Capacitor-Based Voltage Subtractor Circuit Design
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Solution Overview
Problem
Existing voltage subtracters face challenges in achieving accurate difference voltage calculations due to parasitic capacitance and require large circuit areas or high resistance configurations, which restrict their operational range and increase power consumption.
Innovation Solution
A voltage subtracter comprising a first and second charge storage device that store difference voltages between input voltages and a reference ground voltage, followed by a charge sharing operation to generate an output voltage, reducing the impact of parasitic capacitance without increasing circuit area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an operational amplifier is used to design a voltage subtracter, then the voltage subtraction operation can be achieved, but the circuit area increases and power consumption increases
Solution Approach 1:
The patent extracts the operational amplifier from the voltage subtracter circuit, replacing it with a direct capacitor-based charge storage and transfer mechanism. This removes the bulky op-amp component while preserving the voltage subtraction functionality through charge sharing between capacitors, thereby reducing circuit area.
Solution Approach 2:
The patent replaces the electronic amplification mechanism (operational amplifier) with a direct charge transfer and sharing mechanism using capacitors. This substitution eliminates the need for active amplification components and uses passive charge redistribution to achieve the voltage subtraction operation, reducing circuit complexity and area.
2Use of energy by moving object
If resistors with greater resistances are configured to reduce consumption currents, then power consumption decreases, but the circuit area increases
Solution Approach 1:
The patent extracts resistors from the voltage subtracter circuit entirely, replacing the resistor-based current control mechanism with a capacitor-based charge storage and transfer mechanism. This eliminates the need for high-value resistors while maintaining low power consumption through the temporary storage and controlled transfer of electrical charge.
Solution Approach 2:
The patent changes the fundamental operating parameter from resistance-based current control to capacitance-based charge storage and transfer. By using capacitors with specific capacitance values to store and transfer charge, the circuit achieves voltage subtraction without requiring high-resistance elements, thus avoiding the area penalty associated with large resistors.
3Area of stationary object
If capacitors are used in a voltage subtracter without operational amplifier, then circuit area is reduced, but the parasitic capacitance affects the difference voltage level and reduces accuracy
Solution Approach 1:
The patent applies preliminary action by performing charge storage on capacitors during a first time period before the charge sharing operation. This allows the capacitors to fully capture the input voltage differences before transfer, ensuring accurate charge representation of the voltage differences and minimizing the impact of parasitic capacitance on the final output.
Solution Approach 2:
The patent uses periodic action by dividing the operation into distinct time periods: a first time period for charge storage on the capacitors, and a second time period for charge sharing to generate the output. This temporal separation allows the capacitors to stabilize their charge before transfer, reducing the influence of parasitic capacitance and improving measurement accuracy.
4Adaptability or versatility
If operational amplifier is used, then voltage subtraction can be achieved, but the operation range is restricted by voltage operation range of the operational amplifier
Solution Approach 1:
The patent extracts the operational amplifier from the circuit, removing the component that limits the voltage operation range. The capacitor-based charge sharing mechanism has no inherent voltage range limitations imposed by device saturation or operating conditions, thereby expanding the adaptability and voltage range of the voltage subtracter.
Solution Approach 2:
The patent changes the operating principle from voltage amplification (constrained by op-amp voltage ranges) to charge transfer and sharing (constrained only by capacitor breakdown voltages). This parameter change from voltage-based operation to charge-based operation significantly expands the voltage operation range while reducing circuit complexity by eliminating the operational amplifier.
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 allows for accurate calculation of the voltage difference between input voltages while minimizing circuit area and power consumption, achieving an output voltage proportional to the voltage difference without the need for operational amplifiers or high-capacitance circuit elements.
Implementation Method 1
a first charge storage device receives a first voltage and a second voltage during a first time period and stores a first difference voltage between the first voltage and the second voltage
Implementation Method 2
a second charge storage device receives the first voltage and a reference ground voltage during the first time period and stores a second difference voltage between the first voltage and the reference ground voltage
Implementation Method 3
The first charge storage device and the second charge storage device are coupled to an output end during a second time period, such that a charge sharing operation is operated on the first charge storage device and the second charge storage device, so as to generate an output voltage on the output end
Data Source
AI summary
A voltage subtracter includes a first charge storage device and a second charge storage device. The first charge storage device receives a first voltage and a second voltage during a first time period, and storages a first difference voltage between the first voltage and the second voltage. The second charge storage device receives a reference ground voltage and the first voltage during a second time period, and storages a second difference voltage between the reference ground voltage and the first voltage. The first charge storage device and the second charge storage device are coupled to an output end during a second time period, and a charge sharing operation is operatedon the first charge storage device and the second charge storage device to generate an output voltage on the output end.