Capacitor-Switched ADC Reference Circuit for Better Linearity
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Solution Overview
Problem
Analog-to-digital converters face issues with linearity and malfunction due to resistor mismatch in voltage sources, affecting the accuracy of analog-to-digital conversion.
Innovation Solution
The proposed analog-to-digital converter employs a configuration with multiple capacitors and a switch unit controlled by logic circuits, using reference voltages to improve linearity by selectively applying voltages to capacitors based on input signal levels, thereby mitigating the impact of resistor mismatch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a voltage source with resistors is used to provide reference voltages, then the ADC can perform conversion, but linearity deteriorates due to resistor mismatch
Solution Approach 1:
Capacitors are introduced as intermediary elements between the voltage source and the conversion process. These capacitors (first capacitor connected to first input terminal, second capacitor connected to second input terminal) serve as mediators that filter and stabilize the reference voltages, reducing the impact of resistor mismatch on linearity while maintaining conversion accuracy
Solution Approach 2:
The invention changes the electrical parameters by introducing capacitive elements with specific capacitance values. The capacitance values are carefully selected to filter out high-frequency noise and stabilize the reference voltages, thereby improving linearity without sacrificing the ability to perform accurate conversions
2Measurement precision
If multiple capacitors and switches are added to improve linearity, then conversion accuracy improves, but device complexity increases
Solution Approach 1:
The circuit is segmented into distinct functional blocks: voltage source section, capacitor network section (with first and second capacitors), switch control section (with first and second switches), and conversion section. This segmentation allows each part to perform its specific function optimally while making the overall complex system more manageable and analyzable
Solution Approach 2:
The invention introduces dynamic control through switches that can selectively connect or disconnect capacitors based on the conversion requirements. The control signals dynamically adjust the circuit configuration during operation, allowing the system to adapt to different conversion scenarios while maintaining improved linearity
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 configuration enhances the linearity and prevents malfunctions during analog-to-digital conversion by utilizing capacitor matching characteristics to stabilize reference voltages, improving the overall performance of the converter.
Implementation Method 1
a first capacitor having one end or electrode connected to the first input terminal, a second capacitor having one end or electrode connected to the second input terminal
Data Source
AI summary
An analog-to-digital converter includes an analog-to-digital conversion unit configured to output first and second digital signals based on a comparison of first and second reference voltages with an input signal, an amplifier including first and second input terminals and an output terminal, a first capacitor having one end or electrode connected to the first input terminal of the amplifier, a second capacitor having one end or electrode connected to the first input terminal of the amplifier, a third capacitor having one end or electrode connected to the first input terminal of the amplifier, a switch unit configured to selectively provide a third or fourth reference voltage to at least one of the second and third capacitors based on the first and second digital signals, and a control switch between another end or electrode of the first capacitor and the output terminal of the amplifier.