CN101793949A - X-nuclear channel broadband pre-amplifier of high-field nuclear magnetic resonance spectrometer - Google Patents
X-nuclear channel broadband pre-amplifier of high-field nuclear magnetic resonance spectrometer Download PDFInfo
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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
The present invention relates to a kind of nuclear magnetic resonance spectrometer prime amplifier, especially relate to a kind of broadband prime amplifier that is applied to high-field nuclear magnetic resonance spectrometer X nuclear passage high sensitivity and high stability.
Background technology
X nuclear passage prime amplifier is the important component part of nuclear magnetic resonance spectrometer Transmit Receive Unit, is positioned at system foremost, is used to detect the magnetic resonance signal of heteronuclears such as carbon, phosphorus, nitrogen, is the very wide prime amplifier of a kind of frequency range.Because the transmission channel of nuclear magnetic resonance spectrometer radio-frequency front-end time sharing shared access probe when pulse emission and signal reception, so prime amplifier generally includes the radio-frequency transmissions switch and the small-signal low noise amplifies two big functions.During the radio-frequency pulse emission,, give probe coil with high power pulse through radio-frequency (RF) switch as the front end of transmission channel; At the signal reception period, the free induction decay signal from probe is carried out low noise amplify, send the frequency mixer of system's receiving cable to.X nuclear passage prime amplifier noiseproof feature has conclusive effect to the heteronuclear signal received signal to noise ratio of whole receiver, directly has influence on spectrometer and finally tests sensitivity index, therefore requires X nuclear passage prime amplifier to have high-performance.Have only microvolt (uV) order of magnitude from the coil-induced signal that goes out of receiving transducer, this just requires X nuclear passage prime amplifier that suitable enlargement factor should be arranged, and very low noise figure is arranged again.The high performance requirements of X nuclear passage prime amplifier mainly shows:
1. during spectrometer is in accepting state, free induction decay signal is through amplifying front-end protection circuit and low noise amplifier circuit, deliver to frequency mixer, amplify the insertion loss of front-end protection circuit, and the noise figure of low noise amplifier circuit is with the detection sensitivity of final decision prime amplifier;
2. during spectrometer was in emission state, pulse train was through the radio-frequency switch circuit of prime amplifier, and the insertion loss of circuit will influence the radio-frequency power of excited atom nuclear resounce, thereby influence the size of the free induction decay signal of institute's excimer daughter nucleus;
Since from the coil-induced signal intensity that goes out of receiving transducer usually from several microvolts to the hundreds of microvolt, therefore require low noise amplifier circuit to have the reliable range of linearity;
4. the height of radio-frequency switch circuit will reduce firing frequency leakage interference to received signal by isolation;
5. radio-frequency switch circuit should have and receives and dispatches switch speed fast, and prime amplifier is in accepting state fully when guaranteeing to receive;
6. high performance amplification front-end protection circuit will protect amplifying circuit to leak the influence of pair amplifier owing to high power RF during launching.
Nuclear magnetic resonance spectrometer belongs to the high-end large-scale scientific instrument, and is with high content of technology, has wide range of applications, and the high-field nuclear magnetic resonance spectrometer X nuclear passage prime amplifier vitals of system as a whole provides highly sensitive signal amplifying function.Prime amplifier parts in the external high field super pulse type NMR spectroscope all have self-character on project organization or the function, weak point is also arranged.For example, the high-field nuclear magnetic resonance spectrometer X nuclear passage prime amplifier of U.S. Varian company is simple for structure, but there are not duty indication and measuring ability, can't judge the duty and the fault prompting of prime amplifier when therefore spectrometer is worked, and the inband flatness of radio frequency switch isolation degree, gain amplifier is not high enough in the working band; And the high-field nuclear magnetic resonance spectrometer X of German Bruker company nuclear passage prime amplifier structure is comparatively complicated; special complex structure on quatrter-wavelength line that amplifies the front-end protection circuit and state detection circuit; not only may introduce unnecessary interference; and can increase insertion loss and fault error rate, thereby influenced the resistance to overturning of system.
On the other hand, the nuclear magnetic resonance apparatus X nuclear passage prime amplifier of abroad having reported all only relates to amplifier section, and does not comprise the high power RF transmit-receive switch and amplify front end high power RF protection portion.For example: granted United States Patent (USP) " LOW-NOISE PREAMPLIFIER; IN PARTICULAR; FOR NUCLEAR MAGNETICRESONANCE (NMR) " (patent No. is US7123090B2) in 2006 and granted United States Patent (USP) " PREAMPLIFIERCIRCUIT FOR MAGNETIC RESONANCE SYSTEM " (patent No. is US5545999) in 1996, all only be the unique design of the low noise amplifier circuit under the spectrometer accepting state, their prime amplifier does not contain high power RF transmit-receive switch circuit and amplifies front end high power RF holding circuit; The designed prime amplifier of document " C Huan; S.S.Kim; L.Phelps; J.S.Xia; D.Candela andN.S.Sullivan.A Novel Design of a Low Temperature Preamplifier for Pulsed NMR Experiments ofDilute 3He in Solid 4He.Journal of Low Temperature Physics; Published online:1 October 2009 " also only is small signal amplification circuit, and is similar with above-mentioned patent.
Summary of the invention
The object of the present invention is to provide a kind of simple in structure, noise figure is lower, in the band gain flatness higher, amplify that the range of linearity is big, radio-frequency (RF) switch transmitting-receiving switch speed is very fast, higher by isolation, the duty measuring ability is accurately sensitive, stability high-field nuclear magnetic resonance spectrometer X nuclear passage broadband prime amplifier preferably.
The present invention is provided with radio-frequency (RF) switch control circuit, radio-frequency switch circuit, dc bias circuit, amplification front-end protection circuit, quatrter-wavelength line, low noise amplifier circuit, output matching network and Working state checking circuit.
The radio-frequency (RF) switch control level output terminal of radio-frequency (RF) switch control circuit connects the radio-frequency (RF) switch control level input end of radio-frequency switch circuit respectively and amplifies the input end of front-end protection circuit; amplify a port of the external quatrter-wavelength line of another input end of front-end protection circuit; the external probe in the another port of quatrter-wavelength line; the input termination of low noise amplifier circuit is amplified the output terminal of front-end protection circuit; the input end of the output termination output matching network of low noise amplifier circuit; the external next stage parts of the output terminal of output matching network; the external radio-frequency power amplifier output port of radio-frequency switch circuit input end; the external probe of the output terminal of radio-frequency switch circuit; Working state checking circuit links to each other with switch signal generator by interface; the radio-frequency (RF) switch control level signal output part of Working state checking circuit connects the duty detection signal input end of radio-frequency (RF) switch control circuit, and dc bias circuit is connected with Working state checking circuit with low noise amplifier circuit respectively.
Described quatrter-wavelength line can adopt the quarter-wave coaxial cable.
Described radio-frequency switch circuit and radio-frequency (RF) switch control circuit are formed a circuit, amplify front-end protection circuit, low noise amplifier circuit and output matching network and form a circuit, and Working state checking circuit is a circuit, is isolated by shielding cavity between the every circuit.
Described radio-frequency switch circuit can adopt the two-stage series connection PIN diode; Described low noise amplifier circuit can adopt the two-stage amplification circuit structure, and first order amplifying circuit can adopt low noise amplifier circuit, and second level amplifying circuit can adopt silicon twin-stage Darlington amplifier tube; Described amplification front-end protection circuit can adopt three grades of PIN diode structures in parallel; Described Working state checking circuit can adopt the reversal detection architecture, by the LED display working condition, different malfunction resistance ratios is set, and can reflect the duty and the failure condition of prime amplifier accurately and reliably.
Because the present invention forms a circuit with high-power radio-frequency switch circuit and radio-frequency (RF) switch control circuit; low noise small-signal passage amplifies front-end protection circuit, low noise amplifier circuit and output matching circuit and forms a circuit; Working state checking circuit is a circuit; and isolate by shielding cavity between every circuit, therefore be reduced to interfering with each other of signal minimum.Because Working state checking circuit adopts the reversal detection architecture, by the LED display working condition, different malfunction resistance ratios is set, therefore can reflect the duty and the failure condition of prime amplifier accurately and reliably.
Owing to adopted said structure and circuit, therefore the present invention have noise figure low, amplify that the range of linearity is big, radio-frequency (RF) switch transmitting-receiving switch speed is fast, gain flatness height, good stability, advantages of simple structure and simple in, the band accurately sensitive by isolation height, duty measuring ability, can satisfy modern high-field nuclear magnetic resonance spectrometer X nuclear channel signal and detect the high performance requirements that amplifies, and the value of primary element such as capacitor and inductor in the adjustment circuit, realize different operational frequency bandwidth, satisfy the needs of concrete resonant frequency High-Field spectrometer.
Description of drawings
Fig. 1 is the structure composition frame chart of the embodiment of the invention.
Fig. 2 is the low noise amplifier circuit figure of the embodiment of the invention.
Fig. 3 is the amplification front-end protection circuit diagram of the embodiment of the invention.
Fig. 4 is the high power RF on-off circuit figure of the embodiment of the invention.
Fig. 5 is the radio-frequency (RF) switch control circuit figure of the embodiment of the invention.
Fig. 6 is the Working state checking circuit figure of the embodiment of the invention.
Fig. 7 be the embodiment of the invention under emission state, when the quatrter-wavelength line centre frequency was 205MHz, radio-frequency power amplifier output port P3 was to the transport property simulation result figure of the P1 that pops one's head in.In Fig. 7, horizontal ordinate is frequency (MHz), and ordinate is the transport property (dB) of P3 port to the P1 port.
Fig. 8 be the embodiment of the invention under emission state, when the quatrter-wavelength line centre frequency was 125MHz, radio-frequency power amplifier output port P3 was to the transport property simulation result figure of the P1 that pops one's head in.In Fig. 8, horizontal ordinate is frequency (MHz), and ordinate is the transport property (dB) of P3 port to the P1 port.
Fig. 9 be the embodiment of the invention under emission state, when the quatrter-wavelength line centre frequency was 30MHz, radio-frequency power amplifier output port P3 was to the transport property simulation result figure of the P1 that pops one's head in.In Fig. 9, horizontal ordinate is frequency (MHz), and ordinate is the transport property (dB) of P3 port to the P1 port.
Figure 10 be the embodiment of the invention under emission state, when the quatrter-wavelength line centre frequency is 205MHz, output standing wave simulation result figure.In Figure 10, horizontal ordinate is frequency (MHz), and ordinate is the output standing-wave ratio (SWR).
Figure 11 be the embodiment of the invention under emission state, when the quatrter-wavelength line centre frequency is 205MHz, input standing wave simulation result figure.In Figure 11, horizontal ordinate is frequency (MHz), and ordinate is an input vswr.
Figure 12 be the embodiment of the invention under accepting state, stability factor simulation result figure.In Figure 12, horizontal ordinate is frequency (MHz), and ordinate is a stability factor.
Figure 13 be the embodiment of the invention under accepting state, noise figure simulation result figure.In Figure 13, horizontal ordinate is frequency (MHz), and ordinate is noise figure (dB).
Figure 14 be the embodiment of the invention under accepting state, power gain simulation result figure.In Figure 14, horizontal ordinate is frequency (MHz), and ordinate is power gain (dB).
Figure 15 be the embodiment of the invention under accepting state, output standing wave simulation result figure.In Figure 15, horizontal ordinate is frequency (MHz), and ordinate is the output standing wave.
Figure 16 be the embodiment of the invention under accepting state, radio-frequency power amplifier output port P3 is to the transport property simulation result figure of the P1 that pops one's head in.In Figure 16, horizontal ordinate is frequency (MHz), and ordinate is the transport property (dB) of P3 port to the P1 port.
Embodiment
Below in conjunction with accompanying drawing the present invention is described in detail.
As shown in Figure 1, the embodiment of the invention is provided with radio-frequency (RF) switch control circuit 1, radio-frequency switch circuit 2, dc bias circuit 3, amplifies front-end protection circuit 4, quatrter-wavelength line 5, low noise amplifier circuit 6, output matching network 7 and Working state checking circuit 8.
The radio-frequency (RF) switch control level output terminal of radio-frequency (RF) switch control circuit 1 connects the radio-frequency (RF) switch control level input end of radio-frequency switch circuit 2 respectively and amplifies the input end of front-end protection circuit 4; amplify a port P5 of the external quatrter-wavelength line 5 of another input end of front-end protection circuit 4; the external probe of the another port P4 P1 of quatrter-wavelength line 5; the input termination of low noise amplifier circuit 6 is amplified the output terminal of front-end protection circuit 4; the input end of the output termination output matching network 7 of low noise amplifier circuit 6; the external next stage parts of the output terminal of output matching network 7 (frequency mixer); the external radio-frequency power amplifier output port of radio-frequency switch circuit 2 input ends P3; the external probe of the output terminal of radio-frequency switch circuit 2 P1; Working state checking circuit 8 links to each other with switch signal generator with J2 by interface J1; the radio-frequency (RF) switch control level signal output part of Working state checking circuit 8 connects the duty detection signal input end of radio-frequency (RF) switch control circuit 1, and dc bias circuit 3 is connected with Working state checking circuit 8 with low noise amplifier circuit 6 respectively.
Described quatrter-wavelength line 5 adopts the quarter-wave coaxial cable.
The present invention includes large-signal high power circuit, small-signal low noise amplifier circuit and three circuit of Working state checking circuit.The large-signal high power circuit comprises radio-frequency switch circuit 1 and radio-frequency (RF) switch control circuit 2, and radio-frequency (RF) switch control circuit 2 is made up of resistor network.The small-signal low noise circuit comprises amplification front-end protection circuit 4, low noise amplifier circuit 6 and output matching network 7.Large-signal high power circuit, small-signal low noise amplifier circuit and three circuit of Working state checking circuit are loaded on respectively in three shielding cavities of shielding box, isolate mutually, avoid interference.
Described radio-frequency switch circuit can adopt the two-stage series connection PIN diode; Described low noise amplifier circuit can adopt the two-stage amplification circuit structure, and first order amplifying circuit can adopt low noise amplifier circuit, and second level amplifying circuit can adopt silicon twin-stage Darlington amplifier tube; Described amplification front-end protection circuit can adopt three grades of PIN diode structures in parallel; Described Working state checking circuit can adopt the reversal detection architecture, by the LED display working condition, different malfunction resistance ratios is set, and can reflect the duty and the failure condition of prime amplifier accurately and reliably.
The present invention is provided with 5 signal ports.When system was in accepting state, probe P1 detected free induction decay signal was sent into a port P4 of radio-frequency switch circuit 2 and quatrter-wavelength line 5 by probe P1 output port, and the another port of quatrter-wavelength line 5 is P5.The output port P2 of output matching network 7 is external to next parts (frequency mixer).When system was in emission state, the radio-frequency pulse that power amplifier is sent here imported radio-frequency switch circuit 2 of the present invention into by radio-frequency power amplifier output port P3, delivered to probe P1 through radio-frequency switch circuit.Radio-frequency (RF) switch control level signal is by port J1 input, and the power supply of the power supply of dc bias circuit 3 and Working state checking circuit 8 is imported by port J2.
Amplify a port P5 of the external quatrter-wavelength line 5 of another input end of front-end protection circuit 4; the external probe of the another port P4 P1 of quatrter-wavelength line 5; the input termination of low noise amplifier circuit 6 is amplified the output terminal of front-end protection circuit 4; the input end of the output termination output matching network 7 of low noise amplifier circuit 6; the external next stage parts of the output terminal of output matching network 7; the external radio-frequency power amplifier output port of radio-frequency switch circuit 2 input ends P3; the external probe of the output terminal of radio-frequency switch circuit 2 P1, Working state checking circuit 8 links to each other with switch signal generator with J2 by interface J1.
Referring to Fig. 2, adopt the two-stage structure for amplifying in the low noise amplifier circuit, the first order adopts low noise amplifier, as: the MGA62563 of Agilent company, noise figure is all below 1dB in its 20～400MHz scope, have higher dynamic range, and in the desired frequency bandwidth of high-field nuclear magnetic resonance wave spectrum X nuclear passage, this amplifier tube has good gain flatness.Silicon twin-stage Darlington amplifier tube is adopted in the second level, ADA4743 as Agilent company, operating circuit simply is easy to use, and the linearity and gain flatness all can satisfy the design needs, and can constitute good interstage matched and rock-steady structure with first amplifier valve.
Fig. 3 adopts three grades of PIN diode structures in parallel for amplifying the front-end protection circuit, and one of them wavelength line and PIN3 constitute first order protection, and quatrter-wavelength line is inserted by P4 and P5 port.When spectrometer is in emission state; 3A, 4A and 5A end for positive level (as:+4.5V～+ 5V); PIN3, CR1, CR2, CR3 and CR4 conducting; C3, C5, C6, C8 and C9 form high frequency earthing; constitute three grades of PIN diode holding circuits in parallel; hold the impedance infinity of seeing holding circuit at P5 this moment, forms the high frequency off state, and the high power RF signal can't pass through holding circuit.Because the resonant frequency difference of various heteronuclears, and differ greatly, need the quatrter-wavelength line of changing-over different length when therefore detecting different IPs, thereby on the Frequency point of each nuclear, reach best high frequency off state.When spectrometer is in accepting state; 3A, 4A and 5A end for negative level (as: 10V～-15V); PIN3, CR1, CR2, CR3 and CR4 end; amplifying the front-end protection circuit is the normal signal passage; the passage loss is minimum, and the free induction decay signal of being sent here by probe can be smoothly by amplifying the front-end protection circuit.Bypass high resistance measurement R35, R36, R37, R38 provide discharge path for shunt capacitance among the figure, quicken discharge process and suppress the LC vibration, thereby improve switching characteristic.Adjust resistance R 3, R5 and R6 among Fig. 5, can change the electric current of the PIN3 that flows through, CR1, CR2, CR3 and CR4, thereby adjust the conducting degree and the conduction and cut-off speed of circuit.The effective reliable protection of three-level protective structure back level low noise amplifier circuit.
The two-stage PIN diode is a tandem-type connection among Fig. 4, constitutes two-stage series connection high power RF on-off circuit, and PIN diode is selected high power PIN switching diode for use.When spectrometer is in emission state, 1A and 2A end for positive level (as:+4.5V～+ 5V), PIN1 and PIN2 conducting, this moment, radio-frequency pulse was delivered to probe P1 by radio-frequency switch circuit.When spectrometer is in accepting state, 1A and 2A end for negative level (as: 10V～-15V), diode ends, received signal can not be passed through this passage, and by the isolation height, can effectively suppress the accidental release of high power RF pulse, guarantee good accepting state.By adjusting resistance R 1, R2 and R4 among Fig. 5, can change the electric current of flow through PIN1 and PIN2, thereby adjust the conducting degree and the conduction and cut-off speed of PIN on-off circuit.
Fig. 5 is a radio-frequency (RF) switch controlling resistance network.Switch controlling signal is given radio frequency quick closing valve circuit by 1B and 2B end by the input of 7B end respectively through each resistance, is given by 3B, 4B and 5B end and amplifies the front-end protection circuit.By changing the Control current that each resistance value can change flow through radio-frequency switch circuit and holding circuit, thereby adjust the performance that radio-frequency (RF) switch is switched.
Fig. 6 is a Working state checking circuit, and wherein the function of U4 is for detecting negative current.Under the accepting state, if radio-frequency (RF) switch is working properly, the electric current that then flows through the R15 two ends is zero, and U4 is output as low level, compares with reference voltage by voltage comparator U8, and this moment, the output voltage of U8 was zero, but bright by driving LED green light behind the phase inverter U6; If the radio-frequency (RF) switch operation irregularity, promptly the negative current by the R15 two ends is when setting threshold value, and U4 is output as high level, compares with reference voltage by voltage comparator U8, and the output voltage of U8 is a high level at this moment, but the driving LED red light is bright.Regulate R34, the output voltage of scalable U4.Set the output voltage of U7, the i.e. reference voltage of U8 by the resistance that R13 and two resistance of R14 are set.The function of U6 is the positive current of detection radio-frequency (RF) switch control signal and the positive current of amplifying circuit work, utilizes 5 current comparators of its inside, and the two-way load detecting is set, and R15 and R16 are the current sense resistor of this two-way load.When the electric current that flows through R15 and R16 was in setting range, the output voltage of U6 was zero, but this moment is bright by driving LED green light behind the phase inverter U6, on the contrary, went beyond the scope if detect electric current, and then the output voltage of U6 is 11V, but the driving LED red light is bright.Two ports of 7A and 8A connect the two-way load that needs detection respectively, and promptly amplification module and switch module detect the duty of this two-way with this.
Utilize ADS software that high-field nuclear magnetic resonance spectrometer X nuclear passage prime amplifier integrated circuit of the present invention is carried out emulation.With the 500MHz nuclear magnetic resonance spectrometer is example, bandwidth of operation 20～280MHz, simulation result as shown in Figure 7 and Figure 8, the result is:
(1) stability of receiving cable circuit, noise figure and S parameters simulation analysis result show: by optimizing, realized noise figure＜1.2dB (pure circuit noise coefficient is not considered junction loss) in the working band, stability factor K＞1, output standing-wave ratio (SWR)＜1.5, gain＞35dB in the band, end isolation＞40dB in the gain flatness＜1.5dB in the band, radio-frequency (RF) switch band.
(2) the S parameters simulation analysis result of transmission channel circuit shows: by optimizing, realized in-band insertion loss＜0.3dB, protection isolation＞50dB in the front end band is amplified in input and output standing-wave ratio (SWR) in the band＜1.5.
X nuclear passage preamplifier circuit main performance measured result of the present invention is:
(1) measured result of receiving cable circuit: realize in-band noise coefficient＜1.3dB, output standing-wave ratio (SWR)＜1.5, gain＞35dB in the band, by isolation＞50dB, circuit working is stablized no self-sustained oscillation in the gain flatness＜1.5dB in the band, radio-frequency (RF) switch band.
(2) measured result of transmission channel circuit: realized inserting in the working band loss less than 0.3dB, protection isolation＞45dB in the front end band is amplified in input and output standing-wave ratio (SWR) in the band＜1.5.
Claims (6)
1. a high-field nuclear magnetic resonance spectrometer X nuclear passage broadband prime amplifier is characterized in that being provided with radio-frequency (RF) switch control circuit, radio-frequency switch circuit, dc bias circuit, amplification front-end protection circuit, quatrter-wavelength line, low noise amplifier circuit, output matching network and Working state checking circuit;
The radio-frequency (RF) switch control level output terminal of radio-frequency (RF) switch control circuit connects the radio-frequency (RF) switch control level input end of radio-frequency switch circuit respectively and amplifies the input end of front-end protection circuit; amplify a port of the external quatrter-wavelength line of another input end of front-end protection circuit; the external probe in the another port of quatrter-wavelength line; the input termination of low noise amplifier circuit is amplified the output terminal of front-end protection circuit; the input end of the output termination output matching network of low noise amplifier circuit; the external next stage parts of the output terminal of output matching network; the external radio-frequency power amplifier output port of radio-frequency switch circuit input end; the external probe of the output terminal of radio-frequency switch circuit; Working state checking circuit links to each other with switch signal generator by interface; the radio-frequency (RF) switch control level signal output part of Working state checking circuit connects the duty detection signal input end of radio-frequency (RF) switch control circuit, and dc bias circuit is connected with Working state checking circuit with low noise amplifier circuit respectively.
2. a kind of high-field nuclear magnetic resonance spectrometer X nuclear passage as claimed in claim 1 broadband prime amplifier is characterized in that described quatrter-wavelength line is the quarter-wave coaxial cable.
3. a kind of high-field nuclear magnetic resonance spectrometer X nuclear passage as claimed in claim 1 broadband prime amplifier; it is characterized in that circuit of described radio-frequency switch circuit and radio-frequency (RF) switch control circuit composition; amplify front-end protection circuit, low noise amplifier circuit and output matching network and form a circuit; Working state checking circuit is a circuit, is isolated by shielding cavity between the every circuit.
4. a kind of high-field nuclear magnetic resonance spectrometer X nuclear passage as claimed in claim 1 broadband prime amplifier is characterized in that described radio-frequency switch circuit is the two-stage series connection PIN diode.
5. a kind of high-field nuclear magnetic resonance spectrometer X nuclear passage as claimed in claim 1 broadband prime amplifier, it is characterized in that described low noise amplifier circuit is the two-stage amplification circuit structure, first order amplifying circuit adopts low noise amplifier circuit, and second level amplifying circuit adopts silicon twin-stage Darlington amplifier tube.
6. a kind of high-field nuclear magnetic resonance spectrometer X nuclear passage as claimed in claim 1 broadband prime amplifier is characterized in that described amplification front-end protection circuit is three grades of PIN diode structures in parallel.
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| CN104820197A (en) * | 2015-05-01 | 2015-08-05 | 武汉中科波谱技术有限公司 | Pre-posed amplification system for nuclear magnetic resonance spectrometer or imaging instrument |
| CN105227149A (en) * | 2015-09-23 | 2016-01-06 | 中国石油大学(北京) | On-line NMR broadband RF signal power amplification circuit |
| CN105227149B (en) * | 2015-09-23 | 2018-03-27 | 中国石油大学(北京) | On-line NMR broadband RF signal power amplification circuit |
| CN108680883A (en) * | 2018-03-22 | 2018-10-19 | 中国科学院合肥物质科学研究院 | A kind of high-isolation active radio frequency duplexer for condensed state nuclear magnetic resonance |
| CN108680883B (en) * | 2018-03-22 | 2020-09-08 | 中国科学院合肥物质科学研究院 | High-isolation active radio frequency duplexer for condensed nuclear magnetic resonance |
| CN114401026A (en) * | 2021-12-22 | 2022-04-26 | 中国电波传播研究所（中国电子科技集团公司第二十二研究所） | TR subassembly device is synthesized to radio frequency |
| CN114401026B (en) * | 2021-12-22 | 2023-12-01 | 中国电波传播研究所（中国电子科技集团公司第二十二研究所） | Radio frequency comprehensive TR assembly device |
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