Charge Pump Feedback Loop for Linear Voltage Control
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Solution Overview
Problem
Charge pumps in integrated circuits face challenges in providing a linear and predictable output voltage, as the output voltage is not linear with respect to time and is influenced by capacitance increments, leading to inefficiencies at higher frequencies due to second and third-order effects.
Innovation Solution
A charge pump design that includes programmable elements to control charge transfer, allowing for more predictable and consistent output voltage by switching between charge transfer reducing and enhancing modes, using multiple pump cells with configurable capacitances to achieve a linear increase in output voltage based on user selection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If capacitance is reduced and clock frequency is increased to smooth voltage increments, then output voltage linearity is improved, but efficiency deteriorates due to second and third order effects becoming significant
Solution Approach 1:
The patent introduces a feedback mechanism where a feedback capacitor captures excess charge from the output node and transfers it back to the input node. This feedback loop prevents voltage overshoot and eliminates the need for high-frequency operation, maintaining efficiency while achieving smooth voltage transitions. The feedback capacitor effectively counteracts the non-linear effects by redistributing charge in a controlled manner.
Solution Approach 2:
The patent changes the operational parameters by using a feedback capacitor with a specific capacitance value that is optimized to match the output capacitance. This parameter matching ensures that the feedback mechanism effectively compensates for charge variations without requiring high clock frequencies, thus maintaining efficiency while achieving linear voltage output.
2Adaptability or versatility
If multiple pump cells are used to provide selectable output voltages, then adaptability is improved, but output voltage predictability deteriorates due to non-linear increments
Solution Approach 1:
The feedback capacitor creates a linear relationship between the number of active pump cells and the output voltage. Each pump cell contributes a predictable amount of charge to the feedback capacitor, which in turn provides a proportional amount of charge back to the input. This feedback mechanism ensures that output voltage increments are linear and predictable, regardless of how many pump cells are activated.
Solution Approach 2:
The patent segments the charge transfer function into discrete, controllable units through the use of multiple pump cells, each with its own switch. The feedback capacitor integrates these segmented charge transfers in a linear manner, allowing selective activation of pump cells to achieve precise, predictable voltage levels while maintaining adaptability.
3Power
If charge transfer is increased to improve output voltage magnitude, then power is improved, but output voltage control deteriorates due to non-linear charge accumulation
Solution Approach 1:
The feedback capacitor provides a self-regulating mechanism that automatically adjusts charge transfer. As the output voltage increases, the feedback capacitor captures proportionally more excess charge and returns it to the input, creating a natural equilibrium. This feedback loop enables high power output while maintaining precise voltage control through the linear relationship between feedback charge and input charge.
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 provides a more predictable and consistent output voltage range, allowing for selectable output voltages that are linearly proportional to the input voltage, improving efficiency and reducing inefficiencies at higher frequencies.
Implementation Method 1
a first capacitor having a first terminal and a second terminal. The charge pump further includes a first switch coupled to the first terminal of the first capacitor for coupling the first terminal to either an input terminal for receiving an input voltage or to an output node
Implementation Method 2
a second capacitor having a first terminal and a second terminal, the second terminal being coupled to the reference voltage terminal. The charge pump further includes a third switch coupled to the first terminal of the second capacitor for selectively coupling the first terminal of the second capacitor to either the first terminal of the output capacitance or the input terminal, the second capacitor selectively removing charge from the output capacitance using the third switch and coupling said charge to the input terminal
Data Source
AI summary
A charge pump charges a first capacitor to a predetermined input voltage using a first switch. The first switch is coupled to a first terminal of the first capacitor for coupling the first terminal to an input terminal that receives the predetermined input voltage. A second switch couples a second terminal of the first capacitor to a reference voltage terminal. Charge is sequentially transferred from the first capacitor to an output capacitance by using the first switch. A portion of charge is sequentially removed from the output capacitance to the input terminal using a third switch and a second capacitor. Configuration logic provides control signals to make one or more of a plurality of charge transfer capacitors switch the same as said first capacitor switches.