Patent ID: 12212292

While various embodiments discussed herein are amenable to modifications and alternative forms, aspects thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit the disclosure to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the scope of the disclosure including aspects defined in the claims. In addition, the term “example” as used throughout this application is only by way of illustration, and not limitation.

DETAILED DESCRIPTION

Exemplary aspects of the present disclosure are believed to be applicable to a variety of different types of apparatuses (e.g., systems, devices, circuits, etc.) and methods involving circuitry characterized at least in part by T-network as used in a signal amplifier. In certain illustrated examples, the circuit paths integrated with the signal amplifier may be configured as a push-pull amplification circuit, and the T-network may be characterized by a resonance frequency shunts a second harmonic current associated with the resonance frequency, thereby permitting for use of different selected input frequencies. While the present disclosure is not necessarily limited to such aspects or examples, an understanding of specific examples in the following description may be understood from discussion in such specific contexts.

Accordingly, in the following description various specific details are set forth to describe specific examples presented herein. It should be apparent to one skilled in the art, however, that one or more other examples and/or variations of these examples may be practiced without all the specific details given below. In other instances, well known features have not been described in detail so as not to obscure the description of the examples herein. For ease of illustration, the same connotation and/or reference numerals may be used in different diagrams to refer to the same elements or additional instances of the same element. Also, although aspects and features may in some cases be described in individual figures, it will be appreciated that features from one figure or embodiment can be combined with features of another figure or embodiment even though the combination is not explicitly shown or explicitly described as a combination.

Exemplary aspects of the present disclosure are perhaps best understood by considering various specific circuit-based embodiments which, as noted previously, may have a variety of applications. One such apparatus includes a plurality of circuit paths with a first path having a first switching node to respond to an RF input signal that is characterized by a first phase, and with a second path having a second switching node to respond to the RF input signal characterized by a second phase that is different than the first phase; and a T-network. As an example, the first and second phases may be 180 degrees out of phase. The T-network may be electrically arranged between the first and second switching nodes and may include a variable impedance circuit. In more specific aspects, the variable impedance circuit may be adjusted, in accordance with a selected frequency of the RF input signal, and the T-network may be associated with a resonance frequency with the circuitry of the T-network configured to shunt a second harmonic current of the resonance frequency.

Other related example specific embodiments may relate to the above aspects and/or may build on such aspects. In one such related example, the above type of embodiment may be changed to accommodate more than two circuit paths and related phases of the input signal(s). More particularly, such an example may have such circuit paths including first, second and third circuit paths respectively associated with a three-phase signal driving transistors in each such respective circuit path out-of-phase with one another by 120 degrees.

In another specific circuit-based embodiment, an apparatus is directed to push-pull amplification circuitry to be driven at one or more selected frequencies by out-of-phase input signals, and a T-network that is coupled to the push-pull circuitry and that may include a variable impedance circuit which can be adjusted in accordance with the one or more selected frequencies. The adjustment of the variable impedance circuit is made such that a resonance frequency of the T-network is to shunt a second harmonic current associated with the resonance frequency.

Another specific example of the present disclosure is similarly directed to a circuit-amplification method which involves a semiconductor device having such push-pull amplification circuitry and T-network circuitry coupled to the push-pull circuitry. The method may include driving the push-pull amplification circuitry at one or more selected frequencies by out-of-phase input signals and adjusting or changing a variable impedance circuit as part of the T-network to alter, in accordance with the one or more selected frequencies, a resonance frequency associated with the T-network and cause a second harmonic current associated with the resonance frequency to be shunted. Depending on the application and/or specific example, the step of driving may occur before the step of adjusting, the step of driving may occur after the step of adjusting, and/or the step of driving may occur concurrently with the step of adjusting.

As other specific examples related to the above methodology and/or devices, aspects of various embodiments in the present disclosure are directed to apparatuses, systems, methods of use, and methods of manufacture of such apparatuses, such as those in the claims, description and/or the figures included herewith and, in certain instances, as may be applied and understood as discussed in the Appendix B (supplementation entitled, “Push-Pull Class Φ2 RF Power Amplifier”), which forms part of the U.S. Provisional Application Ser. No. 63/085,724 as filed on Sep. 30, 2020, and which this patent document relies on and claims for priority benefit.

Certain more-specific and/or other example aspects and embodiments of the present disclosure are directed to such an apparatus (e.g., a device or a system) and/or methods of using such an apparatus having circuitry wherein the T-network is to be driven at one or more selected frequencies by a multiple phase (out-of-phase) input signal, and is to be configured with circuitry that is associated with a resonant frequency that can be adjusted with changes in the one or more selected frequencies.

In yet further related examples, one or more of the above-characterized specific embodiments may involve a power amplifier having push-pull amplification circuitry, driven at a certain (e.g., adjustable) frequency by out-of-phase signals, and having T-network circuitry associated with a resonant frequency. In one such related yet more-specific approach, the T-network circuitry includes components associated with and setting the resonant frequency by way of at least one inductor and at least one capacitor, and with at least one of these components being variable to adjust the resonant frequency. Circuitry in the T-network may be variable and implemented, for example, using 2 inductors and 1 capacitor, or using the vertical/shunting part of the T-network implemented with one type of impedance (inductive or capacitive) and the two horizontal/top parts of the T-network implemented with the other type of impedance.

In a more specific embodiment of this type, the power amplifier stage is a push-pull (e.g., class-ef2 circuit) which uses such a T-network arranged to provide zero-voltage-switching for the power amplifier as well as shunt the second harmonic current, which shapes the voltage waveform across switches of the power amplifier (see, e.g.,FIG.2with FET switches236(Sa) and246(Sb).

In related yet more specific aspects, the present disclosure is directed to a power amplifier that may have the push-pull amplification circuitry driven at the one or more selected frequencies using a frequency-divider circuit and/or by out-of-phase signals, and with circuitry associated with a resonant frequency that can be adjusted with changes in the one or more selected frequencies. Also, by using such a frequency-divider circuit, a signal-phase signal may be converted into a pair of signals, each out-of-phase and switching at the selected variable one of the multiple frequencies. In another aspect, the pair of signals may be used to control and/or adjust an impedance for setting the adjustable resonant frequency.

Further, certain exemplary power converters according to the present disclosure may be configured to provide efficiency levels and/or power levels that are controlled (e.g., as opposed to being permitted to fluctuate significantly such as on the order of more than 5% or 7%, in some cases more than 10% and in other cases more than 15 or 20%), when the operation occurs outside of a certain nominal or default (e.g., set-up) frequency. In more specific implementations, such power converters according to the present disclosure may be configured to avoid the need for overly-large heatsinks and/or the need for multiple power amplifier stages, each operating at a different frequency.

A more specific example embodiment of the present disclosure is directed to an apparatus which uses a single-stage resonant inverter architecture configured to provide constant power and efficiency levels over a large (e.g., selectable) frequency bandwidth. For example, where a certain bandwidth may be associated with a point of resonance defined by the push-pull power amplifier stage, for applications that require the frequency of the RF power to be adjusted, constant power and/or high efficiency levels may be realized over a large bandwidth.

Consistent with the present disclosure and in various non-limiting examples, aspects of the present disclosure may be directed to apparatuses and their uses being associated with specific (non-limiting) exemplary applications such as RF transmissions, RF broadcasting, semiconductor plasma processing where power demands may be significant, and/or other applications where such applications may find benefit by a power amplifier or power inverter capable of generating hundreds to thousands of watts (e.g., in the form of AC power in a frequency range or ranges characterized by Megahertz (MHz) notation such as 0.1 MHz to 200 MHz), or in the tens of MHz (e.g., 20 MHz to 200 MHz) over a certain bandwidth which bandwidth may be controlled via an adjustability aspect. Depending on the example embodiment, such ranges may be limited by the particular design of the variable impedance circuitry and/or, if used, a bandpass (or band-limiting) frequency filter coupled to the output of the resonant inverter or power amplification circuitry. Further, depending on the application, such a bandwidth may be adjustable by using a control circuit (e.g., analog/digital logic circuitry such as a microcontroller, hard-wired/clippable selector circuit, and/or a microcomputer) with an output for that controls one or more subcircuits or components of the resonant inverter (or inverter architecture) and/or band-limiting filter circuit.

In certain of the example embodiments discussed and/or illustrated herein, the skilled artisan would appreciate that such amplification circuitry may operate relative to a resonant frequency as set by the above-noted variable resonance circuitry, or as a resonant inverter, so as to provide a constant power level and/or constant level of efficiency over a fixed or (adjustably) variable bandwidth. Depending on the example, the bandwidth may or may not be associated with or correspond to use of a band-pass filter or any specific leg/component of the variable resonance circuitry.

Turning now to the drawing,FIG.1is an example block diagram of a resonant inverter, according to the present disclosure, which in some instances may be used as a wideband resonant inverter. More specifically, the illustrated example block diagram exemplifies one of many applicable architectures, with this type of architecture illustrated as featuring a push-pull power amplifier stage110driving a bandpass filter120. Depending on the design for such an example embodiment, the frequency range of the bandpass filter120may be associated with and/or limited by the particular design of a variable impedance circuitry which is in the amplifier stage110. Acting as a band-limiting frequency circuit, the bandpass filter120is coupled to the output of the resonant inverter or power amplification circuitry, so that only one or more (e.g., a selected range of) frequencies as selected in connection with a setting of the variable impedance circuitry, is passed.

Following the bandpass filter120in this illustrated example, in series are a balun130and a matching network stage140. The balun130may be included, as may or may not be applicable, to convert between a balanced signal and an unbalanced signal and/or transform impedances of the high-frequency signal being passed by the balun. The matching network stage140may be similarly configured to match the signal passing through the balun130to the loading circuitry150(e.g., an RF load terminating say at 50 Ohms).

Inputs to the amplifier stage110ofFIG.1include a DC (direct current) voltage source and at least two out-of-phase signals of a certain frequency, depicted as fs. According to certain more-specific examples, a variable capacitor (or an impedance-varying circuit) may be used so that the resonant frequency of the T-network is adjusted as the frequency of the input signal changes. Adjustment of the variable circuitry (e.g., variable capacitor) may be such that the second harmonic current of the resonance frequency is shunted via the T-network. In particular example implementations, the variable circuitry of the T-network uses a switched-capacitor array and/or a phase-switched impedance modulation (PSIM) circuit as is known (see, e.g., U.S. Patent Publication No. 2019/0020313), incorporated by reference specifically for disclosure of circuitry showing tunable impedance-matching network(s).

As an example for how proper gate signals to drive the FETs or circuits of each of the circuit paths between the voltage source and common, a frequency-divider circuit160may be used. The frequency-divider circuit160may be used to convert its received input signal of frequency 2fs, into two out-of-phase signals of frequency fs, each being 180 degrees out of phase. In addition, in connection an example in which a PSIM is used, the 2fssignal can be used to adjust the variable impedance component/circuitry (such as the capacitance or inductance) within the T-network.

FIG.2is an example power-amplifier circuit210, according to the present disclosure, with a single stage shown as a push-pull (e.g., class-ef2) circuit which uses such a T-network having a variable capacitance circuit. The power-amplifier circuit210includes two circuit paths212and216, each associated with various circuits arranged in series between a voltage source VDC and ground (or common). Each of the circuit paths212and216includes an inductor234/244that is coupled to the other inductor244/234; and a drive circuit in the exemplary form of a FET236/246, and further includes a capacitor238/248(equally-valued C1a, C1b) which couples the circuit path212/216to ground.

In operation, input ports (e.g., at gates240and250) are driven by a multiple-phase signal which has two out-of-phase aspects as discussed above. The power-amplifier circuit210also includes a T-network which provides a variable-impedance circuit224. In this particular example, the variable-impedance circuit224has a two equally-valued inductors (L2aand L2b) on opposite legs of the top of the T-network and a capacitor2C2for implementing the vertical leg of the T-network. In this specific example, the value of the capacitor2C2\ may be twice the value of each of the equally-valued capacitors (C1a, C1b) which couples the each of the circuit paths212and216to ground.

As illustrated, the exemplary power amplifier stage may be a push-pull (class-ef2) circuit which uses a T-network of 2 inductors and 1 capacitor. The T-network is used to provide zero-voltage-switching for the power amplifier as well as shunt the second harmonic current, which shapes the voltage waveform across the switches. Detailed explanations and design procedures are provided in examples as in Appendix B of the underlying U.S. Provisional Application.

Referring to the first of the alternative circuits respectively shown inFIGS.3and4,FIG.3is a diagram of an example load network, also according to the present disclosure, which may be used with aspects such as the above-discussed blocks depicted as the bandpass filter120, the balun130, and the matching network140ofFIG.1.FIG.3shows how these blocks can be compressed and combined into one more-integrated circuit structure having significantly fewer components. As the bandpass filter120is to allow RF power of frequencies within the bandwidth to be passed, the circuit ofFIG.3shows that this operation may be achieved through a high-pass stage310with 2Cs and the center-tapped transformer320, and through magnetizing inductance being cascaded with a low-pass stage330via impedance components/circuitry Lmpand Cmp. The center-tapped transformer320may also serve the operation(s) of a balun by converting the differential voltage from the push-pull amplifier to a ground-referenced signal. The circuit structure ofFIG.3may also provide matching from any of a variety of high impedance loads to a lower impedance load. The transformer may have a turns ratio that can provide the appropriate impedance transformation and the inductive-networks (L-networks) of the bandpass filter may also be configured to transforms from high to low impedances. Thus, the combined and integrated structure may serve as a three-stage matching network with only two capacitors, one transformer, and one inductor.

In certain cases, it may be difficult to quickly implement a transformer with a well-controlled-turns ratio and magnetizing inductance with minimal leakage. In this regard, the circuitry shown inFIG.3may be considered as a simplified load network where the components shown inFIG.4may be considered for such a load network with realistic components. As indicated by the alternative circuit400ofFIG.4which may have a similarly-configured center-tapped transformer420, such optimization may be realized by way of one or more additional inductors in the high-pass stage410(associated with the high-pass stage310) and/or in the low-pass stage430(associated with the low-pass stage330). In the high-pass stage410, one or more additional inductors Lst/2may arranged in-series and in one or respective opposing legs of the input (primary) side of the center-tapped transformer420. In the low-pass stage430, an additional shunting inductor Lu,extmay be arranged across the output (secondary) side of the center-tapped transformer420. Values of such inductive components can be found by trial and error and fine-tuned and compensated by way of additional inductors.

The circuit structure300ofFIG.3is to provide another important aspect for such a variable or wideband converter. At the nominal frequency, the impedance seen at the input of the network is purely resistive with no reactance. At higher frequencies, the reactance of the network increases positively, while the resistance negligibly changes. At lower frequencies, the reactance decreases negatively, with nearly constant resistance. This aspect allows the power amplifier stage to achieve zero-voltage switching and near zero-derivative-voltage-switching, which helps to minimize switching loss and circulating current throughout the converter. Thus, this network helps the wideband circuit to achieve high efficiency as well.

FIG.5is a diagram of an example frequency-divider circuit500, also according to the present disclosure, which may be used with aspects of one or more of the above discussed aspects of the present disclosure. The frequency-divider circuit500receives an input signal 2fsat front-end logic circuitry510(e.g., inverter and EXOR gates) which, in turn is used to drive the D-input and clock ports of a flip-flop circuit520. Outputs of the flip-flop circuit520drive (NAND) backend logic530to generate the out-of-phase signals fsat zero degrees and fsat 180 degrees. Consistent with the examples ofFIGS.1and2, the example frequency-divider circuit500may be used to drive certain of the above-discussed variations of a push-pull amplification circuitry. Various types of logic/programmable circuits may be used for providing control over the type of circuit being used to provide the input signal for driving the push-pull amplifier inputs (e.g., such as at the input ofFIG.5or alternatively, at nodes connected where the outputs ofFIG.5might otherwise connect). Such logic/programmable circuits may also be used for providing control over the selectable bandwidth and/or impedance, for example, via such a variable capacitor as discussed above and/or in connection withFIG.2. In more specific examples relating to the above-described aspects, such logic/programmable circuits may involve a computer program product (e.g., non-volatile memory device), which includes a machine or computer-readable medium having stored thereon instructions which may be executed by a computer (or other electronic device) to perform these operations/activities. In certain such CPU-related embodiments, a programmable circuit may be used as one or more computer circuits, including memory circuitry for storing and accessing a program to be executed as a set (or sets) of instructions (and/or to be used as configuration data to define how the programmable circuit is to perform), and an algorithm or process as described above is used by the programmable circuit to perform the related steps, functions, operations, activities, etc. Depending on the application, the instructions (and/or configuration data) can be configured for implementation in logic circuitry, with the instructions (whether characterized in the form of object code, firmware or software) stored in and accessible from a memory (circuit). As another example, where the Specification may make reference to a “first [type of structure]”, a “second [type of structure]”, etc., where the [type of structure] might be replaced with terms such as [“circuit”, “circuitry” and others], the adjectives “first” and “second” are not used to connote any description of the structure or to provide any substantive meaning. Further, as also should be apparent, a component (e.g., conductor, inductor) may be considered alone and/or in combination with other component(s), as circuitry.

In connection with various more-specific example embodiments involving experimental efforts, power amplifiers implemented in accordance with the present disclosure have doubles power output, have used simple design procedures, and have operated across wideband in some instances. In such instances, this has been realized with a single variable capacitor implemented through PSIM, wherein the switching stage of the circuitry (push-pull T-network with dual-phase inputs signal) may drive a reactance-compensating load network, thereby enabling the power amplifier to achieve wideband ZVS, harmonic filtering, multi-stage impedance matching, and power delivery to unbalanced loads. In certain related/experimental examples, the performance of the design in a 300 W system has been demonstrated with a nominal operation at 13.56 MHz and achieving over 90% efficiency across a 4 MHz bandwidth. For further details in connection with such experimental efforts, reference may be made to the attached Appendix (pp. 1-10), which forms part of the present disclosure and is fully incorporated herein by reference.

The skilled artisan would also recognize various terminology as used in the present disclosure by way of their plain meaning. As examples, the Specification may describe and/or illustrates aspects useful for implementing the examples by way of various semiconductor materials/circuits which may be illustrated as or using terms such as block, module, circuit path, device, system, unit, controller, and/or other circuit-type depictions. Also, in connection with such descriptions, the term “source” may refer to source and/or drain of a field-effect-transistor circuit used interchangeably as with the example FET-based circuitry ofFIG.2. Such semiconductor and/or circuit elements and/or related circuitry may be used together with other elements to exemplify how certain examples may be carried out in the form or structures, steps, functions, operations, activities, etc.

It is recognized and appreciated that as specific examples, the above-characterized figures and discussion are provided to help illustrate certain aspects (and advantages in some instances) which may be used in the manufacture of such structures and devices. These structures and devices include the exemplary structures and devices described in connection with each of the figures as well as other devices, as each such described embodiment has one or more related aspects which may be modified and/or combined with the other such devices and examples as described hereinabove may also be found in the Provisional. For example, based upon the above discussion and illustrations, those skilled in the art will also recognize that modifications and changes may be made to the various embodiments without strictly following the illustrated and described circuit or component arrangements herein. For example, methods as exemplified in the figures (e.g., as in the flow ofFIG.1) may involve steps carried out in various orders, with one or more aspects of the embodiments and/or individual aspects or parts therein retained, or may involve fewer or more steps as exemplified by the above discussed integration of circuits viaFIG.3orFIG.4. Also, as shown inFIGS.2,3and4, without departing from the true spirit and scope of various aspects of the disclosure, such modifications may include arrangements of impedance-based circuitry and components, and including specific circuit arrangements which are different than those as illustrated and/or discussed.