Digital Offset Removal in ADC Data Streams Using IIR Filtering
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Solution Overview
Problem
Electrical circuits face accuracy issues due to low frequency offsets introduced by components and signal sources, leading to energy waste and inaccurate measurements if not accounted for.
Innovation Solution
A method involving the use of analog-to-digital converters (ADCs) and filters, such as low pass IIR and FIR filters, implemented in DSPs and FPGAs, to detect and remove low frequency offset components from digital data streams, generating a corrected signal by subtracting filtered outputs from the original data stream.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional calibration methods are used to account for offsets, then initial measurement accuracy can be improved, but the system cannot account for drift or aging effects over time
Solution Approach 1:
The patent implements continuous offset removal by constantly monitoring the digital data stream and subtracting detected offset components in real-time, rather than performing a one-time calibration. This continuous action ensures measurement accuracy is maintained throughout the system's operational life, accounting for drift and aging effects that occur over time.
Solution Approach 2:
The system performs self-correction by automatically detecting and removing its own offset components without requiring external calibration inputs. The offset removal circuitry continuously analyzes the digital data stream, identifies offset components, and subtracts them autonomously, enabling the system to maintain accuracy through self-service rather than relying on periodic external calibration procedures.
2Measurement precision
If offset removal circuitry is added to continuously remove offsets, then long-term measurement accuracy is improved, but device complexity increases
Solution Approach 1:
The patent merges the offset removal functionality with the existing ADC and signal processing pipeline. The offset removal circuitry is integrated into the data flow path, combining multiple functions (signal acquisition, conversion, and offset correction) into a unified system rather than adding completely separate calibration equipment, thereby reducing overall complexity.
Solution Approach 2:
The patent introduces an intermediary offset removal circuit that processes the digital data stream between the ADC and the measurement output. This intermediary component handles the offset correction task specifically, allowing the rest of the system to remain unchanged while adding only the necessary complexity for offset removal, rather than redesigning the entire measurement system.
3Measurement precision
If real-time offset removal is implemented, then measurement accuracy over time is improved, but computational requirements and processing time increase
Solution Approach 1:
The system performs preliminary filtering of the digital data stream to isolate offset components before the subtraction operation. By pre-processing the signal to identify and separate offset frequencies, the system simplifies the subsequent correction step and enables real-time operation without requiring complex computational algorithms during the critical measurement phase.
Data Source
AI summary
A method for removing low frequency offset components from a digital data stream includes receiving, at an input of an analog-to-digital converter (ADC), an analog input signal from one or more analog front end components. The analog input signal has an associated low frequency offset due, at least in part, to the analog front end components. The method also includes generating, at an output of the ADC, a digital data stream representative of the analog input signal. The digital data stream having an associated low frequency offset due, at least in part, to the analog front end components and/or the ADC. One or more low pass infinite impulse response (IIR) filters are applied to the digital data stream to detect the low frequency offset components in the digital data stream, and generate a filtered output signal with only the low frequency offset components present. A corrected digital data stream without the low frequency offset components is generated in response thereto, for example, by taking the difference of the filtered output signal from the digital data stream.