WO2016165571A1 - 磁共振成像装置、功率放大器模组及功率合成器 - Google Patents

磁共振成像装置、功率放大器模组及功率合成器 Download PDF

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Publication number
WO2016165571A1
WO2016165571A1 PCT/CN2016/078474 CN2016078474W WO2016165571A1 WO 2016165571 A1 WO2016165571 A1 WO 2016165571A1 CN 2016078474 W CN2016078474 W CN 2016078474W WO 2016165571 A1 WO2016165571 A1 WO 2016165571A1
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Prior art keywords
transmission line
port
coupled
lumped circuit
power
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English (en)
French (fr)
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陈基锋
宋婷婷
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General Electric Co
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General Electric Co
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Priority to US15/567,011 priority Critical patent/US10833387B2/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
    • H01P5/00—Coupling devices of the waveguide type
    • H01P5/12—Coupling devices having more than two ports
    • H01P5/16—Conjugate devices, i.e. devices having at least one port decoupled from one other port
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
    • G01R33/28—Details of apparatus provided for in groups G01R33/44 - G01R33/64
    • G01R33/32—Excitation or detection systems, e.g. using radio frequency signals
    • G01R33/36—Electrical details, e.g. matching or coupling of the coil to the receiver
    • G01R33/3614—RF power amplifiers

Definitions

  • Embodiments of the present invention relate to a power combiner, a power amplifier module, and a magnetic resonance imaging apparatus.
  • FIG. 1 it is a circuit diagram of a Wilkinson power combiner 900 in the prior art/known art.
  • the Wilkinson power combiner 900 includes a first port 902, a second port 904, a common port 906, a balanced resistance element Zr , a first transmission line 910, and a second transmission line 912.
  • the first transmission line 910 is coupled between the first port 902 and the common port 906, and the second transmission line 912 is coupled between the second port 904 and the common port 906.
  • One end of the balanced resistance element Z r is coupled to a connection point between the first port 902 and the first transmission line 910 , and the other end is coupled to a connection point between the second port 904 and the second transmission line 912 .
  • the first port 902 is configured to receive the first electrical power
  • the second port 904 is configured to receive the second electrical power
  • the Wilkinson power combiner 900 is configured to synthesize the first electrical power and the second electrical power to generate a combined electrical power.
  • the common port 906 is output to the load Z L .
  • the balancing resistance element Z r When the first electric power and the second electric power are unbalanced, the difference power between the first electric power and the second electric power is consumed by the balancing resistance element Z r .
  • the presence of the balancing resistance element Z r causes the following problems: First, when a current flows through the balancing resistance element Z r , the balancing resistance element Z r additionally consumes electric energy, resulting in the efficiency of the Wilkinson power combiner 900. Second, the damage of the balanced resistance element Z r is one of the main reasons for the abnormal operation of the Wilkinson power synthesizer 900 (in particular, in high power applications, the possibility of damage to the balanced resistance element is greatly improved), That is, the reliability of the Wilkinson power combiner 900 is reduced.
  • An aspect of an embodiment of the present invention is to provide a power synthesizer including a first pass a line or lumped circuit component, a second transmission line or lumped circuit component, a third transmission line or lumped circuit component, a fourth transmission line or lumped circuit component, and a balanced capacitive component or a balanced inductive component.
  • a first transmission line or lumped circuit element is coupled to the first port.
  • a second transmission line or lumped circuit element is coupled between the first transmission line or the lumped circuit element and the common port.
  • a third transmission line or lumped circuit element is coupled to the second port.
  • a fourth transmission line or lumped circuit element is coupled between the third transmission line or the lumped circuit element and the common port.
  • a balanced capacitive element or a balanced inductive element coupled to a connection point between the first transmission line or the lumped circuit element and the second transmission line or lumped circuit element and the third transmission line or lumped circuit element and the fourth transmission line or lumped circuit element Between the connection points.
  • a power amplifier module including a first power amplifier for providing a first electrical power, a second power amplifier for providing a second electrical power, and a power combiner.
  • the power combiner includes a first transmission line or lumped circuit component, a second transmission line or lumped circuit component, a third transmission line or lumped circuit component, a fourth transmission line or lumped circuit component, and a balanced capacitive component or a balanced inductive component.
  • the first transmission line or lumped circuit element is coupled to a first port for receiving the first electrical power.
  • a second transmission line or lumped circuit element is coupled between the first transmission line or the lumped circuit element and the common port.
  • a third transmission line or lumped circuit component is coupled to the second port for receiving the second electrical power.
  • a fourth transmission line or lumped circuit element is coupled between the third transmission line or the lumped circuit element and the common port.
  • a balanced capacitive element or a balanced inductive element coupled to a connection point between the first transmission line or the lumped circuit element and the second transmission line or lumped circuit element and the third transmission line or lumped circuit element and the fourth transmission line or lumped circuit element Between the connection points.
  • Another aspect of an embodiment of the present invention is to provide a magnetic resonance imaging system including a main magnet for generating a main magnetic field, a gradient coil assembly, a gradient amplifier, a radio frequency coil assembly, and a radio frequency amplifier.
  • the gradient amplifier is operative to excite the gradient coil assembly to produce a gradient magnetic field acting on the selected magnetic field on the selected gradient axis.
  • the radio frequency amplifier includes a first power amplifier for providing a first electrical power, a second power amplifier for providing a second electrical power, and a power combiner.
  • the power combiner includes a first transmission line or lumped circuit component, a second transmission line or lumped circuit component, a third transmission line or lumped circuit component, a fourth transmission line or lumped circuit component, and a balanced capacitive component or a balanced inductive component.
  • the first transmission line or lumped circuit element is coupled to a first port for receiving the first electrical power.
  • a second transmission line or lumped circuit element is coupled between the first transmission line or the lumped circuit element and the common port.
  • a third transmission line or lumped circuit component is coupled to the second port for receiving the second electrical power.
  • a fourth transmission line or lumped circuit element is coupled between the third transmission line or the lumped circuit element and the common port.
  • the common port is for providing a composite electrical power based on combining the first electrical power and the second electrical power, the synthetic electrical power being used to excite the radio frequency coil assembly to transmit a radio frequency signal.
  • the power combiner provided by the embodiment of the present invention does not include the balanced resistance element, the power consumption of the power combiner is substantially zero, that is, the efficiency of the power combiner is improved. Secondly, without the abnormal operation in the prior art due to the damage of the balance resistance element, the reliability of the power combiner provided by the embodiment of the present invention is improved.
  • FIG. 1 A block diagram illustrating an exemplary computing environment in accordance with the present invention.
  • FIG. 1 is a circuit diagram of a prior art Wilkinson power combiner.
  • FIG. 2 is an even mode excitation circuit of the Wilkinson power combiner shown in FIG. 1.
  • FIG. 3 is an odd-mode excitation circuit of the Wilkinson power combiner shown in FIG. 1.
  • FIG. 4 is an exploded view of the even mode excitation circuit of FIG. 2.
  • Figure 5 is an exploded view of the odd mode excitation circuit of Figure 3.
  • Fig. 6 is a circuit diagram of a power combiner according to a first embodiment of the present invention.
  • Figure 7 is a circuit diagram of a power combiner in accordance with a second embodiment of the present invention.
  • FIG. 8 is a schematic diagram of an odd-mode excitation circuit of the power combiner shown in FIG. 6.
  • FIG. 8 is a schematic diagram of an odd-mode excitation circuit of the power combiner shown in FIG. 6.
  • Figure 9 is an exploded view of the odd mode excitation circuit of Figure 8.
  • Figure 10 is a diagram showing an odd-mode excitation circuit of the power combiner shown in Figure 7.
  • Figure 11 is an exploded view of the odd mode excitation circuit of Figure 10.
  • Figure 12 is a circuit diagram of a power combiner of a third embodiment of the present invention.
  • Figure 13 is a circuit diagram of a power combiner in accordance with a fourth embodiment of the present invention.
  • Figure 14 is a circuit diagram of a power combiner in accordance with a fifth embodiment of the present invention.
  • Figure 15 is a circuit diagram of a power combiner in accordance with a sixth embodiment of the present invention.
  • 16 is a functional block diagram of a power amplifier module according to an embodiment of the present invention.
  • FIG. 17 is a block diagram of a magnetic resonance imaging system according to an embodiment of the present invention.
  • Embodiments of the present invention relate to a power combiner that includes a first port, a second port, and a common port.
  • the first port is for receiving the first electrical power
  • the second port is for receiving the second electrical power
  • the power combiner is configured to synthesize the first electrical power and the second electrical power to generate the combined electrical power.
  • the synthesized electric power is output from a common port.
  • One of the theories is that when the current flowing through the first port is unbalanced with the current flowing through the second port, the voltage of the first port is equal to the voltage of the second port.
  • the embodiment of the present invention first introduces the Wilkinson power combiner 900 shown in FIG. 1 in the prior art/known technology:
  • the impedance value of the balanced resistance element Z r is equal to 2Z 0
  • the characteristic impedance of the first transmission line 910 and the characteristic impedance of the second transmission line 912 are both Z o1
  • the impedance value of Z o1 is equal to
  • the impedance value of the load Z L is equal to Z 0
  • the electrical length of the first transmission line 910 is equal to 1/4 of the wavelength of the signal flowing through the first transmission line 910.
  • the electrical length of the second transmission line 912 is equal to the electrical length of the first transmission line 910 for symmetry reasons.
  • the Wilkinson power combiner 900 shown in FIG. 1 can be decomposed into the even mode excitation circuit shown in FIG. 2 and the odd mode excitation circuit shown in FIG.
  • the even mode excitation source 962 is coupled to the first port 902, and the even mode excitation source 964 is coupled to the second port 904; such that the even mode input current of the first port 902 is I in1_even , second The even mode input current of port 904 is I in2_even .
  • the odd mode excitation source 982 is coupled to the first port 902, and the odd mode excitation source 984 is coupled to the second port 904; such that the odd mode input current of the first port 902 is I in1_odd , second The odd mode input current of port 904 is I in2_odd .
  • the real input current I in1 of the first port 902 and the real input current I in2 of the second port 904 can be expressed by the following formulas (3), (4).
  • I in1 I in_even +I in_odd (3)
  • I in2 I in_even -I in_odd (4)
  • true input voltage U in1 of the first port 902 and the true input voltage U in2 of the second port 904 can be expressed by the following formulas (5), (6).
  • U in1_even and U in1_odd are even mode and odd-mode input voltage of the first voltage input port 902, U in2_even U in2_odd and even mode input voltage respectively the second port 904 and the odd-mode input voltage;
  • Z in1_even and Z In1_odd is the even mode input impedance and odd mode input impedance of the first port 902
  • Z in2_even and Z in2_odd are the even mode input impedance and the odd mode input impedance of the second port 904, respectively.
  • the true input impedance Z in1 of the first port 902 and the true input impedance Z in2 of the second port 904 can be expressed by the following formula (7), ( 8) Representation.
  • the even mode input impedance Z in1_even of the first port 902 can be expressed by the following formula (9).
  • the odd-mode excitation circuit of FIG. 3 can be decomposed into the circuit shown in FIG. In FIG. 5, one end of the resistor Zr/2 is coupled between the first port 902 and the first transmission line 910, and the other end is grounded, while the third port 906 is also grounded.
  • Wilkinson power combiner 900 when the true input port 902 of the first current I in1 I in2 unbalanced real current of the second input port 904, a first receiving port 902 The difference power between the input power and the input power received by the second port 904 will be dissipated by the resistor Zr, which will cause the resistor Zr to overheat and be damaged, thereby causing damage to the Wilkinson power combiner 900.
  • the electrical length of the first transmission line 910 is equal to 1/4 of the wavelength of the signal flowing through the first transmission line 910, and the electrical length of the second transmission line 912 is equal to the electrical length of the first transmission line 910.
  • the electrical lengths of the first transmission line 910 and the second transmission line 912 are too long.
  • FIG. 6 is a circuit diagram of the power combiner 800 of the first embodiment.
  • the power combiner 800 includes a first port 102, a second port 104, a common port 106, a first transmission line 110, a second transmission line 120, a third transmission line 112, a fourth transmission line 122, and a balanced capacitive element Cbal .
  • the electrical length of the first transmission line 110 is equal to the electrical length of the third transmission line 112
  • the characteristic impedance of the first transmission line 110 is equal to the characteristic impedance of the third transmission line 112
  • the electrical length of the second transmission line 120 is the fourth
  • the electrical lengths of the transmission lines 122 are equal, and the characteristic impedance of the second transmission line 120 is equal to the characteristic impedance of the fourth transmission line 122.
  • first transmission line 110, the second transmission line 120, the third transmission line 112, and the fourth transmission line 122 are all coaxial cables. In other embodiments, the first transmission line 110, the second transmission line 120, the third transmission line 112, and the fourth transmission line 122 are all strip lines or micro strip lines.
  • the first transmission line 110 is coupled to the first port 102 and the second transmission line 120 is coupled between the first transmission line 110 and the common port 106.
  • the third transmission line 112 is coupled to the second port 104, and the fourth transmission line 122 is coupled between the third transmission line 112 and the common port 106.
  • One end of the balanced capacitive element C bal is coupled between the first transmission line 110 and the second transmission line 120 , and the other end is coupled between the third transmission line 112 and the fourth transmission line 122 .
  • the first port 102 is configured to receive a first electrical power provided by a first power amplifier (not shown), and the second port 104 is configured to receive a second electrical power provided by a second power amplifier (not shown).
  • the common port 106 is for providing a composite electrical power based on combining the first electrical power and the second electrical power.
  • the MOS FET inside the first power amplifier and the second power amplifier is a current source, in the embodiment of the present invention.
  • the power combiner 800 when the current flowing through the first port 102 I in1 and I in2 when a current flowing through the second port 104 of the imbalance, the voltage U in1 by a first port and a second port 102
  • the voltage U in2 of 104 is equal, so that the power combiner 800 shown in FIG. 6 can work stably because the performance of the MOS FET is determined by Vds.
  • FIG. 8 is an equivalent diagram of an odd-mode excitation circuit of the power combiner 800 of FIG. 6, wherein the first port 102 is connected to the second port 104 by two equivalent capacitive elements connected in series, two equivalent capacitive elements The capacitance value is 2C bal .
  • ⁇ 1 is the electrical length of the second transmission line 120
  • Z o1 is the characteristic impedance of the second transmission line 120.
  • the odd mode output impedance of the first transmission line 110 is calculated by the following formula 17:
  • the odd-mode output impedance Z odd1_a of the second transmission line 120 is calculated by the following formula 18:
  • [alpha] L is the length of a first electrical transmission line 110, wherein Z o1 transmission line 110 is a first impedance;
  • the electrical length of the first transmission line 110 may be any value, and the electrical length of the second transmission line 120 may also be any value.
  • FIG. 7 is a circuit diagram of the power combiner 802 of the second embodiment.
  • the difference between the power combiner 802 shown in FIG. 8 and the power combiner 800 shown in FIG. 6 is that the power combiner 800 shown in FIG. 8 replaces the balanced capacitive element in the power combiner 800 shown in FIG. 6 using the balanced inductance element Lbal .
  • C bal . That is, one end of the balanced inductance element L bal is coupled between the first transmission line 110 and the second transmission line 120 , and the other end is coupled between the third transmission line 112 and the fourth transmission line 122 .
  • 10 is an equivalent diagram of an odd-mode excitation circuit of the power combiner 802 of FIG. 7, wherein the first port 102 is connected to the second port 104 by two equivalent inductance elements connected in series, two equivalent inductance elements
  • the inductance value is L bal /2.
  • L is half the inductance of the balanced inductance element L bal .
  • FIG. 12 is a circuit diagram of the power combiner 804 of the third embodiment.
  • the difference between the power combiner 804 shown in FIG. 9 and the power combiner 800 shown in FIG. 6 is that the power combiner 804 shown in FIG. 9 replaces the power combiner 800 shown in FIG. 6 with the second inductor L2 and the fourth inductor L4, respectively.
  • the second transmission line 120 and the fourth transmission line 122 are also included in the third embodiment.
  • FIG. 12 a derivation method similar to that of the power combiner 800 shown in FIG. 6, when the current flowing through the first port 102 is unbalanced with the current flowing through the second port 104, the voltage of the first port 102 and the second The voltages at port 104 are equal, which ensures that power combiner 804 is stable.
  • the derivation method of the power combiner 804 shown in FIG. 12 is different from the derivation method of the power combiner 800 shown in FIG. 6 in that:
  • the odd-mode input impedance Z odd1_b of the second inductor L2 is calculated by the following formula 20:
  • L is the inductance value of the second inductor L2.
  • the balanced capacitive element C bal in the power combiner 804 shown in FIG. 9 can be replaced with a balanced inductive element, and the object of the embodiment of the present invention can also be achieved.
  • FIG. 13 is a circuit diagram of the power combiner 805 of the fourth embodiment.
  • the difference between the power combiner 805 shown in FIG. 10 and the power combiner 800 shown in FIG. 6 is that the power combiner 805 shown in FIG. 10 replaces the power combiner 800 shown in FIG. 6 with the second capacitor C2 and the fourth capacitor C4, respectively.
  • the second transmission line 120 and the fourth transmission line 122 are also included in the power combiner 805 of the fourth embodiment.
  • FIG. 13 a derivation method similar to that of the power combiner 800 shown in FIG. 6, when the current flowing through the first port 102 is unbalanced with the current flowing through the second port 104, the voltage of the first port 102 and the second The voltages of the ports 104 are equal, which ensures that the power combiner 805 operates stably.
  • the derivation method of the power combiner 805 shown in FIG. 13 is different from the derivation method of the power combiner 800 shown in FIG. 6 in that:
  • the odd-mode input impedance Z odd1_b of the second capacitor C2 is calculated by the following formula 20:
  • the balanced capacitive element C bal in the power combiner 805 shown in FIG. 13 can be replaced with a balanced inductive element, and the purpose of the embodiment of the present invention can also be achieved.
  • FIG. 14 is a circuit diagram of the power combiner 806 of the fifth embodiment.
  • the power combiner 806 includes the first inductance element L1, the second capacitance element C2, the third inductance element L3, the fourth capacitance element C4, and the balanced capacitance element Cbal .
  • the first inductive element L1 is coupled to the first port 102 and the second capacitive element C2 is coupled between the first inductive element L1 and the common port 106.
  • the third inductive element L3 is coupled to the second port 104, and the fourth capacitive element C4 is coupled between the third inductive element L3 and the common port 106.
  • the balanced capacitive element Cbal is coupled between a connection point between the first inductance element L1 and the second capacitance element C2 and a connection point between the third inductance element L3 and the fourth capacitance element C4.
  • FIG. 15 is a circuit diagram of a power combiner 808 of a sixth embodiment.
  • the power combiner 808 includes a first transmission line 110, a second transmission line 120, a third transmission line 112, and a fourth transmission line 122.
  • the first transmission line 110 is coupled to the first port 102 and the second transmission line 120 is coupled between the first transmission line 110 and the common port 106.
  • the third transmission line 112 is coupled to the second port 104, and the fourth transmission line 122 is coupled between the third transmission line 112 and the common port 106.
  • the common port 106 is coupled to the load Z L .
  • the sum of the electrical length of the first transmission line 110 and the electrical length of the second transmission line 120 is equal to half the wavelength of the signal transmitted in the first transmission line 110 and the second transmission line 120, and the electrical length of the third transmission line 112 and the electrical power of the fourth transmission line 122 The sum of the lengths is equal to the third transmission line 112 and the fourth transmission line 122 Half of the wavelength of the signal transmitted.
  • the voltage of the first port 102 is equal to the voltage of the second port 104, thus ensuring stable operation of the power combiner 808.
  • the power amplifier module 990 includes a first power amplifier 910, a second power amplifier 920, and a power combiner 930.
  • the power combiner 930 includes a first port 102, a second port 104, and a common port 106.
  • the first port 102 is for receiving the first electric power provided by the first power amplifier 910
  • the second port 104 is for receiving the second electric power provided by the second power amplifier 920
  • the common port 106 is for providing the first electric power based on the synthesis and the second The combined electrical power of electrical power.
  • This combined electrical power is provided to load 940.
  • the power combiner 930 can be the power combiner 800 shown in FIG. 6, the power combiner 802 shown in FIG. 7, the power combiner 804 shown in FIG. 12, the power combiner 805 shown in FIG. 13, and the power synthesis shown in FIG. 806 and any of the power combiners 808 shown in FIG.
  • FIG. 17 is a schematic diagram of a magnetic resonance imaging (MRI) device 10.
  • the operation of magnetic resonance imaging system 10 can be controlled from operator console 12, which includes a keyboard or other input device 13, control panel 14, and display 16.
  • Console 12 communicates with computer system 20 via link 18 and provides an interface for the operator to specify magnetic resonance scans, display the resulting images, perform image processing on the images, and archive the data and images.
  • Input device 13 may include a mouse, joystick, keyboard, trackball, touch screen, light bar, voice control device, or any similar or equivalent input device, and may be used for interactive geometric specification.
  • Computer system 20 includes a plurality of modules that communicate with one another by, for example, utilizing electrical and/or data connections provided by backplane 20a.
  • the data connection can be a direct wired link or a wireless communication link or the like.
  • the modules of computer system 20 include image processor module 22, central processor module 24, and memory module 26.
  • Memory module 26 may include a frame buffer for storing an array of image data.
  • image processor module 22 may be replaced by an image processing function running on central processor module 24.
  • Computer system 20 can be linked to an archival media device, permanently or Back up the storage storage device or network.
  • Computer system 20 can also communicate with a separate system control computer 32 via link 34.
  • system control computer 32 includes a set of modules that communicate with one another via electrical and/or data connections 32a.
  • the data connection 32a may be a wired link or a wireless communication link or the like.
  • the modules of computer system 20 and system control computer 32 may be implemented on the same computer system or on multiple computer systems.
  • the modules of system control computer 32 include a central processor module 36 and a pulse generator module 38 that is coupled to operator console 12 via communication link 40.
  • the pulse generator module 38 can be integrated into a scanner device, such as the resonant assembly 52.
  • the system control computer 32 receives, via the link 40, a command from the operator indicating that the scan sequence will be executed.
  • the pulse generator module 38 operates to emit (ie, execute) the desired pulse sequence by transmitting instructions, commands, and/or requests describing the timing, intensity, and shape of the generated radio frequency pulses and pulse sequences and the timing and length of the data acquisition window.
  • the pulse generator module 38 is coupled to the gradient amplifier system 42 and produces data called gradient waveforms that control the timing and shape of the gradient pulses that will be used during the scan.
  • the pulse generator module 38 can also receive patient data from the physiological acquisition controller 44, which receives signals from a plurality of different sensors connected to the patient, such as an electrocardiogram from an electrode attached to the patient. signal.
  • the pulse generator module 38 is coupled to a scan room interface circuit 46 that receives signals associated with the condition of the patient and the magnet system from various sensors.
  • the patient positioning system 48 also receives commands to move the patient table to a desired location for scanning by the scan room interface circuit 46.
  • the gradient waveform generated by pulse generator module 38 is applied to gradient amplifier system 42.
  • the gradient amplifier system 42 includes an X-axis gradient amplifier, a Y-axis gradient amplifier, and a Z-axis gradient amplifier.
  • Each gradient amplifier excites a corresponding physical gradient coil in the gradient coil assembly (generally 50) and generates a magnetic field gradient pulse for spatially encoding the acquired signal.
  • the gradient coil assembly 50 forms part of a resonant assembly 52 that includes a polarized superconducting magnet having a superconducting primary coil 54.
  • Resonance assembly 52 can include a whole body radio frequency coil 56, a surface or parallel imaging coil 76, or both.
  • the coils 56, 76 of the radio frequency coil assembly can be configured for transmission and reception, or only transmission, or only reception.
  • the patient or imaging subject 70 can be disposed within the cylindrical patient imaging volume 72 of the resonant assembly 52.
  • Transceiver module 58 in system control computer 32 generates pulses that are amplified by radio frequency amplifier 60 and coupled to radio frequency coils 56, 76 by transmit/receive switches 62.
  • the resulting signal from the stimulated nucleus in the patient can be sensed by the same RF coil 56 and coupled to the preamplifier 64 via the transmit/receive switch 62.
  • the signal emitted by the stimulated core may be sensed by an independent receive coil such as a parallel coil or surface coil 76.
  • the amplified magnetic resonance signals are demodulated, filtered, and digitized in the receiver portion of transceiver 58.
  • Transmit/receive switch 62 is controlled by signals from pulse generator module 38 to electrically connect radio frequency amplifier 60 to radio frequency coil 56 during the transmit mode and to connect preamplifier 64 to radio frequency coil 56 during the receive mode.
  • the transmit/receive switch 62 may also enable the use of a separate radio frequency coil (eg, parallel or surface coil 76) in the transmit or receive mode.
  • Magnetic resonance signals sensed by radio frequency coil 56, or parallel or surface coil 76, are digitized by transceiver module 58 and transmitted to memory module 66 in system control computer 32.
  • data frames corresponding to magnetic resonance signals are temporarily stored in memory module 66 until they are subsequently transformed to create an image.
  • Array processor 68 utilizes known transform methods, most commonly Fourier transforms, to create images from magnetic resonance signals. These images are transmitted over link 34 to computer system 20, which is stored in memory in computer system 20.
  • This image data may be archived in a long term storage device in response to commands received from the operator console 12, or may be further processed by the image processor 22, passed to the operator console 12, and presented on the display 16. .
  • the RF amplifier 60 can be a power amplifier module 990 as shown in FIG.

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Abstract

一种功率合成器，其包括第一传输线（110）或集总电路元件、第二传输线（120）或集总电路元件、第三传输线（112）或集总电路元件、第四传输线（122）或集总电路元件及平衡电容元件（C bal）或平衡电感元件（L bal）。第一传输线（110）或集总电路元件耦合至第一端口（102）。第二传输线（120）或集总电路元件耦合于第一传输线（110）或集总电路元件与公共端口（106）之间。第三传输线（112）或集总电路元件耦合至第二端口（104）。第四传输线（122）或集总电路元件耦合于第三传输线（112）或集总电路元件与公共端口（106）之间。平衡电容元件（C bal）或平衡电感元件（L bal），耦合于第一传输线（110）或集总电路元件和第二传输线（120）或集总电路元件之间的连接点（107）与第三传输线（112）或集总电路元件和第四传输线（122）或集总电路元件之间的连接点（109）之间。还提供一种功率放大器模组及磁共振成像装置。

Description

磁共振成像装置、功率放大器模组及功率合成器 技术领域
本发明实施方式涉及功率合成器、功率放大器模组以及磁共振成像装置。
背景技术
如图1所示，其为现有/公知技术中的威尔金森功率合成器900的电路图。威尔金森功率合成器900包括第一端口902、第二端口904、公共端口906、平衡电阻元件Zr、第一传输线910及第二传输线912。第一传输线910耦合于第一端口902与公共端口906之间，第二传输线912耦合于第二端口904与公共端口906之间。平衡电阻元件Zr的一端耦合于第一端口902与第一传输线910之间的连接点，另一端耦合于第二端口904与第二传输线912之间的连接点。第一端口902用于接收第一电功率，第二端口904用于接收第二电功率，威尔金森功率合成器900用于对第一电功率与第二电功率进行合成以产生合成电功率，该合成电功率从公共端口906输出至负载ZL。
当第一电功率与第二电功率不平衡时，该第一电功率与第二电功率之间的差值功率由平衡电阻元件Zr消耗掉。然而，平衡电阻元件Zr的存在会导致如下问题：其一、当有电流流过平衡电阻元件Zr时，平衡电阻元件Zr会额外地消耗电能，导致威尔金森功率合成器900的效率低；其二、平衡电阻元件Zr的损坏是导致威尔金森功率合成器900异常工作的主要原因之一(尤其，在高功率应用中，平衡电阻元件损坏的可能性大大地提高了)，也即降低了威尔金森功率合成器900的可靠性。
发明内容
现在归纳本发明实施方式的一个或多个方面以便于本发明实施方式的基本理解，其中该归纳并不是本发明实施方式的扩展性纵览，且并非旨在标识本发明实施方式的某些要素，也并非旨在划出其范围。相反，该归纳的主要目的是在下文呈现更详细的描述之前用简化形式呈现本发明实施方式的一些概念。
本发明实施方式的一个方面，在于提供一种功率合成器，其包括第一传 输线或集总电路元件、第二传输线或集总电路元件、第三传输线或集总电路元件、第四传输线或集总电路元件及平衡电容元件或平衡电感元件。第一传输线或集总电路元件耦合至第一端口。第二传输线或集总电路元件耦合于第一传输线或集总电路元件与公共端口之间。第三传输线或集总电路元件耦合至第二端口。第四传输线或集总电路元件耦合于第三传输线或集总电路元件与公共端口之间。平衡电容元件或平衡电感元件，耦合于第一传输线或集总电路元件和第二传输线或集总电路元件之间的连接点与第三传输线或集总电路元件和第四传输线或集总电路元件之间的连接点之间。
本发明实施方式的另一个方面，在于提供一种功率放大器模组，其包括用于提供第一电功率的第一功率放大器、用于提供第二电功率的第二功率放大器及功率合成器。该功率合成器包括第一传输线或集总电路元件、第二传输线或集总电路元件、第三传输线或集总电路元件、第四传输线或集总电路元件及平衡电容元件或平衡电感元件。第一传输线或集总电路元件耦合至用于接收第一电功率的第一端口。第二传输线或集总电路元件耦合于第一传输线或集总电路元件与公共端口之间。第三传输线或集总电路元件耦合至用于接收第二电功率的第二端口。第四传输线或集总电路元件耦合于第三传输线或集总电路元件与公共端口之间。平衡电容元件或平衡电感元件，耦合于第一传输线或集总电路元件和第二传输线或集总电路元件之间的连接点与第三传输线或集总电路元件和第四传输线或集总电路元件之间的连接点之间。
本发明实施方式的另一个方面，在于提供一种磁共振成像系统，其包括用于产生主磁场的主磁体、梯度线圈组件、梯度放大器、射频线圈组件及射频放大器。该梯度放大器用于激励该梯度线圈组件在选定的梯度轴上产生作用到主磁场的梯度磁场。该射频放大器包括用于提供第一电功率的第一功率放大器、用于提供第二电功率的第二功率放大器及功率合成器。该功率合成器包括第一传输线或集总电路元件、第二传输线或集总电路元件、第三传输线或集总电路元件、第四传输线或集总电路元件及平衡电容元件或平衡电感元件。第一传输线或集总电路元件耦合至用于接收第一电功率的第一端口。第二传输线或集总电路元件耦合于第一传输线或集总电路元件与公共端口之间。第三传输线或集总电路元件耦合至用于接收第二电功率的第二端口。第四传输线或集总电路元件耦合于第三传输线或集总电路元件与公共端口之间。平衡电容元件或平衡电感元件，耦合于第一传输线或集总电路元件和第二传输线或集总电路元件之间的连接点与第三传输线或集总电路元件和第四 传输线或集总电路元件之间的连接点之间。该公共端口用于提供基于合成第一电功率和第二电功率的合成电功率，该合成电功率用于激励该射频线圈组件发射射频信号。
由于本发明实施方式提供的功率合成器不包括平衡电阻元件，因此功率合成器的电能消耗大致为零，也即功率合成器的效率得到了提高。其次，没有现有技术中由于平衡电阻元件损坏而导致的异常工作，本发明实施方式提供的功率合成器的可靠性得到了提高。
附图说明
通过结合附图对于本发明的实施方式进行描述，可以更好地理解本发明实施方式，在附图中：
图1为现有技术中的威尔金森功率合成器的电路图。
图2为图1所示威尔金森功率合成器的偶模激励电路。
图3为图1所示威尔金森功率合成器的奇模激励电路。
图4为图2所示偶模激励电路的分解图。
图5为图3所示奇模激励电路的分解图。
图6为本发明第一种实施方式的功率合成器的电路图。
图7为本发明第二种实施方式的功率合成器的电路图。
图8为图6所示功率合成器的奇模激励电路图。
图9为图8所示奇模激励电路的分解图。
图10为图7所示功率合成器的奇模激励电路图。
图11为图10所示奇模激励电路的分解图。
图12为本发明第三种实施方式的功率合成器的电路图。
图13为本发明第四种实施方式的功率合成器的电路图。
图14为本发明第五种实施方式的功率合成器的电路图。
图15为本发明第六种实施方式的功率合成器的电路图。
图16为本发明一种实施方式的功率放大器模组的功能模块图。
图17为本发明一种实施方式的磁共振成像系统的模块示意图。
具体实施方式
以下将描述本发明实施方式的具体实施方式，需要指出的是，在这些实施方式的具体描述过程中，为了进行简明扼要的描述，本说明书不可能对实 际的实施方式的所有特征均作详尽的描述。应当可以理解的是，在任意一种实施方式的实际实施过程中，正如在任意一个工程项目或者设计项目的过程中，为了实现开发者的具体目标，为了满足系统相关的或者商业相关的限制，常常会做出各种各样的具体决策，而这也会从一种实施方式到另一种实施方式之间发生改变。此外，还可以理解的是，虽然这种开发过程中所作出的努力可能是复杂并且冗长的，然而对于与本发明实施方式公开的内容相关的本领域的普通技术人员而言，在本公开揭露的技术内容的基础上进行的一些设计，制造或者生产等变更只是常规的技术手段，不应当理解为本公开的内容不充分。
除非另作定义，权利要求书和说明书中使用的技术术语或者科学术语应当为本发明实施方式所属技术领域内具有一般技能的人士所理解的通常意义。本发明实施方式专利申请说明书以及权利要求书中使用的“第一”、“第二”以及类似的词语并不表示任何顺序、数量或者重要性，而只是用来区分不同的组成部分。“一个”或者“一”等类似词语并不表示数量限制，而是表示存在至少一个。“包括”或者“包含”等类似的词语意指出现在“包括”或者“包含”前面的元件或者物件涵盖出现在“包括”或者“包含”后面列举的元件或者物件及其等同元件，并不排除其他元件或者物件。“连接”或者“相连”等类似的词语并非限定于物理的或者机械的连接，而是可以包括电气的连接，不管是直接的还是间接的。
本发明实施方式涉及一种功率合成器，该功率合成器包括第一端口、第二端口及公共端口。第一端口用于接收第一电功率，第二端口用于接收第二电功率，功率合成器用于对第一电功率和第二电功率进行合成以产生合成电功率。该合成电功率从公共端口输出。其中的一个理论是，当流过第一端口的电流与流过第二端口的电流不平衡时，该第一端口的电压等于第二端口的电压。
为了对上述理论进行解释，本发明实施方式先引入现有/公知技术中的如图1所示的威尔金森功率合成器900进行说明：
在图1中，平衡电阻元件Zr的阻抗值等于2Z0，第一传输线910的特征阻抗与第二传输线912的特征阻抗均为Zo1，Zo1的阻抗值等于
Figure PCTCN2016078474-appb-000001
负载ZL的阻抗值等于Z0，另外，第一传输线910的电长度等于流经第一传输线910的信号的波长的1/4。由于对称的原因，第二传输线912的电长度等于第一传输线910的电长度。
图1所示威尔金森功率合成器900可以被分解成图2所示偶模激励电路及图3所示奇模激励电路。
在图2所示偶模电路中，偶模激励源962耦合至第一端口902，偶模激励源964耦合至第二端口904；使得第一端口902的偶模输入电流为Iin1_even，第二端口904的偶模输入电流为Iin2_even。
在图3所示奇模电路中，奇模激励源982耦合至第一端口902，奇模激励源984耦合至第二端口904；使得第一端口902的奇模输入电流为Iin1_odd，第二端口904的奇模输入电流为Iin2_odd。
由于第一端口902与第二端口904是对称的，图2中的偶模电流Iin1_even及Iin2_even与图1中第一端口902的真实输入电流Iin1及第二端口904的真实输入电流Iin2的关系可以用下述公式(1)表示。
Figure PCTCN2016078474-appb-000002
图2中的奇模电流Iin1_odd及Iin2_odd与图1中第一端口902的真实输入电流Iin1及第二端口904的真实输入电流Iin2的关系可以用下述公式(2)表示。
Figure PCTCN2016078474-appb-000003
根据上述公式(1)及(2)，第一端口902的真实输入电流Iin1及第二端口904的真实输入电流Iin2可以用下述公式(3)、(4)表示。
Iin1＝Iin_even+Iin_odd        (3)
Iin2＝Iin_even-Iin_odd          (4)
同样，第一端口902的真实输入电压Uin1及第二端口904的真实输入电压Uin2可以用下述公式(5)、(6)表示。
Uin1＝Uin1_even+Uin1_odd＝Iin_even*Zin1_even+Iin_odd*Zin1_odd     (5)
Uin2＝Uin2_even+Uin2_odd＝Iin_even*Zin2_even-Iin_odd*Zin2_odd      (6)
其中，Uin1_even及Uin1_odd分别为第一端口902的偶模输入电压及奇模输入电压，Uin2_even及Uin2_odd分别为第二端口904的偶模输入电压及奇模输入电压；Zin1_even及Zin1_odd分别为第一端口902的偶模输入阻抗及奇模输入阻抗，Zin2_even及Zin2_odd分别为第二端口904的偶模输入阻抗及奇模输入阻抗。
由上述公式(3)、(4)、(5)、(6)，第一端口902的真实输入阻抗Zin1及第二端口904的真实输入阻抗Zin2可以用下述公式(7)、(8)表示。
Figure PCTCN2016078474-appb-000004
Figure PCTCN2016078474-appb-000005
对于图2中的偶模激励来说，由于第一端口902的偶模输入电流Iin1_even与第二端口902的偶模输入电流Iin2_even相等，也即，Iin1_even＝Iin2_even，因此没有电流流过电阻Zr，因此电阻Zr可以看作是开路，因此图2所述偶模激励电路可以分解成图4所示电路。在图4中，电阻Zr/2是多余的。
从图4中，第一端口902的偶模输入阻抗Zin1_even可以由下述公式(9)表示。
Figure PCTCN2016078474-appb-000006
由于电路是对称的，Zin2_even＝Zin1_even＝Zin_even＝Z0       (10)
对于图3中的奇模激励来说，由于Iin1_odd＝-Iin2_odd，因此图3所述奇模激励电路可以分解成图5所示电路。在图5中，电阻Zr/2的一端耦合于第一端口902与第一传输线910之间，另一端接地，同时第三端口906也接地。
从图5中可以得出:
Figure PCTCN2016078474-appb-000007
由于电路是对称的，Zin2_odd＝Zin1_odd＝Zin_odd＝Z0       (11)
将公式10、11代入公式7、8可以得到第一端口902的真实输入阻抗Zin1及第二端口904的真实输入阻抗Zin2为：
Figure PCTCN2016078474-appb-000008
Figure PCTCN2016078474-appb-000009
由上述分析可知，由于奇模输入阻抗Zin_odd等于偶模输入阻抗Zin_even，因此即便当第一端口902的真实输入电流Iin1与第二端口904的真实输入电流Iin2不平衡，第一端口902的真实输入阻抗Zin1仍然等于负载ZL的阻抗，第二端口904的真实输入阻抗Zin2仍然等于负载ZL的阻抗，因此威尔金森功率合成器900可以稳定工作。
如前所述，在图1所示威尔金森功率合成器900中，当第一端口902的真实输入电流Iin1与第二端口904的真实输入电流Iin2不平衡时，第一端口902接收的输入功率与第二端口904接收的输入功率之间的差异功率将由电阻Zr消耗掉，这将会导致电阻Zr过热而损坏，进而导致威尔金森功率合成器900损坏。
第一传输线910的电长度等于流经第一传输线910的信号的波长的1/4，第二传输线912的电长度等于第一传输线910的电长度。对于甚高频(very  high frequency，简称VHF)和特高频(ultra high frequency，简称UHF)应用来说，第一传输线910和第二传输线912的电长度太长了。
请参阅图6，其为第一种实施方式的功率合成器800的电路图。功率合成器800包括第一端口102、第二端口104、公共端口106、第一传输线110、第二传输线120、第三传输线112、第四传输线122及平衡电容元件Cbal。在本实施方式中，第一传输线110的电长度与第三传输线112的电长度相等，第一传输线110的特征阻抗与第三传输线112的特征阻抗相等；第二传输线120的电长度与第四传输线122的电长度相等，第二传输线120的特征阻抗与第四传输线122的特征阻抗相等。
在本实施例中，第一传输线110、第二传输线120、第三传输线112及第四传输线122均为同轴电缆(coaxial cable)。在其他的实施例中，第一传输线110、第二传输线120、第三传输线112及第四传输线122均为带状线(strip line)或微带线(micro strip line)。
第一传输线110耦合至第一端口102，第二传输线120耦合于第一传输线110与公共端口106之间。第三传输线112耦合至第二端口104，第四传输线122耦合于第三传输线112与公共端口106之间。平衡电容元件Cbal的一端耦合于第一传输线110与第二传输线120之间，另一端耦合于第三传输线112与第四传输线122之间。
在本实施方式中，第一端口102用于接收第一功率放大器(图未示)提供的第一电功率，第二端口104用于接收第二功率放大器(图未示)提供的第二电功率，公共端口106用于提供基于合成第一电功率和第二电功率的合成电功率。
为了解决图1所示先有/公知威尔金森功率合成器900的上述问题，考虑到上述第一功率放大器及第二功率放大器内部的MOS场效应管为电流源，在本发明实施方式之图6所示功率合成器800中，当流过第一端口102的电流Iin1与流过第二端口104的电流Iin2不平衡时，可以通过使第一端口102的电压Uin1与第二端口104的电压Uin2相等，使得图6所示功率合成器800可以稳定工作，因为MOS场效应管的性能由Vds来决定。
由下述公式14及15可知，当奇模输入阻抗Zin_odd等于零时，即可以确保第一端口102的电压Uin1与第二端口104的电压Uin2相等。
Uin1＝Iin_even*Zin1_even+Iin_odd*Zin1_odd＝Iin_even*Zin1_even       (14)
Uin2＝Iin_even*Zin2_even-Iin_odd*Zin2_odd＝＝Iin_even*Zin2_even       (15)
由于Zin1_even＝Zin2_even＝Zin_even，因此Uin1＝Uin2。
在图6中，由于增加了平衡电容元件Cbal，因此可以确保奇模输入阻抗Zin_odd等于零。其理由如下：
图8为图6所示功率合成器800的奇模激励电路的等效图，其中，第一端口102通过串联连接的两个等效电容元件连接至第二端口104，两个等效电容元件的电容值均为2Cbal。
图9为图8所示奇模激励电路的分解图，其中，第二传输线120的奇模输入阻抗Zodd1_b通过下述公式16来计算：
Figure PCTCN2016078474-appb-000010
其中，βl是第二传输线120的电长度，Zo1是第二传输线120的特征阻抗。
第一传输线110的奇模输出阻抗通过下述公式17来计算：
Figure PCTCN2016078474-appb-000011
其中，C是平衡电容元件Cbal的电容值的2倍，ω是通过第一传输线110和第二传输线120的信号的角频率。
第二传输线120的奇模输出阻抗Zodd1_a通过下述公式18来计算：
Figure PCTCN2016078474-appb-000012
其中，αl是第一传输线110的电长度，Zo1也是第一传输线110的特征阻抗；
若δl+αl＝π，则第二传输线120的奇模输出阻抗Zodd1_a等于零，因此Zin1_odd＝Zodd1_a＝0；又由于对称的原因，Zin2_odd＝Zin1_odd＝Zin_odd＝0；使得当流过第一端口102的电流与流过第二端口104的电流不平衡时，第一端口102的电压与第二端口104的电压相等，如此可以确保功率合成器800稳定工作。
第一传输线110的电长度可以是任意值，第二传输线120的电长度也可以是任意值。
请参阅图7，其为第二种实施方式的功率合成器802的电路图。图8所示功率合成器802与图6所示功率合成器800的区别是：图8所示功率合成器800使用平衡电感元件Lbal取代了图6所示功率合成器800中的平衡电容元件Cbal。也即，平衡电感元件Lbal的一端耦合于第一传输线110与第二传输线120之间，另一端耦合于第三传输线112与第四传输线122之间。
图10为图7所示功率合成器802的奇模激励电路的等效图，其中，第一 端口102通过串联连接的两个等效电感元件连接至第二端口104，两个等效电感元件的电感值均为Lbal/2。
图11为图10所示奇模激励电路的分解图，其中，第二传输线120的奇模输入阻抗Zodd1_b通过下述公式16来计算：
因此，上述公式17中的C对应地替换成L，得到下述公式19。
Figure PCTCN2016078474-appb-000013
其中，L是平衡电感元件Lbal的电感值的一半。
与图6所示功率合成器800类似的推导方法，也即与上述公式16、17及18类似，若δl+αl＝π(注意：δl是指公式19中的δl)，则第二传输线120的奇模输出阻抗Zodd1_a等于零，因此Zin1_odd＝Zodd1_a＝0；又由于对称的原因，Zin2_odd＝Zin1_odd＝Zin_odd＝0；使得当流过第一端口102的电流与流过第二端口104的电流不平衡时，第一端口102的电压与第二端口104的电压相等，如此可以确保功率合成器802稳定工作。
请参阅图12，其为第三种实施方式的功率合成器804的电路图。图9所示功率合成器804与图6所示功率合成器800的区别是：图9所示功率合成器804使用第二电感L2及第四电感L4分别取代了图6所示功率合成器800中的第二传输线120及第四传输线122。
在图12中，与图6所示功率合成器800类似的推导方法，当流过第一端口102的电流与流过第二端口104的电流不平衡时，第一端口102的电压与第二端口104的电压相等，如此可以确保功率合成器804稳定工作。图12所示功率合成器804的推导方法与图6所示功率合成器800的推导方法不同的是：
第二电感L2的奇模输入阻抗Zodd1_b通过下述公式20来计算：
Zodd1_b＝jωL.........公式20
其中，L为第二电感L2的电感值。
可以理解的是，在其他的实施例中，图9所示功率合成器804中的平衡电容元件Cbal可以替换成平衡电感元件，同样可以实现本发明实施方式的目的。
请参阅图13，其为第四种实施方式的功率合成器805的电路图。图10所示功率合成器805与图6所示功率合成器800的区别是：图10所示功率合成器805使用第二电容C2及第四电容C4分别取代了图6所示功率合成器800 中的第二传输线120及第四传输线122。
在图13中，与图6所示功率合成器800类似的推导方法，当流过第一端口102的电流与流过第二端口104的电流不平衡时，第一端口102的电压与第二端口104的电压相等，如此可以确保功率合成器805稳定工作。图13所示功率合成器805的推导方法与图6所示功率合成器800的推导方法不同的是：
第二电容C2的奇模输入阻抗Zodd1_b通过下述公式20来计算：
Zodd1_b＝-j/ωC.........公式20
其中，C为第二电容C2的电容值。
可以理解的是，在其他的实施例中，图13所示功率合成器805中的平衡电容元件Cbal可以替换成平衡电感元件，同样可以实现本发明实施方式的目的。
请参阅图14，其为第五种实施方式的功率合成器806的电路图。功率合成器806包括该第一电感元件L1、第二电容元件C2、第三电感元件L3、第四电容元件C4及平衡电容元件Cbal。第一电感元件L1耦合至第一端口102，第二电容元件C2耦合于第一电感元件L1与公共端口106之间。第三电感元件L3耦合至第二端口104，第四电容元件C4耦合于第三电感元件L3与公共端口106之间。平衡电容元件Cbal耦合于第一电感元件L1和第二电容元件C2之间的连接点与第三电感元件L3和第四电容元件C4之间的连接点之间。
与图6所示功率合成器800类似的推导方法，当流过第一端口102的电流与流过第二端口104的电流不平衡时，第一端口102的电压与第二端口104的电压相等，如此可以确保功率合成器806稳定工作。
请参阅图15，其为第六种实施方式的功率合成器808的电路图。功率合成器808包括第一传输线110、第二传输线120、第三传输线112及第四传输线122。第一传输线110耦合至第一端口102，第二传输线120耦合于第一传输线110与公共端口106之间。第三传输线112耦合至第二端口104，第四传输线122耦合于第三传输线112与公共端口106之间。公共端口106耦合至负载ZL。
第一传输线110的电长度与第二传输线120的电长度之和等于第一传输线110和第二传输线120中传送的信号的波长的一半，第三传输线112的电长度与第四传输线122的电长度之和等于第三传输线112和第四传输线122 中传送的信号的波长的一半。
请再次参阅图9，将图9中的等效电容元件2Cbal删除，即成为图12所示功率合成器808的奇模激励分解电路。由于第一传输线110的电长度与第二传输线120的电长度之和等于第一传输线110和第二传输线120中传送的信号的波长的一半，因此第一端口102的奇模输入阻抗Zin1_odd＝Zodd1_a＝0，由于第一端口102与第二端口104对称，因此第二端口104的奇模输入阻抗Zin2_odd＝Zin1_odd＝Zin_odd＝0。
如此当流过第一端口102的电流与流过第二端口104的电流不平衡时，第一端口102的电压与第二端口104的电压相等，如此可以确保功率合成器808稳定工作。
如图16所示，其为一种实施方式的功率放大器模组990的功能模块图。功率放大器模组990包括第一功率放大器910、第二功率放大器920及功率合成器930。功率合成器930包括第一端口102、第二端口104及公共端口106。第一端口102用于接收第一功率放大器910提供的第一电功率，第二端口104用于接收第二功率放大器920提供的第二电功率，公共端口106用于提供基于合成第一电功率和第二电功率的合成电功率。该合成电功率被提供给负载940。其中，功率合成器930可以是图6所示功率合成器800、图7所示功率合成器802、图12所示功率合成器804、图13所示功率合成器805、图14所示功率合成器806及图15所示功率合成器808中的任意一种。
请参阅图17，其为磁共振成像(MRI)装置10的示意图。磁共振成像系统10的操作可以从操作员控制台12进行控制，操作员控制台12包括键盘或其它输入设备13、控制面板14和显示器16。控制台12通过链路18与计算机系统20通信，并提供接口供操作员用来规定磁共振扫描，显示所得图像，对图像执行图像处理，以及将数据和图像存档。输入设备13可以包括鼠标、操纵杆、键盘、轨迹球、触摸屏、光棒、语音控制设备或任何类似或等效的输入设备，并且可用于交互式几何规定。
计算机系统20包括多个模块，这些模块通过例如通过利用背板20a提供的电和/或数据连接彼此通信。数据连接可以是直接有线链路或者无线通信链路等。计算机系统20的模块包括图像处理器模块22、中央处理器模块24和存储器模块26。存储器模块26可以包括用于存储图像数据阵列的帧缓冲器。在替换的实施方式中，图像处理器模块22可以由中央处理器模块24上运行的图像处理功能进行替代。计算机系统20可以链接到档案媒体设备、永久或 备份存储器存储设备或网络。计算机系统20还可通过链路34与独立的系统控制计算机32进行通信。
在一种实施方式中，系统控制计算机32包括经由电和/或数据连接32a相互通信的一组模块。数据连接32a可以是有线链路或者无线通信链路等。在可替换的实施方式中，计算机系统20和系统控制计算机32的模块可以在相同的计算机系统或多个计算机系统上实现。系统控制计算机32的模块包括中央处理器模块36和通过通信链路40连接到操作员控制台12的脉冲发生器模块38。
在一种实施方式中，脉冲发生器模块38可以集成到扫描仪设备(如共振组件52)中。系统控制计算机32通过链路40接收来自操作员的指示将执行扫描序列的命令。脉冲发生器模块38通过发送描述将产生的射频脉冲和脉冲序列的时序、强度和形状以及数据采集窗的定时和长度的指令、命令和/或请求来操作放出(即，执行)期望的脉冲序列的系统部件。脉冲发生器模块38连接到梯度放大器系统42，并产生称为梯度波形的数据，这些梯度波形控制将在扫描期间使用的梯度脉冲的时序和形状。
在一种实施方式中，脉冲发生器模块38还可从生理采集控制器44接收患者数据，生理采集控制器44从连接到患者的多个不同传感器接收信号，例如来自附着到患者的电极的心电图信号。脉冲生成器模块38连接到扫描室接口电路46，扫描室接口电路46从各种传感器接收与患者和磁体系统的状况相关联的信号。患者定位系统48也通过扫描室接口电路46来接收将患者台移到期望的位置进行扫描的命令。
在一种实施方式中，脉冲生成器模块38产生的梯度波形被作用到梯度放大器系统42。梯度放大器系统42包括X轴梯度放大器、Y轴梯度放大器和Z轴梯度放大器。每个梯度放大器激励梯度线圈组件(一般标50)中对应的物理梯度线圈，并产生磁场梯度脉冲，以用于对所采集的信号进行空间编码。梯度线圈组件50形成共振组件52的一部分，共振组件52包括具有超导主线圈54的极化超导磁体。共振组件52可包括全身射频线圈56、表面或并行成像线圈76、或两者。射频线圈组件的线圈56、76可构造成用于传送和接收、或只传送、或只接收。患者或成像对象70可安置在共振组件52的圆柱形患者成像体积72内。系统控制计算机32中的收发器模块58产生脉冲，这些脉冲由射频放大器60放大，并通过发射/接收开关62耦合到射频线圈56、76。 由患者中的受激核发出的所得信号可由相同的射频线圈56感测，并通过发射/接收开关62耦合到前置放大器64。或者，由受激核发出的信号可由诸如并行线圈或表面线圈76的独立接收线圈感测。在收发器58的接收器部分中对放大的磁共振信号进行解调、滤波和数字化。发射/接收开关62由来自脉冲生成器模块38的信号进行控制，以便在发射模式期间将射频放大器60电连接到射频线圈56，并在接收模式期间将前置放大器64连接到射频线圈56。发射/接收开关62还可使得能够在发射或接收模式中使用独立射频线圈(例如，并行或表面线圈76)。
由射频线圈56、或并行或表面线圈76感测的磁共振信号由收发器模块58数字化，并传送给系统控制计算机32中的存储器模块66。通常，对应于磁共振信号的数据帧临时存储在存储器模块66中，直到随后对它们进行变换以创建图像。阵列处理器68利用已知的变换方法(最常见的有傅里叶变换)来从磁共振信号创建图像。这些图像通过链路34传送给计算机系统20，在计算机系统20中，其存储在存储器中。响应于从操作员控制台12接收的命令，可将此图像数据存档在长期存储设备中，或者可通过图像处理器22对它做进一步处理、传给操作员控制台12并呈现在显示器16上。
在一种实施方式中，射频放大器60可以是如图13所示的功率放大器模组990。
虽然结合特定的实施方式对本发明实施方式进行了说明，但本领域的技术人员可以理解，对本发明实施方式可以作出许多修改和变型。因此，要认识到，权利要求书的意图在于覆盖在本发明实施方式真正构思和范围内的所有这些修改和变型。

Claims (15)

  1. 一种功率合成器，其包括：
    第一传输线或集总电路元件，其耦合至第一端口；
    第二传输线或集总电路元件，其耦合于第一传输线或集总电路元件与公共端口之间；
    第三传输线或集总电路元件，其耦合至第二端口；
    第四传输线或集总电路元件，其耦合于第三传输线或集总电路元件与公共端口之间；
    平衡电容元件或平衡电感元件，其耦合于第一传输线或集总电路元件和第二传输线或集总电路元件之间的连接点与第三传输线或集总电路元件和第四传输线或集总电路元件之间的连接点之间。
  2. 如权利要求1所述的功率合成器，其特征在于：当流过第一端口的电流与流过第二端口的电流不平衡时，第一端口的电压等于第二端口的电压。
  3. 如权利要求1所述的功率合成器，其特征在于：该第一集总电路元件、第二集总电路元件、第三集总电路元件及第四集总电路元件中的每一者包括电容元件或电感元件。
  4. 如权利要求1所述的功率合成器，其特征在于，该功率合成器包括：
    该第一传输线，其耦合至第一端口；
    该第二传输线，其耦合于第一传输线与公共端口之间；
    该第三传输线，其耦合至第二端口；
    该第四传输线，其耦合于第三传输线与公共端口之间；
    该平衡电容元件或平衡电感元件，其耦合于第一和第二传输线之间的连接点与第三和第四传输线之间的连接点之间。
  5. 如权利要求4所述的功率合成器，其特征在于，该第二传输线的奇模输入阻抗通过下述公式1来计算：
    Figure PCTCN2016078474-appb-100001
    其中，βl是第二传输线的电长度，Zo1是第二传输线的特征阻抗；
    该第一传输线的奇模输出阻抗通过下述公式2来计算：
    Figure PCTCN2016078474-appb-100002
    其中，C是平衡电容元件的电容值的2倍，ω是通过第一传输线和第二传输线的信号的角频率；
    该第二传输线的奇模输出阻抗通过下述公式3来计算：
    Figure PCTCN2016078474-appb-100003
    其中，αl是第一传输线的电长度，Zo1也是第一传输线的特征阻抗；
    若δl+αl＝π，则Zin1_odd＝Zodd1_a＝0，Zin2_odd＝Zin1_odd＝0；其中Zin1_odd是第一端口的奇模输入阻抗，Zin2_odd是第二端口的奇模输入阻抗；使得当流过第一端口的电流与流过第二端口的电流不平衡时，第一端口的电压与第二端口的电压相等。
  6. 如权利要求4所述的功率合成器，其特征在于，该第二传输线的奇模输入阻抗通过下述公式1来计算：
    Figure PCTCN2016078474-appb-100004
    其中，βl是第二传输线的电长度，Zo1是第二传输线的特征阻抗；
    该第一传输线的奇模输出阻抗通过下述公式2来计算：
    Figure PCTCN2016078474-appb-100005
    其中，L是平衡电感元件的电感值的一半，ω是通过第一传输线和第二传输线的信号的角频率；
    该第二传输线的奇模输出阻抗通过下述公式3来计算：
    Figure PCTCN2016078474-appb-100006
    其中，αl是第一传输线的电长度，Zo1也是第一传输线的特征阻抗；
    若δl+αl＝π，则Zin1_odd＝Zodd1_a＝0，Zin2_odd＝Zin1_odd＝0；其中Zin1_odd是第一端口的奇模输入阻抗，Zin2_odd是第二端口的奇模输入阻抗；使得当流过第一端口的电流与流过第二端口的电流不平衡时，第一端口的电压与第二端口的电压相等。
  7. 如权利要求4所述的功率合成器，其特征在于：该第一传输线、第二传输线、第三传输线及第四传输线中的每一者的电长度为任意值。
  8. 如权利要求1所述的功率合成器，其特征在于：该第二集总电路元件包括第二电感元件，该第四集总电路元件包括第四电感元件；
    该功率合成器包括：
    该第一传输线，其耦合至第一端口；
    该第二电感元件，其耦合于第一传输线与公共端口之间；
    该第三传输线，其耦合至第二端口；
    该第四电感元件，其耦合于第三传输线与公共端口之间；
    该平衡电容元件，其耦合于第一传输线和第二电感元件之间的连接点与第三传输线和第四电感元件之间的连接点之间。
  9. 如权利要求1所述的功率合成器，其特征在于：该第一集总电路元件包括第一电感元件，该第二集总电路元件包括第二电容元件；该第三集总电路元件包括第三电感元件，该第四集总电路元件包括第四电容元件；
    该功率合成器包括：
    该第一电感元件，其耦合至第一端口；
    该第二电容元件，其耦合于第一电感元件与公共端口之间；
    该第三电感元件，其耦合至第二端口；
    该第四电容元件，其耦合于第三电感元件与公共端口之间；
    该平衡电容元件，其耦合于第一电感元件和第二电容元件之间的连接点与第三电感元件和第四电容元件之间的连接点之间。
  10. 如权利要求1所述的功率合成器，其特征在于：该第一端口用于接收第一电功率，该第二端口用于接收第二电功率，该公共端口用于提供基于合成第一电功率和第二电功率的合成电功率。
  11. 一种功率放大器模组，其特征在于，该功率放大器模组包括：
    第一功率放大器，用于提供第一电功率；
    第二功率放大器，用于提供第二电功率；及
    功率合成器，其包括：
    第一传输线或集总电路元件，其耦合至用于接收第一电功率的第一端口；
    第二传输线或集总电路元件，其耦合于第一传输线或集总电路元件与公共端口之间；
    第三传输线或集总电路元件，其耦合至用于接收第二电功率的第二端口；
    第四传输线或集总电路元件，其耦合于第三传输线或集总电路元件 与公共端口之间；
    平衡电容元件或平衡电感元件，其耦合于第一传输线或集总电路元件和第二传输线或集总电路元件之间的连接点与第三传输线或集总电路元件和第四传输线或集总电路元件之间的连接点之间。
  12. 如权利要求11所述的功率放大器模组，其特征在于：当流过第一端口的电流与流过第二端口的电流不平衡时，第一端口的电压等于第二端口的电压。
  13. 一种磁共振成像系统，其特征在于，该磁共振成像系统包括：
    主磁体，用于产生主磁场；
    梯度线圈组件；
    梯度放大器，用于激励该梯度线圈组件在选定的梯度轴上产生作用到主磁场的梯度磁场；
    射频线圈组件；
    射频放大器，其包括：
    第一功率放大器，用于提供第一电功率；
    第二功率放大器，用于提供第二电功率；及
    功率合成器，其包括：
    第一传输线或集总电路元件，其耦合至用于接收第一电功率的第一端口；
    第二传输线或集总电路元件，其耦合于第一传输线或集总电路元件与公共端口之间；
    第三传输线或集总电路元件，其耦合至用于接收第二电功率的第二端口；
    第四传输线或集总电路元件，其耦合于第三传输线或集总电路元件与公共端口之间；
    平衡电容元件或平衡电感元件，其耦合于第一传输线或集总电路元件和第二传输线或集总电路元件之间的连接点与第三传输线或集总电路元件和第四传输线或集总电路元件之间的连接点之间；
    其中，该公共端口用于提供基于合成第一电功率和第二电功率的合成电功率，该合成电功率用于激励该射频线圈组件发射射频信号。
  14. 如权利要求13所述的磁共振成像系统，其特征在于：当流过第一端口的电流与流过第二端口的电流不平衡时，该第一端口的电压等于第二端口的电压。
  15. 一种功率合成器，其包括：
    第一传输线，其耦合至第一端口；
    第二传输线，其耦合于第一传输线与公共端口之间；
    第三传输线，其耦合至第二端口；
    第四传输线，其耦合于第三传输线与公共端口之间；
    该第一传输线的电长度与第二传输线的电长度之和等于第一传输线和第二传输线中传送的信号的波长的一半，该第三传输线的电长度与第四传输线的电长度之和等于第三传输线和第四传输线中传送的信号的波长的一半。
PCT/CN2016/078474 2015-04-16 2016-04-05 磁共振成像装置、功率放大器模组及功率合成器 Ceased WO2016165571A1 (zh)

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