Bipolar Charge Pump Switching for Wide Output Swing
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Solution Overview
Problem
Existing bipolar output voltage charge pump circuits face challenges in minimizing power consumption, reducing audio artefacts, and accommodating a wide range of output signal levels and input supplies while maintaining efficient operation and adequate signal swing, particularly in portable electronics where power efficiency and compact design are crucial.
Innovation Solution
A charge pump circuit with a network of switching paths and a controller that provides selectively variable bipolar output voltages, allowing for various modes of operation to optimize voltage levels and reduce the number of flying capacitors, thereby minimizing power consumption and eliminating the need for analog level-shifting, while maintaining efficient operation across different supply voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single bipolar output voltage charge pump circuit is used, then the circuit structure is simple, but it cannot accommodate a wide range of output signal levels and input supplies
Solution Approach 1:
The charge pump circuit is divided into multiple independent charge pump stages, each capable of generating bipolar output voltages. Each stage can be independently controlled to provide different output voltage levels, enabling the circuit to accommodate a wide range of output signal levels while maintaining a modular and manageable structure.
Solution Approach 2:
The charge pump circuit is designed to provide multiple bipolar output voltages (e.g., +/−VV, +/−VV/2, +/−VV/4) from a single unipolar input voltage source. This multi-functional capability allows the circuit to serve various applications with different voltage requirements without needing separate charge pump circuits for each voltage level.
2Adaptability or versatility
If multiple flying capacitors are used to provide various bipolar output voltages, then the adaptability to different output signal levels is improved, but the device complexity and power consumption increase
Solution Approach 1:
Multiple charge pump stages share common flying capacitors and switching networks. The flying capacitors are dynamically allocated to different stages based on the required output voltage levels, reducing the total number of capacitors needed while maintaining the ability to provide multiple bipolar output voltages.
Solution Approach 2:
The circuit employs dynamic switching control to reconfigure the flying capacitors and switching paths based on the desired output voltage level. This dynamic reconfiguration allows the same physical components to serve multiple functions across different operating modes, reducing device complexity while maintaining versatility.
3Ease of operation
If analog level-shifting is used to optimize voltage levels, then the signal swing is improved, but the power consumption increases and audio artefacts are generated
Solution Approach 1:
The circuit replaces analog level-shifting mechanisms with a digital-controlled switching architecture. By using switched-capacitor based charge pump stages with controlled switching paths, the circuit achieves the desired voltage levels and signal swing without the continuous power consumption and audio artefacts associated with analog level-shifting circuits.
Solution Approach 2:
The charge pump circuit uses periodic switching of the flying capacitors and switching paths to transfer charge and generate bipolar output voltages. This periodic action, synchronized with the audio signal, enables efficient voltage generation with minimal power consumption and without introducing audio artefacts, unlike continuous analog level-shifting.
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 efficient power management with reduced power consumption, minimized audio artefacts, and compact design, supporting a wide range of output signal levels and input supplies without the need for analog level-shifting, thus enhancing the performance and efficiency of audio output chains in portable electronics.
Implementation Method 1
Bipolar, i.e. dual rail, output voltage charge pump circuits are a type of DC-DC converter that utilize transfer and storage capacitors as devices to respectively transfer and store energy
Implementation Method 2
two flying capacitors connected to the two pairs of flying capacitor nodes
Data Source
AI summary
A bipolar output charge pump circuit having a network of switching paths for selectively connecting an input node and a reference node for connection to an input voltage, a first pair of output nodes and a second pair of output nodes, and two pairs of flying capacitor nodes, and a controller for controlling the switching of the network of switching paths. The controller is operable to control the network of switching paths when in use with two flying capacitors connected to the two pairs of flying capacitor nodes, to provide a first bipolar output voltage at the first pair of output nodes and a second bipolar output voltage at the second pair of bipolar output nodes.