substrate connections) between segments, noise from the switching section is prevented from propagating to the sensitive regulation section, while power flow is maintained through the segmented path.
2Object-generated harmful factors
If the substrate of the transistor in the linear voltage regulation circuit is connected to the switching power supply output, then noise transmission is prevented, but current leaks may occur
Solution Approach 1:
The patent applies local quality by making the substrate connection configuration selective and localized. The first transistor's substrate is connected to the switching power supply output node, but only for the purpose of noise isolation. The source and drain of this transistor are separately configured to maintain proper current flow paths. This localized substrate connection provides noise isolation benefits at the specific location without causing system-wide current leakage issues.
Data Source
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AI summary
The invention relates to an electronic circuit comprising: - a switching power supply (104); - a linear voltage regulation circuit comprising at least one input stage and first and second output stages; and - a first load (102) which can be powered either by the switching power supply in series with the regulation circuit or by the regulation circuit.