Comparator Input Impedance Matching for Low-Kickback Data Converters
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Solution Overview
Problem
Conventional data converters are susceptible to kickback noises due to impedance mismatch between the negative and positive terminals of the comparator, leading to erroneous comparison results and increased harmonic distortion, especially at higher resolutions.
Innovation Solution
A data converter with a comparator, capacitor array, and a switch and impedance matching circuit that adjusts impedance by coupling capacitors to different reference voltages based on control signals, ensuring equivalent impedance matching between input terminals to minimize kickback noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If impedance matching is not performed between comparator input terminals, then the circuit structure is simple, but kickback noise affects comparison accuracy
Solution Approach 1:
The patent introduces a switch and impedance matching circuit as an intermediary component between the capacitor array and the comparator input terminals. This circuit includes switches that can connect to different reference voltages (first reference voltage or second reference voltage) to adjust the equivalent impedance at each comparator input, thereby reducing kickback noise without significantly complicating the overall data converter structure
Solution Approach 2:
The patent changes the impedance parameter dynamically by switching between different reference voltages. The switch and impedance matching circuit adjusts the equivalent impedance at the comparator input terminals by selecting different reference voltage connections, allowing impedance matching to be achieved through parameter adjustment rather than fixed circuit design
2Reliability
If kickback noise is reduced through impedance matching, then comparison accuracy improves, but the device complexity increases due to additional circuits
Solution Approach 1:
The switch and impedance matching circuit serves multiple functions: it acts as both a switching element for capacitor array control and an impedance matching element for kickback noise reduction. By integrating these functions into a single circuit block, the patent reduces overall device complexity while maintaining comparison reliability
Solution Approach 2:
The patent merges the switching function and impedance matching function into a single integrated circuit block. The same switches that control capacitor connections also perform impedance matching by selecting appropriate reference voltage connections, thereby reducing the number of separate components needed
Data Source
AI summary
A data converter and an impedance matching control method are provided. The data converter includes a comparator, a capacitor array as well as a switch and impedance matching circuit. The comparator includes a first input terminal and a second input terminal. The capacitor array includes a plurality of capacitors, and a first end of each capacitor is coupled to the first input terminal or the second input terminal. The switch and impedance matching circuit is coupled to a second end of a target capacitor among the capacitors and configured to couple the second end to a first reference voltage or a second reference voltage according to a control signal and adjust an impedance according to an impedance adjusting signal, in which the impedance is the impedance of the switch and impedance matching circuit. The first reference voltage is different from the second reference voltage.