Multi-ADC Range Switching for Continuous Low-Noise Measurements
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Solution Overview
Problem
Measurement systems face glitches and errors due to changes in signal ranges, particularly when switching between different amplifier configurations, leading to transients, noise, and discontinuities in data collection, which complicates the measurement of materials' properties that vary over decades or orders of magnitude.
Innovation Solution
A measurement system with a gain chain and range selector that dynamically configures gain stages for separate ADCs, allowing seamless transitions between signal ranges by mixing outputs from multiple ADCs, maintaining one ADC online during transitions, and using shared gain stages to reduce noise and eliminate discontinuities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If amplifier configurations are switched between different signal ranges, then the measurement system can accommodate wide dynamic ranges, but glitches and discontinuities are introduced in the measured signal
Solution Approach 1:
The system dynamically adjusts the gain configuration by switching between different amplifier settings based on the input signal level. The gain configuration is changed from a static fixed value to a dynamic value that adapts to the signal range, allowing the system to maintain optimal performance across wide dynamic ranges while minimizing transition effects through controlled switching.
Solution Approach 2:
The system performs preliminary action by pre-configuring multiple gain settings and anticipating signal level changes. The measurement system prepares alternative amplifier configurations in advance and switches between them based on predicted signal ranges, allowing seamless transitions without introducing glitches or discontinuities in the measured signal.
2Measurement precision
If gain is increased to improve resolution for small signals, then noise performance improves, but ADC saturation occurs when signals become larger
Solution Approach 1:
The system uses dynamic gain adjustment where the amplifier gain is changed based on the input signal level. For small signals, high gain is applied to improve resolution and noise performance. For larger signals, the gain is reduced to prevent ADC saturation. This dynamic adaptation allows the system to maintain optimal measurement precision across the entire dynamic range.
Solution Approach 2:
The system changes the gain parameter of the amplifier based on the signal range. By adjusting the gain parameter dynamically, the system optimizes the trade-off between resolution (which requires high gain) and avoiding saturation (which requires low gain). This parameter adaptation enables the system to handle both small and large signals effectively.
3Adaptability or versatility
If amplifier stages are switched on and off to configure gain for different ranges, then flexibility in gain configuration is improved, but transients and noise are introduced during transitions
Solution Approach 1:
The system performs preliminary action by pre-warming up amplifier stages before they are needed. When a range transition is anticipated, the target amplifier configuration is activated and allowed to stabilize beforehand, preventing transients and noise during the actual measurement transition. This ensures smooth gains switching without introducing harmful artifacts in the measured signal.
Data Source
AI summary
A measurement system includes a gain chain configured to amplify an analog input signal; a range selector configured to select a gain between the analog input signal and a plurality of analog-to-digital converter (ADC) outputs from a plurality of ADCs, wherein each ADC output has a path, and a gain of each output path is made up of a plurality of gain stages in the gain chain; and a mixer configured to combine the plurality of ADC outputs into a single mixed output.