Nano-upgrading sample nuclear magnetic resonance detection digital receiver

Abstract

The invention provides a nano-L scale sample nuclear magnetic resonance detection digital receiver which is suitable for carrying out nuclear magnetic resonance spectral analysis on a biological-chemical liquid sample with the volume less than 500 nano-L. The digital receiver is based on the signal detection method of once analog frequency mixing, and once intermediate frequency sampling and digital quadrature demodulation; the receiver consists of an RF pre-positive low noise amplifier, an RF gain controller, a frequency mixer, an intermediate changeable gain amplifier, a data collecting card and the like which are sequentially connected in series; the signal which is obtained by the induction of a nuclear magnetic resonance receiving coil is sent to the receiver; subsequently, the signal is firstly amplified by devices such as the pre-positive noise amplifier and the like; then, the amplified signal is sent to the frequency mixer, thus obtaining an intermediate frequency nuclear magnetic resonance signal; subsequently, the intermediate frequency signal is amplified further and filtrated by low-pass; and finally, D / A (analog-to-digital) conversion of the intermediate frequency signal is carried out by a data collecting card, thus preparing data for the subsequent baseband digital orthogonal demodulation.

Description

technical field [0001] The invention relates to a digital receiver for nuclear magnetic resonance detection, in particular to a digital receiver for nuclear magnetic resonance detection of nanoliter samples. Background technique [0002] Under the condition that the composition of the tested sample is unknown, NMR detection technology can be used to analyze the molecular composition and structure of compounds, and it plays a very important role in the fields of biological research and material research. In recent years, with the development and progress of technology, the depth and breadth of its application are also expanding. However, compared with other chemical analysis techniques such as mass spectrometry, the sensitivity of NMR detection technology is low, and the detection sensitivity increases significantly with the decrease of the measured sample volume. In conventional nuclear magnetic resonance spectroscopy, test tubes with a diameter of 5 mm are generally used a...

AI Technical Summary

Problems solved by technology

Traditional commercial magnetic resonance spectrometers generally use receivers based on analog technology, which are costly and unstable due to the influence of ambient temperature. Moreover, when the receiver uses quadrature detection to process signals, in-phase and quadrature There will be a certain degree of imbalance between the two signals, resulting in spectral distortion after Fourier transform

In particular, receivers based on analog signal processing technology use analog down-conversion and detection technology (analog devices have inherent instability), and there are DC offset errors on the signal processing path, which are easily affected by the ambient temperature, resulting in signal processing. poor repeatability

[0004] In U.S. Patent No. 11690193, a nuclear magnetic resonance digital receiver based on radio frequency sampling technology is disclosed. According to the frequency of the nuclear magnetic resonance signal, the analog-to-digital converter in the receiver uses under-sampling or over-sampling technology to convert the analog The signal is converted into a digital signal, and the receiver has the following deficiencies: 1. The direct radio frequency digital receiver needs higher-performance electronic components, especially a radio frequency bandpass filter and an analog-to-digital converter; The signal is digitized, that is, a higher sampling rate is adopted, which greatly increases the data processing load in the subsequent digital quadrature detection link; 3. It is difficult for the direct digital receiver to maintain the phase relationship with the radio frequency pulse transmission part of the spectrometer Consistent, and the method of increasing the sampling rate can only make the phase relationship between the receiving and sending signals approximately consistent

The above factors determine that this direct radio frequency digital receiver cannot well meet the needs of nanoscale sample nuclear magnetic resonance spectroscopy detection technology

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