Charge Pump Residual Charge Voltage Sensing
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Solution Overview
Problem
Charge pumps face efficiency losses due to significant current consumption by the feedback/sense network, especially in light current-load conditions, leading to increased power consumption and inefficiency.
Innovation Solution
Implementing residual-charge voltage sensing using a flying capacitor, which introduces a sample phase between pump and charge phases to measure output voltage without loading the output, thereby reducing power consumption and optimizing charge pump operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a traditional feedback/sense network is used to sense output voltage, then voltage regulation is achieved, but significant current is drawn especially in light current-load conditions leading to increased power consumption
Solution Approach 1:
The patent extracts the voltage sensing function from the traditional continuous feedback network and implements it through periodic sampling of the flying capacitor voltage. Instead of continuously monitoring VOUT through a dedicated sense network that draws constant current, the system samples the flying capacitor voltage at specific moments during operation, thereby eliminating the need for a continuous current-drawing sense network while maintaining regulation capability.
Solution Approach 2:
The flying capacitor, which already serves the primary function of voltage pumping and storage, is made multi-functional by using its voltage to represent the output voltage for sensing purposes. The same flying capacitor that transfers charge between input and output also provides the sensing signal, eliminating the need for separate sense network components and reducing overall power consumption.
2Reliability
If the charge pump is frequently enabled to maintain regulation, then output voltage regulation is maintained, but efficiency is reduced due to increased switching losses
Solution Approach 1:
The system performs preliminary action by sampling the flying capacitor voltage before the charge pump switches off. This early sampling captures the voltage information while the pump is still operating, allowing the control system to make regulation decisions based on accurate voltage data without requiring continuous pump operation. The regulation band can be wider since sampling occurs at discrete moments rather than continuously.
Solution Approach 2:
Instead of continuous feedback monitoring, the system uses periodic sampling of the flying capacitor voltage at specific phases of the charge pump operation. This periodic action reduces the average current consumption of the sense network while maintaining adequate regulation, as the voltage is sampled at representative moments during each pump cycle rather than being continuously monitored.
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
This approach minimizes power consumption and enhances efficiency by dynamically adjusting the charge pump's operation based on sensed voltage, maintaining regulation within defined limits while reducing die area allocated to voltage sensing.
Implementation Method 1
a charge pump circuit includes at least one flying capacitor Cfly, including a Cfly top plate and a Cfly bottom plate
Data Source
AI summary
A regulated charge pump power supply is implemented with a QP regulation loop providing QP clocking to control pumping operation based on sensing output voltage using residual charge on a flying capacitor Cfly. Cfly is used not only in normal charge pumping operation as an active charge shuttle element, but also to determine/measure output voltage VOUT. Voltage sensing using measured residual charge on Cfly is accomplished by introducing a sample phase into the normal charge pumping operation—after the pump phase and before the charge phase. In the sample phase, VOUT is determined (sampled) based on the residual charge on Cfly corresponding to (Vsense=VOUT−VIN). During the sample phase, the Cfly bottom plate is connected to ground, and the Cfly top plate is sampled (such as with a sense capacitor), with the sample phase completed prior to initiating a charge phase (by connecting the Cfly top plate to VIN).