Switching-Capacitor Feedback Voltage Regulator
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Solution Overview
Problem
Conventional voltage regulators in portable electronic devices require large layout areas for feedback resistors, which occupy a significant portion of the power management IC, especially for low drop-out voltage regulators, leading to inefficient use of space and battery lifespan due to high quiescent current consumption.
Innovation Solution
A switching-capacitor circuit is implemented as a feedback resistor, utilizing a plurality of switching elements and capacitors to extract a division voltage from the output voltage through charge sharing, reducing the need for physical resistors and minimizing layout area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If conventional feedback resistors are used in voltage regulators, then the voltage regulation function is achieved, but the layout area occupied is large
Solution Approach 1:
The patent replaces the conventional resistor-based feedback network with a switching-capacitor circuit. The switching-capacitor circuit uses capacitors C1 and C2 along with switching elements to generate the feedback voltage through charge sharing, eliminating the need for large physical resistors while maintaining the voltage regulation function.
Solution Approach 2:
The patent changes the fundamental parameter from resistance to capacitance in the feedback network. By using capacitors with specific capacitance values (C1 and C2) and controlling their charging/discharging through switching elements, the circuit achieves the same feedback voltage division ratio that would traditionally require large resistors, thereby reducing layout area.
2Stability of the object's composition
If large feedback resistors are used for voltage regulation, then the voltage stability is maintained, but the quiescent current consumption increases
Solution Approach 1:
The switching-capacitor circuit operates periodically, with switching elements alternately charging and discharging capacitors C1 and C2. During each cycle, the capacitors share charge to maintain the feedback voltage. This periodic operation allows the circuit to achieve stable voltage regulation with significantly lower average current consumption compared to continuous current flow through large resistors.
Solution Approach 2:
The patent replaces the continuous current flow through resistors with periodic charge transfer through capacitors. The switching-capacitor circuit achieves the same voltage division and feedback function using discrete charge packets transferred during switching cycles, thereby reducing quiescent current consumption while maintaining voltage stability.
3Reliability
If conventional resistors are used in power management IC, then the voltage regulation is achieved, but the battery lifespan is reduced
Solution Approach 1:
The switching-capacitor circuit uses periodic switching to transfer charge between capacitors C1 and C2, generating the feedback voltage only when needed during each switching cycle. This periodic operation dramatically reduces the average current draw from the battery compared to continuous resistor-based feedback, thereby extending battery lifespan while maintaining reliable voltage regulation.
Solution Approach 2:
The patent substitutes the high static power consumption of resistor-based feedback with the low dynamic power consumption of switching-capacitor feedback. By using capacitors and switching elements instead of resistors, the circuit achieves the same voltage regulation reliability with much lower battery current consumption, extending operational duration.
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 switching-capacitor circuit effectively reduces the layout area required for voltage regulators, enhancing efficiency by minimizing quiescent current consumption and extending battery lifespan while maintaining stable output voltage levels.
Implementation Method 1
The first and second capacitor extracts a division voltage from the output voltage by charge sharing between the first and second capacitors to obtain the feedback voltage
Data Source
AI summary
An electronic circuit is provided. An error amplifier comprises a first input terminal coupled to a reference voltage, a second input terminal coupled to a feedback voltage, and a transistor comprises a first terminal coupled to an input voltage, a control terminal coupled to an output terminal of the error amplifier and a second terminal outputting an output voltage. A switching-capacitor circuit is coupled between the output voltage and the error amplifier and comprises a plurality of switching elements and at least first and second capacitors. The switching elements are switched by non-overlapping clocks such that the second capacitor is discharged to a bias voltage during a first period, and the first and second capacitors are connected together during a second period thereby extracting a division voltage from the output voltage to serve as the feedback voltage.