Alternating Fly-Capacitor Charge Pump for Low-Ripple Output
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Solution Overview
Problem
Conventional charge pump circuits generate ripples and signal distortions in output voltage, which are difficult to filter and reduce power efficiency, and require large output capacitors, increasing device footprint and cost.
Innovation Solution
A reduced-ripple charge pump system using operational transconductance amplifiers and multiple stages with fly capacitors, alternating phases based on a clock signal, adjusts switching frequency to match load current, reducing or eliminating ripples and output capacitor size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a conventional charge pump circuit is used to increase voltage output, then voltage boosting is achieved, but ripples and signal distortions are introduced into the output voltage
Solution Approach 1:
The charge pump is divided into multiple stages (first stage, second stage, third stage) that operate alternately. Each stage includes fly capacitors and switches that transfer charge in discrete steps, allowing the output voltage to be built incrementally while maintaining stability and reducing ripples through the staged charge transfer process
Solution Approach 2:
The multiple stages operate in alternating phases to ensure continuous charge transfer to the output node. While one stage is charging its fly capacitor, another stage is transferring charge to the output, maintaining continuous useful action and smooth voltage output without interruption or large fluctuations
2Power
If conventional charge pump circuits are used to generate regulated voltage levels, then voltage conversion is achieved, but noise and voltage deviations are introduced that reduce power efficiency
Solution Approach 1:
The circuit dynamically adjusts the switching frequency of the stages based on load conditions. The controller monitors the output voltage and adjusts the switching frequency to optimize efficiency across different operating conditions, reducing energy losses while maintaining effective voltage conversion
Solution Approach 2:
A controller monitors the output voltage and adjusts the switching frequency of the charge pump stages accordingly. This feedback mechanism ensures optimal power efficiency by adapting the operating parameters to match the actual load requirements and maintain stable output voltage
3Object-generated harmful factors
If conventional charge pump circuits are used to mitigate ripples, then ripple reduction is achieved, but large output capacitors are required increasing device size
Solution Approach 1:
The ripple reduction is achieved through multiple stages with distributed fly capacitors rather than a single large output capacitor. Each stage's fly capacitor is relatively small, and their combined effect provides smooth voltage output with reduced ripples, avoiding the need for large capacitor structures
Solution Approach 2:
Instead of reducing ripples through a single large capacitor in the output dimension, the patent uses multiple stages operating in time dimension (alternating phases) to achieve ripple reduction. The staged, time-multiplexed charge transfer provides smooth output without requiring large spatial footprint
4Ease of operation
If conventional charge pump circuits operate at fixed switching frequency, then simple control is maintained, but power efficiency decreases under varying load conditions
Solution Approach 1:
The switching frequency of the charge pump stages is made dynamic rather than fixed. The controller adjusts the switching frequency based on load conditions and output voltage requirements, allowing the circuit to optimize efficiency across different operating points while maintaining relatively simple control through frequency modulation
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
Provides increased voltage output with minimal ripples and reduced footprint, enhancing power efficiency and reducing manufacturing costs compared to conventional charge pumps.
Implementation Method 1
each stage may include at least one fly capacitor, switches (e.g., transistors) that operatively connect and disconnect the different leads of a fly capacitor to charge or discharge according to the phase
Data Source
AI summary
An electrical device may include an electrical load that draws current, a charge pump that provides the current to the electrical load, and clock circuitry. The charge pump may include an amplifier, a first fly capacitor, a second fly capacitor, and multiple switches. A first set of the switches may couple the first fly capacitor between a supply and ground based on a first set of clock signals and between the amplifier and the electrical load based on a second set of clock signals. A second set of the switches may couple the second fly capacitor between the supply and ground based on the second set of clock signals and between the amplifier and the electrical load based on the first set of clock signals. The clock circuitry may alternate between generating the first set of clock signals and the second set of clock signals based on the current.