COUPLED-AMPLIFIER MULTI-FREQUENCY CIRCUIT TOPOLOGIES APPLICABLE TO MASS SPECTROMETER RADIO-FREQUENCY DRIVE SYSTEMS

Abstract

A circuit and method for providing high-voltage radio-frequency (RF) energy to an instrument at multiple frequencies includes a plurality of inputs each configured to receive an RF voltage signal oscillating at a corresponding frequency, and a step-up circuit for generating magnified RF voltage signals based on the received RF voltage signals. The step-up circuit includes an LC network operable to isolate the RF voltage signals at the plurality inputs from one another while preserving a voltage magnification from each input to a common output at each of the corresponding frequencies.

Claims

1. A circuit for providing high-voltage radio-frequency (RF) energy to an instrument at multiple frequencies, comprising: a plurality of inputs each configured to receive an RF voltage signal oscillating at a corresponding frequency; and a step-up circuit for generating magnified RF voltage signals based on the received RF voltage signals, the step-up circuit comprising an LC network operable to isolate the RF voltage signals at the plurality inputs from one another while preserving a voltage magnification from each input to a common output at each of the corresponding frequencies.

2. The circuit of claim 1, wherein the step-up circuit comprises: a first LC resonator network operable to resonate at a first frequency F.sub.1 and having a first LC trap that exhibits substantially infinite impedance at a second frequency F.sub.2, and a second LC resonator network operable to resonate at the second frequency F.sub.2 and having a second LC trap that exhibits substantially infinite impedance at the first frequency F.sub.1.

3. The circuit of claim 2, wherein F.sub.1 is less than F.sub.2, and the first LC trap has an inductor L.sub.1 and a capacitor C.sub.1 whose values satisfy F.sub.1=L.sub.1C.sub.1.

4. The circuit of claim 1, wherein the plurality of inputs comprises more than two inputs, each input configured to receive an RF voltage signal oscillating at a corresponding frequency.

5. The circuit of claim 1, wherein the LC network comprises one or more LC traps and at least one of an inductor or a capacitor.

6. The circuit of claim 1, wherein the LC network comprises first and second LC traps.

7. The circuit of claim 6, wherein each LC trap comprises a parallel connection of a resonator and a capacitor.

8. The circuit of claim 6, wherein the first LC trap comprises a parallel connection of a resonator and a capacitor and the second LC trap comprises an inductor.

9. An instrument comprising: an ion-manipulating structure; an ion source for providing ions to the ion-manipulating structure; a detector coupled to the ion-mainpulating structure for detecting ions; and a power source for providing high-voltage RF energy to the ion-manipulating structure, the power source including: first and second RF energy sources configured to provide RF voltage signals at first and second corresponding frequencies, respectively; and a step-up circuit having first and second inputs respectively coupled to the first and second RF energy sources, the step-up circuit configured to generate magnified RF voltage signals based on the RF voltage signals provided by the first and second RF energy sources at the first and second frequencies, the step-up circuit comprising an LC network operable to isolate the RF voltage signals at the first and second inputs from one another while preserving a voltage magnification from each input to a common output at each of the corresponding frequencies.

10. The instrument of claim 9, wherein the instrument is a mass spectrometer.

11. The instrument of claim 9, wherein the ion-manipulating structure comprises a multi-rod assembly.

12. The instrument of claim 11, wherein the multi-rod assembly is a quadrupole.

13. The instrument of claim 11, wherein the multi-rod assembly is a hexapole or octupole.

14. The instrument of claim 9, wherein the ion-manipulating structure comprises a stack of ring electrodes.

15. The instrument of claim 9, wherein the instrument comprises a time-of-flight mass analyzer.

16. A method for generating high-voltage radio-frequency (RF) energy for an instrument at multiple frequencies, comprising: providing an RF voltage signal at each of a plurality of inputs, each RF voltage signal oscillating at a corresponding frequency; and generating magnified RF voltage signals, based on the provided RF voltage signals, using a step-up circuit having an LC network operable to isolate the RF voltage signals at the plurality inputs from one another while preserving a voltage magnification from each input to a common output at each of the corresponding frequencies.

17. The method of any of claim 16, wherein the step-up circuit comprises: a first LC resonator network operable to resonate at a first frequency F.sub.1 and having a first LC trap that exhibits substantially infinite impedance at a second frequency F.sub.2, and a second LC resonator network operable to resonate at the second frequency F.sub.2 and having a second LC trap that exhibits substantially infinite impedance at the first frequency F.sub.1.

18. The method of any of claim 16, wherein the plurality of inputs comprises more than two inputs, each input configured to receive an RF voltage signal oscillating at a corresponding frequency.

19. The method of any of claim 16, wherein the instrument is a mass spectrometer.

20. The method of any of claim 16, wherein the instrument is a time-of-flight analyzer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The accompanying drawings, which are incorporated into and constitute a part of this specification, illustrate one or more examples of embodiments and, together with the description of example embodiments, serve to explain the principles and implementations of the embodiments.

[0010] In the drawings:

[0011] FIG. 1A is a schematic diagram illustrating conventional single-frequency voltage magnification;

[0012] FIG. 1B shows a circuit diagram for facilitating an analysis of the RF performance of the FIG. 1A topology;

[0013] FIG. 2 is a block diagram of a system for providing RF power at multiple high frequencies to an instrument such as a mass spectrometer in accordance with certain embodiments;

[0014] FIG. 3 is a schematic diagram of a multi-frequency RF power source for driving an ion-manipulating structure of an instrument such as a mass spectrometer in accordance with certain embodiments;

[0015] FIGS. 3A-3D are schematic diagrams of circuits used to facilitate analysis of variations on the described topologies; and

[0016] FIG. 4 is a block diagram of an instrument using a multi-frequency RF power source in accordance with certain embodiments.

DESCRIPTION OF EXAMPLE EMBODIMENTS

[0017] The following description is illustrative only and is not intended to be in any way limiting. Other embodiments will readily suggest themselves to those of ordinary skill in the art having the benefit of this disclosure. Reference will be made in detail to implementations of the example embodiments as illustrated in the accompanying drawings. The same reference indicators will be used to the extent possible throughout the drawings and the following description to refer to the same or like items.

[0018] In the description of example embodiments that follows, references to one embodiment, an embodiment, an example embodiment, certain embodiments, etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to effect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

[0019] In the interest of clarity, not all of the routine features of the implementations described herein are shown and described. It will be appreciated that in the development of any such actual implementation, numerous implementation-specific decisions must be made in order to achieve the developer's specific goals, such as compliance with application- and business-related constraints, and that these specific goals will vary from one implementation to another and from one developer to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking of engineering for those of ordinary skill in the art having the benefit of this disclosure.

[0020] The term exemplary when used herein means serving as an example, instance or illustration. Any embodiment described herein as exemplary is not necessarily to be construed as preferred or advantageous over other embodiments.

[0021] FIG. 2 is a block diagram of a system 16 for providing RF power at multiple high frequencies to an instrument such as a mass spectrometer in accordance with certain embodiments. System 16 includes RF energy sources 18 that are coupled to a voltage magnification circuit, for example in the form of a resonant LC network 20. In certain embodiments, one or more of the RF energy sources 18 can comprise an individual oscillator (15) or RF synthesizer for generating an oscillating signal. Alternatively, one or more RF synthesizers can be used to generate multiple oscillating signals. Optionally, one or more of the RF energy sources 18 can include an RF power amplfier (17) for amplifying the oscillating signal before providing it to resonant LC network 20.

[0022] Resonant LC network 20 provides significant voltage magnification or step-up of the RF voltages from each of the RF energy sources 18. The output of resonant LC network 20 is high voltage RF energy for driving an ion-manipulating structure 19, which can be a rod assembly of a mass spectrometer and which presents a substantially capacitive load on the resonant LC network 20. The ion-manipulating structure, which for example can be a rod assembly such as a quadrupole, hexapole, octupole, and so on, can be selectively driven in this mannner at multiple frequencies, either simultaneously, or asynchronously.

[0023] FIG. 3 is a schematic diagram of a multi-frequency RF power source 22 for driving an ion-manipulating structure (for example a rod assembly such as a quadrupole, hexapole, octupole) of an instrument such as a mass spectrometer in accordance with certain embodiments. First and second RF signal sources 24 and 26, respectively operating at frequencies F.sub.1 and F.sub.2, drive first and second RF power amplifiers 28 and 30. Signal sources 24 and 26 may be discrete oscillators or RF synthesizers, or they may be a single RF synthesizer generating signals at the two frequencies. The amplifiers 28 (A.sub.1) and 30 (A.sub.2) are RF power amplifiers each having a very low output impedancethat is, they approximate voltage sources. In certain embodiments, depending on the power level of the oscillating signal sources, RF power amplifiers 28 and 30 may not be necessary. For example, if RF signal sources 24 and 26 comprised high-power fundamental oscillator(s), there would be no need to boost their output, and the use of RF power amplifiers 28 and 30 could be eliminated.

[0024] In the arrangement of FIG. 3, amplifier A.sub.1 produces an output voltage signal at frequency F.sub.1 and amplifier A.sub.2 produces an output voltage signal at frequency F.sub.2. The two output voltage signals are provided to inputs 31 and 33 of a step-up circuit 35. In certain embodiments, step-up circuit 35 comprises an LC network having a first LC resonant nertwork 37 and a second LC resonant network 39. First LC resonant network 37 comprises series-connected inductors L.sub.2 and L.sub.3 coupled to the first input 31, and a capacitor C.sub.2 connected across inductor L.sub.2. Second LC resonant network 39 comprises series-connected inductors L.sub.1 and L.sub.3 coupled to the second input 33, and a capacitor C.sub.1 connected across inductor L.sub.1. Inductors L.sub.1 and L.sub.2 are connected together at node 41. Additional capacitors C disposed at the outputs of amplifiers A.sub.1 and A.sub.2 serve to block DC voltages. Capacitors C are selected to have very low reactances at F.sub.1 and F.sub.2 such that they need not be considered in an RF analysis of circuit operation. Similarly, block Z is a network with a high impedance at F.sub.2 and need not be considered in an RF circuit analysis.

[0025] Inductor L.sub.1 and capacitor C.sub.1 together form a first parallel resonant LC trap, and inductor L.sub.2 and capacitor C.sub.2 together form a second parallel resonant LC trap. For the first LC trap, the component values are chosen such that F.sub.1=L.sub.1C.sub.1. Assuming lossless components, this L.sub.1C.sub.1 trap will exhibit an infinite impedance at F.sub.1. Thus, when analyzing circuit operation at F.sub.1, the L.sub.1C.sub.1 trap and everything upstream of it in the signal path need not be considered.

[0026] For the second LC trap, the component choices and relationships are analogously selected for L.sub.2, C.sub.2, and F.sub.2that is, F.sub.2=L.sub.2C.sub.2, and when analyzing circuit operation at F.sub.2, the L.sub.2C.sub.2 trap will exhibit infinite impedance and therefore it and all components upstream of it need not be considered.

[0027] The operation of the step-up circuit 35 will be analyzed with reference to FIGS. 3A-3D, with the assumption that frequency F.sub.2 is higher than frequency F.sub.1 and that the losses in the inductors are smallthat is, the inductors have high Q values.

[0028] At frequencies below F.sub.2 the L.sub.2C.sub.2 trap will appear inductive; it will look inductive at F.sub.1. That is, as illustrated in FIG. 3A, at frequency F.sub.1, the two trap components L.sub.2C.sub.2 together will act as a single inductor that can be referred to as L.sub.2. The value of L.sub.2 will be a function of frequency. Very close to but just below F.sub.2 the value of L.sub.2 will be very large, while far below F.sub.2, the value of L.sub.2 will be small.

[0029] The values of L.sub.2 and L.sub.3 are chosen such that at frequency F.sub.1 the equation F.sub.1=(L.sub.2+L.sub.3)C.sub.R is satisfied. Then the voltage step-up from V.sub.in1 to V.sub.out1 will be approximately equal to the overall circuit Qthat is, the Q of inductance L.sub.2+L.sub.3, plus the loss effect of L.sub.1, assuming the various capacitors are essentially lossless.

[0030] With reference to FIG. 3B, at frequencies above F.sub.1 the L.sub.1C.sub.1 trap will look capacitive (so it will look capacitive at F.sub.2). That is, the two L.sub.1C.sub.1 trap components together will act as a single capacitor that can be referred to as C.sub.1. The value of C.sub.1 will be a function of frequency. Very close to but just above F.sub.1 the value of C.sub.1 will be very small, while far above F.sub.1, the value of C.sub.1 will be large.

[0031] The value of C.sub.1 is chosen such that at F.sub.2 the equation F.sub.2=L.sub.3 (C.sub.1C.sub.R/(C.sub.1+C.sub.R)) is satisfied. Then the voltage step-up from V.sub.in2 to V.sub.out2 will be approximately equal to C.sub.1/(C.sub.1+C.sub.R) times the circuit Q at F.sub.2. Similarly to the analysis at F.sub.1 and V.sub.in1, the circuit Q at F.sub.2 will be established primarily by the losses in the three inductors L.sub.1-L.sub.3.

[0032] The capacitances C.sub.1 and C.sub.R are in series and form a voltage divider. Thus, for efficient high voltage step-up at F.sub.2 it is desirable to have the ratio C.sub.1/C.sub.R be as high as possible.

[0033] The circuit shown in FIG. 3 can be modified to replace one of the LC traps with an inductor (if, for example C.sub.2 is eliminated). The equivalent RF circuit for analysis is then as seen in FIG. 3C. Capacitor C.sub.1 is the effective capacitance exhibited by the L.sub.1C.sub.1 trap at F.sub.2 as previously explained. The circuit for analysis at F.sub.1 drive signal becomes that shown in FIG. 3D.

[0034] The equation for Z(s) in FIG. 3C is:

[00001]$\begin{array}{cc}Z\left(S\right)=A\left[\frac{\left(S^2+B\right).Math.\left(S^2+C\right)}{S\left(S^2+D\right)}\right]& \left(2\right)\end{array}$

[0035] The general form of this equation after factoring is:

[00002]$\begin{array}{cc}Z\left(S\right)=\frac{L_2.Math.L_3}{L_2+L_3}\left[\frac{S^4+S^2\left(\frac{L_2+L_3}{C_1^{}.Math.L_2.Math.L_3}+\frac{1}{C_R.Math.L_3}\right)+\frac{1}{C_1^{}.Math.C_R.Math.L_2.Math.L_3}}{S\left(S^2+\frac{1}{C_R\left(L_2+L_3\right)}\right)}\right]& \left(3\right)\end{array}$

in which A through D are constants. The equation shows that the voltage magnification peaks at two distinct frequencies indicated by B and C. There is also a frequency indicated by D at which the transmission through the network goes to zero (assuming no losses).

[0036] Those versed in the art will appreciate that various other similar modifications of the FIG. 3 topology are possible in which one or more resonant LC traps are connected in conjunction with one or more additional LC components to form a network that supports resonant voltage step-up from multiple oscillating signal sources operating at different frequencies to a single output node. Thus it should be noted that the achiemement of a multi-frequency output such as V.sub.out1 and V.sub.out2 as described herein does not require a dedicated trap for each of the multi-frequency input signals. An underlying principle of operation of the described arrangement is that each input (for example 31 or 33) is configured to operate efficiently at one frequency, which frequency is different from the frequencies at which any other input is configured to efficiently operate. An important function of the LC topology as described herein is to isolate each input at its operating frequency from any other input so that the sources of oscillation at those other inputs do not short out or unduly attenuate the signal at the input of interest. The step-up circuit such as circuit 35 generates magnified RF voltage signals based on the received RF voltage signals at the circuit inputs 31, 33. Thus in certain embodiments the LC network of the step-up circuit is provided with one or more LC traps, and at least one of an inductor or a capacitor, and serves to isolate the plurality inputs from one another while preserving a voltage magnification from each input to a common output at each of the corresponding frequencies.

[0037] The FIG. 3 topology may be extended to work at more than two frequencies. For three frequencies, F.sub.1, F.sub.2, and F.sub.3, each of the three corresponding amplifiers must be followed by two separate parallel LC traps in series with each other. The first channel must include LC traps at F.sub.2 and F.sub.3, the second channel must include LC traps at F.sub.1 and F.sub.3, and the third channel must include LC traps at F.sub.1 and F.sub.2. For a given number of frequencies, N, the total number of LC traps required is N(N1).

[0038] Although FIG. 3 shows a circuit with a single output to a capacitive load (such as a multi-pole rod assembly or some other configuration) with respect to ground, it is also possible for the resonant drive system to be differential with two high-voltage RF outputs that are equal in amplitude and frequency but differ in phase from each other by 180 degrees. In certain embodiments, such differential drive circuits are used to drive symmetrical rod assemblies.

[0039] The resonator networks described herein do not necessarily dissipate significant amounts of power (because, in certain embodiments, the various impedance elements in them are mostly reactive rather than resistive, and only resistive elements dissipate power). However, in certain embodiments, the networks generate higher levels of circulating RF current in one or more reactive circuit elements than do single-frequency resonators. As a result, the product of the RF voltage magnitude and the RF current magnitude (this product is typically referred to as VA) that the amplifier is required to produce is higher than with single-frequency resonators. When the voltage and current waveforms in the load that an amplifier is driving are in phase with each other, the power dissipated in the load in watts equals the VA. When they are 90 degrees out of phase the power in the load is zero no matter what the VA is. For cases other than ones in which the voltage and current are either in phase alignment or in phase quadrature, the dissipated power magnitude will be non-zero but less than the VA. The voltage swing capability and the current output capability of the amplifier must be based upon the VA that must be supported however so, even in cases where very little power is dissipated in the load, a large power amplifier is required if the VA is high. The same applies to the capacity of the DC power supply supporting the amplifier.

[0040] In certain embodiments, the resonator inductors may be either air core or iron-powder core. In some cases other core materials such as ferrite, metal, laminated metal, or more exotic materials or combinations of materials may be advantageous. Similarly, winding shape may vary depending on the application (solenoid, toroid, flat spiral, or others).

[0041] In certain embodiments, modest amounts of mutual inductance between the multiple inductances in the resonator assembly is not necessarily detrimental to operation and in fact can be advantageous because it allows the inductors to share coil formers and/or cores, which saves space and generally reduces cost. It also causes changes in the exact circuit element values required, which means, in certain embodiments, equation (2) is less precisely applicable (notwithstanding that the equation does not include loss terms and so is, in all cases, not precise in describing the real-world performance anyway).

[0042] FIG. 4 is a block diagram of an instrument 32 using a multi-frequency RF power source 34, such as power source 22 above, in accordance with certain embodiments. The multi-frequency RF power source 34 is used to drive an ion-manipulating structure 36, which can be a rod assembly such as a quadrupole, hexapole, octupole, and so on, as described herein. More generally, any structure that requires a multi-frequency RF power source, for example to influence passing ions, may benefit from the multi-frequency RF power source 34. An ion source 38 delivers ions to the ion-manipulating structure 36, and a detector 40 senses one or more parameters of interest, for example those relating to the presence, mass, charge, atomic configuration, trajectory, time of flight, or other characterisitics of the ions. As explained above, multi-frequency RF power source 34 may used to provide RF power at two or more frequencies simultaneously or in sequence. In certain embodiments, the instrument 44 may be a mass spectrometer, mass analyzer, time-of-flight (TOF) analyzer, or the like.

[0043] Ion source 38 may be an electron impact (EI) source, an electrospray ionization (ESI) source, a chemical ionization (CI) source, a photoionization (PI) source, a matrix assisted laser desorption/ionization (MALDI) source, an inductively coupled plasma (ICP) source, a multi-mode source (such as a combination of ESI and CI), or any other ion source for mass spectrometers.

[0044] In certain embodiments, advantages can be realized in hexapole or octupole cell operation if one of the rod sets is driven with two frequencies simultaneously using schemes as described herein. There may also be advantages in using more than two frequencies or in driving more than one rod set with multiple frequencies in the manner described. In certain embodiments, the use of multiple frequencies in hexapole and octupole cells can eliminate the requirement for the use of resistive rods and allow less costly conductive metal rods to be used instead. The described circuit topologies may also be broadly applied to any application which requires two or more frequencies of high-voltage sine waves to be applied to a common capacitive load, or to a resistive load with the addition of a resonating capacitance.

[0045] In certain embodiments, a DC input 21 (FIG. 2) can be applied to the LC network, to be manifested in its output to the ion-manipulating structure, for example the rod assembly, without disturbing the circuit operation at RF. For example, when the rod assembly is a quadrupole arrangement, a DC voltage may be applied across the quadrupole. The rods in such an arrangement may be connected together in pairs, or rod sets, and the voltage, which may be designated V, is applied from one rod set to the other rod set. The voltage need not be referenced to ground, nor to the manifold case of the rod assembly, in any way. In practice, two separate DC voltages of magnitude V/2 may be produced, one of which is positive with respect to ground and the other of which is negative with respect to ground. Referring to these voltages as U+ and U (or sometimes Ua and Ub), U+ is applied to one set of two rods and U is applied to the other set of two rods.

[0046] In hexapole rod assembly systems, by contrast, a fairly high DC voltage is applied to all six rods with respect to ground (which includes the manifold case and sometimes a shroud surrounding the hexapole). In some cases, it is also desirable to have a slight voltage gradient (in the range of 0 to 10 volts for instance) along the lengths of the rods. When such a gradient is desired, rods that are resistive (as opposed to rods that are near perfect DC conductors) may be employed. In the case with resistive rods and a voltage gradient, the voltage applied to one end of the rods will differ slightly from the voltage applied to the other ends, but the rodes will still all be of the same polarity (for example+200 and +205). In addition, the DC voltage applied to one set of three rods will not differ from the DC voltage applied to the other set of three rods.

EXEMPLARY EMBODIMENTS

[0047] In addition to the embodiments described elsewhere in this disclosure, exemplary embodiments of the present invention include, without being limited to, the following Embodiments:

[0048] 1. A circuit for providing high-voltage radio-frequency (RF) energy to an instrument at multiple frequencies, comprising:

[0049] a plurality of inputs each configured to receive an RF voltage signal oscillating at a corresponding frequency; and

[0050] a step-up circuit for generating magnified RF voltage signals based on the received RF voltage signals, the step-up circuit comprising an LC network operable to isolate the RF voltage signals at the plurality inputs from one another while preserving a voltage magnification from each input to a common output at each of the corresponding frequencies.

[0051] 2. The circuit of Embodiment 1, wherein the LC network comprises one or more LC traps and at least one of an inductor or a capacitor.

[0052] 3. The circuit of Embodiment 1 or 2, wherein the LC network comprises first and second LC traps.

[0053] 4. The circuit of Embodiment 3, wherein each LC trap comprises a parallel connection of a resonator and a capacitor.

[0054] 5. The circuit of Embodiment 3, wherein the first LC trap comprises a parallel connection of a resonator and a capacitor and the second LC trap comprises an inductor.

[0055] 6. The circuit of any of the preceding Embodiments, wherein the step-up circuit comprises:

[0056] a first LC resonator network operable to resonate at a first frequency F.sub.1 and having a first LC trap that exhibits substantially infinite impedance at a second frequency F.sub.2, and a second LC resonator network operable to resonate at the second frequency F.sub.2 and having a second LC trap that exhibits substantially infinite impedance at the first frequency F.sub.1.

[0057] 7. The circuit of Embodiment 6, wherein F.sub.1 is less than F.sub.2, and the first LC trap has an inductor L.sub.1 and a capacitor C.sub.1 whose values satisfy F.sub.1=L.sub.1C.sub.1.

[0058] 8. The circuit of any of the preceding Embodiments, wherein the plurality of inputs comprises more than two inputs, each input configured to receive an RF voltage signal oscillating at a corresponding frequency.

[0059] 9. A power source for providing high-voltage radio-frequency (RF) energy to an instrument at multiple frequencies, comprising:

[0060] first and second RF energy sources;

[0061] a circuit in accordance with any one of the preceding Embodiments, wherein the first RF energy source provides an RF signal at a first input, and the second RF energy source provides the RF signal at a second input.

[0062] 10. The power source of any one of Embodiments 2-9, wherein the first and second RF energy sources comprise first and second RF signal sources coupled to corresponding first and second RF amplifiers.

[0063] 11. An instrument comprising:

[0064] an ion-manipulating structure;

[0065] an ion source for providing ions to the ion-manipulating structure;

[0066] a detector coupled to the ion-mainpulating structure for detecting ions;

[0067] a power source in accordance with Embodiment 9 or 10 for providing high-voltage RF energy to the ion-manipulating structure.

[0068] 12. The instrument of Embodiment 11, wherein the instrument is a mass spectrometer.

[0069] 13. The instrument of Embodiment 11 or 12, wherein the ion-manipulating structure comprises a multi-rod assembly.

[0070] 14. The instrument of Embodiment 13, wherein the multi-rod assembly is a quadrupole.

[0071] 15. The instrument of Embodiment 13, wherein the multi-rod assembly is a hexapole or octupole.

[0072] 16. The instrument of Embodiment 11 or 12, wherein the ion-manipulating structure comprises a stack of ring electrodes.

[0073] 17. The instrument of any of the preceding Embodiments, wherein the instrument comprises a time-of-flight mass analyzer.

[0074] 18. A method for generating high-voltage radio-frequency (RF) energy for an instrument at multiple frequencies, comprising:

[0075] providing an RF voltage signal at each of a plurality of inputs, each RF voltage signal oscillating at a corresponding frequency; and

[0076] generating magnified RF voltage signals, based on the provided RF voltage signals, using a step-up circuit having an LC network operable to isolate the RF voltage signals at the plurality inputs from one another while preserving a voltage magnification from each input to a common output at each of the corresponding frequencies.

[0077] 19. The method of Embodiment 18, wherein the LC network comprises one or more LC traps and at least one of an inductor or a capacitor.

[0078] 20. The circuit of Embodiment 18, wherein the LC network comprises first and second LC traps.

[0079] 21. The circuit of Embodiment 20, wherein each LC trap comprises a parallel connection of a resonator and a capacitor.

[0080] 22. The circuit of Embodiment 20, wherein the first LC trap comprises a parallel connection of a resonator and a capacitor and the second LC trap comprises an inductor.

[0081] 23. The method of any of Embodiments 18-22, wherein the step-up circuit comprises:

[0082] a first LC resonator network operable to resonate at a first frequency F.sub.1 and having a first LC trap that exhibits substantially infinite impedance at a second frequency F.sub.2, and a second LC resonator network operable to resonate at the second frequency F.sub.2 and having a second LC trap that exhibits substantially infinite impedance at the first frequency F.sub.1.

[0083] 24. The method of Embodiment 23, wherein F.sub.1 is less than F.sub.2, and the first LC trap has an inductor L1 and a capacitor C1 whose values satisfy F1=L.sub.1C.sub.1.

[0084] 25. The method of any of Embodiments 18-24, further comprising delivering the RF voltage signal at each of a plurality of inputs using first and second RF signal sources coupled to corresponding first and second RF amplifiers.

[0085] 26. The method of any of Embodiments 18-25, wherein the plurality of inputs comprises more than two inputs, each input configured to receive an RF voltage signal oscillating at a corresponding frequency.

[0086] 27. The method of any of Embodiments 18-26, wherein the instrument is a mass spectrometer.

[0087] 28. The method of any of Embodiments 18-26, wherein the instrument is a time-of-flight analyzer.

[0088] 29. The method of any of Embodiments 18-26, wherein the instrument is a quadrupole.

[0089] While embodiments and applications have been shown and described, it would be apparent to those skilled in the art having the benefit of this disclosure that many more modifications than mentioned above are possible without departing from the inventive concepts disclosed herein. The invention, therefore, is not to be restricted based on the foregoing description.