Switched Mode Assisted Linear Regulator Decoupling Bandwidth
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Solution Overview
Problem
Hybrid amplifier/regulator architectures face challenges in reducing noise and distortion, particularly due to switching noise from switched mode converters, which affects the output impedance and signal path bandwidth, especially in envelope modulated power supplies for RF applications with high peak-to-average power ratio signals.
Innovation Solution
The implementation of a switched mode assisted linear (SMAL) amplifier architecture decouples signal path bandwidth from output impedance bandwidth using first and second negative feedback loops, where the first feedback loop controls output impedance and the second controls signal path bandwidth, allowing the linear amplifier to supply regulated load voltage and the switched converter to supply load current, optimizing efficiency and noise reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a switched mode converter is used to improve efficiency, then energy efficiency is improved, but switching noise is generated that affects output impedance and signal quality
Solution Approach 1:
The patent divides the regulator into two separate paths: a switched mode converter path for DC average voltage regulation (high efficiency) and a linear amplifier path for AC signal content (low noise). This segmentation allows each path to optimize for its specific function, with the switched mode converter handling efficiency-critical DC regulation and the linear amplifier handling noise-critical AC signals.
Solution Approach 2:
The patent introduces an AC coupling capacitor as an intermediary between the switched mode converter and linear amplifier. This capacitor blocks DC components from the switched mode converter while allowing AC signal content to pass to the linear amplifier, effectively separating the noise sources from the signal path.
2Object-generated harmful factors
If the linear amplifier bandwidth is increased to reduce noise, then noise reduction is improved, but device complexity and power consumption increase
Solution Approach 1:
The patent applies partial action by having the linear amplifier handle only the AC signal content portion of the output, rather than the full bandwidth signal. The DC average voltage is handled by the switched mode converter, allowing the linear amplifier to operate with reduced bandwidth requirements and lower complexity while still providing noise reduction for the signal path.
3Object-generated harmful factors
If the switched mode converter operates at higher frequency to reduce noise, then switching noise frequency is increased, but power loss in inductors and switches increases
Solution Approach 1:
The patent extracts the AC signal content from the switched mode converter output through AC coupling, removing the noise concern. This allows the switched mode converter to operate at lower frequencies with reduced power loss, while the extracted AC content is handled separately by the linear amplifier without being affected by switching noise.
Data Source
AI summary
A switched mode assisted linear (SMAL) amplifier/regulator architecture can be configured to supply regulated power to a dynamic load, such as an RF power amplifier. Embodiments of a SMAL regulator can include a linear amplifier and a switched mode converter parallel coupled at a supply node, and configured such that the amplifier sets load voltage, while the amplifier and the switched converter are cooperatively controlled to supply load current. The amplifier can include separate feedback loops: an external relatively lower speed feedback loop for controlling signal path bandwidth, and an internal relatively higher speed feedback loop for controlling output impedance bandwidth of the linear amplifier. The linear amplifier can be AC coupled to the supply node, and the switched converter can be configured with a capacitive charge control loop that controls the switched converter to effectively control the amplifier to provide capacitive charge control.