Charge Pump Circuit Split-Rail Voltage Adaptation
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Solution Overview
Problem
Existing dual rail charge pump circuits are inefficient when used to power circuitry that amplifies signals with amplitudes much smaller than the power supply, as they produce output voltages with a rail-to-rail magnitude greater than the input voltage, resulting in significant power wastage as heat.
Innovation Solution
A charge pump circuit with a network of switches and a controller that generates split-rail supply voltages by transferring charge packets between flying and reservoir capacitors, allowing for positive and negative output voltages spanning approximately the input voltage and centered on a common terminal, with operational states optimized for efficient power delivery based on load conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If known dual rail charge pumps produce output voltage with magnitude twice the input voltage (VDD), then the full output range is available for powering circuitry, but most of the output power is wasted in producing heat instead of driving the signal
Solution Approach 1:
The charge pump circuit dynamically adjusts its output voltage range based on the actual signal requirements of the connected circuitry. The controller monitors load conditions and modifies the charging sequence of the flying capacitors to provide either the full ±VDD output range when needed or a reduced ±VDD/2 range when sufficient, thereby adapting the power delivery to match actual demand and minimize energy waste as heat.
Solution Approach 2:
The invention changes the operating parameters of the charge pump by implementing multiple charging sequences. When the connected circuitry requires smaller signal amplitudes, the system transitions from generating ±VDD output to generating ±VDD/2 output by modifying how the flying capacitors are charged and connected. This parameter adjustment reduces the voltage differential across which power is dissipated as heat while maintaining sufficient operating range for the application.
2Loss of energy
If the charge pump circuit adjusts output voltages to match input voltage for efficient power delivery, then power wastage is reduced, but the ability to provide full output range may be limited
Solution Approach 1:
The charge pump circuit is designed with multi-functionality to serve different operating modes. The same circuit hardware can operate in either efficiency-optimized mode (±VDD/2 output) or full-range mode (±VDD output) depending on the connected circuitry's requirements. The controller selects between different switching sequences and capacitor connection configurations, making the circuit universal enough to handle both power-efficient operations and full-power delivery scenarios without requiring separate circuits.
3Adaptability or versatility
If the charge pump uses a network of switches and controller to manage capacitor connections, then operational flexibility is improved, but device complexity increases
Solution Approach 1:
The controller implements periodic switching sequences that cycle through different capacitor connection configurations. By using regular, repeating patterns of switch activation, the complex multi-capacitor system is managed through predictable, periodic control rather than complex real-time decision-making. This periodic action simplifies the control logic while maintaining the ability to achieve multiple output voltage configurations through the cyclic reconfiguration of the flying and reservoir capacitors.
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 delivery by adjusting output voltages to match the input voltage, reducing power wastage and heat generation, while maintaining flexibility to operate within the full output range when needed.
Implementation Method 1
transfer packets of charge to the reservoir capacitors via the flying capacitors and thereby generating a the split rail supply with positive and negative output voltages
Data Source
AI summary
A charge pump circuit, and associated method and apparatuses, for providing a split-rail voltage supply, the circuit having a network of switches that is operable in a number of different states and a controller for operating the switches in a sequence of said states so as to generate positive and negative output voltages together spanning a voltage approximately equal to the input voltage and centered on the voltage at the common terminal.