Flying-Capacitor Booster Stage for Instant Power Amplifier Voltage Doubling
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Solution Overview
Problem
Existing power amplifier circuits face limitations in output voltage range due to supply voltage constraints, particularly in battery-operated devices with high crest-factor signals, and existing booster circuits suffer from inefficiencies, charging delays, and power dissipation.
Innovation Solution
A booster stage circuit that uses a flying capacitor automatically recharged by an inductor to instantaneously double the supply voltage without delay, alternating between normal and boosted modes to maintain efficiency and avoid discharge, using transistors and inductors for switching.
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 supply with power dissipation during recharging
Solution Approach 1:
The patent replaces the traditional diode-based recharging mechanism with a transistor-controlled switching mechanism. Instead of using a diode that dissipates power during recharging, the invention uses transistors (Q1, Q2) to control the charging and discharging of the flying capacitor (C1), enabling efficient energy transfer and eliminating the power loss associated with diode voltage drops.
Solution Approach 2:
The invention implements periodic switching between normal operation mode and boosted operation mode. The transistors alternately connect the flying capacitor to the supply voltage for recharging and then to the output for voltage doubling, creating a rhythmic charge-discharge cycle that maintains capacitor voltage while providing extended output range only when needed.
2Strength
If a switching power stage 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 external supply causing momentary drop in output
Solution Approach 1:
The flying capacitor is pre-charged to the supply voltage during normal operation through the transistor-controlled switching mechanism. This preliminary charging ensures that when boosted operation is needed, the capacitor is already ready to immediately double the supply voltage without any charging delay, eliminating the momentary output drop problem.
Solution Approach 2:
The invention extracts the essential voltage doubling function from a complex switching power stage with inductor and capacitor, using only a flying capacitor with controlled switching. This simplified approach removes the inductor charging delay and associated right-half-plane zero problem, providing instantaneous voltage boosting capability.
3Strength
If a switching booster with inductor is used, then voltage boost is achieved, but the supply current always runs through the primary inductor causing additional losses due to parasitic resistance
Solution Approach 1:
The invention removes the inductor component entirely from the voltage boosting mechanism, using only a flying capacitor with transistor-controlled switching. This eliminates the parasitic resistance of the inductor and the associated continuous power losses, while still achieving the desired voltage doubling function through capacitive energy storage and switching.
Solution Approach 2:
The patent replaces the inductor-based magnetic energy storage mechanism with a capacitor-based electric field energy storage mechanism. This substitution eliminates the parasitic resistance losses inherent in inductors while maintaining the voltage boosting capability through alternative physical principles.
4Reliability
If headroom is provided in control of supply or delay is added in processing, then the right-half-plane zero problem is mitigated, but device complexity increases
Solution Approach 1:
The invention extracts the voltage boosting function from a complex switching power stage and implements it using a simple flying capacitor with transistor switching. This eliminates the right-half-plane zero problem entirely, removing the need for additional control complexity such as headroom provision or delay circuits.
Solution Approach 2:
The periodic switching between normal and boosted modes is controlled by simple transistor switching signals that are synchronized with the audio signal processing. This periodic action provides reliable voltage boosting without introducing the control stability issues and complexity associated with continuous switching power stages.
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
Enables efficient and instantaneous voltage doubling with reduced power loss, suitable for audio and other amplifiers, including battery-powered devices, by optimizing switching between modes and using high-efficiency recharging.
Implementation Method 1
an inductor to instantaneously double the supply voltage without delay, alternating between normal and boosted modes
Implementation Method 2
a flying capacitor automatically recharged by an inductor to instantaneously double the supply voltage
Data Source
Figure 1a~2
Figure 3a~4
Figure 5~7
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.