CN102664595B - Preamplifier and magnetic resonance amplifying device - Google Patents
Preamplifier and magnetic resonance amplifying device Download PDFInfo
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- CN102664595B CN102664595B CN201210137145.7A CN201210137145A CN102664595B CN 102664595 B CN102664595 B CN 102664595B CN 201210137145 A CN201210137145 A CN 201210137145A CN 102664595 B CN102664595 B CN 102664595B
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Abstract
Preamplifier and magnetic resonance amplifying device, comprising: amplifying circuit, for amplifying signal; And biasing circuit, for the quiescent operation point control online property amplification region of described amplifying circuit; Described amplifying circuit comprises: the first amplifier tube, for amplifying the signal of input; Second amplifier tube, for amplifying the output signal of described first amplifier tube; Interstage coupling unit, is coupled to described first amplifier tube and described second amplifier tube.By the first amplifier tube Q1 of this programme and the characteristic of the second amplifier tube Q2, interstage coupling units match first amplifier tube and the second amplifier tube, can reflection coefficient be reduced, ensure low-noise factor, high stability and high linearity, and then improve the gain of preamplifier.
Description
Technical field
The present invention relates to signal amplification technique, particularly relate to a kind of preamplifier and magnetic resonance amplifying device.
Background technology
Along with the development of electronics technology, most electronic equipment is all provided with preamplifier.Preamplifier amplifies the signal of input, and as by the voice signal of microphone pickup, because it is more weak, needing first to be amplified to certain level just can in other level.Usually preposition have higher voltage gain, can by low level signal amplification on fiduciary level.
For for different electronic equipments, not consistent to the parameter request of preamplifier yet.At MRI(Magnetic Resonance Imaging) in mr techniques imaging device, radio system is the important component part of MRI equipment, and preamplifier is one of key technology of radio frequency reception link in magnetic resonance imaging system.In Signal reception process, the signal of preamplifier radio frequency Coil Detector amplifies, and then passes to the post-module of radio-frequency receiving system.Preamplifier is the first order amplification module of whole receiving system, its noise factor and gain are the key factors of whole radio-frequency receiving system performance, and the signal sent by RF receiving coil generally only has millivolt (mV) magnitude even lower, this just requires that preamplifier has higher gain and minimum noise factor.
Therefore, noise-reduction coefficient is one of technological difficulties of preamplifier.
Summary of the invention
Based on this, be necessary the preamplifier providing a kind of noise factor lower.
A kind of preamplifier, comprising: amplifying circuit, for amplifying signal; And biasing circuit, for the quiescent operation point control online property amplification region of described amplifying circuit; Described amplifying circuit comprises: the first amplifier tube, for amplifying the signal of input; Second amplifier tube, for amplifying the output signal of described first amplifier tube; Interstage coupling unit, is coupled to described first amplifier tube and described second amplifier tube.
Wherein in an embodiment, described biasing circuit comprises: the first bias unit, couples described first amplifier tube, for the quiescent operation point control online property amplification region of described first amplifier tube; Second bias unit, couples described second amplifier tube, for the quiescent operation point control online property amplification region of described second amplifier tube.
Wherein in an embodiment, also comprise: input matching network, couple described first amplifier tube, for realizing input noise coupling; Output matching networking, couples described second amplifier tube, for realizing output noise coupling.
Wherein in an embodiment, also comprise: input protection unit, couple described input matching network, for the protection of the safety that described amplifying circuit inputs; Output protection unit, couples described input matching network, for ensureing the signal stabilization that described amplifying circuit exports.
In addition, a kind of magnetic resonance amplifying device is also provided.
A kind of magnetic resonance amplifying device, comprising: balanced-to-unbalanced transformer; Preamplifier; And matching network, be coupled to described balanced-to-unbalanced transformer and described preamplifier, for mating the impedance between described balanced-to-unbalanced transformer and described preamplifier; Described preamplifier, comprising: amplifying circuit, for amplification input signal; And biasing circuit, for the quiescent operation point control online property amplification region of described amplifying circuit; Described amplifying circuit comprises: the first amplifier tube, for amplifying the signal of input; Second amplifier tube, for amplifying the output signal of described first amplifier tube; Interstage coupling unit, is coupled to described first amplifier tube and described second amplifier tube.
Wherein in an embodiment, described balanced-to-unbalanced transformer comprises at least one two microstrip line unit, and described pair of microstrip line unit comprises ground plane and signals layer, and described signals layer is arranged between described ground plane; Capacitor, the ground plane two ends of described capacitor and described pair of microstrip line unit are connected in parallel.
Wherein in an embodiment, described pair of microstrip line unit is set to straightway, curved line or helix shape.
Wherein in an embodiment, described biasing circuit comprises: the first bias unit, couples described first amplifier tube, for the quiescent operation point control online property amplification region of described first amplifier tube; Second bias unit, couples described second amplifier tube, for the quiescent operation point control online property amplification region of described second amplifier tube.
Wherein in an embodiment, also comprise: input matching network, couple described first amplifier tube, for realizing input noise coupling; Output matching networking, couples described second amplifier tube, for realizing output noise coupling.
Wherein in an embodiment, also comprise: input protection unit, couple described input matching network, for the protection of the safety that described amplifying circuit inputs; Output protection unit, couples described input matching network, for ensureing the signal stabilization that described amplifying circuit exports.
By the first amplifier tube Q1 of this programme and the characteristic of the second amplifier tube Q2, interstage coupling units match first amplifier tube and the second amplifier tube, can reflection coefficient be reduced, ensure low-noise factor, high stability and high linearity, and then improve the gain of preamplifier.
Accompanying drawing explanation
Fig. 1 is the logic diagram of preamplifier;
Fig. 2 is the circuit diagram of preamplifier;
Fig. 3 is the logic diagram of magnetic resonance amplifying device;
Fig. 4 is the balanced-to-unbalanced transformer schematic diagram of magnetic resonance amplifying device in Fig. 3;
Fig. 5 is the balanced-to-unbalanced transformer rectangular coil vertical view of magnetic resonance amplifying device in Fig. 3;
Fig. 6 is the circuit diagram of the matching network of magnetic resonance amplifying device in Fig. 3.
Embodiment
In order to solve the higher problem of preamplifier noise factor, propose the preamplifier realizing noise-reduction coefficient.
By reference to the accompanying drawings 1 ~ 2, preamplifier comprises: amplifying circuit and biasing circuit.
Amplifying circuit, for amplifying signal.Amplifying circuit comprises:
First amplifier tube Q1, for amplifying the signal of input.First amplifier tube Q1 is IGBT(Insulated Gate Bipolar Transistor insulated gate bipolar transistor) or MOSFET(Metal-Oxide-Semiconductor Field-Effect Transistor metal-oxide half field effect transistor).IGBT or MOSFET can independent of the intensity of external magnetic field and direction.
Second amplifier tube Q2, for amplifying the output signal of the first amplifier tube Q1.Second amplifier tube Q2 is IGBT or MOSFET.
Interstage coupling unit, is coupled to the first amplifier tube Q1 and the second amplifier tube Q2.Interstage coupling units match first amplifier tube Q1 and the second amplifier tube Q2, reduces reflection coefficient, ensures low-noise factor, high stability and high linearity, and then improves the gain of preamplifier.
Interstage coupling unit comprises capacitor C5, inductance L 3, resistance R5.The signal of the drain electrode output of the first amplifier tube Q1 is connected to the grid of the second amplifier tube Q2 by capacitor C5, use resistance-capacitance coupling mode to carry out Linear Amplifer to faint input signal.One end of inductance L 3 is connected with the drain electrode of the first amplifier tube Q1, and the other end is connected with resistance R5, has choking effect to amplifying circuit, and the other end of resistance R5 is connected with power supply VCC by biasing circuit.The grid of the first amplifier tube Q1 is connected with analog output signal input port A1in, and source electrode is by biasing circuit ground connection.The drain electrode of the second amplifier tube Q2 is connected with power supply VCC by biasing circuit, and source electrode is by biasing circuit ground connection.
Biasing circuit, for the quiescent operation point control online property amplification region of amplifying circuit.
By the first amplifier tube Q1 of this programme and the characteristic of the second amplifier tube Q2, noise can be reduced and improve gain, and then the noise factor of preamplifier is reduced.
In one embodiment, biasing circuit comprises: the first bias unit and the second bias unit.
First bias unit, couples the first amplifier tube, for the quiescent operation point control online property amplification region of the first amplifier tube Q1.First bias unit comprises: resistance R1, R2, R3 and R4, in circuit the effect of its current limliting or dividing potential drop; Capacitor C4, C6 and C7, have the effects such as filtering, coupling or coupling in circuit; Inductance L 2, has the effect of filtering or current limliting in circuit.Resistance R2 one end is connected to the grid of the first amplifier tube Q1, and resistance R3 is connected with the other end of resistance R2.Resistance R4 and capacitor C7 is connected in parallel, and one end is connected with resistance R3, other end ground connection.Capacitor C6 one end is connected between resistance R2 and R3, other end ground connection.Resistance R1 and capacitor C4 is connected in parallel, and one end is connected to the source electrode of the first amplifier tube Q1, and the other end is connected with inductance L 2, inductance L 2 other end ground connection.
Resistance R2, R3 of being connected on the first amplifier tube Q1 grid and the resistance R1, the capacitor C4 that are connected on the first amplifier tube Q1 source electrode, inductor L2 realize the quiescent operation point control to the first amplifier tube Q1, resistance R4 and capacitor C7 has the effect suppressing quiescent operation point drift, and the first bias unit can also to DC power supply filtering ripple.
Second bias unit, couples the second amplifier tube Q2, for the quiescent operation point control online property amplification region of the second amplifier tube.Second bias unit comprises: resistance R6, R7 and R8, in circuit the effect of its current limliting or dividing potential drop; Capacitor C8, C9 and C12, have the effects such as filtering, coupling or coupling in circuit; Inductance L 4, has the effect of filtering or current limliting in circuit; Voltage stabilizing didoe D5, plays pressure stabilization function to DC power supply VCC; Diode D6, plays protective circuit in circuit, particularly prevents reverse connecting protection effect to DC power supply VCC.The positive pole of diode D6 is connected with power supply VCC, and negative pole is connected with resistance R8.Resistance R8 is connected with the resistance R5 of interstage coupling unit respectively, and resistance R8 also and between resistance R3 and the R4 of the first bias unit is connected.One end of inductance L 4 is connected with the drain electrode of the second amplifier tube Q2, and the other end is connected with resistance R8, has choking effect to amplifier tube.Capacitor C8 one end is connected with resistance R8, other end ground connection.The negative pole of voltage stabilizing didoe D5 is connected with resistance R8, plus earth.Capacitor C9 one end is connected with power supply VCC, other end ground connection.Resistance R6 is connected with the grid of the second amplifier tube Q2, and the other end is connected with analog output signal output port A1 out.Resistance R7 and capacitor C12 is connected in parallel, and one end is connected with the source electrode of the second amplifier tube Q2, other end ground connection.
Be connected on the resistor R6 of the second amplifier tube Q2 grid, inductor L4, resistor R8 provides with the resistor R7, the capacitor C12 that are connected on the second amplifier tube Q2 source electrode and arranges the quiescent point of the second amplifier tube Q2, and the second bias unit can also to DC power supply filtering ripple.
In one embodiment, preamplifier also comprises: input matching network and output matching networking.
Input matching network, couples the first amplifier tube, for realizing input noise coupling.Input matching network comprises: capacitor C1, C2 and C3, has the effects such as filtering, coupling or coupling in circuit; Inductance L 1, has the effect of filtering or current limliting in circuit.Capacitor C2 and C3, inductance L 1 form T-shaped input matching network, namely capacitor C2 and C3 connects, the capacitor C3 other end is connected with the grid of the first amplifier tube Q1, and the capacitor C2 other end is connected with capacitor C1, and the capacitor C1 other end is connected with analog output signal input port A1in.Inductance L 1 one end is connected between capacitor C2 and C3, other end ground connection.Wherein, capacitor C2 and C3 can be adjustable condenser, and capacitor C1 connects A1 in can isolated DC signal.
Input matching network realizes the noise matching to preamplifier, and when reaching best input noise coupling, the noise factor of preamplifier reaches minimum value.The T-shaped matching network that capacitor C2, C3 and inductance L 1 are formed makes the input impedance of amplifier tube mate with the output impedance of front stage circuits, reduces reflection coefficient further.
Output matching networking, couples the second amplifier tube, for realizing output noise coupling.Output matching networking comprises: capacitor C10 and C11, has the effects such as filtering, coupling or coupling in circuit; Inductance L 5, has the effect of filtering or current limliting in circuit.Capacitor C11 and inductance L 5 are connected in parallel, and one end is connected with the drain electrode of capacitor C10, the second amplifier tube Q2 respectively, other end ground connection.The other end of capacitor C10 is connected with analog output signal output port A1 out, and capacitor C10 can play isolated DC.Wherein, capacitor C10 can be adjustable condenser.
This output matching network, makes output interface and late-class circuit realize noise matching, reduces reflection coefficient, can reach narrower bandwidth.
In one embodiment, preamplifier also comprises: input protection unit and output protection unit.
Input protection unit, couples input matching network, for the protection of the safety of amplifying circuit input.Input protection unit comprises diode D1 and D2, plays pressure stabilization function to DC power supply.After the negative pole of diode D1 is connected with the positive pole of diode D2, the positive pole of access analog output signal input port A1 in, diode D1 is connected with the negative pole of diode D2 ground connection afterwards.
Input protection unit can make preamplifier not cause damage because of the impact of overvoltage signal; ensure the safety of amplifier tube and do not affect measured signal; when input signal is larger, the diode current flow of protective circuit, thus protection amplifier tube is not below damaged by large voltage.
Output protection unit, couples input matching network, for ensureing the signal stabilization that amplifying circuit exports.Output protection unit comprises diode D3 and D4, plays pressure stabilization function to DC power supply.After the negative pole of diode D3 is connected with the positive pole of diode D4, the positive pole of access analog output signal output port A1 out, diode D3 is connected with the negative pole of diode D4 ground connection afterwards.
Output protection unit ensures the stability of output signal, makes output port and late-class circuit exempt from damage.
Based on above-mentioned preamplifier, by reference to the accompanying drawings 3, also propose magnetic resonance amplifying device and comprise: balanced-to-unbalanced transformer, preamplifier and matching network.
In one embodiment, by reference to the accompanying drawings 4 ~ 5, balanced-to-unbalanced transformer comprises at least one two microstrip line unit, and two microstrip line unit comprises ground plane and signals layer, and signals layer is arranged between ground plane; Capacitor, capacitor is connected in parallel with the ground plane two ends of two microstrip line unit.Particularly, the antiresonant circuit that the ground plane of two microstrip line unit and capacitor are formed, its resonance frequency tunings is to a certain kind of atom nuclear harmonic vibration frequency place of specific MR imaging apparatus, and its resonance impedance is higher, can suppress the interference of common-mode signal well.
Further, two microstrip line unit is stratiform and is symmetrical arranged, and the first half is identical with the latter half.The first half is provided with 2 ground planes and 1 signals layer, and wherein ground plane arranges both sides, middle signalization layer.In other embodiments, two microstrip line unit also can only have the first half or the latter half.
Be interconnected between two microstrip line unit, corresponding ground plane and signals layer are cross-linked, and namely go up the signals layer of the latter half of a two microstrip line unit, the signals layer of the first half of the next two microstrip line unit of corresponding connection; In like manner, the ground plane of correspondence position is also corresponding connects.In the particular embodiment, the magnetic resonance equipment of 7T, the characteristic impedance between the signals layer of two microstrip line unit and ground plane is 50/75 ohm, can directly and the coaxial line of magnetic resonance or RF receiving coil interconnect.And balanced-to-unbalanced transformer is correlated with, major parameter is: characteristic impedance Z
0=50 Ω, DIELECTRIC CONSTANT ε
r=4.4, fill medium thickness b=1.0mm, copper conduction band thickness t=0.1mm, copper conduction band width W=1.75mm.
In other embodiments, two microstrip line unit is set to straightway, curved line or helix shape.Two microstrip line unit can be arranged on a printed circuit board, determines the number of plies of printed circuit board according to the quantity of the signals layer arranged, ground plane.In the present embodiment, the number of plies of printed circuit board is six layers, and the signals layer of the first half and the latter half and ground plane use via hole to be connected.Adopt the balanced-to-unbalanced transformer of printed circuit board mode, the volume of self can be reduced, can be applicable to more high accuracy magnetic resonance equipment, but also the volume of relevant device can be reduced, expand its application surface.Meanwhile, adopt the board-like balanced-to-unbalanced transformer of printed circuit to enhance productivity, reduce costs.
In other embodiments, balanced-to-unbalanced transformer can omit capacitor, capacitor can be equivalent between the signals layer of balanced-to-unbalanced transformer and ground plane, the capacitance size regulative mode of this equivalent condenser can be reached by the distance between conditioning signal layer and ground plane, make the use of balanced-to-unbalanced transformer in the present embodiment flexible, be applicable to the magnetic resonance equipment of different characteristic frequency.
Preamplifier, comprising: amplifying circuit and biasing circuit.
Amplifying circuit, for amplifying signal.Amplifying circuit comprises:
First amplifier tube Q1, for amplifying the signal of input.First amplifier tube Q1 is IGBT(Insulated Gate Bipolar Transistor insulated gate bipolar transistor) or MOSFET(Metal-Oxide-Semiconductor Field-Effect Transistor metal-oxide half field effect transistor).
Second amplifier tube Q2, for amplifying the output signal of the first amplifier tube Q1.Second amplifier tube Q2 is IGBT or MOSFET.
Interstage coupling unit, is coupled to the first amplifier tube Q1 and the second amplifier tube Q2.Interstage coupling units match first amplifier tube Q1 and the second amplifier tube Q2, reduces reflection coefficient, ensures low-noise factor, high stability and high linearity, and then improves the gain of preamplifier.
Interstage coupling unit comprises capacitor C5, inductance L 3, resistance R5.The signal of the drain electrode output of the first amplifier tube Q1 is connected to the grid of the second amplifier tube Q2 by capacitor C5, use resistance-capacitance coupling mode to carry out Linear Amplifer to faint input signal.One end of inductance L 3 is connected with the drain electrode of the first amplifier tube Q1, and the other end is connected with resistance R5, has choking effect to amplifying circuit, and the other end of resistance R5 is connected with power supply VCC by biasing circuit.The grid of the first amplifier tube Q1 is connected with analog output signal input port A1 in, and source electrode is by biasing circuit ground connection.The drain electrode of the second amplifier tube Q2 is connected with power supply VCC by biasing circuit, and source electrode is by biasing circuit ground connection.
Biasing circuit, for the quiescent operation point control online property amplification region of amplifying circuit.
By the first amplifier tube Q1 of this programme and the characteristic of the second amplifier tube Q2, noise can be reduced and improve gain, and then the noise factor of preamplifier is reduced.
In one embodiment, biasing circuit comprises: the first bias unit and the second bias unit.
First bias unit, couples the first amplifier tube, for the quiescent operation point control online property amplification region of the first amplifier tube.First bias unit comprises resistance R1, R2, R3 and R4, in circuit the effect of its current limliting or dividing potential drop.Capacitor C4, C6 and C7, have the effects such as filtering, coupling or coupling in circuit.Inductance L 2, has the effect of filtering or current limliting in circuit.Resistance R2 one end is connected to the grid of the first amplifier tube Q1, and resistance R3 is connected with the other end of resistance R2.Resistance R4 and capacitor C7 is connected in parallel, and one end is connected with resistance R3, other end ground connection.Capacitor C6 one end is connected between resistance R2 and R3, other end ground connection.Resistance R1 and capacitor C4 is connected in parallel, and one end is connected to the source electrode of the first amplifier tube Q1, and the other end is connected with inductance L 2, inductance L 2 other end ground connection.
Resistor R2, R3 of being connected on the first amplifier tube Q1 grid and the resistance R1, the capacitor C4 that are connected on the first amplifier tube Q1 source electrode, inductor L2 realize the quiescent operation point control to the first amplifier tube Q1, resistance R4 and capacitor C7 has the effect suppressing quiescent operation point drift, and the first bias unit can also to DC power supply filtering ripple.
Second bias unit, couples the second amplifier tube Q2, for the quiescent operation point control online property amplification region of the second amplifier tube.Second bias unit comprises resistance R6, R7 and R8, in circuit the effect of its current limliting or dividing potential drop.Capacitor C8, C9 and C12, have the effects such as filtering, coupling or coupling in circuit.Inductance L 4, has the effect of filtering or current limliting in circuit.Voltage stabilizing didoe D5, plays pressure stabilization function to DC power supply VCC.Diode D6, plays protective circuit in circuit, particularly prevents reverse connecting protection effect to DC power supply VCC.The positive pole of diode D6 is connected with power supply VCC, and negative pole is connected with resistance R8.Resistance R8 is connected with the resistance R5 of interstage coupling unit respectively, and resistance R8 also and between resistance R3 and the R4 of the first bias unit is connected.One end of inductance L 4 is connected with the drain electrode of the second amplifier tube Q2, and the other end is connected with resistance R8, has choking effect to amplifier tube.Capacitor C8 one end is connected with resistance R8, other end ground connection.The negative pole of voltage stabilizing didoe D5 is connected with resistance R8, plus earth.Capacitor C9 one end is connected with power supply VCC, other end ground connection.Resistance R6 is connected with the grid of the second amplifier tube Q2, and the other end is connected with analog output signal output port A1out.Resistance R7 and capacitor C12 is connected in parallel, and one end is connected with the source electrode of the second amplifier tube Q2, other end ground connection.
Be connected on the resistor R6 of the second amplifier tube Q2 grid, inductor L4, resistor R8 provides with the resistor R7, the capacitor C12 that are connected on the second amplifier tube Q2 source electrode and arranges the quiescent point of the second amplifier tube Q2, and the second bias unit can also to DC power supply filtering ripple.
In one embodiment, preamplifier also comprises: input matching network and output matching networking.
Input matching network, couples the first amplifier tube, for realizing input noise coupling.Input matching network comprises capacitor C1, C2 and C3, has the effects such as filtering, coupling or coupling in circuit.Inductance L 1, has the effect of filtering or current limliting in circuit.Capacitor C2 and C3, inductance L 1 form T-shaped input matching network, namely capacitor C2 and C3 connects, the capacitor C3 other end is connected with the grid of the first amplifier tube Q1, and the capacitor C2 other end is connected with capacitor C1, and the capacitor C1 other end is connected with analog output signal input port A1in.Inductance L 1 one end is connected between capacitor C2 and C3, other end ground connection.Wherein, capacitor C2 and C3 can be adjustable condenser, and capacitor C1 connects A1 in can isolated DC signal.
Input matching network realizes the noise matching to preamplifier, and when reaching best input noise coupling, the noise factor of preamplifier reaches minimum value.The T-shaped matching network that capacitor C2, C3 and inductance L 1 are formed makes the input impedance of amplifier tube mate with the output impedance of front stage circuits, reduces reflection coefficient further.
Output matching networking, couples the second amplifier tube, for realizing output noise coupling.Output matching networking comprises capacitor C10 and C11, has the effects such as filtering, coupling or coupling in circuit.Inductance L 5, has the effect of filtering or current limliting in circuit.Capacitor C11 and inductance L 5 are connected in parallel, and one end is connected with the drain electrode of capacitor C10, the second amplifier tube Q2 respectively, other end ground connection.The other end of capacitor C10 is connected with analog output signal output port A1 out, and capacitor C10 can play isolated DC.Wherein, capacitor C10 can be adjustable condenser.
This output matching network, makes output interface and late-class circuit realize noise matching, reduces reflection coefficient, can reach narrower bandwidth.
In one embodiment, preamplifier also comprises: input protection unit and output protection unit.
Input protection unit, couples input matching network, for the protection of the safety of amplifying circuit input.Input protection unit comprises diode D1 and D2, plays pressure stabilization function to DC power supply.After the negative pole of diode D1 is connected with the positive pole of diode D2, the positive pole of access analog output signal input port A1 in, diode D1 is connected with the negative pole of diode D2 ground connection afterwards.
Input protection unit can make preamplifier not cause damage because of the impact of overvoltage signal; ensure the safety of amplifier tube and do not affect measured signal; when input signal is larger, the diode current flow of protective circuit, thus protection amplifier tube is not below damaged by large voltage.
Output protection unit, couples input matching network, for ensureing the signal stabilization that amplifying circuit exports.Output protection unit comprises diode D3 and D4, plays pressure stabilization function to DC power supply.After the negative pole of diode D3 is connected with the positive pole of diode D4, the positive pole of access analog output signal output port A1 out, diode D3 is connected with the negative pole of diode D4 ground connection afterwards.
Output protection unit ensures the stability of output signal, makes output port and late-class circuit exempt from damage.
By reference to the accompanying drawings 6, matching network, is coupled to balanced-to-unbalanced transformer and preamplifier, for mating the impedance between balanced-to-unbalanced transformer and preamplifier.The way of realization of matching network has multiple, and the mode of the present embodiment is: inductance L 0, capacitor C0.Input port A2 in and output port A2 out, capacitor C0 one end of inductance L 0 difference connecting analog output signal are connected with analog output signal output port A2 out, other end ground connection.By regulating inductor L0 and capacitor C0, make the input resistant matching of balanced-to-unbalanced transformer and preamplifier, with optimal performances such as the high-gain reached, high stability and low-noise factors.In the present embodiment, the input port A2 in of matching network and balanced-to-unbalanced transformer couple, and the output port A2 out of matching network and the input port A1 in of preamplifier couples.
Adopt the magnetic resonance amplifying device of the application, balanced-to-unbalanced transformer, preamplifier and matching network can be made integrated, and good stability, antijamming capability is strong, working band is wider, has wider gain, the linearity and lower noise factor.
Magnetic resonance amplifying device can directly and the coaxial line of magnetic resonance or RF receiving coil interconnect, be applicable to the magnetic resonance radio frequency equipment of different field intensity.
The above embodiment only have expressed several execution mode of the present invention, and it describes comparatively concrete and detailed, but therefore can not be interpreted as the restriction to the scope of the claims of the present invention.It should be pointed out that for the person of ordinary skill of the art, without departing from the inventive concept of the premise, can also make some distortion and improvement, these all belong to protection scope of the present invention.Therefore, the protection range of patent of the present invention should be as the criterion with claims.
Claims (7)
1. a preamplifier, is characterized in that, comprising:
Amplifying circuit, for amplifying signal; And
Biasing circuit, for the quiescent operation point control online property amplification region of described amplifying circuit;
Described amplifying circuit comprises:
First amplifier tube Q1, for amplifying the signal of input;
Second amplifier tube Q2, for amplifying the output signal of described first amplifier tube Q1;
Interstage coupling unit, is coupled to described first amplifier tube Q1 and described second amplifier tube Q2;
Described biasing circuit comprises: the first bias unit, couples described first amplifier tube Q1, for the quiescent operation point control online property amplification region of described first amplifier tube Q1; Second bias unit, couples described second amplifier tube Q2, for the quiescent operation point control online property amplification region of described second amplifier tube Q2;
Described first bias unit comprises: resistance R1, R2, R3 and R4; Capacitor C4, C6 and C7; Inductance L 2; Resistance R2 one end is connected to the grid of the first amplifier tube Q1, and resistance R3 one end is connected with the other end of resistance R2; Resistance R4 and capacitor C7 is connected in parallel, and one end is connected with the other end of resistance R3, other end ground connection; Capacitor C6 one end is connected between resistance R2 and R3, other end ground connection; Resistance R1 and capacitor C4 is connected in parallel, and one end is connected to the source electrode of the first amplifier tube Q1, and the other end is connected with inductance L 2, inductance L 2 other end ground connection;
Described second bias unit comprises: resistance R6, R7 and R8; Capacitor C8, C9 and C12; Inductance L 4; Voltage stabilizing didoe D5; Diode D6; The positive pole of diode D6 is connected with power supply VCC, and negative pole is connected with resistance R8 one end; The resistance R8 other end is connected with one end of the resistance R5 of interstage coupling unit respectively, and the resistance R8 other end also and between resistance R3 and the R4 of the first bias unit is connected; One end of inductance L 4 is connected with the drain electrode of the second amplifier tube Q2, and the other end is connected with the resistance R8 other end, has choking effect to amplifier tube; Capacitor C8 one end is connected with the resistance R8 other end, other end ground connection; The negative pole of voltage stabilizing didoe D5 is connected with the resistance R8 other end, plus earth; Capacitor C9 one end is connected with power supply VCC, other end ground connection; Resistance R6 one end is connected with the grid of the second amplifier tube Q2, and the other end is connected with the drain electrode of analog output signal output port A1 out, the second amplifier tube Q2; Resistance R7 and capacitor C12 is connected in parallel, and one end is connected with the source electrode of the second amplifier tube Q2, other end ground connection;
Described interstage coupling unit comprises: capacitor C5, inductance L 3, resistance R5; The signal of the drain electrode output of the first amplifier tube Q1 is connected to the grid of the second amplifier tube Q2 by capacitor C5, use resistance-capacitance coupling mode to carry out Linear Amplifer to faint input signal; One end of inductance L 3 is connected with the drain electrode of the first amplifier tube Q1, and the other end is connected with the other end of resistance R5, has choking effect to amplifying circuit, and one end of resistance R5 is connected with power supply VCC by biasing circuit; The grid of the first amplifier tube Q1 is connected with analog output signal input port A1 in, and source electrode is by biasing circuit ground connection; The drain electrode of the second amplifier tube Q2 is connected with power supply VCC by biasing circuit, and source electrode is by biasing circuit ground connection.
2. preamplifier according to claim 1, is characterized in that, also comprises:
Input matching network, couples described first amplifier tube Q1, for realizing input noise coupling;
Output matching network, couples described second amplifier tube Q2, for realizing output noise coupling.
3. preamplifier according to claim 2, is characterized in that, also comprises:
Input protection unit, couples described input matching network, for the protection of the safety that described amplifying circuit inputs;
Output protection unit, couples described output matching network, for ensureing the signal stabilization that described amplifying circuit exports.
4. a magnetic resonance amplifying device, is characterized in that, comprising:
Balanced-to-unbalanced transformer;
Preamplifier; And
Matching network, is coupled to described balanced-to-unbalanced transformer and described preamplifier, for mating the impedance between described balanced-to-unbalanced transformer and described preamplifier;
Described preamplifier, comprising:
Amplifying circuit, for amplification input signal; And
Biasing circuit, for the quiescent operation point control online property amplification region of described amplifying circuit;
Described amplifying circuit comprises:
First amplifier tube Q1, for amplifying the signal of input;
Second amplifier tube Q2, for amplifying the output signal of described first amplifier tube Q1;
Interstage coupling unit, is coupled to described first amplifier tube Q1 and described second amplifier tube Q2;
Described balanced-to-unbalanced transformer comprises at least one two microstrip line unit, and described pair of microstrip line unit comprises ground plane and signals layer, and described signals layer is arranged between described ground plane; Capacitor, the ground plane two ends of described capacitor and described pair of microstrip line unit are connected in parallel;
Described pair of microstrip line unit is stratiform and is symmetrical arranged, and the first half is identical with the latter half; The first half is provided with 2 ground planes and 1 signals layer, and wherein ground plane arranges both sides, middle signalization layer; Be interconnected between described pair of microstrip line unit, corresponding ground plane and signals layer are cross-linked;
Described biasing circuit comprises: the first bias unit, couples described first amplifier tube Q1, for the quiescent operation point control online property amplification region of described first amplifier tube Q1; Second bias unit, couples described second amplifier tube Q2, for the quiescent operation point control online property amplification region of described second amplifier tube Q2;
Described first bias unit comprises: resistance R1, R2, R3 and R4; Capacitor C4, C6 and C7; Inductance L 2; Resistance R2 one end is connected to the grid of the first amplifier tube Q1, and resistance R3 one end is connected with the other end of resistance R2; Resistance R4 and capacitor C7 is connected in parallel, and one end is connected with the other end of resistance R3, other end ground connection; Capacitor C6 one end is connected between resistance R2 and R3, other end ground connection; Resistance R1 and capacitor C4 is connected in parallel, and one end is connected to the source electrode of the first amplifier tube Q1, and the other end is connected with inductance L 2, inductance L 2 other end ground connection;
Described second bias unit comprises: resistance R6, R7 and R8; Capacitor C8, C9 and C12; Inductance L 4; Voltage stabilizing didoe D5; Diode D6; The positive pole of diode D6 is connected with power supply VCC, and negative pole is connected with resistance R8 one end; The resistance R8 other end is connected with one end of the resistance R5 of interstage coupling unit respectively, and the resistance R8 other end also and between resistance R3 and the R4 of the first bias unit is connected; One end of inductance L 4 is connected with the drain electrode of the second amplifier tube Q2, and the other end is connected with the resistance R8 other end, has choking effect to amplifier tube; Capacitor C8 one end is connected with the resistance R8 other end, other end ground connection; The negative pole of voltage stabilizing didoe D5 is connected with the resistance R8 other end, plus earth; Capacitor C9 one end is connected with power supply VCC, other end ground connection; Resistance R6 one end is connected with the grid of the second amplifier tube Q2, and the other end is connected with the drain electrode of analog output signal output port A1 out, the second amplifier tube Q2; Resistance R7 and capacitor C12 is connected in parallel, and one end is connected with the source electrode of the second amplifier tube Q2, other end ground connection;
Described interstage coupling unit comprises: capacitor C5, inductance L 3, resistance R5; The signal of the drain electrode output of the first amplifier tube Q1 is connected to the grid of the second amplifier tube Q2 by capacitor C5, use resistance-capacitance coupling mode to carry out Linear Amplifer to faint input signal; One end of inductance L 3 is connected with the drain electrode of the first amplifier tube Q1, and the other end is connected with the other end of resistance R5, has choking effect to amplifying circuit, and one end of resistance R5 is connected with power supply VCC by biasing circuit; The grid of the first amplifier tube Q1 is connected with analog output signal input port A1 in, and source electrode is by biasing circuit ground connection; The drain electrode of the second amplifier tube Q2 is connected with power supply VCC by biasing circuit, and source electrode is by biasing circuit ground connection.
5. magnetic resonance amplifying device according to claim 4, is characterized in that, described pair of microstrip line unit is set to straightway, curved line or helix shape.
6. magnetic resonance amplifying device according to claim 5, is characterized in that, also comprise:
Input matching network, couples described first amplifier tube Q1, for realizing input noise coupling;
Output matching network, couples described second amplifier tube Q2, for realizing output noise coupling.
7. magnetic resonance amplifying device according to claim 6, is characterized in that, also comprise:
Input protection unit, couples described input matching network, for the protection of the safety that described amplifying circuit inputs;
Output protection unit, couples described output matching network, for ensureing the signal stabilization that described amplifying circuit exports.
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| CN201210137145.7A CN102664595B (en) | 2011-12-12 | 2012-05-04 | Preamplifier and magnetic resonance amplifying device |
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| CN201110412076.1 | 2011-12-12 | ||
| CN201110412076 | 2011-12-12 | ||
| CN2011104120761 | 2011-12-12 | ||
| CN201210137145.7A CN102664595B (en) | 2011-12-12 | 2012-05-04 | Preamplifier and magnetic resonance amplifying device |
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| CN102664595B true CN102664595B (en) | 2015-09-30 |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN103973236B (en) * | 2013-01-28 | 2018-03-30 | 北京大学 | Input protection circuit |
| CN105301534B (en) * | 2014-05-27 | 2018-05-15 | 上海辰光医疗科技股份有限公司 | A kind of preamplifier for magnetic resonance imaging radiofrequency coil |
| CN104467690A (en) * | 2014-12-04 | 2015-03-25 | 上海联影医疗科技有限公司 | Low-noise amplifier circuit |
| CN108649910A (en) * | 2018-06-26 | 2018-10-12 | 深圳先进技术研究院 | A kind of preamplifier |
| WO2020000168A1 (en) * | 2018-06-26 | 2020-01-02 | 深圳先进技术研究院 | Preamplifier |
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| CN85103310A (en) * | 1985-05-13 | 1987-02-04 | 菲利浦光灯制造公司 | Be used for the transmission of high frequency and the MR equipment of measurement coil |
| US7378851B1 (en) * | 2006-12-11 | 2008-05-27 | General Electric Company | Integrated low noise amplifier and balun for MRI receivers |
| CN201541238U (en) * | 2009-09-11 | 2010-08-04 | 清华大学 | Preamplifier of magnetic resonance imaging MRI system capable of reducing low-frequency noise |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN85103310A (en) * | 1985-05-13 | 1987-02-04 | 菲利浦光灯制造公司 | Be used for the transmission of high frequency and the MR equipment of measurement coil |
| US7378851B1 (en) * | 2006-12-11 | 2008-05-27 | General Electric Company | Integrated low noise amplifier and balun for MRI receivers |
| CN201541238U (en) * | 2009-09-11 | 2010-08-04 | 清华大学 | Preamplifier of magnetic resonance imaging MRI system capable of reducing low-frequency noise |
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