Differential power amplifier

Abstract

This invention provides a differential power amplifier that can optimize the pass characteristics for each band in a configuration using multiple differential amplifiers. [Solution] The differential power amplifier includes a plurality of differential amplifiers and has a first mode in which both the first differential amplifier 1 and the second differential amplifier 2 perform amplification operations, and a second mode in which the first differential amplifier 1 performs amplification operations and the second differential amplifier 2 does not perform amplification operations. It includes a first balun transformer 3 that converts the balanced output signal of the first differential amplifier 1 into an unbalanced signal, a second balun transformer 4 that converts the balanced output signal of the second differential amplifier 2 into an unbalanced signal, and a switch circuit 5 that, in the first mode, directly connects the unbalanced output terminal of the first balun transformer 3 and the unbalanced output terminal of the second balun transformer 4, and in the second mode, connects the unbalanced output terminal of the first balun transformer 3 and the unbalanced output terminal of the second balun transformer 4 via a capacitor C.

Description

Technical Field

[0001] The present disclosure relates to a differential power amplifier.

Background Art

[0002] In the field of mobile communication such as mobile phones, a power amplification circuit combining a plurality of differential amplifiers has been disclosed. Patent Document 1 below describes that broadband frequency characteristics are realized by synthesizing the outputs of a plurality of differential amplifiers.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Patent Document 1 above does not describe a configuration for attenuating harmonic components in differential amplification. Further, when attempting to implement, for example, EN-DC (E-UTRAN New Radio - Dual Connectivity) using a plurality of differential amplifiers, it is necessary to optimize the passing characteristics for each band.

[0005] The present disclosure has been made in view of the above, and an object thereof is to realize a differential power amplifier capable of optimizing the passing characteristics for each band in a configuration using a plurality of differential amplifiers.

Means for Solving the Problems

[0006] A differential power amplifier according to one aspect of the present disclosure includes a plurality of differential amplifiers and has a first mode in which a first differential amplifier and a second differential amplifier both perform amplification operations, and a second mode in which the first differential amplifier performs amplification operations and the second differential amplifier does not, and comprises a first balun transformer that converts the balanced output signal of the first differential amplifier to an unbalanced signal, a second balun transformer that converts the balanced output signal of the second differential amplifier to an unbalanced signal, and a switch circuit that in the first mode directly connects the unbalanced output terminal of the first balun transformer and the unbalanced output terminal of the second balun transformer, and in the second mode connects the unbalanced output terminal of the first balun transformer and the unbalanced output terminal of the second balun transformer via a capacitor. [Effects of the Invention]

[0007] According to this disclosure, a differential power amplifier can be realized that can optimize the pass characteristics for each band in a configuration using multiple differential amplifiers. [Brief explanation of the drawing]

[0008] [Figure 1A] Figure 1A is the first figure showing an example configuration of a differential power amplifier according to Embodiment 1. [Figure 1B] Figure 1B is the second figure showing an example configuration of a differential power amplifier according to Embodiment 1. [Figure 2] Figure 2 shows an example of the simulation results of the frequency-gain characteristics in the second mode of the differential power amplifier according to Embodiment 1. [Figure 3A] Figure 3A is the first figure showing an example configuration of a differential power amplifier according to Embodiment 2. [Figure 3B] Figure 3B is the second figure showing an example configuration of a differential power amplifier according to Embodiment 2. [Figure 4] Figure 4 shows an example of the simulation results of the frequency-gain characteristics in the second mode of the differential power amplifier according to Embodiment 2. [Figure 5A] Figure 5A is the first figure showing an example of the configuration of a differential power amplifier according to a modified embodiment of the second embodiment. [Figure 5B] Figure 5B is the second figure showing an example of the configuration of a differential power amplifier according to a modified embodiment of the second embodiment. [Modes for carrying out the invention]

[0009] A differential power amplifier according to an embodiment will be described in detail below with reference to the drawings. However, the present invention is not limited by this embodiment. Furthermore, the components of each embodiment include those that are easily substituted or substantially identical to those that are substituted by those skilled in the art. Each embodiment is illustrative, and partial substitution or combination of the configurations shown in different embodiments is possible. From Embodiment 2 onward, descriptions of matters common to Embodiment 1 will be omitted, and only the differences will be described. In particular, similar effects and advantages due to similar configurations will not be mentioned sequentially for each embodiment.

[0010] (Embodiment 1) Figure 1A is the first figure showing an example configuration of a differential power amplifier according to Embodiment 1. Figure 1B is the second figure showing an example configuration of a differential power amplifier according to Embodiment 1. As shown in Figures 1A and 1B, the differential power amplifier 100 according to Embodiment 1 includes a first differential amplifier 1, a second differential amplifier 2, a first balun transformer 3, a second balun transformer 4, and a switch circuit 5.

[0011] In this disclosure, the band of the first differential signal input to the first differential amplifier 1 and the band of the second differential signal input to the second differential amplifier 2 are the same. The differential power amplifier 100 according to Embodiment 1 has a first mode in which both the first differential amplifier 1 and the second differential amplifier 2 perform amplification operations, and a second mode in which the first differential amplifier 1 performs amplification operations and the second differential amplifier 2 does not perform amplification operations. Figure 1A shows the state in the first mode, and Figure 1B shows the state in the second mode.

[0012] In the present disclosure, the input signal in the first mode is, for example, a signal in a frequency band (band) defined by 2G (second-generation mobile communication system). Also, in the present disclosure, the input signal in the second mode is, for example, a signal in a frequency band (band) defined by 5G (fifth-generation mobile communication system). Note that the input signal in the second mode is not limited to 5G, and may be a signal in a frequency band (band) defined by 4G (fourth-generation mobile communication system) or 6G (sixth-generation mobile communication system).

[0013] In the examples shown in FIGS. 1A and 1B, an example is illustrated in which both the output signal RFOUT1 in the first mode and the output signal RFOUT2 in the second mode are output from the same node as the unbalanced output terminal of the first balun 3, but it is not limited thereto. For example, the output signal RFOUT1 in the first mode may be output from the same node as the unbalanced output terminal of the second balun 4.

[0014] The first differential amplifier 1 includes two amplifiers 11 and 12 that amplify the first differential signal. Amplifier 11 amplifies the input signal RFIN1P. Amplifier 12 amplifies the input signal RFIN1N.

[0015] The second differential amplifier 2 includes two amplifiers 21 and 22 that amplify the second differential signal. Amplifier 21 amplifies the input signal RFIN2P. Amplifier 22 amplifies the input signal RFIN2N.

[0016] The amplifiers 11, 12, 21, and 22 may be configured by, for example, bipolar transistors, or may be configured by, for example, FETs. When the amplifiers 11, 12, 21, and 22 are configured by bipolar transistors, for example, HBTs are exemplified. The present disclosure is not limited by the configuration of the amplifiers 11, 12, 21, and 22.

[0017] The first balun 3 includes an input-side winding 31 and an output-side winding 32.

[0018] The input-side winding 31 is connected between the output OUT1P and the output OUT1N of the first differential amplifier 1. A center tap is provided at the midpoint of the input-side winding 31, and the power supply voltage VCC1 is applied to this center tap.

[0019] The input-side winding 31 and the output-side winding 32 of the first balun 3 are electromagnetically coupled. Thereby, the balanced output signal output from the first differential amplifier 1 is converted from balanced to unbalanced by the first balun 3.

[0020] The second balun 4 includes an input-side winding 41 and an output-side winding 42.

[0021] The input-side winding 41 is connected between the output OUT2P and the output OUT2N of the second differential amplifier 2. A center tap is provided at the midpoint of the input-side winding 41, and the power supply voltage VCC2 is applied to this center tap.

[0022] The input-side winding 41 and the output-side winding 42 of the second balun 4 are electromagnetically coupled. Thereby, the balanced output signal output from the second differential amplifier 2 is converted from balanced to unbalanced by the second balun 4.

[0023] In the example shown in FIGS. 1A and 1B, the switch circuit 5 is, for example, a 2-to-1 multiplexer. The configuration of the switch circuit 5 shown in FIGS. 1A and 1B is an example, and the present disclosure is not limited by the configuration of the switch circuit 5.

[0024] In the differential power amplifier 100 according to Embodiment 1, as shown in FIG. 1A, in the first mode, the switch circuit 5 directly connects the unbalanced output terminal of the first balun 3 and the unbalanced output terminal of the second balun 4. Thereby, the output power of the first differential amplifier 1 and the output power of the second differential amplifier 2 are combined, and relatively large power can be output.

[0025] Furthermore, as shown in Figure 1B, the switch circuit 5 connects the unbalanced output terminal of the first balun transformer 3 and the unbalanced output terminal of the second balun transformer 4 via a capacitor C in the second mode. This constitutes an LC series resonant circuit utilizing the output winding 42 of the second balun transformer 4.

[0026] Figure 2 shows an example of the simulation results of the frequency-gain characteristics in the second mode of the differential power amplifier according to Embodiment 1. In the example shown in Figure 2, the dashed line shows the simulation results of the frequency-gain characteristics in the second mode when capacitor C is not provided. In the second mode, by connecting the unbalanced output terminal of the first balun transformer 3 and the unbalanced output terminal of the second balun transformer 4 via capacitor C, an LC series resonant circuit with a predetermined frequency as the resonant frequency f0 is configured, as shown by the solid line in Figure 2.

[0027] In the configuration of the differential power amplifier 100 according to Embodiment 1, the capacitance value of capacitor C can be appropriately set according to the band of the first differential signal input to the first differential amplifier 1, thereby effectively attenuating harmonic components. This makes it possible to optimize the pass characteristics of the first differential signal.

[0028] Furthermore, by using the output winding 42 of the second balun transformer 4 as an inductor in an LC series resonant circuit, it is possible to contribute to miniaturizing the differential power amplifier.

[0029] (Embodiment 2) Figure 3A is the first figure showing an example configuration of a differential power amplifier according to Embodiment 2. Figure 3B is the second figure showing an example configuration of a differential power amplifier according to Embodiment 2.

[0030] In the examples shown in Figures 3A and 3B, the capacitance values ​​of each capacitor C1, C2, and C3 are different. Also, in the examples shown in Figures 3A and 3B, the switch circuit 5a is, for example, an n-to-1 connected multiplexer (here, n=4). The configuration of the switch circuit 5a shown in Figures 3A and 3B is just one example, and this disclosure is not limited by the configuration of the switch circuit 5a.

[0031] In the differential power amplifier 100a according to Embodiment 2, as shown in Figure 3A, the switch circuit 5a directly connects the unbalanced output terminal of the first balun transformer 3 and the unbalanced output terminal of the second balun transformer 4 in the first mode. As a result, the output power of the first differential amplifier 1 and the output power of the second differential amplifier 2 are combined, and a relatively large power output is possible.

[0032] Furthermore, as shown in Figure 3B, the switch circuit 5a switches the capacitance of the capacitor connected between the unbalanced output terminal of the first balun transformer 3 and the unbalanced output terminal of the second balun transformer 4 in the second mode. The example shown in Figure 3B illustrates a configuration in which capacitor C1 is connected between the unbalanced output terminal of the first balun transformer 3 and the unbalanced output terminal of the second balun transformer 4.

[0033] Figure 4 shows an example of the simulation results of the frequency-gain characteristics in the second mode of the differential power amplifier according to Embodiment 2. Each line shown in Figure 4 shows the simulation results of the frequency-gain characteristics in the second mode when capacitors C1, C2, and C3 are provided. In the example shown in Figure 4, the relationship between the capacitance values ​​of capacitors C1, C2, and C3 is C1 > C2 > C3. In this case, the relationship between the resonance frequencies f01, f02, and f03 is f01 <f02<f03となる。

[0034] In the configuration of the differential power amplifier 100a according to Embodiment 2, by selecting a capacitor with a capacitance value corresponding to the band of the first differential signal input to the first differential amplifier 1, harmonic components of different frequencies for each band can be effectively attenuated. This makes it possible to optimize the pass characteristics of the first differential signal for each band.

[0035] (modified version) Figure 5A is the first figure showing an example configuration of a differential power amplifier according to a modified embodiment of Embodiment 2. Figure 5B is the second figure showing an example configuration of a differential power amplifier according to a modified embodiment of Embodiment 2.

[0036] In the examples shown in Figures 5A and 5B, the capacitance values ​​of the three capacitors C may be the same or they may each have different capacitance values. Furthermore, the configuration of the switch circuit 5b shown in Figures 5A and 5B is just one example, and the present disclosure is not limited by the configuration of the switch circuit 5b.

[0037] In the differential power amplifier 100b according to a modified embodiment of the second embodiment, the switch circuit 5b directly connects the unbalanced output terminal of the first balun transformer 3 and the unbalanced output terminal of the second balun transformer 4 in the first mode, as shown in Figure 5A. As a result, the output power of the first differential amplifier 1 and the output power of the second differential amplifier 2 are combined, and a relatively large power output is possible.

[0038] Furthermore, as shown in Figure 5B, the switch circuit 5b changes the number of capacitors connected between the unbalanced output terminals of the first balun transformer 3 and the unbalanced output terminals of the second balun transformer 4 in the second mode. The example shown in Figure 5B illustrates a configuration in which one capacitor C is connected between the unbalanced output terminals of the first balun transformer 3 and the unbalanced output terminals of the second balun transformer 4.

[0039] In the configuration of the differential power amplifier 100b according to a modified embodiment of Embodiment 2, the capacitance value corresponding to the band of the first differential signal input to the first differential amplifier 1 can be set by changing the number of capacitors connected between the unbalanced output terminal of the first balun transformer 3 and the unbalanced output terminal of the second balun transformer 4. This makes it possible to optimize the pass characteristics of the first differential signal for each band, similar to the differential power amplifier 100a according to Embodiment 2.

[0040] The embodiments described above are provided to facilitate understanding of this disclosure and are not intended to limit the invention. This disclosure may be modified or improved without departing from its spirit, and equivalents thereof are included. [Explanation of Symbols]

[0041] 1. First differential amplifier 2. Second differential amplifier 3. First Balant Trans 4. Second Balantrance 5, 5a, 5b Switch Circuit 11,12 Amplifier (First Differential Amplifier) 21,22 Amplifier (Second Differential Amplifier) 31 Input side winding (first balun transformer) 32 Output winding (first balun transformer) 41 Input winding (second balun transformer) 42 Output winding (second balun transformer) 100, 100a, 100b Differential Power Amplifier

Claims

1. Includes multiple differential amplifiers, A first mode in which both the first differential amplifier and the second differential amplifier perform amplification operations, A second mode in which the first differential amplifier performs amplification and the second differential amplifier does not perform amplification, It has, A first balun transformer that converts the balanced output signal of the first differential amplifier into an unbalanced signal, A second balun transformer that converts the balanced output signal of the second differential amplifier into an unbalanced signal, In the first mode, the unbalanced output terminal of the first balun transformer and the unbalanced output terminal of the second balun transformer are directly connected, and in the second mode, the unbalanced output terminal of the first balun transformer and the unbalanced output terminal of the second balun transformer are connected via a capacitor, and Equipped with, Differential power amplifier.

2. A differential power amplifier according to claim 1, The aforementioned switch circuit is In the second mode, the capacitance of the capacitor connected between the unbalanced output terminal of the first balun transformer and the unbalanced output terminal of the second balun transformer is switchable. Differential power amplifier.

3. A differential power amplifier according to claim 1 or 2, The aforementioned switch circuit is In the second mode, the number of capacitors connected between the unbalanced output terminal of the first balun transformer and the unbalanced output terminal of the second balun transformer can be changed. Differential power amplifier.

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