Current Sensing Circuit With Noise-Aware ADC Sampling
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Solution Overview
Problem
Current detection circuits are prone to errors due to high-frequency noise, such as switching noise, which is superimposed on the current detection signal, leading to inaccurate current detection values.
Innovation Solution
A current detection circuit that includes a filter circuit to extract high-frequency noise and a comparing unit to generate a comparison signal indicating noise detection timing, allowing the arithmetic circuit to delay the sampling timing of the amplified signal, thereby avoiding noise detection timing and reducing the influence of high-frequency noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If sampling is performed at a predetermined cycle, then continuous current detection is achieved, but high-frequency noise is superimposed on the detection signal causing measurement errors
Solution Approach 1:
The filter circuit performs preliminary noise component extraction from the amplified signal before sampling. By identifying noise detection timing in advance using the filter circuit and comparing unit, the system can adjust sampling timing to avoid noise periods, thus preventing noise superposition on current detection values
Solution Approach 2:
The sampling timing is made dynamic and adjustable based on noise conditions. The arithmetic circuit delays sampling timing by a predetermined time when noise is detected, allowing the system to adapt sampling moments to avoid high-frequency noise while maintaining continuous detection capability
2Measurement precision
If low-pass filters are used to remove high-frequency noise, then measurement precision is improved, but signal delay occurs reducing detection responsiveness
Solution Approach 1:
Instead of using low-pass filters to remove noise components, the filter circuit extracts only the noise component from the amplified signal. The comparing unit then identifies noise detection timing based on this extracted noise, allowing the main signal path to remain unaffected and avoid delays
Solution Approach 2:
The filter circuit acts as an intermediary that processes a copy of the amplified signal to identify noise timing, without interfering with the main signal path. This mediator approach allows noise detection and sampling timing adjustment without introducing signal delay to the current detection path
Data Source
AI summary
A current detection circuit, including: an output circuit to output a signal indicating a voltage drop between a pair of detection terminals; an amplifier circuit to amplify the signal from the output circuit; an AD conversion circuit to generate a digital signal by sampling, at a predetermined cycle, an amplified signal amplified by the amplifier circuit; a filter circuit configured to extract, from the amplified signal amplified by the amplifier circuit, a noise component having a frequency higher than a sampling frequency of the AD conversion circuit; a comparing unit to output a comparison signal indicating a noise detection timing at which an output signal of the filter circuit exceeds a predetermined reference value for detecting the noise component; and an arithmetic circuit to delay a timing at which the amplified signal is sampled by the AD conversion circuit for a predetermined time based on the comparison signal.