Triple-Mode Charge Pump Circuit for Audio Power Supply
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Solution Overview
Problem
Current charge pumps face challenges in generating voltages with step-down, invert, and doubler functionalities using a minimum number of switches with one flying capacitor, while maintaining low noise and efficient power consumption for audio systems.
Innovation Solution
A charge pump circuit with a digital controller, eight switches, and two reservoir capacitors, capable of operating in doubler, inverter, or half the input supply voltage modes, utilizing a single flying capacitor and controlling the switching sequence to achieve these modes efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a charge pump uses a single flying capacitor with minimum number of switches to generate step-down, invert and doubler voltages, then device complexity is reduced, but it becomes difficult to achieve all three voltage modes efficiently
Solution Approach 1:
The charge pump circuit is designed with a single flying capacitor and eight switches that can operate in three different modes (step-down, invert, and doubler) by controlling the switching sequence. This multi-functional design allows the same hardware components to achieve multiple voltage generation objectives without requiring separate circuits for each mode, thus reducing overall device complexity while maintaining versatility.
Solution Approach 2:
The circuit employs dynamic switching control where the eight switches are activated in specific sequences depending on the desired output mode. By dynamically reconfiguring the connections between the flying capacitor, reservoir capacitors, and output nodes through controlled switching, the circuit adapts its behavior to achieve step-down, invert, or doubler functionality from the same hardware configuration.
2Power
If a charge pump generates doubler voltage using conventional circuits, then voltage doubling is achieved, but it creates a noisy negative rail that degrades audio quality
Solution Approach 1:
The circuit segments the voltage generation function by using two separate reservoir capacitors (first and second reservoir capacitors) that independently handle different aspects of voltage regulation. The first reservoir capacitor is connected to the positive output node and the second to the negative output node, allowing each to be optimized for its specific function. This segmentation enables clean voltage doubling without the noise propagation issues that occur in conventional single-capacitor designs.
Solution Approach 2:
The flying capacitor acts as an intermediary energy transfer element between the input voltage source and the output nodes. By using the flying capacitor in conjunction with the two reservoir capacitors and eight switches, the circuit mediates the voltage transformation process in a way that isolates the noise-generating switching operations from the negative rail, thereby achieving voltage doubling without degrading audio quality.
3Reliability
If a charge pump uses more switches and capacitors to achieve stable voltage output, then voltage stability improves, but the number of external components and pin count increases
Solution Approach 1:
The circuit merges the functions of voltage storage and regulation into a unified architecture using one flying capacitor and two reservoir capacitors working together with eight switches. This combined approach achieves stable voltage output across all three modes (step-down, invert, doubler) while maintaining a compact component count that is suitable for integration, thereby balancing reliability with device complexity.
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 enables a triple-mode charge pump that doubles input voltages without creating a noisy negative rail, improves AC coupling for higher signal levels, and reduces the number of external components and pin count, ensuring efficient and clean power supply for audio amplifiers.
Implementation Method 1
A charge pump circuit with a digital controller, eight switches, and two reservoir capacitors, capable of operating in doubler, inverter, or half the input supply voltage modes, utilizing a single flying capacitor
Data Source
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AI summary
Systems and methods to achieve a charge pump for generating from a single input supply voltage Vdd in three modes efficient output supply voltages having a value of 2xVdd, ½ Vdd, and inverted Vdd. The charge pump requires 8 switches and one flying capacitor only.