X-nuclear channel broadband pre-amplifier of high-field nuclear magnetic resonance spectrometer

Abstract

The invention discloses an X-nuclear channel broadband pre-amplifier of a high-field nuclear magnetic resonance spectrometer and relates to the pre-amplifier of the nuclear magnetic resonance spectrometer. The pre-amplifier is provided with a radio frequency switch control circuit, a radio frequency switch circuit, a direct current bias circuit, an amplification front-end protection circuit, a quarter-wavelength line, a low-noise amplifier circuit, an output matching network and a working state detection circuit. The output end of the radio frequency switch control circuit is connected with the input end of the radio frequency switch circuit and the input end of the amplification front-end protection circuit, the other input end of the amplification front-end protection circuit is externally connected with a port of the quarter-wavelength line, the other port of the quarter-wavelength line is externally connected with a probe, the input end of the low-noise amplifier circuit is connected with the output end of the amplification front-end protection circuit, the low-noise amplifier circuit is externally connected with the next-level part via the output matching network, the output end of the radio frequency switch circuit is externally connected with the probe, the working state detection circuit is connected with a switch signal generator, and the output end of the working state detection circuit is connected with the input end of the radio frequency switch control circuit.

Description

technical field [0001] The invention relates to a nuclear magnetic resonance spectrometer preamplifier, in particular to a high-sensitivity and high-stability broadband preamplifier applied to the X nuclear channel of a high-field nuclear magnetic resonance spectrometer. Background technique [0002] The X nuclear channel preamplifier is an important part of the radio frequency transceiver unit of the nuclear magnetic resonance spectrometer. It is located at the front end of the system and is used to detect the magnetic resonance signals of carbon, phosphorus, nitrogen and other heteronuclei. amplifier. Since the NMR spectrometer's RF front-end shares the transmission channel of the access probe when the pulse is transmitted and the signal is received, the preamplifier usually includes two functions: a radio frequency transmission switch and a small-signal low-noise amplification. During the radio frequency pulse transmission, as the front end of the transmission channel, t...

AI Technical Summary

Problems solved by technology

For example, the X nuclear channel preamplifier of the high-field nuclear magnetic resonance spectrometer produced by Varian Corporation of the United States has a simple structure, but it has no working status indication and detection function, so the working status and fault prompt of the preamplifier cannot be judged when the spectrometer is working, and the working frequency band The isolation of the internal RF switch and the in-band flatness of the amplification gain are not high enough; while the structure of the X nuclear channel preamplifier of the high-field nuclear magnetic resonance spectrometer of the German Bruker company is relatively complicated, especially in the quarter-wavelength line of the front-end protection circuit of the amplification The complex structure on the state detection circuit may not only introduce unnecessary interference, but also increase insertion loss and fault error rate, thus affecting the overall stability of the system

[0010] On the other hand, the X nuclear channel preamplifiers of nuclear magnetic resonance instruments that have been reported abroad only involve the amplification part, and do not include the high-power RF transceiver switch and the high-power RF protection part of the front end of the amplification.

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