Power Amplifier Booster Stage With Inductor-Recharged Flying Capacitor
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Solution Overview
Problem
Existing booster stage circuits for power amplifiers face limitations in output voltage range due to supply voltage constraints, particularly in battery-operated devices with high crest-factor audio amplifiers. Current solutions, such as flying capacitors and switching boosters, suffer from inefficiencies, charging delays, and increased power dissipation.
Innovation Solution
The proposed booster stage circuit utilizes a flying capacitor that is automatically recharged with high efficiency through an inductor, allowing for instantaneous doubling of the supply voltage without charging delays. This circuit alternates between normal and boosted supply modes quickly, using a small capacitance value while minimizing discharge, and avoids power inefficiencies by recharging through an inductor rather than a diode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a flying capacitor is used to double the supply voltage, then the output voltage range is extended, but the capacitor discharges during use and can only achieve maximum doubling of the supply with power dissipation during recharging
Solution Approach 1:
The patent changes the recharging mechanism from a diode-based dissipative circuit to an inductor-based resonant circuit. By utilizing the resonant frequency of the LC circuit, the capacitor is recharged through oscillating current flow in the inductor, achieving energy transfer without significant power dissipation. This transforms the recharging process from a lossy operation to an efficient energy recovery process.
2Strength
If a switching booster with inductor and capacitor is used to generate local supply, then the supply voltage can be boosted, but it takes time to charge the local supply above the external supply with initial voltage drop
Solution Approach 1:
The patent pre-charges the flying capacitor to the external supply voltage during normal operation before a boost phase is needed. When boosting is required, the capacitor is already charged and can immediately be switched into series configuration with the external supply through the bridge circuit, eliminating the charging delay and initial voltage drop associated with traditional switching boosters.
Solution Approach 2:
The patent employs dynamic switching of the bridge circuit configuration to transition between normal supply mode and boosted supply mode. The switching mechanism allows the flying capacitor to be rapidly connected in series with the external supply, enabling fast response to boosting requirements without the slow charging characteristic of conventional inductor-based boosters.
3Strength
If a switching booster is used to boost the supply voltage, then the local supply can be increased above external supply, but the supply current always runs through the primary inductor causing additional losses
Solution Approach 1:
The patent extracts the capacitor from the continuous current path through the inductor. By using the flying capacitor in parallel with the external supply during normal operation and only engaging it in series during boost phases, the inductor is removed from the current path during non-boost operation, eliminating continuous power losses through the inductor's parasitic resistance.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides efficient and instantaneous voltage boosting, maintaining high power efficiency by recharging the capacitor through an inductor, and avoiding the limitations of traditional flying capacitor and switching booster circuits.
Implementation Method 1
an inductor, also increasing the voltage across the flying capacitor to above the external supply
Implementation Method 2
a flying capacitor that can momentarily double the supply
Data Source
AI summary
The present invention is in the field of booster stage circuit for a power amplifier, and an external supply voltage power amplifier comprising said booster stage circuit, such as for amplifying an electronic signal to a speaker system. These amplifiers may be provided with an external supply voltage.