Quadrupole RF Amplitude Digital Control for Faster Mass Spectrometry
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Solution Overview
Problem
Mass spectrometers face performance limitations due to the slow response time and increased costs associated with analog feedback circuitry used to control the amplitude of radio frequency (RF) signals in mass analyzers, leading to discrepancies between actual and expected RF signal amplitudes.
Innovation Solution
A digital control system that includes an analog-to-digital converter (ADC) and a controller circuit to determine the actual amplitude of the RF signal, adjust the amplifier input signal based on current and historical environmental and performance parameters, and correct the amplitude to match the expected value, reducing the need for complex analog feedback circuitry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If analog feedback circuitry is used to control RF signal amplitude, then the system can maintain expected amplitude accuracy, but the response time becomes slow and device complexity increases
Solution Approach 1:
The patent replaces the analog feedback circuitry with a digital control system that uses an analog-to-digital converter (ADC) to sample the RF signal amplitude and a digital processor to calculate correction factors. This substitution of digital electronics for analog circuitry enables faster processing and response times while maintaining amplitude accuracy through computational algorithms that consider environmental parameters and historical data.
2Measurement precision
If analog feedback circuitry is used to control RF signal amplitude, then the system can maintain expected amplitude accuracy, but the device complexity and cost increase
Solution Approach 1:
The patent replaces complex analog feedback circuitry with a digital control system comprising an ADC, digital processor, and software algorithms. This substitution reduces hardware complexity by eliminating analog components such as voltage-controlled oscillators, mixers, and analog filters, while achieving the same amplitude control function through digital signal processing and computational methods.
Solution Approach 2:
The digital control system incorporates self-calibration capabilities by automatically determining correction factors based on environmental parameter sensors (temperature, humidity, pressure) and historical performance data. The system performs self-diagnosis and adjusts RF signal amplitude without requiring external calibration equipment or manual intervention, reducing operational complexity and maintaining accuracy autonomously.
3Reliability
If analog feedback circuitry is used, then the system structure is established, but the throughput and performance of the mass spectrometer are reduced
Solution Approach 1:
The patent replaces slow analog feedback circuitry with a digital control system that processes amplitude measurements and calculates corrections at much higher speeds. The ADC samples the RF signal amplitude rapidly, and the digital processor computes correction factors using pre-stored lookup tables and environmental parameter data, enabling real-time adjustments that maintain system stability while significantly increasing mass spectrometer throughput by reducing the time required for each measurement cycle.
Data Source
AI summary
Control of an amplitude of a signal applied to rods of a quadrupole is described. In one aspect, a mass spectrometer includes an amplifier circuit that causes a radio frequency (RF) signal to be applied to the rods of the quadrupole. A controller circuit can determine that the actual amplitude of the RF signal differs than the expected amplitude and, in response, identify current and past environmental and performance parameters to adjust the amplitude.