Chopper Amplifier Feedback High-Pass Filter for Low-Frequency Noise
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Solution Overview
Problem
Conventional chopper amplifiers face challenges in effectively reducing input offset voltage and low frequency noise, leading to output chopping ripple and spectral integrity corruption, with existing solutions either requiring complex compensation paths or high power consumption.
Innovation Solution
Incorporating a chopper amplifier with an input chopping circuit, amplification circuit, low frequency content detection circuit, and output chopping circuit in a cascade configuration, along with a high pass filter that operates as a transconductance or gain circuit to filter input offset voltage and low frequency noise, thereby suppressing output chopping ripple.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional chopper amplifiers use complex compensation paths to reduce input offset voltage and low frequency noise, then spectral output purity is improved, but device complexity increases
Solution Approach 1:
The patent extracts and removes low frequency noise and DC offset components from the signal path using a high pass filter before the chopper amplification stage. By taking out these harmful low frequency components beforehand, the system achieves spectral output purity without requiring complex post-compensation paths, thus resolving the contradiction between measurement precision and device complexity
Solution Approach 2:
The high pass filter is placed before the chopper amplification stage to preliminarily remove low frequency noise and DC offset. This preliminary action prevents these components from entering the amplification stage, eliminating the need for complex compensation paths and reducing overall device complexity while maintaining spectral output purity
2Measurement precision
If conventional chopper amplifiers use complex compensation paths to suppress chopping ripple, then output signal quality is improved, but power consumption increases
Solution Approach 1:
The high pass filter extracts and removes low frequency noise and DC offset before chopper amplification, preventing these components from generating chopping ripple. This extraction approach improves output signal quality without requiring power-intensive complex compensation circuits, thus resolving the contradiction between measurement precision and power consumption
3Measurement precision
If conventional chopper amplifiers filter low frequency noise after amplification, then spectral output purity is improved, but chopping ripple is not effectively suppressed
Solution Approach 1:
The high pass filter performs preliminary filtering of low frequency noise and DC offset before the signal enters the chopper amplification stage. By acting beforehand, it prevents these components from being modulated by the chopper, thereby effectively suppressing chopping ripple generation at its source while improving spectral output purity
Solution Approach 2:
The high pass filter acts as an intermediary component between the input signal and the chopper amplification stage. It mediates by removing harmful low frequency components before they can interact with the chopper mechanism, thus preventing chopping ripple generation while maintaining spectral output purity
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 approach reduces or eliminates wide bandwidth low frequency noise sources and DC offset, resulting in lower flicker noise current and enhanced spectral output purity, while avoiding the need for additional transconductance circuitry and providing flexible filtering characteristics independent of chopping frequency.
Implementation Method 1
a high pass filter configured to provide high pass filtering to the amplified differential signal based on providing feedback from the differential output of the amplification circuit to the differential signal path
Data Source
AI summary
Chopper amplifiers with high pass filters for suppressing chopping ripple are provided herein. In certain embodiments, a chopper amplifier includes an input chopping circuit, an amplification circuit, a low frequency content detection circuit, and an output chopping circuit electrically connected in a cascade. The low frequency content detection circuit operates in combination with a transconductance or other gain circuit as a high pass filter that filters input offset voltage and/or low frequency noise of the amplification circuit, thereby suppressing output chopping ripple from arising.