Push-pull amplifier

Abstract

The invention provides a push-pull amplifier which comprises a first main circuit, and a first low-pass filter balun, a first transistor and a first high-pass filter balun are sequentially arranged from the input end to the output end of the first main circuit; and the second main circuit is arranged in parallel with the first main circuit, and a second high-pass filter balun, a second transistor and a second low-pass filter balun are sequentially arranged from the input end to the output end of the second main circuit. According to the push-pull amplifier provided by the invention, the low-pass filter balun, the transistor and the high-pass filter balun are sequentially arranged on the first branch, and the high-pass filter balun, the transistor and the low-pass filter balun are sequentially arranged on the second branch, so that a signal phase reversal function is realized; moreover, the suppression effect on second harmonics and out-of-band spurious signals is improved, the size of the push-pull amplifier is reduced, and the device cost is reduced.

Description

Technical Field

[0001] The present invention relates to the field of electronic technology, and particularly to a push-pull amplifier. Background Art

[0002] A balun is a three-port device, which is a broadband radio frequency transmission line transformer that realizes the connection between a balanced transmission line circuit and an unbalanced transmission line circuit by converting a matching input into a differential output. The function of the balun is to make the system have different impedances or be compatible with differential / single-ended signaling, and is used in modern communication systems such as mobile phones and data transmission networks. Baluns are divided into various types, some of which are used for impedance conversion, and some are used to connect transmission lines with different impedances, and are used in push-pull amplifiers, broadband antennas, balanced mixers, balanced frequency multipliers and modulators, phase shifters, and any circuit design that requires the transmission of equal amplitudes and a 180-degree phase difference on two lines.

[0003] However, most current circuit designs use transmission line baluns, and transmission line baluns have the following deficiencies: (1) The transmission line balun has poor suppression effects on second harmonics and out-of-band spurious signals; (2) The length of the transmission line balun depends on the frequency, and it occupies a large space on the printed circuit board (PCB) at low frequencies; (3) Transmission line baluns with special impedances need to be customized, and the cost is relatively high. Summary of the Invention

[0004] Based on this, in view of the problems in the above background art, it is necessary to provide a push-pull amplifier that can at least improve the suppression effects on second harmonics and out-of-band spurious signals, while reducing the volume and cost.

[0005] To achieve the above and other related objects, one aspect of the present application provides a push-pull amplifier, including:

[0006] A first main path, where a first low-pass filter balun, a first transistor, and a first high-pass filter balun are sequentially arranged from the input end to the output end of the first main path;

[0007] A second main path, which is arranged in parallel with the first main path, and a second high-pass filter balun, a second transistor, and a second low-pass filter balun are sequentially arranged from the input end to the output end of the second main path.

[0008] In one embodiment, the low-pass filter balun includes:

[0009] A main path inductor, which is connected in series to the main path of the push-pull amplifier;

[0010] A branch capacitor, where the first end of the branch capacitor is connected to the first end or the second end of the main path inductor;

[0011] An auxiliary inductor is connected in series with a branch capacitor, and two ends of the auxiliary inductor are respectively connected to a second end of the branch capacitor and a zero potential point.

[0012] In one embodiment, a zero resonance frequency of the low-pass filter balun is associated with the branch capacitor and the auxiliary inductor. Based on adjusting the auxiliary inductor, the zero resonance frequency of the low-pass filter balun is set at a second harmonic frequency or a high-frequency spurious frequency of the push-pull amplifier to eliminate the second harmonic signal or the high-frequency spurious signal.

[0013] In one embodiment, a high-pass filter balun includes:

[0014] A main path capacitor is connected in series on the main path of the push-pull amplifier;

[0015] A branch inductor, a first end of the branch inductor is connected to a first end or a second end of the main path capacitor;

[0016] An auxiliary capacitor is connected in series with the branch inductor, and two ends of the auxiliary capacitor are respectively connected to a second end of the branch inductor and a zero potential point.

[0017] In one embodiment, a zero resonance frequency of the high-pass filter balun is associated with the branch inductor and the auxiliary capacitor. Based on adjusting the branch inductor, the zero resonance frequency of the high-pass filter balun is set at a low-frequency spurious frequency of the push-pull amplifier to eliminate the low-frequency spurious signal.

[0018] In one embodiment, a first low-pass filter balun and a second high-pass filter balun form an input terminal filter balun, and a first high-pass filter balun and a second low-pass filter balun form an output terminal filter balun.

[0019] In one embodiment, a common-phase signal is input to an input end of the input terminal filter balun, and an anti-phase signal with a phase difference of 180° is output from an output end of the input terminal filter balun; an anti-phase signal with a phase difference of 180° is input to an input end of the output terminal filter balun, and a common-phase signal is output from an output end of the output terminal filter balun.

[0020] In one embodiment, an output end of the first low-pass filter balun is connected to a gate of the first transistor, an input end of the first high-pass filter balun is connected to a drain of the first transistor, an output end of the second high-pass filter balun is connected to a gate of the second transistor, and an input end of the second low-pass filter balun is connected to a drain of the second transistor.

[0021] In one embodiment, the first low-pass filter balun and the second high-pass filter balun are used for input impedance matching of the push-pull amplifier to match the gates of the first transistor and the second transistor to a target impedance value, and the first high-pass filter balun and the second low-pass filter balun are used for output impedance matching of the push-pull amplifier to match the drains of the first transistor and the second transistor to a target impedance value.

[0022] In one embodiment, the push - pull amplifier further includes:

[0023] A power splitter, the input ends of the first low - pass filter balun and the second high - pass filter balun are both connected to the power splitter;

[0024] A combiner, the output ends of the first high - pass filter balun and the second low - pass filter balun are both connected to the combiner.

[0025] According to the push - pull amplifier provided by the present invention, by sequentially arranging a low - pass filter balun, a transistor, and a high - pass filter balun on the first branch, and sequentially arranging a high - pass filter balun, a transistor, and a low - pass filter balun on the second branch, not only the signal inversion function is realized, but also the suppression effect on the second - harmonic and out - of - band spurious signals is improved. At the same time, the volume of the push - pull amplification is reduced, and the device cost is lowered. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] To better describe and illustrate the embodiments and / or examples of those applications disclosed herein, one or more drawings may be referred to. Additional details or examples used to describe the drawings should not be considered as limiting the scope of any of the disclosed applications, the currently described embodiments and / or examples, and the currently understood best mode of these applications.

[0027] Figure 1 It is a schematic circuit diagram of a push - pull amplifier provided in an embodiment;

[0028] Figure 2 It is a schematic diagram of the zero - point resonance frequency of the low - pass filter balun provided in an embodiment;

[0029] Figure 3 It is a schematic diagram of the zero - point resonance frequency of the high - pass filter balun provided in an embodiment.

[0030] Description of the reference numerals:

[0031] 110, the first low - pass filter balun; 120, the first transistor; 130, the first high - pass filter balun; 210, the second high - pass filter balun; 220, the second transistor; 230, the second low - pass filter balun; 310, the power splitter; 320, the combiner. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] To facilitate the understanding of this application, the following will describe this application more comprehensively with reference to the relevant drawings. Preferred embodiments of this application are shown in the drawings. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the disclosure of this application more thorough and comprehensive.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The term "and / or" as used herein includes any and all combinations of one or more of the related listed items.

[0034] The purpose of the terms used herein is only to describe specific embodiments and is not a limitation of this application. As used herein, the singular forms "a", "an", and "the" are also intended to include the plural forms unless the context clearly dictates otherwise. It should also be understood that the terms "comprising" and / or "including", when used in this specification, identify the presence of the stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups. As used herein, the term "and / or" includes any and all combinations of the related listed items.

[0035] It should be noted that the illustrations provided in this embodiment only schematically illustrate the basic concept of this application. Although only the components related to this application are shown in the illustrations and are not drawn according to the number, shape, and size of the components in actual implementation, the types, quantities, and proportions of the components in actual implementation can be arbitrarily changed, and the component layout type may also be more complex.

[0036] In view of the above problems, the present invention provides a push-pull amplifier, as Figure 1 shown, comprising:

[0037] A first main path, where a first low-pass filter balun 110, a first transistor 120, and a first high-pass filter balun 130 are sequentially arranged from the input end to the output end of the first main path;

[0038] A second main path, which is arranged in parallel with the first main path, and a second high-pass filter balun 210, a second transistor 220, and a second low-pass filter balun 230 are sequentially arranged from the input end to the output end of the second main path.

[0039] In one embodiment, the push-pull amplifier further includes a power divider 310 and a combiner 320. The first end of the power divider 310 is connected to the signal input port to obtain an input signal and divide the input signal into multiple in-phase signals. The second end of the power divider 310 is connected to at least two main paths of the push-pull amplifier, wherein the number of signals output by the power divider 310 is the same as the number of main paths in the push-pull amplifier. In Figure 1In the illustrated embodiment, the push-pull amplifier includes two main paths. Therefore, the power splitter 310 divides the input signal into two in-phase signals, and the second ends of the power splitter 310 are respectively connected to the input ends of the first low-pass filter balun 110 and the second high-pass filter balun 210. The first end of the combiner 320 is connected to at least two main paths of the push-pull amplifier to obtain the output signals of the respective main paths of the push-pull amplifier and combine the multiple in-phase output signals into one output signal. In Figure 1 the illustrated embodiment, the push-pull amplifier includes two main paths. Therefore, the combiner 320 combines the output signal of the first main path and the output signal of the second main path into the output signal of the push-pull amplifier.

[0040] Exemplarily, the low-pass filter balun includes: a main path inductor, which is connected in series on the main path of the push-pull amplifier; a branch capacitor, the first end of which is connected to the first end or the second end of the main path inductor; an auxiliary inductor, which is connected in series with the branch capacitor, and both ends of the auxiliary inductor are respectively connected to the second end of the branch capacitor and the zero potential point.

[0041] Exemplarily, the high-pass filter balun includes: a main path capacitor, which is connected in series on the main path of the push-pull amplifier; a branch inductor, the first end of which is connected to the first end or the second end of the main path capacitor; an auxiliary capacitor, which is connected in series with the branch inductor, and both ends of the auxiliary capacitor are respectively connected to the second end of the branch inductor and the zero potential point.

[0042] In one embodiment, referring to Figure 1 as shown, the first low-pass filter balun 110 is a low-pass filter balun (LPF), and the first low-pass filter balun 110 includes one main path inductor, two branch capacitors, and two auxiliary inductors. Specifically, the main path inductor of the first low-pass filter balun 110 is the first inductor L1. The first end of the first inductor L1 is the input end of the first low-pass filter balun 110, which is connected to the power splitter 310. The second end of the first inductor L1 is the output end of the first low-pass filter balun 110, which is connected to the input end of the first transistor 120, that is, the gate of the first transistor 120. The branch capacitors include a first capacitor C1 and a second capacitor C2. The first end of the first capacitor C1 is connected to the first end of the first inductor L1, and the first end of the second capacitor C2 is connected to the second end of the first inductor L2. The auxiliary inductors include a second inductor L2 and a third inductor L3. The second inductor L2 is connected in series with the first capacitor C1. The first end of the second inductor L2 is connected to the second end of the first capacitor C1, and the second end of the second inductor L2 is connected to the zero potential point (for example, GND). The third inductor L3 is connected in series with the second capacitor C2. The first end of the third inductor L3 is connected to the second end of the second capacitor C2, and the second end of the third inductor L3 is connected to the zero potential point (for example, GND).

[0043] In one embodiment, referring to Figure 1As shown, the first high-pass filter balun 130 is a high-pass filter balun (HPF). The first high-pass filter balun 130 includes a main path capacitor, two branch inductors, and two auxiliary capacitors. Specifically, the main path capacitor of the first high-pass filter balun 130 is the third capacitor C3. The first end of the third capacitor C3 is the input end of the first high-pass filter balun 130, which is connected to the output end of the first transistor 120, that is, the drain of the first transistor 120. The second end of the third capacitor C3 is the output end of the first high-pass filter balun 130, which is connected to the input end of the combiner 320. The branch inductors include the fourth inductor L4 and the fifth inductor L5. The first end of the fourth inductor L4 is connected to the first end of the third capacitor C3, and the first end of the fifth inductor L5 is connected to the second end of the third capacitor C3. The auxiliary capacitors include the fourth capacitor C4 and the fifth capacitor C5. The fourth capacitor C4 is connected in series with the fourth inductor L4. The first end of the fourth capacitor C4 is connected to the second end of the fourth inductor L4, and the second end of the fourth capacitor C4 is connected to the zero potential point (for example, GND). The fifth capacitor C5 is connected in series with the fifth inductor L5. The first end of the fifth capacitor C5 is connected to the second end of the fifth inductor L5, and the second end of the fifth capacitor C5 is connected to the zero potential point (for example, GND).

[0044] In one embodiment, referring to Figure 1 As shown, the second high-pass filter balun 210 is a high-pass filter balun (HPF). The second high-pass filter balun 210 includes a main path capacitor, two branch inductors, and two auxiliary capacitors. Specifically, the main path capacitor of the second high-pass filter balun 210 is the sixth capacitor C6. The first end of the sixth capacitor C6 is the input end of the second high-pass filter balun 210, which is connected to the power divider 310. The second end of the sixth capacitor C6 is the output end of the second high-pass filter balun 210, which is connected to the input end of the second transistor 220, that is, the gate of the second transistor 220. The branch inductors include the sixth inductor L6 and the seventh inductor L7. The first end of the sixth inductor L6 is connected to the first end of the sixth capacitor C6, and the first end of the seventh inductor L7 is connected to the second end of the sixth capacitor C6. The auxiliary capacitors include the seventh capacitor C7 and the eighth capacitor C8. The seventh capacitor C7 is connected in series with the sixth inductor L6. The first end of the seventh capacitor C7 is connected to the second end of the sixth inductor L6, and the second end of the seventh capacitor C7 is connected to the zero potential point (for example, GND). The eighth capacitor C8 is connected in series with the seventh inductor L7. The first end of the eighth capacitor C8 is connected to the second end of the seventh inductor L7, and the second end of the eighth capacitor C8 is connected to the zero potential point (for example, GND).

[0045] In one embodiment, referring to Figure 1As shown, the second low-pass filter balun 230 is a low-pass filter balun (LPF), and the second low-pass filter balun 230 includes a main path inductor, two branch capacitors, and two auxiliary inductors. Specifically, the main path inductor of the second low-pass filter balun 230 is the eighth inductor L8. The first end of the eighth inductor L8 is the input end of the second low-pass filter balun 230, which is connected to the output end of the second transistor 220, that is, the drain of the second transistor 220. The second end of the eighth inductor L8 is the output end of the second low-pass filter balun 230, which is connected to the input end of the combiner 320. The branch capacitors include a ninth capacitor C9 and a tenth capacitor C10. The first end of the ninth capacitor C9 is connected to the first end of the eighth inductor L8, and the first end of the tenth capacitor C10 is connected to the second end of the eighth inductor L8. The auxiliary inductors include a ninth inductor L9 and a tenth inductor L10. The ninth inductor L9 is in series with the ninth capacitor C9. The first end of the ninth inductor L9 is connected to the second end of the ninth capacitor C9, and the second end of the ninth inductor L9 is connected to a zero potential point (for example, GND). The tenth inductor L10 is in series with the tenth capacitor C10. The first end of the tenth inductor L10 is connected to the second end of the tenth capacitor C10, and the second end of the tenth inductor L10 is connected to a zero potential point (for example, GND).

[0046] By combining inductors and capacitors to form a low-pass filter balun or a high-pass filter balun, compared with a transmission line balun, the space occupied on a printed circuit board (PCB) is reduced, which is beneficial to the miniaturization of a push-pull amplifier.

[0047] In one embodiment, the first low-pass filter balun 110 and the second high-pass filter balun 210 form an input end filter balun, and the first high-pass filter balun 130 and the second low-pass filter balun 230 form an output end filter balun. The input end filter balun receives the in-phase signals output by the power splitter 310 and outputs anti-phase signals with a phase difference of 180°. Specifically, the input ends of the first low-pass filter balun 110 and the second high-pass filter balun 210 input in-phase signals, and the output ends of the first low-pass filter balun 110 and the second high-pass filter balun 210 output anti-phase signals with a phase difference of 180°. These anti-phase signals with a phase difference of 180° respectively enter the first transistor 120 and the second transistor 220. After being amplified by the first transistor 120 and the second transistor 2, they are output to the output end filter balun. The output end filter balun receives the anti-phase signals with a phase difference of 180° output by the transistors and outputs in-phase signals. Specifically, the input ends of the first high-pass filter balun 130 and the second low-pass filter balun 230 input anti-phase signals with a phase difference of 180°, and the output ends of the first high-pass filter balun 130 and the second low-pass filter balun 230 output in-phase signals.

[0048] In one embodiment, both the first transistor 120 and the second transistor 220 are transistors. The input end of the transistor is the gate, which is connected to the input end filter balun. The output end of the transistor is the drain, which is connected to the output end filter balun. The source of the transistor is connected to the zero potential point (e.g., GND).

[0049] Exemplarily, the zero resonance frequency of the low-pass filter balun is associated with the branch capacitance and the auxiliary inductor. Based on adjusting the auxiliary inductor, the zero resonance frequency of the low-pass filter balun is set at the second harmonic frequency or the high-frequency spurious frequency of the push-pull amplifier to eliminate the second harmonic signal or the high-frequency spurious signal.

[0050] Exemplarily, the zero resonance frequency of the high-pass filter balun is associated with the branch inductor and the auxiliary capacitor. Based on adjusting the branch inductor, the zero resonance frequency of the high-pass filter balun is set at the low-frequency spurious frequency of the push-pull amplifier to eliminate the low-frequency spurious signal.

[0051] In one embodiment, referring to Figure 1 As shown, for the low-pass filter balun (LPF), an inductor is connected in series on the parallel branch, that is, an auxiliary inductor is connected in series between the branch capacitance and the zero potential point. Referring to Figure 2 As shown, a resonance point (zero point) can be formed at a high frequency (e.g., m6), and the zero resonance frequency is:

[0052] (Equation 1)

[0053] Where, f LPF_0 represents the zero resonance frequency of the low-pass filter balun, L 辅助 represents the inductance value of the auxiliary inductor, and C 支路 represents the capacitance value of the branch capacitance.

[0054] Therefore, the high-frequency resonance frequency of the low-pass filter balun (LPF) can be adjusted by the magnitude of the auxiliary inductor L 辅助 . Specifically, when the main signal frequency of the push-pull amplifier is f0, the second harmonic frequency is 2×f0. By adjusting the magnitude of the auxiliary inductor L 辅助 , such that f LPF_0 = 2×f0, so that the second harmonic component is at the zero point position of the low-pass filter balun (LPF). As can be seen from Figure 2 , the frequency range at the zero point position of the low-pass filter balun (LPF) is between 2.4 GHz and 2.8 GHz, and the signal attenuation is more than -60 dB. Therefore, by setting the zero resonance frequency of the low-pass filter balun (LPF) to the second harmonic frequency of the push-pull amplifier, the second harmonic signal can be filtered out. When the high-frequency spurious signal frequency of the push-pull amplifier is f1, by adjusting the magnitude of the auxiliary inductor L 辅助 , such that fLPF_0 = f1, so that the high-frequency spurious components are at the zero position of the low-pass filter balun (LPF), and the signal attenuation is more than -60 dB. Therefore, by setting the zero resonance frequency of the low-pass filter balun (LPF) to the high-frequency spurious frequency of the push-pull amplifier, the high-frequency spurious signals can be filtered out.

[0055] In one embodiment, referring to Figure 1 as shown, for the high-pass filter balun (HPF), a capacitor is connected in series on the parallel branch, that is, an auxiliary capacitor is connected in series between the branch inductor and the zero potential point. Referring to Figure 3 as shown, a resonance point (zero point) can be formed at low frequencies, and the zero resonance frequency is:

[0056] (Equation 2)

[0057] where f HPF_0 represents the zero resonance frequency of the high-pass filter balun, L 支路 represents the inductance value of the branch inductor, and C 辅助 represents the capacitance value of the auxiliary capacitor.

[0058] Therefore, the low-frequency resonance frequency of the high-pass filter balun (HPF) can be adjusted by the magnitude of the branch inductor L 支路 . Specifically, when the low-frequency spurious signal frequency of the push-pull amplifier is f2, by adjusting the magnitude of the branch inductor L 支路 , so that f HPF_0 = f2, so that the low-frequency spurious components are at the zero position of the high-pass filter balun (HPF). As known from Figure 3 , the frequency range at the zero position of the high-pass filter balun (HPF) is between 0 GHz and 0.5 GHz, and the signal attenuation is more than -60 dB. Therefore, by setting the zero resonance frequency of the high-pass filter balun (HPF) to the low-frequency spurious frequency of the push-pull amplifier, the low-frequency spurious signals can be filtered out.

[0059] In one embodiment, the input filter balun receives the signal output by the power splitter 310. The first low-pass filter balun 110 filters out high-frequency stray signals, that is, out-of-band high-frequency stray signals are blocked from entering the push-pull amplifier. The second high-pass filter balun 210 filters out low-frequency stray signals, that is, out-of-band low-frequency stray signals are blocked from entering the push-pull amplifier. Therefore, after the signal output by the power splitter 310 passes through the input filter balun, an in-phase signal with a phase difference of 180° is output, and at the same time, the out-of-band stray signal filtering function is completed, avoiding interference signals from entering the transistor for amplification. The first transistor 120 and the second transistor 220 receive the 180° in-phase signals output by the input filter balun and amplify the signals. At the same time, harmonic signals and stray signals are inevitably generated. The output filter balun receives the signal output by the transistor. The first high-pass filter balun 130 filters out the second harmonic signals and high-frequency stray signals, and the second low-pass filter balun 230 filters out low-frequency stray signals. Therefore, after the signal output by the transistor passes through the output filter balun, an in-phase signal is output, and at the same time, the filtering function of the second harmonic signals and out-of-band stray signals is completed.

[0060] Combining an inductor and a capacitor to form a low-pass filter balun or a high-pass filter balun can, compared with a transmission line balun, suppress the second harmonic and out-of-band stray signals while forming an in-phase signal.

[0061] Exemplarily, the output end of the first low-pass filter balun 110 is connected to the gate of the first transistor 120, the input end of the first high-pass filter balun 130 is connected to the drain of the first transistor 120, the output end of the second high-pass filter balun 210 is connected to the gate of the second transistor 220, and the input end of the second low-pass filter balun 230 is connected to the drain of the second transistor 220. The first low-pass filter balun 110 and the second high-pass filter balun 210 are used for the input impedance matching of the push-pull amplifier to match the gates of the first transistor 120 and the second transistor 220 to the target impedance value. The first high-pass filter balun 130 and the second low-pass filter balun 230 are used for the output impedance matching of the push-pull amplifier to match the drains of the first transistor 120 and the second transistor 220 to the target impedance value.

[0062] In one embodiment, the input filter balun has an impedance matching function to match the gate impedance of the transistor to a target impedance value through the input filter balun. Specifically, the signals output by the power divider 310 enter the first low-pass filter balun 110 and the second high-pass filter balun 210 respectively. The output end of the first low-pass filter balun 110 is connected to the gate of the first transistor 120, and the output end of the second high-pass filter balun 210 is connected to the gate of the second transistor 220. The first low-pass filter balun 110 and the second high-pass filter balun 210 are used for the input impedance matching of the push-pull amplifier to match the gate impedance values of the first transistor 120 and the second transistor 220 to the target impedance value (for example, 50 Ω). The output filter balun has an impedance matching function to match the drain impedance of the transistor to a target impedance value through the output filter balun. Specifically, the signals output by the transistors enter the first high-pass filter balun 130 and the second low-pass filter balun 230 respectively. The input end of the first high-pass filter balun 130 is connected to the drain of the first transistor 120, and the input end of the second low-pass filter balun 230 is connected to the drain of the second transistor 220. The first high-pass filter balun 130 and the second low-pass filter balun 230 are used for the output impedance matching of the push-pull amplifier to match the drain impedance values of the first transistor 120 and the second transistor 220 to the target impedance value (for example, 50 Ω). In this way, the input and output impedance matching of the push-pull amplifier is completed.

[0063] By combining an inductor and a capacitor to form a low-pass filter balun or a high-pass filter balun, it can be used for impedance matching without customizing different transmission line baluns for different impedances, reducing the device cost.

[0064] In Figure 1In the illustrated embodiment, the power splitter 310 obtains an input signal, divides the input signal into two in-phase signals, and provides them to the input filter balun. The input filter balun includes a first low-pass filter balun 110 and a second high-pass filter balun 210. The first low-pass filter balun 110 filters out high-frequency spurious signals to block out-of-band high-frequency spurious signals from entering the push-pull amplifier. The second high-pass filter balun 210 filters out low-frequency spurious signals to block out-of-band low-frequency spurious signals from entering the push-pull amplifier. The output ends of the first low-pass filter balun 110 and the second high-pass filter balun 210 output anti-phase signals with a phase difference of 180°. At the same time, the first low-pass filter balun 110 and the second high-pass filter balun 210 also match the gate impedance values of the first transistor 120 and the second transistor 220 to the target impedance value (for example, 50 Ω). The first transistor 120 and the second transistor 220 receive the 180° anti-phase signals output by the input filter balun, amplify the signals, and inevitably generate harmonic signals and spurious signals, which are output to the output filter balun. The output filter balun includes a first high-pass filter balun 130 and a second low-pass filter balun 230. The input ends of the first high-pass filter balun 130 and the second low-pass filter balun 230 input anti-phase signals with a phase difference of 180°. The output ends of the first high-pass filter balun 130 and the second low-pass filter balun 230 output in-phase signals. At the same time, the first high-pass filter balun 130 filters out second harmonic signals and high-frequency spurious signals, and the second low-pass filter balun 230 filters out low-frequency spurious signals. Moreover, the first high-pass filter balun 130 and the second low-pass filter balun 230 match the drains of the first transistor 120 and the second transistor 220 to the target impedance value (for example, 50 Ω). The in-phase signals output by the output ends of the first high-pass filter balun 130 and the second low-pass filter balun 230 are combined in the combiner 320 to form the output signal of the push-pull amplifier.

[0065] According to the push-pull amplifier provided by the present invention, by sequentially arranging a low-pass filter balun, a transistor, and a high-pass filter balun on the first branch, and sequentially arranging a high-pass filter balun, a transistor, and a low-pass filter balun on the second branch, not only the signal inversion function is realized, but also the suppression effect on second harmonics and out-of-band spurious signals is improved. At the same time, the volume of the push-pull amplification is reduced, and the device cost is lowered.

[0066] Please note that the above embodiments are for illustrative purposes only and do not imply any limitation to this application.

[0067] Each embodiment in this specification is described in a progressive manner. The key point of each embodiment is to illustrate the differences from other embodiments. The same or similar parts among the embodiments can be referred to each other.

[0068] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0069] The above-described embodiments only represent several implementation manners of the present application. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all belong to the protection scope of the present application.

Claims

1. A push-pull amplifier, characterized in that, Comprising: A first main path, where a first low-pass filter balun, a first transistor, and a first high-pass filter balun are sequentially arranged from the input end to the output end of the first main path; A second main path, arranged in parallel with the first main path, where a second high-pass filter balun, a second transistor, and a second low-pass filter balun are sequentially arranged from the input end to the output end of the second main path.

2. The push-pull amplifier according to claim 1, wherein The low-pass filter balun includes: A main path inductor, which is connected in series to the main path of the push-pull amplifier; A branch capacitor, where the first end of the branch capacitor is connected to the first end or the second end of the main path inductor; An auxiliary inductor, connected in series with the branch capacitor, and both ends of the auxiliary inductor are respectively connected to the second end of the branch capacitor and the zero potential point.

3. The push-pull amplifier according to claim 2, wherein The zero resonance frequency of the low-pass filter balun is associated with the branch capacitor and the auxiliary inductor. Based on adjusting the auxiliary inductor, the zero resonance frequency of the low-pass filter balun is set at the second harmonic frequency or the high-frequency spurious frequency of the push-pull amplifier to eliminate the second harmonic signal or the high-frequency spurious signal.

4. The push-pull amplifier according to claim 1, wherein The high-pass filter balun includes: A main path capacitor, which is connected in series to the main path of the push-pull amplifier; A branch inductor, where the first end of the branch inductor is connected to the first end or the second end of the main path capacitor; An auxiliary capacitor, connected in series with the branch inductor, and both ends of the auxiliary capacitor are respectively connected to the second end of the branch inductor and the zero potential point.

5. The push-pull amplifier according to claim 4, wherein The zero resonance frequency of the high-pass filter balun is associated with the branch inductor and the auxiliary capacitor. Based on adjusting the branch inductor, the zero resonance frequency of the high-pass filter balun is set at the low-frequency spurious frequency of the push-pull amplifier to eliminate the low-frequency spurious signal.

6. The push-pull amplifier according to claim 1, characterized in that The first low-pass filter balun and the second high-pass filter balun form an input end filter balun, and the first high-pass filter balun and the second low-pass filter balun form an output end filter balun.

7. The push-pull amplifier according to claim 6, characterized in that, The input end of the input end filter balun inputs a in-phase signal, and the output end of the input end filter balun outputs an anti-phase signal with a phase difference of 180°; the input end of the output end filter balun inputs an anti-phase signal with a phase difference of 180°, and the output end of the output end filter balun outputs a in-phase signal.

8. The push-pull amplifier according to claim 1, wherein The output end of the first low-pass filter balun is connected to the gate of the first transistor, the input end of the first high-pass filter balun is connected to the drain of the first transistor, the output end of the second high-pass filter balun is connected to the gate of the second transistor, and the input end of the second low-pass filter balun is connected to the drain of the second transistor.

9. The push-pull amplifier according to claim 8, characterized in that, The first low-pass filter balun and the second high-pass filter balun are used for the input impedance matching of the push-pull amplifier to match the gates of the first transistor and the second transistor to the target impedance value, and the first high-pass filter balun and the second low-pass filter balun are used for the output impedance matching of the push-pull amplifier to match the drains of the first transistor and the second transistor to the target impedance value.

10. The push-pull amplifier according to claim 1, characterized in that, The push-pull amplifier further includes: Power splitter, the input ends of the first low-pass filter balun and the second high-pass filter balun are both connected to the power splitter; Combiner, the output ends of the first high-pass filter balun and the second low-pass filter balun are both connected to the combiner.

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