JPH05113474A - Control device for high frequency power for nuclear magnetic resonance - Google Patents

Abstract

PURPOSE:To bring out a sufficient performance as NMR by applying appropriate power to various kinds of probes. CONSTITUTION:The titled device is provided with the following controllers: a NMR controller 1 for setting the maximum permiscible power value of a probe by reference to a probe file 9 while reading the status set in the probe; and a power controller 2 for comparing the saturated power value of a power amplifier 6 reading from an amplifier data memory 3 for setting characteristics of the amplifier 6 with the maximum permissible power value of the probe receiving from the controller 1, and for setting the gain of a gain controller 5 provided to the front stage of the amplifier 6 and the attenuation quantity of an attenuator of the back stage of the amplifier 6. Both of the saturated output level and the linear gain of the amplifier 6 are controlled within a fixed range of performance, and the occurrence of the probe damage can be prevented because the output is saturated even if by any chance the input may become an excessive level.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high frequency power control device used in a nuclear magnetic resonance (NMR) device.

[0002]

2. Description of the Related Art An NMR apparatus observes an echo signal obtained from magnetization when a sample placed in a static magnetic field is irradiated with an electromagnetic wave of tens to hundreds of megahertz order. If too much, discharge may occur in the probe coil, resulting in damage. Normally, the power amplifier of an NMR spectrometer has a constant output, and various detection probes are attached to this power amplifier for use. Therefore, some probes easily cause the above-mentioned discharge. Therefore, in the past,
In order to avoid discharge in the probe, the output of the power amplifier has been set low and other measures have been taken.

[0003]

However, in the conventional method, the power is suppressed to a low level so that the discharge is not generated, and it is possible to apply an appropriately high power within the range in which the discharge is not generated by each probe. However, there is a problem in that the performance as NMR cannot be fully brought out.

The present invention is intended to solve the above-mentioned problems, in which an appropriate power is applied to various probes and the NM
It is an object of the present invention to provide a high frequency power control device for nuclear magnetic resonance capable of sufficiently obtaining the performance as R.

[0005]

In a nuclear magnetic resonance high-frequency power control apparatus according to the present invention, an oscillator output is amplified by a power amplifier and supplied to a probe. And the NMR controller for setting the maximum allowable power value of the probe by referring to the probe file, the saturation power value of the power amplifier read from the amplifier data storage where the characteristics of the power amplifier are set, and the NMR controller It is characterized in that it is provided with a power controller that compares the obtained maximum allowable probe power value and sets the gain and the attenuation amount of the gain controller and the attenuator provided in the front and rear stages of the power amplifier, respectively.

[0006]

According to the present invention, the maximum allowable power value of the probe is read from the probe file in which the probe status provided for each NMR probe is stored and the probe setting conditions are stored, while the power for each main frequency in each frequency range is read. By reading the saturation power value of the power amplifier from the amplifier data memory in which the amplification characteristics of the amplifier are set and comparing it with the maximum allowable power value, both the saturation output level and linear gain of the power amplifier are kept within a certain level. Even if the input becomes excessively high, the output is saturated and the probe damage can be prevented.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing a configuration of a control device of the present invention, FIG. 2 is a diagram showing input / output characteristics, and FIGS. 3 and 4 are gain corrections in a linear region when a saturation level is attenuated. It is a figure for explaining. In the figure, 1 is an NMR controller,
2 is a power controller, 3 is an amplifier data storage device, 4
Is an oscillator, 5 is a gain controller, 6 is a high frequency power amplifier, 7 is an attenuator, 8 is an NMR probe, 9 is a probe file, and 10 is an operating unit.

The NMR probe 8 is provided with a contact group, and the probe status for each type is coded and set depending on which contact is grounded. When the probe is set, the NMR controller 1 is used. The probe status code can be read. The probe file 9 records various probe setting conditions for the probe status (maximum limit power, usable sample name, usable frequency, necessity of sample cooling, magnetic field correction data number, etc.). The high-frequency power amplifier 6 has input / output characteristics as shown in FIG. 2 for each main measurement frequency in each frequency range (output value with respect to reference input in linear region / saturation region).
Are coded by the contact group and set, and when the high frequency power amplifier 6 is set, the coded information is read into the amplifier data storage unit 3. When the measurement condition is set by the operation of the operation unit 10, the NMR controller 1 sends necessary information to the power controller 2 in response to the setting. The power controller 2 reads the power characteristic and the amplification degree characteristic of the high frequency power amplifier 6 from the amplifier data storage device 3 and
Together with the information sent from the controller 1, the attenuation amount / amplification amount for the gain controller 5 and the attenuation amount for the attenuator 7 are determined and set.

The control in the linear region in the input / output characteristics of the high frequency power amplifier 6 will be described. For example, assuming that the input level of the NMR probe 8 is 2 W (33 dBm) such as during decoupling, the signal level sent from the oscillator 4 to the amplification system has a standard amplification factor of the variation of the high frequency power amplifier 6. The value obtained by dividing 33 dBm by
For example, it is -20 dBm. At this time, the gain controller 5 works so that the amplification degree of the entire amplification system (gain controller 5, high frequency power amplifier 6, attenuator 7) is 33 dBm − (− 20 dBm) = 53 dB.
If the attenuator 7 is 2 dB in dB, the gain G of the gain controller 5 is set to G = 53 dB- (56 dB-2 dB) =-1 dB.

Next, the full power control of the power amplifier 6 will be described. As the large output pulse power for NMR observation, the saturation power of the power amplifier is usually applied. That is, when the probe status code is read from the NMR probe 8, the NMR controller 1 refers to the probe file 9 and sets the maximum power value in the power controller 2. Power controller 2 is amplifier data memory 3
Then, the saturation power of the power amplifier 6 is read, and compared with the value read from the probe file 9, the gain is set in the gain controller 5 and the attenuation amount is set in the attenuator 7.

For example, assuming that the value set in the amplifier data storage 3 is an output of 150 W when the input level is 4 dBm, the maximum allowable power read from the probe file 9 for the status code of the attached NMR probe. Is 100 W, the power controller 2 refers to a table calculated in advance from two inputs of 150 W and 100 W, and sets the attenuation amount of 1.75 dB in the attenuator 7. As a result, the input / output characteristic of the entire amplification system changes from the broken line to the solid line as shown in FIG. 3, and the output saturation level is limited to 100 W.

However, as can be seen from FIG. 3, the output attenuator 7 adds 1.75 dB to the reference input of -20 dBm and the output of 2 W, so that the output of 2 W is attenuated to 1.34 W. .. Therefore, from the power controller 2 to the gain controller 5,
A command for amplifying the attenuation amount of 1.75 dB in the attenuator 7 is issued. As a result, as shown in FIG. 4, it becomes possible to match the input / output characteristics of the power amplifier with a constant reference of -20 dBm input for output 2 W and 4 dBm input for output 100 W.

It is also possible to set the maximum power by adjusting the input in the linear region of the input / output characteristics, but since the output changes as it is due to the change of the input signal, if the input becomes large, it may cause a probe error. There is a risk of damage due to excessive power being added, but if the output saturation region shown in Fig. 2 is used for full-power output for observation pulses, the output will be saturated and will not increase even if the input becomes large. It is possible to prevent damage to the probe.

[0014]

As described above, according to the present invention, both the saturated output level and the linear gain of a power amplifier having a relatively large variation can be kept within a certain level of performance, and the static characteristics of input and output can be obtained. Small power (2W) and large power (1
(00W) is combined, it is possible to instantly switch the small signal portion with large power, small power, and even small power by the gain control in the preceding stage of the power amplifier. In addition, even if the input becomes excessively high, the output will not be significantly higher in the saturation region, so the probe will not be damaged, and the applied power will not be affected by the same NMR spectrometer and power amplifier system. It can be used without damage even if various probes with restrictions are attached, and the saturation power and gain correction values are set for each frequency range, so the power is supplied to the probe with appropriate power and gain over a wide frequency range. It is possible to

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a power control device of the present invention.

FIG. 2 is a diagram showing input / output characteristics.

FIG. 3 is an explanatory diagram of input / output characteristics when a saturated output is attenuated.

FIG. 4 is a diagram showing an input / output characteristic in which the attenuation in a linear region when the saturated output is attenuated is corrected.

[Explanation of symbols]

1 ... NMR controller, 2 ... power controller, 3
… Amplifier data memory, 4… Oscillator, 5… Gain controller, 6… High frequency power amplifier, 7… Attenuator,
8 ... NMR probe, 9 ... Probe file, 10 ... Operation part.

Claims (1)

[Claims] 1. A nuclear magnetic resonance apparatus in which an oscillator output is amplified by a power amplifier and supplied to a probe,
While reading the status provided on the probe,
An NMR controller for setting the maximum allowable probe power value by referring to the probe file, the saturation power value of the power amplifier read from the amplifier data storage device in which the characteristics of the power amplifier are set, and the probe sent from the NMR controller. A high frequency power control device for nuclear magnetic resonance, comprising: a gain controller provided before and after a power amplifier, and a power controller for setting a gain and an attenuation amount of an attenuator, respectively, by comparing with an allowable maximum power value.