Time-of-flight mass spectrometer dynamic range control
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Solution Overview
Problem
Current 8-bit digitizers in time-of-flight mass analyzers have limited dynamic range, leading to inaccurate recording of low-level signals as noise and high-level signals being clipped, and increasing data volume when using two digitizers simultaneously, which overwhelms processing systems.
Innovation Solution
A system utilizing two 8-bit analog-to-digital converters with different voltage ranges, operating in overlapping time windows to extend the dynamic range without reducing resolution, allowing for accurate digitization of a wide range of signal amplitudes and reducing data processing burdens.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the dynamic range of the 8-bit ADC is extended to accept higher analog signals, then the ability to record high-level signals is improved, but the resolution deteriorates because of the increased coarseness of each conversion step
Solution Approach 1:
The patent divides the dynamic range coverage into multiple segments by using two 8-bit ADCs with different voltage ranges. The first ADC handles lower voltage signals with fine resolution, while the second ADC handles higher voltage signals. This segmentation allows each ADC to operate within its optimal range, maintaining high resolution while extending the overall dynamic range capability.
Solution Approach 2:
The patent adds a temporal dimension to the data acquisition system by implementing time-multiplexed operation of two ADCs with overlapping time windows. Instead of using a single ADC with compromised resolution across the entire range, the system uses multiple ADCs operating at different times, combining their outputs to achieve extended dynamic range without sacrificing resolution in either range.
2Adaptability or versatility
If two digitizers are used simultaneously to increase dynamic range, then the ability to capture a wider range of signal amplitudes is improved, but the data volume increases and overwhelms the processing system
Solution Approach 1:
The patent implements partial action by having the two ADCs operate with overlapping time windows rather than continuously simultaneously. The first ADC operates during a first time window and the second ADC operates during a second time window that overlaps with the first. This partial temporal overlap allows the system to capture the full dynamic range while reducing the total data volume compared to continuous dual-ADC operation, as each ADC is active only during its designated time window.
3Measurement precision
If a digitizer with higher resolution capabilities beyond one byte is used, then the resolution is improved, but the sampling rate is limited to less than 1 GHz operation and/or the cost and power requirements increase
Solution Approach 1:
The patent segments the resolution requirement by using two 8-bit ADCs instead of one higher-resolution ADC. Each 8-bit ADC operates at full sampling rate (≥1 GHz) within its designated voltage range, achieving the necessary effective resolution through the combination of two segmented ranges rather than requiring a single high-resolution converter that would compromise sampling rate.
Solution Approach 2:
The patent uses multiple lower-cost, lower-resolution ADCs (8-bit) that can operate at high sampling rates, rather than investing in expensive high-resolution ADCs that are limited to lower sampling rates. This approach trades the use of expensive, high-resolution, low-speed components for multiple inexpensive, moderate-resolution, high-speed components, achieving the same effective performance at lower cost and power consumption.
Data Source
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AI summary
A mass spectrometer of the type useful in mass cytometry includes an ion detector. A digitizing system for converting analog signals from the ion detector includes two analog-to-digital converters. The analog-to-digital converters are configured to provide an increased dynamic range for a targeted period while limiting the amount of data generated.