Differential ADC Noise Compensation Using Input Buffer Feedback
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Solution Overview
Problem
Analog-to-digital converters face noise issues due to circuit non-linearity and harmonic signals when converting single-ended analog inputs to differential signals, affecting the accuracy of digital representation.
Innovation Solution
An analog-to-digital converter design that includes an input buffer generating noise compensation signals, which are used by the analog-to-digital conversion module to eliminate noise through a comparator, specifically utilizing operational amplifiers and virtual ground terminals to separate signal and noise portions in differential signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an input buffer is used for signal inversion in differential architecture, then the single-ended analog input can be converted to differential signals, but noise problems occur due to circuit non-linearity and harmonic signals
Solution Approach 1:
The patent segments the noise compensation function into separate circuits: a first noise compensation circuit processes the positive differential signal while a second noise compensation circuit processes the negative differential signal. This segmentation allows independent noise handling for each signal path, effectively addressing the noise introduced by the input buffer during differential conversion.
Solution Approach 2:
The patent implements feedback mechanisms where noise compensation signals are generated based on the actual noise present in the differential signals. The compensation circuits receive feedback from the differential signals and adjust their compensation output accordingly, creating a closed-loop system that continuously reduces noise throughout the conversion process.
2Measurement precision
If noise compensation signals are extracted from virtual ground terminals, then noise information can be obtained for compensation, but the circuit complexity increases
Solution Approach 1:
The virtual ground terminals in the input buffer automatically generate noise compensation signals that reflect the actual noise conditions. The circuit serves itself by using its own internal noise characteristics (captured at virtual ground terminals) to compensate for the noise it introduces, eliminating the need for external noise sensing circuits and reducing overall system complexity.
Solution Approach 2:
The virtual ground terminals serve dual functions: they maintain the operational stability of the input buffer while simultaneously providing noise compensation signals. This multi-functionality allows the same circuit nodes to perform both their primary buffering role and the secondary noise sensing role, avoiding additional dedicated noise sensing circuitry.
Data Source
AI summary
An analog-to-digital converter with noise elimination is disclosed. The analog-to-digital converter converts a single-ended analog input into digital representation, and comprises an input buffer and an analog-to-digital conversion module. The input buffer outputs a positive differential signal and a negative differential signal based on the single-ended analog input. The analog-to-digital conversion module receives the positive differential signal and the negative differential signal to generate the digital representation. The input buffer further transmits a noise compensation signal to the analog-to-digital conversion module. The noise compensation signal contains noise information about noise transmitted from the input buffer to the analog-to-digital conversion module through the positive differential signal and the negative differential signal. The analog-to-digital conversion module uses the noise compensation signal to compensate for the noise transmitted from the input buffer to the analog-to-digital conversion module through the positive differential signal and the negative differential signal.