Chopper Amplifier Offset Calibration for Flicker Noise Suppression
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Solution Overview
Problem
Analog signal processing systems introduce noise and offset as audio signals pass through amplifiers, degrading signal quality, and existing methods like modulation-demodulation techniques often result in residual ripple and thermal noise, which affect audio quality and resolution.
Innovation Solution
The implementation of a system with modulation and demodulation circuits to separate audio signals from flicker noise and offset, combined with an offset calibration circuit that generates compensation signals to adjust the amplification circuit and mitigate residual ripple and offset drift.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If modulation-demodulation techniques are used to separate signal from noise and offset, then signal quality is improved, but residual ripple and thermal noise are introduced
Solution Approach 1:
The patent extracts and removes the harmful residual ripple and thermal noise components from the amplified signal using a calibration circuit that identifies and eliminates these specific artifacts introduced by the modulation-demodulation process
Solution Approach 2:
The patent implements a feedback mechanism where the output of the amplification circuit is fed back to the calibration circuit, which continuously monitors and adjusts compensation signals to eliminate residual ripple and thermal noise while preserving the benefits of modulation-demodulation
2Power
If amplifier gain is increased to amplify audio signals, then signal strength is improved, but noise and offset are also amplified
Solution Approach 1:
The patent segments the amplification process into distinct stages: modulation, amplification, and demodulation, with separate calibration circuits for each stage. This allows selective compensation of noise and offset at each segment rather than treating the entire chain as a single unit
Solution Approach 2:
The patent introduces modulation and demodulation as intermediary processes between the input signal and the final output. These intermediaries transfer the signal to a different domain (frequency-shifted) where amplification occurs, then convert back, effectively isolating the signal from direct coupling with amplifier noise and offset
3Area of stationary object
If device size is reduced to improve integration, then manufacturing efficiency is improved, but noise mitigation capability is worsened
Solution Approach 1:
The patent merges multiple functions into integrated circuits: the modulation circuit, amplification circuit, demodulation circuit, and calibration circuit are combined into a single integrated system. This consolidation maintains noise mitigation capabilities while achieving compact form factor suitable for modern audio devices
Data Source
AI summary
A system includes an amplification circuit and offset calibration circuit. The amplification circuit includes a modulation circuit operable to modulate a received signal, an amplifier operable to amplify the modulated signal, and a modulation circuit operable to demodulate the amplified signal. The offset calibration circuit includes a logic circuit operable to set a control signal and adjust the control signal based on an output of the amplification circuit, where the output is based on the demodulated signal, and a compensation signal generator operable to generate a compensation signal based on the control signal to compensate for an offset associated with the amplification circuit, and apply the compensation signal on the amplification circuit to adjust the output of the amplification circuit. The offset calibration circuit in conjunction with the application circuit reduces flicker, offset, and offset drift, and also suppresses the upmodulate ripple due to chopping.