CN114726397A

CN114726397A - Radio frequency switching circuit, control method thereof, radio frequency transceiving link and magnetic resonance equipment

Info

Publication number: CN114726397A
Application number: CN202210389106.XA
Authority: CN
Inventors: 徐友磊; 张玉满; 侯方焰
Original assignee: Wuhan United Imaging Life Science Instrument Co Ltd
Current assignee: Wuhan United Imaging Life Science Instrument Co Ltd
Priority date: 2022-04-12
Filing date: 2022-04-12
Publication date: 2022-07-08

Abstract

The invention relates to a radio frequency switching circuit and a control method thereof, a radio frequency transceiving link and magnetic resonance equipment, wherein the radio frequency switching circuit comprises a switch control bridge circuit and a diode which are electrically connected, the switch control bridge circuit comprises at least one power device, and the diode is arranged on the radio frequency link; wherein, through the switching of the open-close of at least one power device of control, form at least one discharge circuit in the bridge circuit of switch control. The invention utilizes the bridge circuit to construct the switch control bridge circuit, different discharge loops are formed in the switch control bridge circuit through the on-off of the power device in the switch control bridge circuit, when the diode is in a switching state, the inherent recovery time is reduced by utilizing the discharge loops, the purpose of rapidly switching different radio frequency links is achieved, and the switching rate of the switch is improved.

Description

Radio frequency switching circuit, control method thereof, radio frequency transceiving link and magnetic resonance equipment

Technical Field

The invention relates to the technical field of radio frequency, in particular to a radio frequency switching circuit, a control method thereof, a radio frequency transceiving link and magnetic resonance equipment.

Background

In a magnetic resonance imaging apparatus, a radio frequency system is a functional unit that performs radio frequency excitation and receives and processes radio frequency signals. The radio frequency system comprises a radio frequency transmitting chain and a radio frequency receiving chain. The radio frequency transmitting link generates various radio frequency pulses meeting the sequence requirements under the action of the time schedule controller. The radio frequency receiving link receives magnetic resonance signals generated by a human body under the action of the time schedule controller.

In the existing magnetic resonance system, a radio frequency transceiving link needs to be switched by controlling the on or off of a diode, and because inherent recovery time exists in the state switching process of the diode, the switching of the radio frequency transceiving link is delayed. However, the broadband rf transceiving link for some switches often has a high requirement on the switching rate, which needs to reach several microseconds, but the existing scheme cannot meet the requirement.

Disclosure of Invention

In view of the above, it is desirable to provide a radio frequency switching circuit, a control method thereof, a radio frequency transceiver link and a magnetic resonance apparatus, so as to overcome the problem in the prior art that the inherent recovery time of a diode is apt to interfere with the switching rate of the radio frequency link.

In order to solve the above technical problem, the present invention provides a radio frequency switching circuit, including a switch control bridge circuit and a diode electrically connected, where the switch control bridge circuit includes at least one power device, and the diode is disposed on a radio frequency link; wherein at least one discharge loop is formed in the switch-controlled bridge circuit by controlling the switching of the at least one power device.

Further, the switch control bridge circuit adopts a full-bridge circuit structure and comprises a first rectifying circuit, a second rectifying circuit and a shunt branch circuit, wherein the first rectifying circuit is electrically connected to the anode of the diode, the second rectifying circuit is electrically connected to the cathode of the diode, and the shunt branch circuit is connected in parallel at two ends of the diode.

Further, the first rectifying circuit comprises a first inductor and a first capacitor which are electrically connected, a first resistor and a first power device which are connected in series, and a second power device which is electrically connected to the first power device.

Further, the second rectifying circuit comprises a second inductor and a second capacitor which are electrically connected, and a third power device and a fourth power device which are electrically connected.

Further, the shunt branch includes the fifth power device and a second resistor that are electrically connected in sequence, where: one end of the fifth power device, which is far away from the second resistor, is electrically connected to the anode of the diode, and one end of the second resistor, which is far away from the fifth power device, is electrically connected to the cathode of the diode.

The invention also provides a radio frequency transceiving link, which comprises the radio frequency switching circuit, at least one radio frequency receiving link and/or at least one radio frequency transmitting link, wherein a diode in the radio frequency switching circuit is respectively arranged on the at least one radio frequency receiving link and/or the at least one radio frequency transmitting link.

The invention also provides a control method of the radio frequency switching circuit, which is based on the radio frequency switching circuit and comprises the following steps:

acquiring a set transceiving state;

determining a radio frequency link formed between corresponding transmitting and receiving ends when the set transmitting and receiving state is reached according to the set transmitting and receiving state;

and controlling the on-off of at least one power device corresponding to each diode according to the formed radio frequency link, forming at least one discharge loop in a switch control bridge circuit, and reducing the inherent recovery time of each diode during the switching of the conduction state so as to accelerate the switching rate of the formed radio frequency link.

Further, the controlling, according to the formed radio frequency link, the switching of at least one power device corresponding to each diode, and forming at least one discharge loop in a switch control bridge circuit includes:

and controlling a corresponding switch to control the on-off of at least one power device in the bridge circuit according to the diode needing to be conducted on the formed radio frequency link, so that the diode needing to be conducted is conducted in the forward direction, and other diodes are cut off in the reverse direction.

Further, the at least one power device includes a first power device to a fifth power device, and the controlling of the on/off of at least one power device in the corresponding transceiver circuit to turn on the diode to be turned on and turn off the other diodes includes:

when the diode needs to be conducted in the forward direction, the first power device and the fourth power device are controlled to be conducted, and after the forward conduction is finished, the second power device, the fourth power device and the fifth power device are controlled to be conducted;

and when the diode needs to be reversely cut off, controlling the second power device and the third power device to be conducted, and after the reverse cut-off is finished, controlling the second power device, the fourth power device and the fifth power device to be conducted.

The present invention also provides a magnetic resonance apparatus comprising:

a scanner for generating magnetic resonance radio frequency signals;

at least one radio frequency transmit chain for processing the magnetic resonance radio frequency signals and transmitting magnetic resonance radio frequency signals;

at least one radio frequency receiving link for receiving the magnetic resonance radio frequency signal and converting the magnetic resonance radio frequency signal into a digital signal;

and according to the radio frequency switching circuit and the processor, the diodes in the radio frequency switching circuit are respectively arranged on at least one radio frequency receiving link and/or at least one radio frequency transmitting link, and the processor is used for executing the control method of the radio frequency switching circuit on the radio frequency switching circuit.

Compared with the prior art, the invention has the beneficial effects that:

in the radio frequency switching circuit, the on-off state of a diode in a transceiver circuit is switched, different radio frequency links are formed between transceiver ends, the radio frequency links are formed between the preset transceiver ends under the specific application requirement, the conversion of different transceiver states is realized, meanwhile, a plurality of power devices in a bridge circuit are controlled to be switched on and off by using a switch, different discharging loops are constructed in the switching process of controlling the on-off of the diode, electric charges are consumed through the circuit structure of the discharging loops, the inherent recovery time of the diode is reduced, the switching speed of the diode is accelerated, and therefore the switching speed of different radio frequency links is effectively improved.

In the control method of the radio frequency switching circuit, firstly, the set receiving and sending state is effectively obtained; then, according to the set transceiving state, determining a preset transceiving end; and finally, determining a radio frequency link which is required to be formed by a preset transceiving end corresponding to different set transceiving states, controlling the on-off of a power device in a transceiving circuit corresponding to each diode in the radio frequency link, constructing different discharge loops when the diodes are switched to be in an on state or an off state, accelerating the switching rate of the discharge loops, forming the radio frequency link corresponding to the set transceiving state under the combination of the on state and the off state of different diodes, reducing the influence caused by inherent recovery time when the diodes are switched, and accelerating the efficiency when the radio frequency link is switched.

In the magnetic resonance equipment, a processor is used for executing a related control method on the radio frequency switching circuit, the switching of a power device is effectively controlled, and the switching of the on-off state of a diode is accelerated, so that the switching efficiency of a radio frequency link is accelerated, and the rapidity of the magnetic resonance equipment for switching different receiving and transmitting states is ensured.

In summary, the invention uses the bridge circuit to construct the switch control bridge circuit, and forms different discharge loops in the switch control bridge circuit through the on/off of the power device therein, when the diode switches state, the inherent recovery time of the diode is reduced by using the discharge loop, thereby achieving the purpose of rapidly switching different radio frequency links, and effectively improving the switch switching rate.

Drawings

Fig. 1 is a schematic structural diagram of an embodiment of a radio frequency switching circuit according to the present invention;

FIG. 2 is a schematic diagram of an embodiment of a switch-controlled bridge circuit according to the present invention;

FIG. 3 is a schematic diagram of a switch-controlled bridge circuit according to an embodiment of the present invention;

FIG. 4 is a schematic structural diagram of a diode according to an embodiment of the present invention in a forward conduction mode;

FIG. 5 is a schematic diagram of a specific structure of an embodiment of a diode reverse recovery discharge provided by the present invention;

FIG. 6 is a schematic diagram of an embodiment of a reverse cut-off according to the present invention;

FIG. 7 is a schematic diagram of a specific structure of an embodiment of a diode forward recovery discharge provided by the present invention;

fig. 8 is a schematic structural diagram of an embodiment of a radio frequency transceiving link provided in the present invention;

FIG. 9 is a schematic diagram of a specific structure of an embodiment of a radio frequency transceiving link according to the present invention

FIG. 10 is a schematic structural diagram of an embodiment of a driving rear-stage transmitting coil provided in the present invention;

fig. 11 is a schematic flowchart illustrating a control method of the rf switch circuit according to an embodiment of the present invention;

fig. 12 is a schematic structural diagram of a control device of an rf switching circuit according to an embodiment of the present invention.

Detailed Description

The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate preferred embodiments of the invention and together with the description, serve to explain the principles of the invention and not to limit the scope of the invention.

In the description of the present invention, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implying any number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. Further, "plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.

Reference throughout this specification to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the present invention. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. It is explicitly and implicitly understood by one skilled in the art that the described embodiments can be combined with other embodiments.

The invention provides a radio frequency switching circuit and a control method thereof, a radio frequency transceiving link and magnetic resonance equipment, wherein the conduction of diodes between different transceiving ends is controlled by a plurality of power devices in a switch control bridge circuit, the switching speed of the states of the diodes is improved, different radio frequency links are formed between different transceiving ends, and a new thought is provided for further improving the rapidity of a radio frequency link switching switch.

Before describing the specific embodiments, the terms involved are to be construed accordingly as follows:

a magnetic resonance apparatus: generally comprises a magnetic resonance machine frame, a main magnet is arranged in the machine frame, and the main magnet can be formed by a superconducting coil and is used for generating a main magnetic field; during magnetic resonance imaging, an imaging object is carried by a sickbed and is moved into a region with uniform magnetic field distribution of a main magnetic field along with the movement of the sickbed, a pulse control unit in magnetic resonance equipment controls a radio-frequency pulse generating unit to generate radio-frequency pulses, the imaging object generates corresponding magnetic resonance signals by resonance according to radio-frequency excitation, and the imaging object can be acquired by a radio-frequency body coil or a local coil and carries out image reconstruction according to the magnetic resonance signals to form a magnetic resonance image;

and the radio frequency transceiving link: acquiring frequency signals corresponding to nuclides concerned by specific application for analysis, wherein the analysis result can provide important data support for clinical, preclinical and advanced scientific research achievements of experts in a specific field; comprises a transmitting link and a receiving link; in a transmitting link, a radio frequency pulse is amplified by a radio frequency power amplifier, passes through a switch control unit and is finally emitted by a radio frequency body coil or a local coil to carry out radio frequency excitation on an imaging object; similarly, in the receiving link, the radio frequency body coil or the local coil collects the signals through the switch control unit, namely the radio frequency receiving coil collects the signals;

multi-core transmit/receive state: when the load of the radio frequency link is a multi-core coil and the radio frequency link is a transmitting link, the radio frequency link is in a multi-core transmitting state; when the load of the radio frequency link is a multi-core coil and the radio frequency link is a receiving link, the radio frequency link is in a multi-core receiving state; multi-core transmission means that the frequencies transmitted in different time periods are different (for example, the first time period t1 is 20MHz, the second time period t2 is 40MHz, the third time period t3 is 60MHz, etc.), and a common narrow-band (for example, 60MHz ± 1MHz) radio frequency switch cannot be compatible with such multiple frequencies, so that a multi-core transmission switch is required;

based on the above technical terms, in the prior art, the self-sending and self-receiving of the multi-core radio frequency coil requires the control of the broadband radio frequency switch to form different radio frequency receiving and transmitting links, and the radio frequency transmitting links or the radio frequency receiving links also require the on-off control of the radio frequency switch, and the control of the switch is realized by controlling the switching between the on state and the off state of the diode, but the inherent recovery characteristic of the diode requires a certain time to discharge, which affects the switching rate of the switch.

Modern pulse circuits use transistors or diodes as switches in large numbers or use logic integrated circuits which are mainly composed of them. The diode used as a switch mainly utilizes the on (small resistance) and off (large resistance) characteristics of the diode, namely the switching action of the diode on forward and reverse currents. Diodes differ from ordinary switches in that "on" and "off" are determined by the polarity of the applied voltage, and there is a slight voltage drop in the "on" state and a slight current in the "off" state. When the voltage changes from the forward direction to the reverse direction, the current does not reach the preset state immediately, but the reverse current is always large in a period of time, and the diode is not turned off. After a period of time, the reverse current gradually decreases, and after a period of time, the current of the diode reaches a preset state. This is actually caused by the charge storage effect, the intrinsic recovery time being the time required for the stored charge to deplete, and the time it takes to reach a predetermined state, which varies, is called the intrinsic recovery time.

Wherein the intrinsic recovery time includes a forward recovery time and a reverse recovery time. When the switch transitions from an on-state to an off-state, the diode or rectifier needs to first discharge the stored charge before the diode blocks the reverse current, this discharge time being referred to as the reverse recovery time during which current flows in reverse through the diode. That is, the time from when the forward conduction current is 0 to when the fully off state is entered; otherwise, the time is the forward recovery time.

Therefore, in order to solve the above problems, the present invention provides a radio frequency switching circuit and a control method thereof, a radio frequency transceiving link, and a magnetic resonance apparatus, which are described in detail below:

the embodiment of the present invention provides a radio frequency switching circuit, and as seen in fig. 1, fig. 1 is a schematic structural diagram of an embodiment of the radio frequency switching circuit provided by the present invention, the radio frequency switching circuit 1 includes a switch control bridge circuit 101 and a diode D which are electrically connected, the switch control bridge circuit 101 includes at least one power device, and the diode D is disposed on a radio frequency link; wherein at least one discharge loop is formed in the switch-controlled bridge circuit 101 by controlling the switching of at least one power device.

In the embodiment of the invention, in the radio frequency switching circuit, the on-off state of a diode in the transceiver circuit is changed, different radio frequency links are formed between the transceiver ends, so that the conversion of different transceiver states is realized, meanwhile, a switch is utilized to control the on-off of a plurality of power devices in the bridge circuit, different discharging loops are constructed in the switching process of controlling the on-off of the diode, and the circuit structure of the discharging loops consumes charges, so that the inherent recovery time of the diode is avoided, the switching speed of the diode is accelerated, and the switching speed of different radio frequency links is effectively improved.

It should be noted that the diode itself has a forward recovery time and a reverse recovery time, i.e., an inherent recovery time, which affects the switching rate of the circuit. Thus, the present invention constructs a discharge loop, avoiding the inherent recovery time of the diode. In addition, a large LC filter circuit exists in a dc path of a general rf switching circuit, which affects the discharge time of charges, and the construction of a discharge loop can consume charges and accelerate the switching rate thereof.

In a preferred embodiment, the one or more power devices are GaN power devices.

It should be noted that the rf switch needs to use a broadband rf switch. Broadband radio frequency switches generally fall into two categories: an integrated device class and a discrete device class. The integrated device has a high speed, is still in the us level, is expensive and has low overall compatible transmitting power; the speed of the separating devices is low, the circuit is relatively complex, and the occupied area of the PCB is large. The existing scheme selects switching devices such as MOSFET, solid-state relay and IGBT to switch forward current and reverse high voltage, the switching speed of the devices is generally low, the impact of electric charge in the switching moment is large, large dynamic power consumption is brought to the whole circuit, and meanwhile, the requirement on the driving capability of negative high voltage is high.

In the embodiment of the invention, in order to solve the problem that the existing switching device cannot meet the switching requirement of magnetic resonance at a faster and faster speed, the GaN power device is adopted, and because the PN junction does not exist, a body diode does not exist, and therefore the problem of reverse recovery does not exist, and the switching speed can be greatly improved. On one hand, the switching efficiency of the GaN power device is much higher than that of an MOSFET transistor and an IGBT transistor, so that the size of the GaN power device can be small, and the size of a control unit is effectively reduced; on the other hand, the GaN power device has no reverse recovery time, so that the reverse recovery time can be further avoided, and the switching efficiency of the switch is improved.

As a preferred embodiment, referring to fig. 2, fig. 2 is a schematic structural diagram of an embodiment of a switching control bridge circuit provided by the present invention, and the switching control bridge circuit 101 adopts a full-bridge circuit structure and includes a first rectifying circuit 201, a second rectifying circuit 202 and a shunt branch 203, wherein the first rectifying circuit 201 is electrically connected to an anode of a diode D, the second rectifying circuit 202 is electrically connected to a cathode of the diode D, and the shunt branch 203 is connected in parallel to two ends of the diode D.

In the embodiment of the invention, a full-bridge circuit structure is adopted, a circuit structure formed by a first rectifying circuit, a second rectifying circuit and a shunt branch is utilized, electric signal transmission among the first rectifying circuit, the second rectifying circuit and the shunt branch is utilized at two ends of a diode through the shunt branch to trigger the conduction of the diode, and the corresponding control switching time sequence is carried out.

As a preferred embodiment, referring to fig. 3, fig. 3 is a schematic diagram of a specific structure of an embodiment of a switching control bridge circuit provided by the present invention, where the power devices include a first power device Q1 to a second power device Q2, the first rectification circuit 201 includes a first inductor L1 and a first capacitor C1, which are electrically connected in sequence, a first resistor R1 and a first power device Q1 connected in series, and a second power device Q2 electrically connected to the first power device Q1, where:

one end of the first resistor R1, which is far away from the first power device Q1, is connected to a first preset voltage V1, one end of the second power device Q2, which is far away from the first power device Q1, is grounded, one end of the first inductor L1, which is near to the first capacitor C1, is electrically connected between the first power device Q1 and the second power device Q2, one end of the first inductor L1, which is far away from the first capacitor C1, is electrically connected to an anode of the diode D, and one end of the first capacitor C1, which is far away from the first inductor L1, is grounded.

In the embodiment of the invention, through the electric connection structure among the first resistor, the first power device, the second power device, the first inductor and the first capacitor, the on-voltage or the off-voltage is effectively applied to the diode to promote the diode to be switched on or off, and the circuit devices in the first rectifying circuit are utilized to construct the discharge loops related to the two ends of the diode to promote the diode to quickly consume electric charges, so that the aims of reducing the inherent recovery time length and improving the switching rate of the switch are fulfilled.

As a more specific example, the source of the first power device Q1 is electrically connected to the drain of the second power device Q2, the drain of the first power device Q1 is electrically connected to the first resistor R1, and the source of the second power device Q2 is grounded. In the embodiment of the invention, the connection structure of the first power device Q1 and the second power device Q2 effectively utilizes the characteristics of field effect transistors, realizes the conduction control of a circuit, and constructs a corresponding discharge loop. In addition, referring to fig. 3, the first power device Q1 is taken as an example (the other power devices are the same as the first power device Q1), the source is the labeled S pole, the drain is the labeled D pole, and the gate is the labeled G pole.

As a preferred embodiment, still referring to fig. 3, the power devices include a third power device Q3 to a fourth power device Q4, the second rectification circuit 202 includes a second inductor L2 and a second capacitor C2 which are electrically connected in sequence, and a third power device Q3 and a fourth power device Q4 which are electrically connected in sequence, wherein:

one end of the third power device Q3, which is far away from the fourth power device Q4, is connected to the second preset voltage V2, one end of the fourth power device Q4, which is far away from the third power device Q3, is grounded, one end of the second inductor L2, which is near to the second capacitor C2, is electrically connected between the third power device Q3 and the fourth power device Q4, one end of the second inductor L2, which is far away from the second capacitor C2, is electrically connected to the cathode of the diode D, and one end of the second capacitor C2, which is far away from the second inductor L2, is grounded.

In the embodiment of the invention, through the electric connection structure among the third power device, the fourth power device, the second inductor and the second capacitor, the on-voltage or the off-voltage is effectively applied to the diode to enable the diode to be switched on or off, and the circuit device in the second rectifying circuit is matched with the circuit device in the first rectifying circuit to construct the discharging loop related to the two ends of the diode, so that the diode can quickly consume electric charges, and the purposes of shortening the inherent recovery time and improving the switching rate of the switch are achieved.

As a more specific example, the source of the third power device Q3 is electrically connected to the drain of the fourth power device Q4, the drain of the third power device Q3 is connected to a second predetermined voltage, and the source of the fourth power device Q4 is connected to ground. In the embodiment of the invention, the connection structure of the third power device Q3 and the fourth power device Q4 effectively utilizes the characteristics of field effect transistors thereof to realize the conduction control of a circuit and construct a corresponding discharge loop.

In a specific embodiment, the first predetermined voltage V1 is +5V, and the second predetermined voltage V2 is + 200V. In the embodiment of the invention, the diode is effectively driven to be switched on or switched off by applying the forward small voltage and the reverse high voltage to the two ends of the diode.

It should be noted that a small forward voltage, for example, a first preset voltage (corresponding to a current of, for example, 100mA) is applied to the diode to turn on the diode (after being turned on, the diode is equivalent to a low impedance, for example, 0.1 Ω, with respect to the rf signal), and a high reverse voltage, for example, a second preset voltage is applied to turn off the diode (when being turned off, the diode is equivalent to a high impedance, for example, 1M Ω, with respect to the rf signal), and a voltage value is related to the input power, for example, 1kW approximately corresponds to about 250V.

As a preferred embodiment, still referring to fig. 3, the power device includes a fifth power device Q5, and the shunt branch includes a fifth power device Q5 and a second resistor R2 electrically connected in sequence, where: an end of the fifth power device Q5 away from the second resistor R2 is electrically connected to an anode of the diode D, and an end of the second resistor R2 away from the fifth power device Q5 is electrically connected to a cathode of the diode D.

In the embodiment of the invention, the first rectifying circuit and the second rectifying circuit are electrically connected by utilizing the parallel connection structure of the shunt branch circuit at the two ends of the diode, so that a plurality of discharging loops are effectively constructed at the two ends of the diode, discharging can be accelerated by utilizing the resistance value of the second resistor, and the switching speed is accelerated.

As a more specific example, the source of the fifth power device Q5 is electrically connected to the anode of the diode D, and the drain of the fifth power device Q5 is electrically connected to the second resistor R. In the embodiment of the invention, the conduction control of the circuit is realized through the characteristics of the field effect transistor of the fifth power device Q5, and a corresponding discharge loop is constructed.

It should be noted that the discharge time is mainly determined by the equivalent resistances of the second resistor R2 and the first inductor L1 and the second inductor L2, because the amount of the charge accumulated in a single cycle is fixed, the charge is consumed by converting the charge into heat through the resistors, the larger the relative resistance value is, the faster the charge is discharged, but the larger the resistance value is, the current of the discharge loop is also reduced.

In a specific embodiment of the present invention, still referring to fig. 3, the anode of the diode D1 is electrically connected to the receiving terminal RFIN through the third capacitor C3, the cathode of the diode D1 is electrically connected to the transmitting terminal RFOUT through the fourth capacitor C4, and when the diode D1 is turned on, the rf link is passed through from RFIN to RFOUT1, forming a transmitting state.

Referring to fig. 4 to 7, fig. 4 is a schematic structural diagram of an embodiment of forward conduction of a diode provided by the present invention, fig. 5 is a schematic structural diagram of an embodiment of reverse recovery discharge of a diode provided by the present invention, fig. 6 is a schematic structural diagram of an embodiment of reverse cut-off provided by the present invention, fig. 7 is a schematic structural diagram of an embodiment of forward recovery discharge of a diode provided by the present invention, a principle that a radio frequency switching circuit forms different discharge loops to accelerate a switching rate is described with a specific embodiment, and a control timing sequence thereof is described as follows:

taking fig. 4 as an example, the first power device Q1 and the fourth power device Q4 are controlled to be turned on, and the other power devices are turned off, so that the diode D1 is forward-turned on, wherein a forward small voltage (a first preset voltage) is applied to the diode D1 to cause the diode D1 to be forward-turned on;

taking fig. 5 as an example, after the forward conduction of the diode D1 is finished, the second power device Q2, the fourth power device Q4 and the fifth power device Q5 are controlled to be turned on, and the first power device Q1 and the third power device Q3 are controlled to be turned off, at this time, because of the existence of the first inductor L1 and the second inductor L2, the direction of the instantaneous current remains unchanged, and two discharge loops are formed as follows:

1. the charges sequentially pass through a fifth power device Q5, a second resistor R2, a second inductor L2, a fourth power device Q4, GND, a second power device Q2 and a first inductor L1;

2. the charges sequentially pass through the anode of the diode D1, the fifth power device Q5, the second resistor R2 and the cathode of the diode D1;

after the forward conduction of the diode D1 is completed, the fourth power device Q4, GND and the second power device Q2 are quickly consumed through the second resistor R2; meanwhile, due to the parasitic capacitance effect of the diode D1, the anode assumes a positive polarity, and positive charge is dissipated via the fifth power device Q5 and the second resistor R2. The current directions of the two discharging paths are consistent, the discharging paths are discharged by the second resistor R2, and the resistance value of the second resistor R2 can be adjusted to accelerate the discharging time;

taking fig. 6 as an example, the second power device Q2 and the third power device Q3 are controlled to be turned on, and the other power devices are turned off, so that the diode D1 is reversed, wherein a reverse high voltage (a second preset voltage) is applied to the diode D1 to cause the diode D1 to be reversely turned off;

taking fig. 7 as an example, after the diode D1 is turned off in the reverse direction, the second power device Q2, the fourth power device Q4 and the fifth power device Q5 are controlled to be turned on, and the first power device Q1 and the third power device Q3 are controlled to be turned off, at this time, because of the existence of the first inductor L1 and the second inductor L2, the direction of the instantaneous current remains unchanged, and two discharge loops are formed as follows:

1. the charges sequentially pass through a fifth power device Q5, a first inductor L1, a second power device Q2, GND, a fourth power device Q4, a second inductor L2 and a second resistor R2;

2. the charges sequentially pass through the cathode of the diode D1, the second resistor R2 and the anode of the diode D1 of the fifth power device Q5;

after the diode D1 is turned off in the reverse direction, the second power device Q2, the fourth power device Q4, and the fifth power device Q5 are turned on, the first power device Q1, and the third power device Q3 are turned off, and at this time, charges stored in the first inductor L1, the second inductor L2, and the diode D1 are released through two paths, so that rapid discharge is completed.

It should be further noted that when the diode D1 is electrically connected to the first receiving terminal RFIN and the first transmitting terminal RFOUT1 through the third capacitor C3 and the fourth capacitor C4, respectively, when the diode D1 is turned on (by the first power device Q1 and the fourth power device Q4), a radio frequency link is formed between the first receiving terminal RFIN and the first transmitting terminal RFOUT 1; when a radio frequency link does not need to be formed between the first receiving end RFIN and the first transmitting end RFOUT1, when the diode D1 is switched from on to off, after the forward conduction of the diode D1 is finished, the second power device Q2, the fourth power device Q4 and the fifth power device Q5 are controlled to be on, the first power device Q1 and the third power device Q3 are controlled to be off, two discharge loops are constructed, the inherent recovery time of the two discharge loops is shortened, the second power device Q2 and the third power device Q3 are controlled to be on, and the other power devices are controlled to be off, so that the diode D1 is reversed, the switching rate is increased, and the rapidness of switching of a radio frequency link switch is improved.

Fig. 8 is a schematic structural diagram of an embodiment of the radio frequency transceiving link provided by the present invention, and the radio frequency transceiving link includes the radio frequency switching circuit 1, at least one radio frequency receiving link and/or at least one radio frequency transmitting link, as described above, and the diode D in the radio frequency switching circuit 1 is respectively disposed on the at least one radio frequency receiving link and/or the at least one radio frequency transmitting link.

In the embodiment of the invention, the radio frequency switching circuit is arranged on the radio frequency link to switch the on-off state of a diode in the radio frequency switching circuit, different radio frequency links are formed between the receiving end and the transmitting end, the radio frequency link is formed between the preset transmitting and receiving ends under the specific application requirement, the conversion of different transmitting and receiving states is realized, meanwhile, a switch is utilized to control the on-off of a plurality of power devices in the bridge circuit, different discharging loops are constructed in the switching process of controlling the on-off of the diode, the inherent recovery time of the diode is reduced through the circuit structure consumption charge of the discharging loop, the switching speed of the diode is accelerated, and the switching speed of different radio frequency links is effectively improved.

As a preferred embodiment, the at least one radio frequency receive chain or the at least one radio frequency transmit chain comprises a receive end and a transmit end, between which at least one diode D is arranged.

In the embodiment of the invention, the on-off between the receiving end and the transmitting end is effectively controlled by the on-off of the diode.

As a preferred embodiment, both ends of the diode are electrically connected to one end of the receiving/transmitting/another diode through a capacitor.

In the embodiment of the invention, two ends of each diode are electrically connected to the transmitting end, the receiving end or one end of another diode through a capacitor, and each diode is loaded with a corresponding switch control bridge circuit at the two ends. In the embodiment of the invention, the radio frequency link formed by conducting a plurality of diodes is formed through the electric connection relationship between the diodes and the electric connection structure between the diodes and the transmitting end or the receiving end, so that the aim of switching different radio frequency links is fulfilled. It can be understood that the aforementioned transceiving end includes a transmitting end and a receiving end.

As a preferred embodiment, referring to fig. 9, fig. 9 is a schematic structural diagram of an embodiment of a radio frequency transceiving link provided by the present invention, where the radio frequency transceiving link includes a multi-core receiving link, and at least one radio frequency transmitting link includes a multi-core transmitting link and a hydrogen-core transmitting link, where:

a first diode D1 and a fourth diode D4 are arranged between the receiving end and the transmitting end of the multi-core transmitting link;

a third diode D3 is arranged between the receiving end and the transmitting end of the multi-core receiving link;

and a second diode D2 is arranged between the receiving end and the transmitting end of the hydrogen nuclear transmitting chain.

In the embodiment of the invention, the on-off of the related radio frequency links is triggered by setting the radio frequency links and utilizing the on-off of the diodes, so that the conversion of different radio frequency receiving states or radio frequency transmitting states is realized.

Referring to fig. 9, a specific embodiment of the radio frequency switching circuit for multi-core self-transmitting and self-receiving switching is described as follows:

when there are a first receiving terminal RFIN, a second receiving terminal RX, a first transmitting terminal RFOUT1, and a second transmitting terminal RFOUT2, the first receiving terminal RFIN is electrically connected to the first transmitting terminal RFOUT1 through a first diode D1 and a fourth diode D4, the first receiving terminal RFIN is electrically connected to the second transmitting terminal RFOUT2 through a second diode D2, the second receiving terminal RX is electrically connected to the second transmitting terminal RFOUT2 through a third diode D3, and the first diode D1 to the fourth diode D4 are all correspondingly provided with a switch control bridge circuit (the switch control bridge circuit corresponding to the diode is omitted, and is respectively loaded at two ends of the corresponding diode), wherein:

when the first diode D1 and the fourth diode D4 are turned on and the second diode D2 and the third diode D3 are turned off, the radio frequency link is connected from the first receiving terminal RFIN to the first transmitting terminal RFOUT1, the load is a multi-core coil, and at this time, the load is in a multi-core transmitting state;

when the third diode D3 is turned on and the first diode D1, the second diode D2 and the fourth diode D4 are turned off, the radio frequency link is from the first transmitting end RFOUT1 to the second receiving end RX, and the radio frequency signal returned by the multicore coil is sent to the acquisition system, and at this time, the multicore receiving state is achieved;

when the second diode D2 is turned on and the first diode D1, the fourth diode D4 and the third diode D3 are all turned off, the radio frequency link from the first receiving terminal RFIN to the second transmitting terminal RFOUT2 may be connected to the hydrogen nuclear transmitting coil at the rear end, which is a state in which the multi-nuclear transmission is converted into the hydrogen nuclear transmission;

it should be noted that multi-core transmission refers to that the frequencies transmitted in different time periods are different (for example, t1 is 20MHz, t2 is 40MHz, t3 is 60MHz, etc.), and a common narrow-band (for example, 60MHz ± 1MHz) radio frequency switch cannot be compatible with such multiple frequencies, so that a multi-core transmission switch is required;

further, in the multi-core self-receiving and self-transmitting coil unit, the switching of the TX/RX link is completed through the switching circuit, taking the fourth diode D4 and the third diode D3 as an example, the fourth diode D4 turns on the third diode D3 and turns off, and the transmitting state is set; the fourth diode D4 turns off the third diode D3 and turns on, and is in a receiving state;

meanwhile, the selection of the transmission chain may also be performed by controlling the first diode D1 and the second diode D2. Such as: the first diode D1 is used for controlling the multi-core transmission link; the second diode D2 can be selected as the 1H nuclear transmit channel, etc. (the latter stage can be connected to a 3dB bridge, outputting orthogonally coupled radio frequency signals to drive the latter stage transmit coil).

It should be noted that, referring to fig. 10, fig. 10 is a schematic structural diagram of an embodiment of the driving rear-stage transmitting coil provided by the present invention, where port 1 is an input port, ports 2 and 3 are output ports, port 4 is an isolation port, and is connected to 50 Ω, and the circuit function is to generate rf signals with equal power and 90 ° phase difference, and it can be known from fig. 9 that the rf signals have a direct relationship with the input signal wavelength (i.e., frequency) and can only be applied to rf transmission under a narrow band, and therefore, the rf signals are only used under hydrogen nuclear transmission to output orthogonally coupled rf signals to drive the rear-stage transmitting coil.

An embodiment of the present invention provides a method for controlling a radio frequency switching circuit, based on the method for controlling a radio frequency switching circuit described above, and with reference to fig. 11, fig. 11 is a flowchart illustrating an embodiment of the method for controlling a radio frequency switching circuit provided by the present invention, and includes steps S1101 to S1102, where:

in step S1101, a set transmission/reception state is acquired;

in step S1102, according to the set transceiving state, determining a radio frequency link formed between the corresponding transceiving ends when the set transceiving state is reached;

in step S1103, the on/off of at least one power device corresponding to each diode is controlled according to the formed rf link, at least one discharging loop is formed in the switch control bridge circuit, and the intrinsic recovery time when the on state of each diode is switched is reduced, so as to accelerate the switching rate of the formed rf link.

In the embodiment of the invention, firstly, the set transceiving state is effectively obtained; then, corresponding to different set receiving and transmitting states, the on-off of a power device in the receiving and transmitting circuit corresponding to each diode is controlled, when the diodes are switched to be in the on-off state, different discharging loops are constructed, the switching speed of the discharging loops is accelerated, and under the combination of the on-off states of the different diodes, a radio frequency link in the set receiving and transmitting state is formed, so that the influence caused by inherent recovery time when the diodes are switched is reduced, and the efficiency when the radio frequency link is switched is accelerated.

As a preferred embodiment, the step S1102 includes:

according to the formed diode needing to be conducted on the radio frequency link, the corresponding switch is controlled to control the on-off of at least one power device in the bridge circuit, so that the diode needing to be conducted is conducted in the forward direction, and other diodes are cut off in the reverse direction.

In the embodiment of the invention, a radio frequency link which needs to be formed correspondingly is determined according to a set receiving and sending state, a diode which needs to be conducted for forming the radio frequency link is determined, switches loaded at two ends of the diode are controlled to control the on and off of a power device in a bridge circuit, the diode is enabled to be conducted or cut off, and in the switching process, a discharge loop constructed by the power device is utilized to accelerate the switching rate of the discharge loop.

Specifically, still referring to fig. 9, the set transceiving states include a multi-core transmitting state, a multi-core receiving state, and a hydrogen core transmitting state, and according to different set transceiving states, a diode that needs to be turned on and a diode that needs to be turned off are determined, and a corresponding switch is controlled to control the on/off of a power device in the bridge circuit to perform state switching on the corresponding diode. The diodes that need to be turned on or off corresponding to the multi-core emission state, the multi-core reception state, and the hydrogen-core emission state are referred to the above description, and are not described herein again.

As a preferred embodiment, the controlling of the on/off of at least one power device in the corresponding transceiver circuit to turn on the diode to be turned on and turn off the other diodes includes:

when the diode D needs to be conducted in the forward direction, the first power device Q1 and the fourth power device Q4 are controlled to be conducted, and after the forward conduction is finished, the second power device Q2, the fourth power device Q4 and the fifth power device Q5 are controlled to be conducted;

when the diode D needs to be reversely cut off, the second power device Q2 and the third power device Q3 are controlled to be turned on, and after the reverse cut-off is finished, the second power device Q2, the fourth power device Q4 and the fifth power device Q5 are controlled to be turned on.

In the embodiment of the invention, the on-off of the diode is promoted by utilizing the on-off of the relevant power device, and meanwhile, different discharge loops are constructed in the process of switching the state by utilizing the on-off time sequence of the relevant power device, so that the switching speed of the discharge loops is accelerated.

The following explains the technical solution of the present invention more clearly with a specific application example and still referring to fig. 9:

the method comprises the steps of firstly, acquiring a set transceiving state as a multi-core transmitting state; it should be noted that, the setting can be performed by the relevant user according to the actual scanning requirement;

in the second step, when the multi-core transmission state is determined, the corresponding radio frequency link is directly connected from the first receiving terminal RFIN to the first transmitting terminal RFOUT1, the first diode D1 and the fourth diode D4 between the first receiving terminal RFIN and the first transmitting terminal RFOUT1 need to be connected, and other diodes (the second diode D2 and the third diode D3) need to be cut off;

for the first diode D1 and the fourth diode D4, the power devices loaded in the switch control bridge circuit at the two ends are controlled to be turned on, taking the first diode D1 as an example, the first power device Q1 and the fourth power device Q4 are controlled to be turned on, and the other power devices are turned off, so that the diode D1 is turned on in the forward direction; if the original state of the first diode D1 is reverse cut-off, when the reverse cut-off is finished, the second power device Q2, the fourth power device Q4 and the fifth power device Q5 are controlled to be switched on, the first power device Q1 and the third power device Q3 are controlled to be switched off, the first power device Q1 and the fourth power device Q4 are controlled to be switched on, and other power devices are switched off, so that the inherent recovery time is shortened, the speed of switching the state is increased, and the switching speed of the whole radio frequency link is ensured;

for the second diode D2 and the third diode D3, the corresponding switches loaded at the two ends are controlled to control the power devices in the bridge circuit to be turned off. The switching sequence and the switching principle of the specific turn-off process are similar to those of the turn-on process, and are referred to the above description, and are not described herein again.

An embodiment of the present invention further provides a magnetic resonance apparatus, including:

a scanner for generating a main magnetic field and capable of exciting nuclear spins of a plurality of specific nuclear species of an examination object in the main magnetic field to generate magnetic resonance radio frequency signals;

at least one radio frequency transmission link, including a broadband radio frequency power amplifier, a driving circuit module, a transmission filtering module, a first firmware and a digital-to-analog converter, for processing the magnetic resonance radio frequency signal and transmitting the magnetic resonance radio frequency signal;

at least one radio frequency receiving link, including a secondary amplifier, a second firmware, a receiving filter module and an analog-to-digital converter, for receiving the magnetic resonance radio frequency signal and converting the magnetic resonance radio frequency signal into a digital signal;

and, according to the radio frequency switching circuit and the processor as described above, the diode (D) in the radio frequency switching circuit is disposed on at least one radio frequency receive link and/or at least one radio frequency transmit link, and the processor is configured to perform the control method of the radio frequency switching circuit as described above on the radio frequency switching circuit.

For a more detailed implementation of each unit of the magnetic resonance apparatus, reference may be made to the description of the radio frequency switching circuit and the control method thereof, and similar beneficial effects may be obtained, and details are not described herein again.

Fig. 12 is a schematic structural diagram of an embodiment of a control device of a radio frequency switching circuit, where fig. 12 is combined with fig. 12, and the control device 1200 of the radio frequency switching circuit includes:

an obtaining unit 1201, configured to obtain a set transceiving state;

a processing unit 1202, configured to determine, according to a set transceiving state, a radio frequency link formed between corresponding transceiving ends when the set transceiving state is reached;

the control unit 1203 is configured to control, according to the formed radio frequency link, on/off of at least one power device corresponding to each diode, form at least one discharge loop in the switch control bridge circuit, and reduce an inherent recovery time when the conduction state of each diode is switched, so as to increase a switching rate of the formed radio frequency link.

For a more detailed implementation of each unit of the control apparatus of the radio frequency switching circuit, reference may be made to the description of the control method of the radio frequency switching circuit, and similar beneficial effects are obtained, and details are not repeated herein.

An embodiment of the present invention further provides a computer-readable storage medium, on which a computer program is stored, where the computer program, when executed by a processor, implements the control method for the radio frequency switching circuit as described above.

Generally, computer instructions for carrying out the methods of the present invention may be carried using any combination of one or more computer-readable storage media. Non-transitory computer readable storage media may include any computer readable medium except for the signal itself, which is temporarily propagating.

A computer readable storage medium may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination of the foregoing. More specific examples (a non-exhaustive list) of the computer readable storage medium would include the following: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the context of this document, a computer readable storage medium may be any tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device.

Computer program code for carrying out operations for aspects of the present invention may be written in any combination of one or more programming languages, including an object oriented programming language such as Java, Smalltalk, C + +, and conventional procedural programming languages, such as the "C" programming language or similar programming languages, and in particular may employ Python languages suitable for neural network computing and TensorFlow, PyTorch-based platform frameworks. The program code may execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the case of a remote computer, the remote computer may be connected to the user's computer through any type of network, including a Local Area Network (LAN) or a Wide Area Network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet service provider).

The embodiment of the invention also provides electronic equipment which comprises a memory, a processor and a computer program which is stored on the memory and can run on the processor, wherein when the processor executes the program, the control method of the radio frequency switching circuit is realized.

According to the computer-readable storage medium and the electronic device provided by the above embodiments of the present invention, the content specifically described in the method for implementing the control of the radio frequency switching circuit according to the present invention can be referred to, and the method has similar beneficial effects to the method for controlling the radio frequency switching circuit described above, and details are not repeated herein.

The invention discloses a radio frequency switching circuit and a control method thereof, a radio frequency transceiving link and a magnetic resonance device, wherein in the radio frequency switching circuit, the on-off state of a diode in the transceiving circuit is switched, different radio frequency links are formed between transceiving ends, the switching of different transceiving states is realized, meanwhile, a switch is utilized to control the on-off of a plurality of power devices in a bridge circuit, and in the switching process of controlling the on-off of the diode, different discharging loops are constructed, so that the inherent recovery time of the diode is avoided, the charge of the diode is consumed, the switching speed of the diode is accelerated, and the switching speed of different radio frequency links is effectively improved. In the control method of the radio frequency switching circuit, firstly, the set receiving and sending state is effectively obtained; then, corresponding to different set transceiving states, the power device in the transceiving circuit corresponding to each diode is controlled to be switched on and off, when the diodes are switched to be switched on or switched off, different discharge loops are constructed, the switching speed of the discharge loops is accelerated, and under the condition that different diodes are switched on or switched off, a radio frequency link in the set transceiving state is formed, so that the influence caused by inherent recovery time when the diodes are switched is reduced, and the efficiency when the radio frequency link is switched is accelerated.

According to the technical scheme, the bridge circuit is constructed by the bridge circuit, different discharging loops are formed in the switch control bridge circuit through the on-off of the power device in the bridge circuit, when the diode is in a switching state, the inherent recovery time of the diode is shortened by the discharging loops, the purpose of rapidly switching different radio frequency links is achieved, and the switching speed of the switch is effectively improved.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention.

Claims

1. A radio frequency switching circuit, comprising a switch control bridge circuit (101) and a diode (D) electrically connected, the switch control bridge circuit comprising at least one power device, the diode (D) being arranged on a radio frequency link; wherein at least one discharge loop is formed in the switch-controlled bridge circuit (101) by controlling the switching of the at least one power device.

2. The radio frequency switching circuit according to claim 1, wherein the switch control bridge circuit (101) is a full bridge circuit structure, and comprises a first rectifying circuit (201), a second rectifying circuit (202) and a shunt branch (203), wherein the first rectifying circuit (201) is electrically connected to an anode of the diode (D), the second rectifying circuit (202) is electrically connected to a cathode of the diode (D), and the shunt branch (203) is connected in parallel across the diode (D).

3. The radio frequency switching circuit according to claim 2, wherein the first rectifying circuit (201) comprises a first inductor (L1) and a first capacitor (C1) electrically connected, a first resistor (R1) and a first power device (Q1) connected in series, and a second power device (Q2) electrically connected to the first power device (Q1).

4. The radio frequency switching circuit according to claim 2, wherein the second rectifying circuit (202) comprises a second inductor (L2) and a second capacitor (C2) electrically connected, and a third power device (Q3) and a fourth power device (Q4) electrically connected.

5. The radio frequency switching circuit according to claim 2, wherein the shunt branch (203) comprises a fifth power device (Q5) and a second resistor (R2) electrically connected, wherein: one end of the fifth power device (Q5) far away from the second resistor (R2) is electrically connected to the anode of the diode (D), and one end of the second resistor (R2) far away from the fifth power device (Q5) is electrically connected to the cathode of the diode (D).

6. Radio frequency transceiving link, comprising a radio frequency switching circuit (1) according to any of claims 1 to 5, at least one radio frequency receiving link and/or at least one radio frequency transmitting link, wherein a diode (D) in the radio frequency switching circuit is disposed on the at least one radio frequency receiving link and/or the at least one radio frequency transmitting link.

7. A control method of a radio frequency switching circuit, based on the radio frequency switching circuit according to any one of claims 1 to 5, the control method comprising:

acquiring a set transceiving state;

8. The method according to claim 7, wherein said controlling the on/off of at least one power device corresponding to each diode according to the formed rf link to form at least one discharge loop in a switch-controlled bridge circuit comprises:

9. The method for controlling the rf switching circuit according to claim 8, wherein the at least one power device includes a first power device to a fifth power device, and the controlling on/off of at least one power device in the corresponding transceiver circuit to turn on the diode to be turned on and turn off the other diodes comprises:

10. A magnetic resonance apparatus, characterized by comprising:

a scanner for generating magnetic resonance radio frequency signals;

and, the radio frequency switching circuit according to any one of claims 1 to 5 and a processor, wherein the diode (D) in the radio frequency switching circuit is respectively disposed on at least one radio frequency receiving link and/or at least one radio frequency transmitting link, and the processor is configured to perform the control method of the radio frequency switching circuit according to any one of claims 7 to 9 on the radio frequency switching circuit.