Noise suppression device with adjustable parameters applicable to digital ion trap mass spectrometers

Abstract

The present invention provides a noise suppression device with adjustable parameters applicable to a digital ion trap mass spectrometer and the digital ion trap mass spectrometer. The device includes receiving parameters from a host computer through a signal analysis circuit via a host computer communication circuit, analyzing the output signal of the secondary amplification circuit according to the parameters, generating a signal with the same frequency and opposite phase in part of the frequency band of the output signal of the secondary amplification circuit, inputting the generated signal into a signal coupling circuit, and transmitting the obtained coupling signal as an output signal to a mass spectrometer signal acquisition circuit. The present invention effectively improves the signal-to-noise ratio of the original signal before software processing of the mass spectrometer, can configure algorithm parameters according to the host computer, flexibly modify the filtering algorithm in the device, does not need to transmit data to the host computer for processing, and has an extremely fast response to signal changes.

Description

Technical Field

[0001] The present invention relates to the field of mass spectrometry analysis, and specifically, to a noise suppression device with adjustable parameters applicable to a digital ion trap mass spectrometer and the digital ion trap mass spectrometer. Background Art

[0002] Patent document CN104051218A discloses a method for processing a detector signal adjustable by a user of a mass spectrometer, including setting a threshold for a pre-stage signal that has been initially amplified by a pre-amplification circuit and then buffered and amplified by a multi-stage amplification circuit using a background subtraction circuit, and then inputting the signal after the threshold processing into a waveform transformation circuit.

[0003] Patent document CN104051218A belongs to a general solution, and its effect on noise suppression needs to be improved.

[0004] The present invention adds a frequency domain analysis algorithm to a traditional signal analysis circuit and adds a signal coupling circuit to directly process the original signal (the usual practice is to transmit the ADC signal back to the upper computer for processing), thereby effectively improving the signal-to-noise ratio of the original signal before software processing of the mass spectrometer. Summary of the Invention

[0005] Aiming at the defects in the prior art, the purpose of the present invention is to provide a noise suppression device with adjustable parameters applicable to a digital ion trap mass spectrometer.

[0006] A noise suppression device with adjustable parameters applicable to a digital ion trap mass spectrometer according to the present invention includes: a primary amplification circuit, a secondary amplification circuit, a signal analysis circuit, a signal coupling circuit, and an upper computer communication circuit;

[0007] The primary amplification circuit initially amplifies the output signal of the mass detector to obtain an initially amplified signal and outputs it to the secondary amplification circuit;

[0008] The secondary amplification circuit performs multi-stage buffering and amplification on the initially amplified signal and outputs it to the signal analysis circuit and the signal coupling circuit respectively;

[0009] The signal analysis circuit receives parameters from the upper computer through the upper computer communication circuit, analyzes the output signal of the secondary amplification circuit according to the parameters, and generates a signal with the same frequency and opposite phase as a partial frequency band of the output signal of the secondary amplification circuit and inputs it into the signal coupling circuit; wherein, the parameters are set by the user on the upper computer, and the parameters are used to reduce the noise of the mass spectrometry signal;

[0010] The signal coupling circuit couples the output signal of the signal analysis circuit with the output signal of the secondary amplification circuit, and the obtained coupled signal is used as an output signal and transmitted to the mass spectrometer signal acquisition circuit.

[0011] Preferably, it further includes an independent power supply circuit;

[0012] The power supply circuit supplies power to the primary amplification circuit, the secondary amplification circuit, the signal analysis circuit, and the signal coupling circuit;

[0013] The power supply circuit includes any one or more of a linear power supply, a switching power supply, and a battery.

[0014] Preferably, the primary amplification circuit is a current feedback amplifier or a voltage feedback amplifier with the conversion characteristics of a current feedback amplifier;

[0015] The secondary amplification circuit includes a JFET input operational amplifier;

[0016] The signal coupling circuit uses an adder for signal coupling.

[0017] Preferably, the signal analysis circuit includes an ADC chip, a DAC chip, a programmable MCU chip, and a DDR chip;

[0018] The ADC chip collects the output signal of the secondary amplification circuit and stores it in the DDR chip. The programmable MCU chip retrieves the data corresponding to the output signal of the secondary amplification circuit from the DDR chip, processes the signal, and then stores it in the DDR chip; the MCU chip retrieves the processed data from the DDR chip and outputs it to the signal coupling circuit through the DAC chip.

[0019] Preferably, in the signal processing, some high-frequency signals are screened out as noise by analyzing the input data, and then data with the same frequency and opposite phase as the noise is generated as output data and stored in the DDR chip.

[0020] Preferably, the signal analysis circuit starts the data acquisition and signal processing process of the MCU chip for the DDR chip according to an external trigger signal; wherein, the port of the signal analysis circuit for receiving the external trigger signal is connected to the trigger signal port of the mass spectrometer data acquisition board.

[0021] Preferably, the host computer communication circuit includes a USB interface or a network interface, and adjusts the parameters of the signal processing algorithm adopted for the signal processing according to the host computer instruction.

[0022] Preferably, after power-on, the signal analysis circuit updates the parameters transmitted by the host computer through the communication circuit. If the host computer is not connected, the default parameters stored in the DDR chip are used. After the signal analysis circuit updates the parameters, it will wait in a loop for an external trigger signal that serves as an acquisition trigger signal. After the signal analysis circuit detects the trigger signal, it acquires the signal amplified by the primary amplifier circuit and the secondary amplifier circuit through the ADC chip and stores the signal in the DDR chip. The programmable MCU chip of the signal analysis circuit retrieves the signal data from the DDR chip, filters out some frequency-domain signals as noise through the analysis of the input data, then generates data with the same frequency and opposite phase as the noise as output data and stores it in the DDR chip, and retrieves the processed data corresponding to the previous acquisition from the DDR chip and outputs it to the signal coupling circuit through the DAC chip. The signal coupled by the signal coupling circuit serves as the original signal collected by the mass spectrometer.

[0023] A digital ion trap mass spectrometer provided by the present invention includes a mass analyzer, a mass detector, and a signal acquisition circuit, and is characterized in that it further includes the noise suppression device with adjustable parameters applicable to the digital ion trap mass spectrometer.

[0024] The mass analyzer, the mass detector, the noise suppression device with adjustable parameters applicable to the digital ion trap mass spectrometer, and the signal acquisition circuit are connected in sequence. The noise suppression device with adjustable parameters applicable to the digital ion trap mass spectrometer outputs the output signal of the mass detector to the signal acquisition circuit after signal noise suppression.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. Most of the noise suppression of the signals of the existing digital ion trap mass spectrometers is filtered by the host computer software algorithm. The higher the signal-to-noise ratio of the original signal transmitted from the mass spectrometer to the host computer, the better the filtering effect of the software algorithm. The noise suppression device provided by the present invention can effectively improve the signal-to-noise ratio of the original signal before software processing of the mass spectrometer.

[0027] 2. The noise suppression device provided by the present invention can configure algorithm parameters according to the host computer and can flexibly modify the filtering algorithm in the device according to actual needs.

[0028] 3. The noise suppression device provided by the present invention does not need to transmit data to the host computer for processing, so the response to signal changes is extremely fast.

[0029] 4. The present invention adopts an independent power supply circuit, thereby reducing the noise interference on the power ground. Description of the Drawings

[0030] Other features, objectives, and advantages of the present invention will become more apparent by reading the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0031] Figure 1 It is a schematic diagram of a partial instrument in a mass spectrometer related to a mass detector and a signal acquisition and amplification circuit in the prior art.

[0032] Figure 2 It is a principle block diagram of a noise suppression device with adjustable parameters applicable to a digital ion trap mass spectrometer provided by the present invention.

[0033] Figure 3 It is a schematic diagram of the connection method of a noise suppression device with adjustable parameters applicable to a digital ion trap mass spectrometer provided by the present invention.

[0034] Figure 4 It is a frequency domain analysis of the spectrum of a digital ion trap mass spectrometer using a signal amplification circuit.

[0035] Figure 5 It is a frequency domain analysis of the spectrum of a digital ion trap mass spectrometer after using the noise suppression device described in the present invention.

[0036] Figure 6 It is a spectrum of a digital ion trap mass spectrometer using a signal amplification circuit.

[0037] Figure 7 It is a spectrum of a digital ion trap mass spectrometer using the noise suppression device described in the present invention.

[0038] Figure 4 、 Figure 5 The abscissa in and is the frequency distribution of the signal, and the ordinate is the DC component of the signal corresponding to the frequency. X and Y in the figure represent the frequency and DC component of a certain signal component respectively.

[0039] Figure 6 、 Figure 7 The abscissa in and is the mass number distribution of the mass spectrometry signal, and the ordinate is the signal intensity of the mass spectrometry signal corresponding to the mass. Detailed Embodiments

[0040] The present invention will be described in detail below with reference to specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several changes and improvements can still be made. These all fall within the protection scope of the present invention.

[0041] The noise suppression device with adjustable parameters applicable to a digital ion trap mass spectrometer provided by the present invention can quickly reduce the noise of the mass spectrometry signal according to the parameters set by the user, and can conveniently, quickly and effectively improve the signal-to-noise ratio of the mass spectrometer signal. The noise suppression device with adjustable parameters applicable to a digital ion trap mass spectrometer includes: a primary amplification circuit for receiving the signal output by the mass detector and performing primary amplification; a secondary amplification circuit for receiving the output signal of the primary amplification circuit and performing multi-stage buffering and amplification on it; a signal analysis circuit for receiving the output signal of the secondary amplification circuit, analyzing it, and then generating a signal with the same frequency and opposite phase as the partial frequency band of the signal; a signal coupling circuit for coupling the output signal of the signal analysis circuit with the output signal of the secondary amplification circuit; and a host computer communication circuit for performing data interaction with the host computer.

[0042] As Figure 2 shown, the noise suppression device with adjustable parameters applicable to a digital ion trap mass spectrometer provided by the present invention includes:

[0043] A primary amplification circuit for receiving the signal output by the mass detector, performing primary amplification to obtain a primary amplified signal, and then outputting it to the next-stage circuit, i.e., the secondary amplification circuit; the primary amplification circuit is a high-speed current feedback amplifier or a high-speed voltage feedback amplifier with the conversion characteristics of a current feedback amplifier;

[0044] A secondary amplification circuit for receiving the output signal from the primary amplification circuit, performing multi-stage buffering and amplification on the primary amplified signal, and then inputting it to the next-stage circuits, including the signal analysis circuit and the signal coupling circuit; the secondary amplification circuit includes a JFET input operational amplifier;

[0045] A signal analysis circuit for receiving the output signal of the secondary amplification circuit, analyzing the output signal of the secondary amplification circuit, and then performing signal processing to generate a signal with the same frequency and opposite phase as the partial frequency band of the output signal of the secondary amplification circuit and inputting it to the next-stage circuit, i.e., the signal coupling circuit; the signal analysis circuit includes a high-speed ADC chip, a high-speed DAC chip, a programmable MCU chip, and a DDR chip; the signal processing algorithms used for signal processing include Fourier algorithm, inverse Fourier algorithm, and partial filter noise reduction algorithm; the signal analysis circuit starts the data acquisition and processing process according to an external trigger signal;

[0046] A signal coupling circuit for coupling the output signal of the signal analysis circuit with the output signal of the secondary amplification circuit and outputting a coupled signal; the signal after being coupled by the signal coupling circuit is used as the output signal of the noise suppression device; the signal coupling circuit uses an adder for signal coupling;

[0047] The host computer communication circuit is used to connect to the signal analysis circuit and perform data interaction with the host computer. The host computer communication circuit includes a USB interface or a network interface.

[0048] The present invention will be described in more detail below.

[0049] After the noise suppression device is powered on, the signal analysis circuit will update the parameters transmitted by the host computer through the communication circuit. If the host computer is not connected, the default parameters stored in the DDR chip will be used; after the signal analysis circuit updates the parameters, it will wait in a loop for the acquisition trigger signal;

[0050] After the signal analysis circuit detects the trigger signal, it will collect the signal amplified by the primary amplifier circuit and the secondary amplifier circuit through the ADC chip and store the signal in the DDR chip;

[0051] The programmable MCU chip of the signal analysis circuit will retrieve the signal data from the DDR chip, screen out some frequency domain signals as noise through the analysis of the input data, and then generate data with the same frequency and opposite phase as the noise as the output data and store it in the DDR chip;

[0052] When the signal analysis circuit detects the trigger signal again, it will repeat the signal acquisition process, and at the same time retrieve the data that has been processed in the previous step from the DDR chip and output it to the signal coupling circuit through the DAC chip;

[0053] The signal coupled by the signal coupling circuit is used as the original signal collected by the mass spectrometer.

[0054] The digital ion trap mass spectrometer provided by the present invention will be described in detail below.

[0055] As Figure 3 shown, in the digital ion trap mass spectrometer, the signal inlet of the noise suppression device with adjustable parameters applicable to the digital ion trap mass spectrometer provided by the present invention is connected to the mass detector, the signal outlet is connected to the signal acquisition circuit of the mass spectrometer, and the trigger signal is connected to the trigger signal port of the mass spectrometer data acquisition board. In this embodiment, the mass analyzer uses a hyperbolic rod ion trap, the ionization source uses an electron bombardment source, and the mass detector uses a Faraday cup. The signal acquisition circuit uses a data acquisition card with a sampling rate of 4M / s. The sampling end is connected to the signal output end of the noise suppression device, and the trigger signal end is connected to the trigger signal end of the noise suppression device. The data acquisition card can perform data acquisition according to the sampling time set by the host computer and transmit it to the host computer through the USB interface. The host computer uses a computer with a WINDOWS system and installs instrument control software. The instrument control software can control and measure the mass spectrometer through the USB interface. The data analysis software uses MatLab software for analyzing mass spectrometry data.

[0056] The technical effects of the present invention will be compared and described below.

[0057] Example 1: Use a certain digital ion trap mass spectrometer.

[0058] Step 1: Establish a vacuum environment for the ion trap mass spectrometer;

[0059] Step 2: Turn off the ionization source of the ion trap mass spectrometer;

[0060] Step 3: Turn on the high voltage of the ion trap mass spectrometer;

[0061] Step 4: Use the host computer instrument control software to adjust the acquisition card with a sampling rate of 4M / s to 1M / s, and set not to use any filtering algorithm;

[0062] Step 5: Use the host computer instrument control software to start the acquisition of the mass spectrometer spectrum. Since the ionization source is not turned on, the collected data can be recognized as electronic noise;

[0063] Step 6: Use MatLab software to perform frequency domain analysis on the collected noise data, record the noise frequency domain distribution, and the frequency distribution of the noise is as Figure 4 shown;

[0064] Step 7: Use the host computer instrument control software to stop the acquisition of the mass spectrometer spectrum, remove the signal amplification circuit of the mass spectrometer, and replace it with the noise suppression device described in the present invention;

[0065] Step 8: Set the parameters of the noise suppression device described in the present invention according to the frequency distribution of the noise;

[0066] Step 9: Start the acquisition of the mass spectrometer spectrum again, use MatLab software to perform frequency domain analysis on the collected noise data, and it can be seen that the high-frequency noise is significantly suppressed, and the frequency distribution of the noise is as Figure 5 shown.

[0067] It can be seen that the noise suppression device described in the present invention can conveniently, quickly and effectively suppress the high-frequency noise in the original signal of the digital ion trap mass spectrometer.

[0068] Example 2: Use a certain digital ion trap mass spectrometer.

[0069] Step 1: Establish a vacuum environment for the ion trap mass spectrometer;

[0070] Step 2: Turn on the ionization source of the ion trap mass spectrometer;

[0071] Step 3: Turn on the high voltage of the ion trap mass spectrometer;

[0072] Step 4: Use the host computer instrument control software to adjust the acquisition card with a sampling rate of 4M / s to 1M / s, and set not to use any filtering algorithm;

[0073] Step 5: Use the host computer instrument control software to start collecting the mass spectrometer spectrum. The collected spectrum is as Figure 6 shown;

[0074] Step 6: Use the host computer instrument control software to stop collecting the mass spectrometer spectrum. Remove the signal amplification circuit of the mass spectrometer and replace it with the noise suppression device described in the present invention;

[0075] Step 7: Set the parameters of the noise suppression device described in the present invention according to the noise frequency distribution recorded in Embodiment 1;

[0076] Step 8: Start collecting the mass spectrometer spectrum again. It can be seen from the collected spectrum that the noise is significantly suppressed. The spectrum is as Figure 7 shown.

[0077] In summary, the device described in the present invention can conveniently, quickly, and effectively suppress the high-frequency noise in the original signal of the digital ion trap mass spectrometer.

[0078] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Without conflict, the embodiments of the present application and the features in the embodiments can be arbitrarily combined with each other.

Claims

1. An adjustable parameter noise suppression device applicable to a digital ion trap mass spectrometer, characterized in that, Including: A primary amplification circuit, a secondary amplification circuit, a signal analysis circuit, a signal coupling circuit, and a host computer communication circuit; The primary amplification circuit initially amplifies the output signal of the quality detector to obtain an initially amplified signal and outputs it to the secondary amplification circuit; The secondary amplification circuit performs multi-stage buffering and amplification on the initially amplified signal and outputs it to the signal analysis circuit and the signal coupling circuit respectively; The signal analysis circuit receives parameters from the host computer through the host computer communication circuit, analyzes the output signal of the secondary amplification circuit according to the parameters, and generates a signal with the same frequency and opposite phase in part of the frequency band of the output signal of the secondary amplification circuit and inputs it into the signal coupling circuit; wherein, the parameters are set by the user on the host computer, and the parameters are used to reduce the noise of the mass spectrometry signal; The signal coupling circuit couples the output signal of the signal analysis circuit with the output signal of the secondary amplification circuit, and the obtained coupled signal is used as the output signal and transmitted to the mass spectrometer signal acquisition circuit; The primary amplification circuit is a current feedback amplifier or a voltage feedback amplifier with the conversion characteristics of a current feedback amplifier; The secondary amplification circuit includes a JFET input operational amplifier; The signal coupling circuit uses an adder for signal coupling; The signal analysis circuit includes an ADC chip, a DAC chip, a programmable MCU chip, and a DDR chip; The ADC chip collects the output signal of the secondary amplification circuit and stores it in the DDR chip. The programmable MCU chip takes out the data corresponding to the output signal of the secondary amplification circuit from the DDR chip, processes the signal, and then stores it in the DDR chip; the MCU chip takes out the processed data from the DDR chip and outputs it to the signal coupling circuit through the DAC chip.

2. The noise suppression device with adjustable parameters applicable to a digital ion trap mass spectrometer according to claim 1, wherein It also includes an independent power supply circuit; The power supply circuit supplies power to the primary amplification circuit, the secondary amplification circuit, the signal analysis circuit, and the signal coupling circuit; The power supply circuit includes any one or any combination of a linear power supply, a switching power supply, and a battery.

3. The noise suppression device with adjustable parameters for a digital ion trap mass spectrometer according to claim 1, characterized in that, In the signal processing, part of the high-frequency signals are selected as noise by analyzing the input data, and then data with the same frequency and opposite phase as the noise is generated and stored in the DDR chip as the output data.

4. The noise suppression device with adjustable parameters applicable to a digital ion trap mass spectrometer according to claim 1, characterized in that, The signal analysis circuit starts the data acquisition and signal processing process of the MCU chip for the DDR chip according to an external trigger signal; wherein, the port of the signal analysis circuit receiving the external trigger signal is connected to the trigger signal port of the mass spectrometer data acquisition board.

5. The noise suppression device with adjustable parameters applicable to a digital ion trap mass spectrometer according to claim 1, characterized in that, The host computer communication circuit includes a USB interface or a network interface, and adjusts the parameters of the signal processing algorithm adopted by the signal processing according to the host computer instruction.

6. The noise suppression device with adjustable parameters applicable to a digital ion trap mass spectrometer according to claim 4, characterized in that, After power-on, the signal analysis circuit will update the parameters transmitted by the host computer through the communication circuit. If the host computer is not connected, the default parameters stored in the DDR chip will be used. After the signal analysis circuit updates the parameters, it will wait in a loop for an external trigger signal that serves as the acquisition trigger signal. After detecting the trigger signal, the signal analysis circuit collects the signal amplified by the primary amplification circuit and the secondary amplification circuit through the ADC chip and stores the signal in the DDR chip. The programmable MCU chip of the signal analysis circuit retrieves the signal data from the DDR chip, filters out some frequency-domain signals as noise by analyzing the input data, then generates data with the same frequency and opposite phase as the noise as output data and stores it in the DDR chip, and retrieves the processed data corresponding to the previous acquisition from the DDR chip and outputs it to the signal coupling circuit through the DAC chip. The signal coupled by the signal coupling circuit serves as the original signal collected by the mass spectrometer.

7. A digital ion trap mass spectrometer, comprising a mass analyzer, a mass detector, and a signal acquisition circuit, characterized in that, It further includes a noise suppression device with adjustable parameters applicable to a digital ion trap mass spectrometer according to any one of claims 1 to 6. The mass analyzer, the mass detector, the noise suppression device with adjustable parameters applicable to a digital ion trap mass spectrometer, and the signal acquisition circuit are connected in sequence. The noise suppression device with adjustable parameters applicable to a digital ion trap mass spectrometer outputs the output signal of the mass detector to the signal acquisition circuit after signal noise suppression.

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