Distributed Dynamic Chopping in Differential Amplifiers for DC Offset
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Solution Overview
Problem
Differential amplifier circuits introduce DC offsets due to transistor mismatches, which contribute to errors in operational amplifiers alongside 1/f noise and drift.
Innovation Solution
The implementation of chopper circuits at input and output ports of the amplifier circuit, with control signals selectively connecting transistors to different terminals, effectively reduces the offset by alternating the connection of transistors to amplify differential signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If differential amplifier circuits are used to amplify signals, then signal amplification is achieved, but DC offset is introduced due to transistor mismatches
Solution Approach 1:
The patent applies periodic action by using chopper circuits that periodically switch the connections of transistors to different terminals. The chopper circuits alternate between connecting transistors to first terminals and second terminals at different time periods, which modulates the DC offset to higher frequencies where it can be filtered out, thereby reducing the impact of transistor mismatches on output accuracy while maintaining signal amplification
Solution Approach 2:
The patent implements dynamics by making the transistor connections dynamic rather than static. The chopper circuits dynamically reconfigure which transistors are connected to which terminals based on control signals, allowing the system to adapt and cancel out mismatch effects over time. This dynamic switching enables the amplifier to maintain high output accuracy despite inherent transistor variations
2Measurement precision
If chopper circuits are added to reduce DC offset, then output accuracy is improved, but device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the amplifier circuit into multiple independent amplifier units, each with its own chopper circuits. Instead of using a single complex chopper system for the entire amplifier, the patent segments the functionality across multiple simpler units, where each unit handles a portion of the signal processing. This segmentation reduces the complexity of individual chopper circuits while collectively achieving the desired offset reduction across the full amplifier system
Data Source
AI summary
Embodiments relate to an amplifier circuit. The amplifier circuit includes multiple transistors. Each transistor is configured to receive an input signal and output an amplified signal. The amplifier circuit additionally includes a set of input chopper circuits and a set of output chopper circuits. Each output chopper circuit corresponds to one input chopper of the set of input choppers. Each input chopper circuit and its corresponding output chopper are controlled by one or more control signals from a set of control signals. Each input chopper circuit is configured to selectively connect each transistor of a transistor pair to a first input terminal or a second input terminal based on a value of the one or more control signals. Moreover, each output chopper circuit is configured to selectively connect each transistor of the transistor pair to a first output terminal or a second output terminal based on the value of the one or more control signals.