Amplification circuit and mass spectrometer provided with same

Abstract

An amplifier circuit (101) is provided with: a first current source circuit (113) that outputs a predetermined amount of current to a first wiring (L1); a voltage amplifier circuit (110) that amplifies the voltage of the input signal; a first level shift circuit (111) which is connected between the first wiring (L1) and the output of the voltage amplifier circuit (110) and shifts the voltage of the signal output from the voltage amplifier circuit (110); a first voltage follower (117) that is connected to the first wiring (L1) and amplifies a signal in the first wiring (L1); and a first capacitor (210) connected between the first wiring (L1) and the output of the voltage amplifier circuit (110).

Description

Technical Field

[0001] The present invention relates to an amplifier circuit and a mass spectrometry apparatus including the amplifier circuit, and more particularly to a technique for achieving both high-frequency operation and high power of the amplifier circuit and the mass spectrometry apparatus. Background Art

[0002] For example, Patent Document 1 discloses a technique for achieving high-frequency operation of an amplifier circuit. That is, Patent Document 1 discloses that, in order to achieve both high gain and wide bandwidth, an amplifier circuit is configured by cascading a plurality of amplifiers each including a source-grounded transistor, a drain-grounded transistor, and a feedback resistor.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2004-96308 Summary of the Invention

[0006] Problems to be Solved by the Invention

[0007] As shown in Patent Document 1, when amplifiers are cascaded, there is a problem that the occupied area (hereinafter, also simply referred to as the size) of the amplifier circuit becomes large. In addition, an amplifier that achieves both high gain and wide bandwidth generally has a problem of high power consumption.

[0008] An object of the present invention is to provide an amplifier circuit and a mass spectrometry apparatus including the amplifier circuit that can achieve both high-frequency operation and high power while suppressing heat generation and an increase in size.

[0009] Other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[0010] Means for Solving the Problems

[0011] If the outline of a representative embodiment in the embodiments disclosed in the present application is briefly described, it is as follows.

[0012] That is, an amplifier circuit according to one embodiment includes: a first current source circuit that outputs a predetermined amount of current to a first wiring; a voltage amplifier circuit that amplifies the voltage of an input signal; a first level shift circuit that is connected between the first wiring and the output of the voltage amplifier circuit and shifts the voltage of the signal output from the voltage amplifier circuit; a first voltage follower that is connected to the first wiring and amplifies the signal in the first wiring; and a first capacitor that is connected between the first wiring and the output of the voltage amplifier circuit.

[0013] In addition, in another embodiment, a quality analysis device is provided. The quality analysis device in the other embodiment includes an amplifier circuit having characteristics suitable as an amplifier circuit used in the quality analysis device.

[0014] Advantages of the Invention

[0015] When briefly explaining the effects obtained from the representative embodiments in the invention disclosed in the present application, an amplifier circuit capable of achieving high-frequency operation and high-power operation while suppressing heat generation and increase in size, and a quality analysis device including the amplifier circuit can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a circuit diagram showing the structure of the amplifier circuit of Embodiment 1.

[0017] Figure 2 It is a circuit diagram showing the structure of the amplifier circuit of the comparative example.

[0018] Figure 3 (A) to (C) thereof are waveform diagrams for explaining the operation of the amplifier circuit of the comparative example.

[0019] Figure 4 (A) to (D) thereof are waveform diagrams for explaining the effects of the capacitor of Embodiment 1.

[0020] Figure 5 (A) and (B) thereof are waveform diagrams showing the output signals of the amplifier circuit of Embodiment 1 and the amplifier circuit of the comparative example.

[0021] Figure 6 (A) and (B) thereof are circuit diagrams for explaining the amplifier circuit of Embodiment 2.

[0022] Figure 7 It is a block diagram showing the structure of the quality analysis device of Embodiment 3.

[0023] Figure 8 It is a circuit diagram showing the structure of the RF signal generation unit of Embodiment 3.

[0024] Figure 9 It is a diagram showing the mathematical formula of the embodiment. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] The embodiments will be described with reference to the drawings. It should be noted that the embodiments described below do not limit the invention covered by the patent protection scope, and in addition, not all of the elements and combinations thereof described in the embodiments are necessarily essential for the solution means of the invention.

[0026] (Embodiment 1)

[0027] <Overall Structure of Amplifier Circuit>

[0028] Figure 1 is a circuit diagram showing the structure of the amplifier circuit of Embodiment 1. In Figure 1 101 represents the amplifier circuit.

[0029] The amplifier circuit 101 includes a voltage amplifier circuit 110, a first level shifter circuit 111, a first capacitor 210, a second level shifter circuit 112, a second capacitor 220, a first current source circuit 113, a second current source circuit 114, a positive power supply 115, a negative power supply 116, a first voltage follower 117, and a second voltage follower 118.

[0030] The output terminal of the voltage amplifier circuit 110 is connected to the first level shifter circuit 111 and the second level shifter circuit 112. The first current source circuit 113 is connected to the positive power supply 115, and the first current source circuit 113 is connected to the first level shifter circuit 111 through the first wiring L1. In addition, the second current source circuit 114 is connected to the negative power supply 116, and the second current source circuit 114 is connected to the second level shifter circuit 112 through the second wiring L2. That is, the first current source circuit 113 and the first level shifter circuit 111 are connected in series between the output terminal of the voltage amplifier circuit 110 and the positive power supply 115, and the second current source circuit 114 and the second level shifter circuit 112 are connected in series between the output terminal of the voltage amplifier circuit 110 and the negative power supply 116.

[0031] The first voltage follower 117 is connected between the positive power supply 115 and the output terminal of the amplifier circuit 101, and the input terminal of the first voltage follower 117 is connected to the first wiring L1. In addition, the second voltage follower 118 is connected between the negative power supply 116 and the output terminal of the amplifier circuit 101, and the input terminal of the second voltage follower 118 is connected to the second wiring L2. That is, the first voltage follower 117 and the second voltage follower 118 are connected in series between the positive power supply 115 and the negative power supply 116.

[0032] <Structure of Each Circuit Constituting the Amplifier Circuit>

[0033] Next, with reference to Figure 1 each circuit constituting the amplifier circuit 101 will be described.

[0034] The voltage amplifier circuit 110 amplifies the voltage amplitude of the input signal VIN supplied to the input terminal and outputs an output signal Svg having the amplified voltage amplitude from the output terminal.

[0035] The first level-shifting circuit 111 includes a load resistor 119 and an N-channel MOS (metal-oxide-semiconductor) transistor (hereinafter also referred to as an N-type transistor) Q1. The load resistor 119 is connected between the source of the N-type transistor Q1 and the output terminal of the voltage amplification circuit 110, and the drain and gate of the N-type transistor Q1 are connected to one end of the first wiring L1. In addition, the N-type transistor Q1 functions as a diode (voltage element) by connecting the drain and the gate.

[0036] One terminal of the first capacitor 210 is connected to the source of the N-type transistor Q1, and the other terminal is connected to the drain and gate of the N-type transistor Q1.

[0037] The second level-shifting circuit 112 includes a load resistor 120 and a P-channel MOS transistor (hereinafter also referred to as a P-type transistor) Q2. The load resistor 120 is connected between the source of the P-type transistor Q2 and the output terminal of the voltage amplification circuit 110, and the drain and gate of the P-type transistor Q2 are connected to one end of the second wiring L2. The P-type transistor Q2 also functions as a diode (voltage element) by connecting the drain and the gate.

[0038] One terminal of the second capacitor 220 is connected to the source of the P-type transistor Q2, and the other terminal is connected to the drain and gate of the P-type transistor Q2.

[0039] The first level-shifting circuit 111 takes the output signal Svg from the voltage amplification circuit 110 as an input and outputs a positive-side level-shifted signal Shs to the first wiring L1. That is, the first level-shifting circuit 111 outputs a level-shifted signal Shs, which is a signal obtained by shifting the output signal Svg by a voltage amount specified by the diode formed by the N-type transistor Q1 toward the positive power supply 115 side.

[0040] In addition, the second level-shifting circuit 112 takes the output signal Svg from the voltage amplification circuit 110 as an input and outputs a negative-side level-shifted signal Sls to the second wiring L2. That is, the second level-shifting circuit 112 outputs a level-shifted signal Sls, which is a signal obtained by shifting the output signal Svg by a voltage amount specified by the diode formed by the P-type transistor Q2 toward the negative power supply 116 side.

[0041] The first capacitor 210 and the second capacitor 220 will be described later, so the description thereof is omitted here.

[0042] The first current source circuit 113 is connected to the other end of the first wiring L1, and outputs a drive current Ihs of a predetermined value (current amount) to the first level shifter circuit 111 via the first wiring L1. Similarly, the second current source circuit 114 is connected to the other end of the second wiring L2, and outputs a drive current Ils of a predetermined value to the second level shifter circuit 112 via the second wiring L2.

[0043] In Embodiment 1, the first voltage follower 117 is constituted by a source follower circuit. That is, the first voltage follower 117 includes an N-type transistor Q3 with its drain grounded and a load resistor 121. The drain of the N-type transistor Q3 is connected to the positive power supply 115, the source is connected to the output terminal of the amplifier circuit 101 via the load resistor 121, and the gate is connected to the first wiring L1.

[0044] In Embodiment 1, the second voltage follower 118 is also constituted by a source follower circuit. That is, the second voltage follower 118 includes a P-type transistor Q4 with its drain grounded and a load resistor 122. The drain of the P-type transistor Q4 is connected to the negative power supply 116, the source is connected to the output terminal of the amplifier circuit 101 via the load resistor 122, and the gate is connected to the second wiring L2.

[0045] The first voltage follower 117 uses the gate of the N-type transistor Q3 as an input terminal, inputs the positive-side level shift signal Shs in the first wiring L1, uses the source of the N-type transistor Q3 as an output terminal, and outputs a positive-side output signal Shp corresponding to the positive-side level shift signal Shs. In contrast, the second voltage follower 118 uses the gate of the P-type transistor Q4 as an input terminal, inputs the negative-side level shift signal Sls in the second wiring L2, uses the source of the P-type transistor Q4 as an output terminal, and outputs a negative-side output signal Slp corresponding to the negative-side level shift signal Sls.

[0046] The output signal Shp and the output signal Slp are synthesized (added) via the load resistors 121 and 122 to become the output signal OUT (= Shp + Slp) of the amplifier circuit 101.

[0047] Functionally, the amplifier circuit 101 can be regarded as being roughly composed of a voltage amplification stage, a level shift stage, and an output stage.

[0048] Here, the input stage corresponds to the part including the voltage amplifier circuit 110. The voltage amplifier circuit 110, for example, sets a voltage amplification factor in the design stage and has the set voltage amplification factor. The input stage amplifies the voltage of the input signal VIN according to the preset voltage amplification factor and outputs an amplified output signal Svg.

[0049] The voltage shift stage corresponds to a part composed of a first voltage shift circuit 111 on the positive electrode side, a first current source circuit 113, a second voltage shift circuit 112 on the negative electrode side, and a second current source circuit 114.

[0050] The first voltage shift circuit 111 takes the output signal Svg obtained by amplification as an input and outputs a voltage shift signal Shs on the positive electrode side. Here, the voltage shift signal Shs becomes a value obtained by shifting the output signal Svg to the positive electrode side by a voltage amount determined by the amount of current flowing through the N-type transistor Q1 in the drive current Ihs output from the first current source circuit 113 to the first wiring L1. That is, by passing a current through the diode formed by the N-type transistor Q1, the output signal Svg is shifted to the positive electrode side by the voltage amount generated in this diode.

[0051] Similarly, the second voltage shift circuit 112 takes the output signal Svg obtained by amplification as an input and outputs a voltage shift signal Sls on the negative electrode side. Here, the voltage shift signal Sls becomes a value obtained by shifting the output signal Svg to the negative electrode side by a voltage amount determined by the amount of current flowing through the P-type transistor Q2 in the drive current Ils output from the second current source circuit 114 to the second wiring L2. That is, by passing a current through the diode formed by the P-type transistor Q2, the output signal Svg is shifted to the negative electrode side by the voltage amount generated in this diode.

[0052] The first capacitor 210 and the second capacitor 220 connected to the first voltage shift circuit 111 and the second voltage shift circuit 112 have the function of charging the parasitic capacitances parasitic on the first wiring L1 and the second wiring L2. As the capacitance parasitic on the first wiring L1, for example, there is a capacitance of a circuit connected to this second wiring, such as the parasitic capacitance of the input terminal of the first voltage follower 117. As the parasitic capacitance of the input terminal of the first voltage follower 117, the gate capacitance of the N-type transistor Q3 can be cited. The capacitance parasitic on the second wiring L2 is the same as the capacitance parasitic on the first wiring L1. For example, there is a capacitance of a circuit connected to this wiring L2, such as the parasitic capacitance of the input terminal of the second voltage follower 118. As the parasitic capacitance of the input terminal of the second voltage follower 118, the gate capacitance of the P-type transistor Q4 can be cited.

[0053] In addition, in this specification, unless otherwise specified, charging of a capacitor means both discharging and charging.

[0054] The output stage corresponds to a part composed of a first voltage follower 117 on the positive electrode side and a second voltage follower 118 on the negative electrode side. The voltage follower includes a MOS transistor and a load resistor. The first voltage follower 117 takes the level shift signal Shs on the positive electrode side as an input and outputs an output signal Shp after the voltage has dropped by the threshold amount of the N-type transistor Q3. At this time, when the voltage of the level shift signal Shs on the positive electrode side becomes a voltage exceeding the threshold in the N-type transistor Q3, the N-type transistor Q3 becomes in a conducting state, and a current flows through the positive electrode side. That is, a current corresponding to the voltage of the level shift signal Shs flows from the positive power supply 115 to the output terminal of the amplifier circuit 101 via the N-type transistor Q3.

[0055] The second voltage follower 118 is the same as the first voltage follower 117. That is, the second voltage follower 118 takes the level shift signal Sls on the negative electrode side as an input and outputs an output signal Slp after the voltage has dropped by the threshold amount of the P-type transistor Q4. At this time, when the voltage of the level shift signal Sls becomes a voltage exceeding the threshold in the P-type transistor Q4, the P-type transistor Q4 becomes in a conducting state, and a current flows through the negative electrode side. That is, a current corresponding to the voltage of the level shift signal Sls flows from the negative power supply 116 to the output terminal of the amplifier circuit 101 via the P-type transistor Q4.

[0056] The voltage of the input signal VIN is referenced to the ground voltage and, for example, alternately changes on the positive electrode side and the negative electrode side. Thereby, the operation of causing the current on the positive electrode side to flow and the operation of causing the current on the negative electrode side to flow are alternately performed, and the output stage realizes a push-pull operation.

[0057] In Figure 1 it was described that a source follower circuit is used as the voltage follower, but it is not limited to this. For example, when a bipolar transistor is used instead of a MOS transistor, the first voltage follower 117 and the second voltage follower 118 are constituted by an emitter follower circuit.

[0058] <The First Capacitor and the Second Capacitor>

[0059] Next, the effects of the first capacitor 210 and the second capacitor 220 connected to the level shift circuits 111 and 112 are described. The effect of the second capacitor 220 is the same as the effect of the first capacitor 210, so only the first capacitor 210 is described here.

[0060] For easy understanding, first, an amplifier circuit that does not connect the first capacitor 210 and the second capacitor 220 to the first level shift circuit and the second level shift circuit is described as a comparative example.

[0061] <<Comparative Example>>

[0062] Figure 2 is a circuit diagram showing the structure of the amplifier circuit of the comparative example. The amplifier circuit 301 shown in this figure is similar to Figure 1 the amplifier circuit 101 shown. The main difference is that Figure 2 the amplifier circuit 301 shown does not have Figure 1 the first capacitor 210 and the second capacitor 220 shown. In Figure 2 , Ihs represents the drive current of a predetermined value output by the first current source circuit 113 to drive the N-type transistor Q1 of the first level shifter circuit 111, and Vhh represents the level shift voltage of the first level shifter circuit 111.

[0063] Figure 3 is a waveform diagram for explaining the operation of the amplifier circuit of the comparative example. Figure 3 (A) shows the current waveform of the input signal of the first voltage follower 117, Figure 3 (B) shows the voltage waveform of the input signal of the first voltage follower 117, Figure 3 (C) shows the waveform of the output signal OUT of the amplifier circuit 301. In Figure 3 (A) to (C), the dashed line extending horizontally and labeled with the reference numeral 0 represents the ground voltage (0 V) or the reference current (0 A).

[0064] In the interval tA, as Figure 3 (B) shows, the input voltage of the first voltage follower 117 starts to rise from 0 V. Then, as Figure 3 (A) shows, the input current flows through the first voltage follower 117. At the time point when the value of the input voltage of the first voltage follower 117 becomes the maximum (when transferring from the interval tA to the interval tB), that is, at the time point when the change amount of the input voltage becomes 0, the input current flowing through the first voltage follower 117 becomes 0 A.

[0065] In the interval tB, as Figure 3 (B) shows, the input voltage starts to decrease from the maximum value. Then, as Figure 3 (A) shows, a negative current starts to flow. At the time point when the value of the input voltage becomes 0 V (when transferring from the interval tB to the interval tC), that is, at the time point when the change amount of the input voltage becomes the maximum, the value of the flowing input current becomes the maximum. When transferring from this interval tB to the interval tC, as Figure 3 (B) shows, the input voltage switches from a positive voltage to a negative voltage. At this time, the parasitic capacitance attached to the input terminal of the first voltage follower 117 discharges, and as shown by the reference numeral 310, a large current Iht ( Figure 2 ) flows transiently. A transient large current Iht for discharging the parasitic capacitance is supplied from the first current source circuit 113.

[0066] However, the first current source circuit 113 is outputting a drive current Ihs to the first level shift circuit 111. Since a transient large current Iht flows through the first voltage follower 117, the value of the drive current flowing through the first level shift circuit 111 changes. Due to the change in the supplied drive current, the level shift voltage Vhh of the first level shift circuit 111 changes.

[0067] The positive-side level shift signal Shs output by the first level shift circuit 111 is a signal obtained by shifting the output signal Svg of the voltage amplifier circuit 110 by the level shift voltage Vhh. As a result, the level shift signal Shs also changes similarly.

[0068] Since the level shift signal Shs is the input signal of the first voltage follower 117, as shown by reference numeral 320 in (B) of Figure 3 , this input signal is also a signal distorted due to the transient large current Iht. Moreover, since the waveform of the output signal of the first voltage follower 117 is a waveform obtained by decreasing the voltage of the input signal of the first voltage follower 117 by the threshold amount of the N-type transistor Q3, the output signal OUT of the amplifier circuit 301 becomes a waveform including Figure 3 the distortion shown by reference numeral 330 in (C) of

[0069] <<Effects of the First and Second Capacitors>>

[0070] Next, the case where the first capacitor 210 and the second capacitor 220 are provided as shown in Figure 1 will be described.

[0071] Figure 4 is a waveform diagram for explaining the effects of the capacitors in Embodiment 1. In this figure, the current flowing through the first capacitor 210, the input voltage of the first voltage follower 117, and the input current of the first voltage follower 117 are simply shown. Here, Figure 4 (A) of Figure 4 shows the waveform of the input current of the first voltage follower 117, Figure 4 (B) of Figure 4 shows the waveform of the current flowing through the first capacitor 210. In addition,

[0072] (C) of Figure 4 shows the waveform of the input voltage of the first voltage follower 117, and

[0073] shows the waveform of the output signal OUT of the amplifier circuit 101.

[0072] In (A) to (D) of Figure 4 , the dotted line extending horizontally and labeled with reference numeral 0 represents the ground voltage (0V) or the reference current 0A. In these figures, the upper side of the dotted line is the positive side, and the lower side is the negative side.

[0073] In the first voltage follower 117 that constitutes the output stage, the gate of the N-type transistor Q3 functions as an input terminal connected to the first wiring L1. Since there is a parasitic gate capacitance attached to the gate of the N-type transistor Q3, there is a parasitic capacitance attached to the first wiring L1, and the parasitic capacitance in the first wiring L1 is connected to the first capacitor 210.

[0074] In the period tA, when the input voltage of the first voltage follower 117 rises from 0V as shown in (C) of Figure 4 , an input current flows through the first voltage follower 117 as shown in (A) of Figure 4 . When transferring from the period tA to the period tB, as shown in (C) of Figure 4 , the value of the input voltage of the first voltage follower 117 reaches the maximum value, the change amount of the input voltage becomes 0, and as shown in (A) of Figure 4 , the input current flowing through the first voltage follower 117 becomes 0A.

[0075] In the period tB, the input voltage of the first voltage follower 117 starts to decrease from the maximum value as shown in (C) of Figure 4 . When the input voltage starts to decrease, a negative (negative electrode side) input current starts to flow through the first voltage follower 117 as shown in (A) of Figure 4 . As shown in (C) of Figure 4 , when the value of the input voltage of the first voltage follower 117 reaches 0V, that is, when the change amount of the input voltage is the largest, the value of this negative input current becomes the largest.

[0076] When transferring from the period tB to the period tC, the input voltage of the first voltage follower 117 switches from a positive (positive electrode side) voltage to a negative (negative electrode side) voltage as shown in (C) of Figure 4 . At this time, the parasitic capacitance attached to the input terminal of the first voltage follower 117 discharges, and a large current flows transiently as indicated by the reference numeral 410 in (A) of Figure 4 .

[0077] In the first embodiment, as shown in (B) of Figure 4 , this transient large current flows through the first capacitor 210, and the first capacitor 210 is charged. Thereby, it is possible to prevent the value of the drive current Ihs flowing through the first level shift circuit 111 from fluctuating due to the transient large current, and it can be maintained at a constant value.

[0078] By keeping the value of the current flowing through the level shift circuit 111 constant, it is possible to prevent the level shift voltage shifted by the level shift circuit 111 from fluctuating, and the level shift signal Shs on the positive electrode side can be stably output. As a result, as shown in (B) of Figure 4As shown in (D), the output signal OUT of the amplifier circuit 101 becomes a signal with reduced distortion.

[0079] From the interval tC to the interval tD, the positive and negative sides alternate, but the same operations as from the interval tA to the interval tB are performed. Thereafter, in the interval tE and thereafter, the same operations as from the interval tA to the interval tD are repeated. From the interval tC to the interval tD, the polarity alternates compared to from the interval tA to the interval tB. Therefore, as Figure 4 shown in (A), when transferring from the interval tD to the interval tE, the parasitic capacitance attached to the input terminal of the first voltage follower 117 is charged. At this time, as Figure 4 shown in (B), the first capacitor 210 discharges in order to charge the parasitic capacitance.

[0080] Through this series of operations, even when a transient large current flows to charge and discharge the parasitic capacitance attached to the first wiring L1, the output signal OUT of the amplifier circuit 101 can be a low-distortion signal. In addition, in Figure 4 (D), the positive side of the output signal OUT is output from the first voltage follower 117, and the negative side of the output signal OUT is output from the second voltage follower 118.

[0081] As the parasitic capacitance charged and discharged by the first capacitor 210, the parasitic capacitance attached to the input terminal of the first voltage follower 117 is taken as an example, but the parasitic capacitance charged and discharged by the first capacitor 210 is not limited to this. That is, the first capacitor 210 not only charges and discharges the parasitic capacitance attached to the input terminal of the first voltage follower 117, but also charges and discharges the parasitic capacitance attached to the first wiring L1, stabilizing the current flowing through the first level shift circuit.

[0082] In order to reduce the transient large current generated by the parasitic capacitance attached to the first wiring L1, the first capacitor 210 performs a charge and discharge operation. The first capacitor 210 of Embodiment 1 has a current supply ability to charge (charge and discharge) the parasitic capacitance attached to the first wiring L1. In addition, since the first capacitor 210 is driven by the voltage amplifier circuit 110, the voltage amplifier circuit 110 has a current supply ability to charge (charge and discharge) the first capacitor 210. Thus, in Embodiment 1, the transient large current can be canceled by the charge and discharge of the first capacitor 210.

[0083] Figure 5 is a waveform diagram showing the output signals of the amplifier circuit of Embodiment 1 and the amplifier circuit of the comparative example. Here, Figure 5 (A) represents Figure 2 the waveform of the output signal of the amplifier circuit of the comparative example described above, Figure 5The waveform of the output signal of the amplifier circuit according to Embodiment 1 is shown in (B).

[0084] In Figure 5 610 and 620 represent the voltage waveforms of the input signals input to the amplifier circuit, and 611 and 621 represent the voltage waveforms of the output signals output from the amplifier circuit.

[0085] As Figure 5 shown in (A), in the amplifier circuit of the comparative example, distortion occurs near the maximum value of the output signal. In contrast, in the amplifier circuit of Embodiment 1, by charging (charging and discharging) the capacitor connected to the level shift circuit, the variation of the current supplied to the level shift circuit is reduced. As Figure 5 shown in (B), distortion is removed even near the maximum value of the output signal. That is, it is possible to obtain a large-amplitude output signal through a push-pull operation while reducing signal waveform distortion.

[0086] <Suppression of heat generation and size increase>

[0087] It is also possible to cope with the waveform distortion of the output signal caused by the above-mentioned transient large current by the structure of the first current source circuit 113 and the second current source circuit 114 that supply the driving currents Ihs and Ils to the first level shift circuit and the second level shift circuit. That is, by forming the first current source circuit and the second current source circuit from a plurality of unit current source circuits in multiple stages, the first current source circuit and the second current source circuit are made to have a high output impedance, and even if a transient large current is generated, the influence on the driving currents Ihs and Ils can be suppressed.

[0088] However, in order to make the plurality of unit current source circuits multi-stage, the positive power supply 115 and the negative power supply 116 that supply power to the first current source circuit 113 and the second current source circuit 114 thus formed must be made into high voltages (voltages with a high absolute value). When the positive power supply 115 and the negative power supply 116 are made into high voltages, the heat generated in the first voltage follower 117 and the second voltage follower 118 increases, which causes a heat generation problem. In addition, since the first current source circuit and the second current source circuit are each composed of a plurality of unit current source circuits, the number of semiconductor elements constituting the first current source circuit and the second current source circuit increases, the sizes of the first current source circuit and the second current source circuit become larger, and further the size of the amplifier circuit becomes larger.

[0089] In the amplifier circuit of Embodiment 1, waveform distortion of the output signal can be reduced by the first capacitor and the second capacitor. Therefore, even if the first current source circuit 113 and the second current source circuit 114 are constituted by a multi-stage unit current source circuit in addition to the first capacitor and the second capacitor, the number of stages of the multi-stage unit current source circuit can be reduced. In order to provide the first capacitor and the second capacitor, the size increases accordingly, but the number of stages of the unit current source circuit can be reduced, so an increase in size can be suppressed. In addition, since the number of stages can be reduced, a high voltage of the positive power supply 115 and the negative power supply 116 can be suppressed, and heat generation can be suppressed.

[0090] In addition, in Embodiment 1, the first level shift circuit and the second level shift circuit are constituted by MOS transistors connected in series and a load resistor, so they can be constituted with a smaller number of elements, and an increase in size can be suppressed.

[0091] (Embodiment 2)

[0092] Figure 6 is a circuit diagram for explaining the amplifier circuit of Embodiment 2. Here, Figure 6 (A) of is a circuit diagram showing the structure of the amplifier circuit of Embodiment 2. In addition, Figure 6 (B) of is a circuit diagram showing the structure of a comparison circuit for explaining the amplifier circuit of Embodiment 2.

[0093] In Figure 6 , only a part (positive electrode side) corresponding to a part of the amplifier circuit shown in Figure 1 is shown. That is, in Figure 6 (A) of, only the part corresponding to the first level shift circuit 111, the first current source circuit 113, and the first voltage follower 117 shown in Figure 1 is shown, and other parts are omitted. The structure of the negative electrode side is only that the transistor is replaced by a P-type transistor, and it has the same structure as Figure 6 (A) of.

[0094] In Embodiment 2, the first current source circuit 113 is constituted by one unit current source circuit UVI. In Figure 6 (A) of, the voltage drop of this unit current source circuit UVI is indicated by the reference symbol Vi.

[0095] Similar to Embodiment 1, a first capacitor 210 is connected to the first level shift circuit 111. Thus, as described above, even if a transient large current flows, by charging and discharging with the first capacitor 210, waveform distortion of the output signal can be reduced. In other words, the transient large current is canceled by the first capacitor 210.

[0096] Therefore, even if the output impedance of the first current source circuit 113 is relatively low, it is possible to prevent the drive current supplied to the first level shift circuit 111 from varying due to a transient large current.

[0097] Figure 6 The comparative example shown in (B) of Figure 6 is similar to Figure 6 (A) of

[0098] Figure 6 The unit current source circuit UVI shown in (B) of Figure 6 is the same as that shown in (A) of Figure 6 In (B) of Figure 6 , by multiplying the unit current source circuit UVI, the drive current Ihs supplied to the first level shift circuit 111 becomes the same value as the drive current Ihs in Figure 6 (A) of

[0099] However, in Figure 6 (A) and (B) of Figure 6 , in order to make the voltage of the signal Shp output from the first voltage follower 117 the same value, the voltage of the positive power supply 115 is different in

[0100] That is, in Figure 6 (A) of

[0101] , the positive voltage of the positive power supply 115 is set to VHj, and in order to make the signal Shp a predetermined voltage value, a voltage Vqc is applied between the source and drain of the N-type transistor Q3 constituting the first voltage follower 117. Figure 6 In contrast, in the structure of (B) of Figure 6 , in order to obtain the signal Shp of the same predetermined voltage value, the first current source circuit 113 is composed of two-stage unit current source circuits UVI, so the voltage drop of the first current source circuit 113 becomes twice the voltage drop Vi, Figure 9 The positive voltage VHk of the positive power supply in (B) of Figure 6 becomes the value represented by the formula (1) shown in Figure 9The voltage Vqi obtained by the formula (2) shown. That is, when the first current source circuit 113 is composed of a multi-stage unit current source circuit, it is necessary to make the amplifier circuit perform high-voltage operation, the voltage applied to the first voltage follower 117 becomes larger, and the power consumption increases. Due to the increase in power consumption, the circuit generates heat.

[0102] Due to heat generation, there is a risk that the temperature of the semiconductor element exceeds the rated value of the semiconductor element. Therefore, in order to suppress heat generation, a heat sink or a cooling fan is sometimes used. However, the installation of such a cooling mechanism directly leads to an increase in circuit size and production cost, so it is not preferred.

[0103] According to Embodiment 2, by using one unit current source circuit, the first capacitor, and the second capacitor, it is possible to suppress waveform distortion of the output signal and suppress an increase in size and heat generation.

[0104] (Embodiment 3)

[0105] In Embodiment 3, a quality analysis device including the amplifier circuit described in Embodiment 1 will be described. Figure 7 It is a block diagram showing the structure of the quality analysis device of Embodiment 3. In Figure 7 , 701 represents the quality analysis device.

[0106] The quality analysis device 701 includes a measurement unit 702, which is composed of the following components: an ion source 710 that ionizes the sample to be analyzed delivered from the pretreatment unit; a convergence unit 711 that converges the ionized analysis sample 728; a separation unit 712 that filters the converged ions according to the mass-to-charge ratio and allows only the ionized sample of the detection object to pass through; and a detection unit 713 that collides the passed ionized sample with a conversion dynode 714, changes the ionized sample into electrons 715, and makes the electrons incident on a scintillator 716 to output photons corresponding to the amount of electrons. Moreover, the quality analysis device 701 further includes: a detector 717 that outputs an electrical signal corresponding to the photons output from the detection unit 713; an analysis result processing unit 718 that processes the electrical signal output from the detector 717; a driver 719 that drives the measurement unit 702; a monitor 720 that monitors the measurement unit 702; a power supply 721 that supplies power to each part; and a control unit 722 that controls quality analysis.

[0107] The control unit 722 includes: an RF signal generation unit 723 that generates an AC signal; a DC signal generation unit 724 that generates a DC signal; an oscillation unit 725 that boosts the input signal through a resonant circuit and outputs it; and a pretreatment unit 726 that processes the signal input from the oscillation unit 725 and outputs it to an MS filter 727 included in the separation unit 712.

[0108] Next, use Figure 7 to illustrate the operation until the ionized analytical sample 728 reaches the detection unit 713.

[0109] The MS filter 727 included in the separation unit 712 is composed of four electrodes. The polarities of the opposing electrodes are the same, and a voltage obtained by overlapping a DC voltage U and an AC voltage Vcos(ωt) is applied. The value of the applied voltage is represented by Figure 9 the formula (3) shown. The MS filter 727 forms an electric field corresponding to the voltage represented by the formula (3). In addition, in the formula (3), ω = 2πf, f represents the frequency of the AC voltage, and V represents the maximum value of the AC voltage.

[0110] When the ionized analytical sample 728 enters the electric field formed by the MS filter 727 of the separation unit 712, it advances toward the detection unit 713 while vibrating up and down, left and right. At this time, with respect to the voltage value applied to the MS filter 727, only the ions having a specific mass analysis ratio m / z perform a stable amplitude motion and pass through the MS filter 727 to reach the detection unit 713. On the other hand, the amplitudes of the ions having other mass analysis ratios m / z become larger and diverge, and they collide with the electrodes. Thus, only the ions having the set mass analysis ratio m / z reach the detection unit 713.

[0111] The mass analysis ratio m / z of the ions measured by the mass analyzer 701 is set by the magnitude V of the AC voltage applied to the MS filter 727, its frequency ω, and the distance 2ro between the electrodes of the MS filter 727. The mass analysis ratio m / z is represented by Figure 9 the formula (4) shown. In addition, in the formula (4), ^2 represents square.

[0112] According to Equation (4) of the mass analysis ratio m / z, in order to analyze ions with a large mass, it is considered to increase the value V of the alternating voltage, and decrease the values of the distance ro and the vibration number ω. However, due to the structure of the actual mass analysis device 701, the distance ro cannot be set to less than several millimeters. If the vibration number ω is made too small, the ions cannot vibrate sufficiently. Therefore, the measurement range of ions can be expanded by increasing the value V of the alternating voltage, thereby analyzing ions with a large mass. In addition, the resolution of the mass analysis device 701 depends on the assembly accuracy of the electrodes of the MS filter 727, the machining accuracy of the electrode surface, the stability of the value of the DC voltage U and the value of the alternating voltage V, and the vibration number ω of the alternating voltage. The vibration number ω determines the number of vibrations of the ions when passing through the MS filter 727. The more vibrations, the higher the resolution can be obtained. Therefore, if the vibration number ω is high and the electrode length of the MS filter 727 is long, the device has a high resolution. For these main reasons, in order to expand the measurement range and improve the resolution of the mass analysis device 701, it is required that the voltage applied to the MS filter 727 be a high voltage and a high frequency.

[0113] As Figure 7 shown, for the MS filter 727, the alternating current signal output from the RF signal generation unit 723 is boosted in the oscillation unit 725, and then applied to the MS filter 727 via the preprocessing unit 726. The signal applied to the MS filter 727 must have high frequency stability. Therefore, an LC circuit that achieves a high Q value is used in the oscillation unit 725. However, in order to achieve both high voltage and high frequency in this LC circuit, it is necessary to increase the drive current from the RF signal generation unit 723.

[0114] Figure 8 is a circuit diagram showing the structure of the RF signal generation unit of Embodiment 3. In Figure 8 is shown Figure 7 a specific example of the RF signal generation unit 723 shown and the oscillation unit 725 supplied with the signal from the RF signal generation unit 723.

[0115] The RF signal generation unit 723 includes a generation unit 730 that generates an RF signal and an amplifier circuit. In Figure 8 as the amplifier circuit, the Figure 1 amplifier circuit 101 shown is used.

[0116] The structure and operation of the amplifier circuit 101 have been described in Embodiment 1, and thus detailed description thereof is omitted. A generation unit 730 generates an AC signal whose voltage changes periodically. This AC signal is input as an input signal VIN to the amplifier circuit 101. The output terminal of the amplifier circuit 101 is connected to an LC circuit constituting an oscillation unit 725. Thus, the output signal, i.e., the AC signal, output from the amplifier circuit 101 is supplied to the LC circuit, and is supplied to a preprocessing unit 726 via the LC circuit, and further supplied to the electrodes of a separation unit 712.

[0117] According to Figure 8 It can also be understood that a first capacitor 210 and a load resistor 119 are connected in series between a first wiring L1 and the output terminal of a voltage amplifier circuit 110. Therefore, it can be regarded as a filter (hereinafter, also referred to as a first filter) constituted by the first capacitor 210 and the load resistor 119. Similarly, it can be regarded as a filter (hereinafter, also referred to as a second filter) constituted by a second capacitor 220 and a load resistor 120.

[0118] In Embodiment 3, the values of the first capacitor 210, the second capacitor 220, and the load resistors 119 and 120 are set such that the cutoff frequencies of the first filter and the second filter are higher than the resonance frequency of the separation unit 712. More specifically, the values of the capacitors and the load resistors are set such that the cutoff frequencies of the first filter and the second filter are higher than the resonance frequency of the MS filter 727 of the separation unit 712 ( Figure 7 )).

[0119] Thus, while suppressing an increase in size and heat generation, an AC signal amplified by the amplifier circuit 101 to become a high drive current can be supplied to the oscillation unit 725. By making the AC signal supplied to the oscillation unit 725 a high drive current, the voltage applied to the MS filter 727 can be made high voltage. In addition, waveform distortion can be suppressed in the amplifier circuit 101, and since the cutoff frequencies of the first filter and the second filter are higher than the resonance frequency of the MS filter, the output signal from the voltage amplifier circuit 110 can be transmitted to the MS filter 727 without distortion.

[0120] That is, high voltage and high frequency of the voltage applied to the MS filter 727 can be achieved, and an expansion of the measurement range and an improvement in resolution of the mass analysis device 701 can be achieved without causing an increase in the size and heat generation of the mass analysis device.

[0121] The amplifier circuit 101 described in Embodiments 1 to 3 may be formed on a single semiconductor chip, or may be constituted by combining a plurality of discrete semiconductor elements.

[0122] In addition, in Embodiments 1 to 3, a voltage follower has been described as an example, but it is not limited to a voltage follower. That is, a current amplification circuit that amplifies current can be used instead of the voltage follower.

[0123] The invention completed by the present inventor has been specifically described based on the embodiments, but the present invention is not limited to the above embodiments, and various changes can of course be made without departing from the gist thereof.

[0124] Description of Reference Numerals

[0125] 101, 301 Amplification Circuit

[0126] 119, 120, 121, 122 Load Resistor

[0127] L1 First Wiring

[0128] L2 Second Wiring

[0129] Q1, Q3 N-type Transistors

[0130] Q2, Q4 P-type Transistors

[0131] UVI Unit Current Source Circuit.

Claims

1. An amplifier circuit that outputs an output signal corresponding to an input signal, characterized in that, the amplifier circuit includes: a first current source circuit that outputs a predetermined amount of current to a first wiring; a voltage amplifier circuit that amplifies the voltage of the input signal; a first level shift circuit connected between the first wiring and the output of the voltage amplifier circuit to shift the voltage of the signal output from the voltage amplifier circuit; a first voltage follower connected to the first wiring to amplify the signal in the first wiring; and a first capacitor connected between the first wiring and the output of the voltage amplifier circuit.

2. The amplifier circuit according to claim 1, characterized in that, the first capacitor has a current supply ability to charge the parasitic capacitance parasitic on the first wiring, and the voltage amplifier circuit has a current supply ability to charge the first capacitor.

3. The amplifier circuit according to claim 1, characterized in that, the first level shift circuit includes a resistance element and a voltage element connected in series between the first wiring and the output of the voltage amplifier circuit, and the first capacitor is connected in parallel with the voltage element.

4. The amplifier circuit according to claim 1, characterized in that, the amplifier circuit further includes: a second current source circuit that outputs a predetermined amount of current to a second wiring different from the first wiring; a second level shift circuit connected between the second wiring and the output of the voltage amplifier circuit to shift the voltage of the signal output from the voltage amplifier circuit; a second voltage follower connected to the second wiring to amplify the signal in the second wiring; and a second capacitor connected between the second wiring and the output of the voltage amplifier circuit, and the outputs of the first voltage follower and the second voltage follower are combined and output as the output signal.

5. A mass analysis device including the amplifier circuit according to claim 3, characterized in that, the mass analysis device includes a separation unit that allows only the ionized sample to be detected to pass through, and the capacitance value of the first capacitor is set such that the cut-off frequency defined by the resistance element and the first capacitor is higher than the resonance frequency of the separation unit.

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