ADC Data Stream Offset Removal Using Low-Pass FIR Filtering
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Solution Overview
Problem
Electrical circuits face accuracy issues due to low frequency offset components introduced by components and signal sources, leading to energy waste and inaccurate measurements if not accounted for.
Innovation Solution
A method involving an analog-to-digital converter (ADC) and low pass finite impulse response (FIR) filters, specifically cascaded integrated comb (CIC) decimation filters, to detect and remove low frequency offset components from digital data streams, generating a corrected stream without these offsets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If low frequency offset components are not removed from the digital data stream, then the circuit operates without additional processing, but measurement accuracy deteriorates and energy is wasted
Solution Approach 1:
The patent extracts and removes low frequency offset components from the digital data stream using a low pass FIR filter. The filter isolates the unwanted offset components, which are then subtracted from the original signal to produce a corrected data stream free from these interfering components, thereby improving measurement accuracy and preventing energy waste from incorrect measurements
Solution Approach 2:
The system continuously monitors the digital data stream for low frequency offset components and dynamically adjusts by subtracting the filtered offset signal from the original signal. This closed-loop approach ensures ongoing correction of offset errors, maintaining measurement accuracy and preventing cumulative energy waste
2Measurement precision
If calibration is performed to remove offset components, then measurement accuracy improves, but the system requires calibration procedures and additional complexity
Solution Approach 1:
The system performs self-correction by automatically detecting and removing low frequency offset components through the low pass FIR filter and subtraction circuitry. The offset removal process is autonomous and does not require external calibration procedures, manual adjustments, or additional calibration equipment, thereby improving measurement accuracy without increasing operational complexity
Solution Approach 2:
The low pass FIR filter is pre-configured with appropriate cutoff frequencies and filter coefficients to automatically identify and isolate low frequency offset components before they corrupt the measurement data. This preliminary filtering action occurs continuously in the signal processing chain, eliminating the need for separate calibration steps
3Measurement precision
If complex filtering methods are used to remove offset components, then offset removal accuracy improves, but computational complexity and processing time increase
Solution Approach 1:
The patent applies a low pass FIR filter that targets only the specific frequency range of low frequency offset components, rather than using a more complex all-encompassing filtering approach. This partial action focuses computational resources on removing only the problematic offset frequencies while preserving the rest of the signal spectrum, achieving sufficient offset removal accuracy without excessive processing overhead
Solution Approach 2:
The signal processing is segmented into distinct stages: first, the low pass FIR filter extracts low frequency offset components; second, a subtraction circuit removes these components from the original digital data stream. This segmentation allows each stage to be optimized independently, with the filter focusing on offset detection and the subtraction circuit handling removal, improving overall processing efficiency while maintaining accuracy
4Measurement precision
If continuous offset removal is performed on every sample, then measurement accuracy is maintained, but computational energy consumption increases
Solution Approach 1:
The low pass FIR filter operates continuously on the incoming digital data stream, maintaining a running estimate of low frequency offset components. This continuous operation ensures that offset removal is applied to every sample without interruption, preserving measurement accuracy throughout the entire measurement period while using efficient filter algorithms to minimize computational energy consumption
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 the ADC. One or more low pass finite impulse response (FIR) 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.