Differential Signal Processing Circuit With Pre-Stage Noise Filtering
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Solution Overview
Problem
Existing signal processing circuits for analog-to-digital conversion have poor noise removal capabilities, particularly in increasing input range and resolution, due to limitations in differential amplifier configurations.
Innovation Solution
The proposed signal processing circuit employs a differential output amplifier with low-pass filters and feedback connections to effectively remove high-frequency and common-mode noise, enhancing noise resistance and resolution by using resistive and capacitative elements to form low-pass filters and ensuring balanced signal processing between pre-stage circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a differential amplifier configuration is used for AD conversion, then the circuit can process differential input signals, but the noise removing effect is poor and cannot increase input range and resolution
Solution Approach 1:
The circuit is divided into separate pre-stage circuits for each input terminal, with independent low-pass filters before the differential amplifier. This segmentation allows each input channel to be optimized independently for noise filtering while maintaining differential signaling benefits.
Solution Approach 2:
Low-pass filters are placed in the pre-stage circuits before the differential amplifier to preliminarily remove high-frequency noise from input signals. This preliminary noise removal action prevents noise from being amplified along with the signal, improving the overall signal-to-noise ratio and resolution.
2Object-affected harmful factors
If low-pass filters are added to remove high-frequency noise, then noise removal capability improves, but circuit complexity increases
Solution Approach 1:
The low-pass filter circuits are merged with the pre-stage circuits of the differential amplifier, sharing common structural elements and signal paths. This integration approach adds noise filtering functionality while minimizing the increase in overall circuit complexity by reusing existing circuit components and topologies.
3Measurement precision
If pre-stage circuits are added to each input terminal with low-pass filters, then noise removal and resolution improve, but the number of circuit elements increases
Solution Approach 1:
Low-pass filter circuits are selectively added only to the pre-stage circuits of the differential amplifier input terminals where noise filtering is most needed, rather than uniformly across the entire circuit. This local quality approach optimizes noise removal at critical points while minimizing the total number of added circuit elements.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration significantly increases the input range and resolution of the analog-to-digital conversion process, providing an excellent noise removal function and improved dynamic range.
Implementation Method 1
the first resistive element and the first capacitative element form a low-pass filter
Implementation Method 2
it is possible to remove common-mode noise of a differential input signal with the differential output amplifier
Data Source
Figure 1
Figure 2a~2c
Figure 3
AI summary
A signal processing circuit (5) with high noise resistance is realized. The signal processing circuit (5) includes: a first pre-stage circuit (10) that includes a first input terminal (i1); and a second pre-stage circuit (20) that includes a second input terminal (i2). A resistive element (R1) with one end connected to the first input terminal (i1) and a capacitative element (C1) with one electrode connected to the ground are provided in the first pre-stage circuit (10). The other end of the first resistive element (R1) and the other electrode of the first capacitative element (C1) are connected to each other. An output node (K1) of the first pre-stage circuit (10) and an output node (K2) of the second pre-stage circuit (10) are connected to a post-stage circuit (30).