Power Supply Circuit Noise Reduction via Input Voltage Control
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Solution Overview
Problem
Existing power supply circuits using DC-to-DC converters and series regulators face challenges in reducing noise and power dissipation due to the requirement for a significant voltage difference between the input and output of the series regulator, which increases efficiency loss and heat generation.
Innovation Solution
A power supply circuit configuration that includes a DC-to-DC converter and a series regulator, where the series regulator is operated by the input supply voltage, allowing it to control the output transistor with a higher voltage and minimizing the voltage drop across the output transistor, thereby reducing power loss and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a series regulator is used to reduce noise, then noise level is reduced, but power dissipation increases due to the required voltage difference between input and output
Solution Approach 1:
The invention changes the operating voltage parameter of the series regulator from the DC-to-DC converter output voltage to the input supply voltage. This parameter change allows the regulator to operate with a smaller voltage differential, reducing power dissipation while maintaining noise filtering capability through the output transistor's control function.
Solution Approach 2:
The invention dynamically adjusts the voltage supply to the series regulator control circuit based on operating conditions. By using the input supply voltage (which is higher) instead of the DC-to-DC converter output, the system optimizes the voltage headroom available to the output transistor, enabling better control with lower power loss across varying load conditions.
2Use of energy by moving object
If a DC-to-DC converter is used to increase efficiency, then power conversion efficiency is improved, but output voltage contains ripple and high level noises
Solution Approach 1:
The invention introduces a series regulator with an output transistor as an intermediary component between the DC-to-DC converter and the load. This intermediary filters the ripple and noise from the converter output while maintaining the efficiency benefits, as the regulator operates with optimized voltage headroom from the input supply rather than relying on a large voltage drop.
3Use of energy by moving object
If a cascade connection between series regulator and DC-to-DC converter is used to achieve high efficiency and low noise, then efficiency and noise performance are improved, but power dissipation increases due to voltage difference requirement
Solution Approach 1:
The invention fundamentally changes the voltage supply parameter to the series regulator control circuit, using the input supply voltage instead of the DC-to-DC converter output voltage. This parameter change reduces the voltage differential that the output transistor must handle, thereby reducing power dissipation (P=V×I) while preserving the cascade connection's efficiency and noise filtering benefits.
Data Source
AI summary
A power supply circuit includes: a DC-to-DC converter outputting a first voltage dropped from an input supply voltage; and a series regulator outputting a second voltage dropped from an output of the DC-to-DC converter, the series regulator including: an output transistor supplied with the output of the DC-to-DC converter and outputting the second voltage, and a first control circuit operated by the input supply voltage and controlling the output transistor.