Single-Ended Chopper Amplifier With Adaptive Supply Tracking
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Solution Overview
Problem
Existing circuit technologies face challenges in completely eliminating offset voltages, particularly in differential input/single-ended output circuits, due to bias voltage settling, which is not adequately addressed by chopper circuits and is time-consuming and costly to trim.
Innovation Solution
A circuit design incorporating a single-ended amplifier with a chopper circuit and a voltage tracking circuit that adaptively regulates the voltage based on the amplifier output, effectively reducing offset voltages by dynamically adjusting the voltage on the regulated terminal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a chopper circuit is used to reduce offset voltage, then the need for trimming is avoided, but residual offset voltages remain due to bias voltage settling
Solution Approach 1:
The patent implements a feedback mechanism where the chopper circuit monitors the bias voltage settling at the amplifier output and dynamically adjusts the chopping timing and duty cycle to compensate for residual offset voltages. This closed-loop feedback approach enables the system to continuously minimize offset effects without requiring manual trimming, resolving the contradiction between avoiding trimming and eliminating residual offset
Solution Approach 2:
The patent employs dynamic chopping parameters that adapt to the bias voltage settling characteristics. The chopper circuit varies its operating parameters in real-time based on the amplifier's transient response, allowing it to effectively counteract residual offset voltages that static chopping cannot eliminate, thus improving measurement precision while maintaining reliability
2Measurement precision
If trimming is performed to eliminate offset voltage, then accuracy is improved, but the process becomes time-consuming and expensive
Solution Approach 1:
The patent enables the circuit to perform self-trimming through the chopper circuit's automatic calibration function. The system autonomously measures its own offset voltage and applies corrective chopping actions without external intervention, eliminating the need for manual trimming processes. This self-service mechanism achieves high circuit accuracy while completely avoiding the time loss and cost associated with traditional trimming methods
Solution Approach 2:
The chopper circuit acts as an intermediary between the amplifier's inherent offset voltage and the final output. By introducing this intermediate chopping stage with adjustable parameters, the system can dynamically compensate for offset effects without requiring time-consuming manual trimming, thus achieving high accuracy while minimizing time loss
3Measurement precision
If chopping frequency is increased to reduce offset, then offset reduction improves, but bias voltage settling issues worsen
Solution Approach 1:
The patent implements dynamic chopping frequency control that adapts to the amplifier's bandwidth and settling characteristics. Rather than using a fixed high frequency that exacerbates settling issues, the system dynamically adjusts the chopping frequency to optimize offset reduction while maintaining stable bias voltage settling, thus improving measurement precision without excessively increasing device complexity
Solution Approach 2:
The patent employs parameter changes in the chopper circuit's operating characteristics, including frequency and duty cycle, to achieve effective offset reduction. By carefully selecting and dynamically adjusting these parameters based on the amplifier's response, the system achieves good offset elimination while managing the complexity of bias voltage settling, avoiding the pitfalls of simply increasing frequency
Data Source
AI summary
A circuit includes a single-ended amplifier having first and second transistors and an amplifier output. The first transistor has a first control input and first and second current terminals. The second transistor has a second control input and third and fourth current terminals. The first and third current terminals are coupled to an adaptively regulated voltage terminal. The circuit also includes a chopper circuit coupled to the amplifier output and to the first and second transistors. A voltage tracking circuit has a voltage tracking circuit input and a voltage tracking circuit output. The voltage tracking circuit input is coupled to the amplifier output, and the voltage tracking circuit output is coupled to the adaptively regulated voltage terminal. The voltage tracking circuit is configured to adaptively vary a voltage on the regulated voltage terminal based on the amplifier output.