Multi-Path Chopper Amplifier for Chopper Ripple Attenuation
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Solution Overview
Problem
Chopper amplifiers produce chopper ripple at the chopping frequency, which significantly limits system dynamic range and existing methods like synchronous switched capacitor notch filters or feedback loops provide insufficient attenuation.
Innovation Solution
The implementation of a multi-gain stage chopper amplifier circuit with multiple bypass amplification paths, including a low frequency, intermediate frequency, and high frequency amplifier path, where the chopping frequency is set such that the high frequency path provides higher gain than the intermediate and low frequency paths, allowing for enhanced attenuation of chopper ripple.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional chopper amplifier circuits are used, then offset voltage is reduced through chopping techniques, but chopper ripple is introduced at the chopping frequency which limits system dynamic range
Solution Approach 1:
The amplifier circuit is divided into multiple parallel paths (first amplifier path with chopper circuitry, second amplifier path as feedforward path, and third amplifier path bypassing portions of other paths). Each path processes different frequency components of the signal, with the chopper ripple being attenuated by the multi-gain stage configuration in the first path while the feedforward paths preserve high-frequency signal components.
Solution Approach 2:
Different gain stages are configured with specific gain values tailored to different frequency ranges. The multi-gain stage architecture applies different attenuation characteristics to different frequency components, with higher attenuation at the chopping frequency and preserved gain at signal frequencies, achieving frequency-selective ripple reduction.
2Object-affected harmful factors
If synchronous switched capacitor notch filters or feedback loops are used to attenuate chopper ripple, then some ripple reduction is achieved, but the attenuation is insufficient and system dynamic range remains limited
Solution Approach 1:
The circuit employs feedback loops in the amplifier paths that enable the system to respond to and compensate for chopper ripple. The feedback mechanism allows the amplifier to maintain stability while achieving superior ripple attenuation through the coordinated action of multiple feedback paths with different gain characteristics.
Solution Approach 2:
The invention changes the gain parameters across multiple stages and paths to achieve frequency-selective attenuation. By configuring different gain values in the multi-gain stage architecture, the system achieves maximum attenuation at the chopping frequency while preserving signal frequencies, thereby expanding dynamic range.
3Object-affected harmful factors
If multiple gain stages are used to attenuate chopper ripple, then ripple reduction is improved, but circuit complexity increases
Solution Approach 1:
The multiple gain stages and amplifier paths serve dual functions: they provide the necessary signal amplification while simultaneously achieving chopper ripple attenuation. The feedforward paths and bypass paths contribute to both signal transmission and ripple rejection, reducing the need for separate dedicated ripple filtering components.
Data Source
AI summary
A chopper amplifier circuit includes a first amplifier path, a second amplifier path, and a third amplifier path. The first amplifier path includes chopper circuitry configured to modulate an input signal and an offset voltage at a chopping frequency, and ripple reduction circuitry configured to attenuate the chopping frequency in a signal in the first amplifier path. The second amplifier path includes a feedforward gain stage, and is configured to apply higher gain to intermediate signal frequencies than is applied in the first amplifier path. The third amplifier path includes a feedforward gain stage, and is configured to apply higher gain to high signal frequencies than is applied in the first amplifier path and the second amplifier path. The intermediate signal frequencies are lower than the high signal frequencies.