Dual-Path Amplifier Feedback for Offset and Low-Frequency Noise
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Solution Overview
Problem
Conventional signal amplifiers face issues with voltage offset and low-frequency noise, leading to degraded signal quality and increased current consumption, particularly in MEMS applications where small space, low input capacitance, high impedance, and low noise are required.
Innovation Solution
The proposed amplifier arrangement incorporates a first and second coupling path with impedance elements and a filter device, allowing for frequency-dependent signal amplification while minimizing noise, using a buffer circuit to isolate loop signals and a voltage source to maintain a fixed voltage offset, enabling low-noise, rail-to-rail output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If capacitive decoupling is used to suppress low frequency components, then low frequency noise is suppressed, but capacitance values must be relatively large which increases cost
Solution Approach 1:
The patent changes the parameter of capacitance value by introducing a switchable capacitor that can be toggled between different states. During startup, the capacitor is connected to provide capacitive decoupling for suppressing low frequency noise. After startup, the capacitor can be disconnected to reduce its impact on noise performance and current consumption, thus resolving the contradiction between noise suppression and cost/performance optimization
2Object-affected harmful factors
If capacitive decoupling is used to suppress low frequency components, then low frequency noise is suppressed, but resistance values must be relatively large which negatively impact noise performance
Solution Approach 1:
The patent applies periodic action through a startup sequence where capacitive decoupling is temporarily activated only during the startup phase to suppress low frequency noise. After startup completion, the decoupling is deactivated, allowing the circuit to operate with lower resistance values and better noise performance for the actual signal processing task
3Power
If voltage offset and low frequency noise are amplified, then signal amplification is achieved, but signal quality is degraded and current consumption increases
Solution Approach 1:
The patent applies preliminary action by performing capacitive decoupling of low frequency noise and voltage offset before the signal amplification process. The switchable capacitor is activated during startup to remove unwanted low frequency components from the input signal, ensuring that only the desired high frequency signal components are amplified, thus preventing degradation of signal quality and reducing unnecessary current consumption
Data Source
AI summary
An amplifier arrangement has an amplifier (3) with a signal input (31), a feedback input (32) and a signal output (33). A first coupling path (FB1), which has a first impedance element (R1), connects the feedback input (32) to the signal output (33). A second coupling path (FB2) has a filter device (4), a buffer circuit (5) and a second impedance element (R2) connected in series, and connects the feedback input (32) to the signal output (33) or to the signal input (31).