JP2009171154A - Amplifier circuit, and communication device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an amplifier circuit which can be miniaturized while making linearity of amplification and power efficiency compatible, and to provide a communication device. <P>SOLUTION: The amplifier circuit is provided, which includes: a first amplification part which outputs a first input signal obtained by amplifying a first constant envelope signal; a second amplification part which outputs a second input signal obtained by amplifying a second constant envelope signal; and a magnetic coupling transformer to the primary side of which the first input signal and the second input signal are each input, and which composites the first input signal with the second input signal to output an output signal whose amplitude is modulated on the secondary side, wherein the magnetic coupling transformer includes: a primary side first inductor and a primary side first capacitor constituting a first primary side; a secondary side first inductor and a secondary side first capacitor constituting a first secondary side; a primary side second inductor and a primary side second capacitor constituting a second primary side; a secondary side second inductor and a secondary side second capacitor constituting a second secondary side; and a compositing part which outputs the output signal. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an amplifier circuit and a communication device.

  In the wireless communication field, higher transmission speed is required year by year, and frequency resources are limited. Under such circumstances, in the wireless communication field, for example, a multi-valued digital modulation signal is used as a transmission signal so that high-speed communication can be performed in a limited frequency resource.

  Examples of the digital modulation signal include an OFDM (Orthogonal Frequency Division Multiplexing) signal. In the OFDM signal, the ratio of the average power to the maximum power is as large as 10 dB or more. Therefore, in order to amplify a digital modulation signal having a large amplitude change as described above with low distortion, an amplifier circuit with high linearity is required. However, increasing the linearity reduces the power efficiency of the amplifier circuit. Here, particularly in a communication device that operates on a battery, a reduction in power efficiency of the amplifier circuit cannot be ignored from the viewpoint of extending the operable time as much as possible.

  Under such circumstances, a technique related to an amplifier circuit that achieves both amplification linearity and power efficiency has been developed. Non-patent Document 1 is an example of a technique related to an amplifier circuit that divides a transmission signal into two constant envelope signals having different phases and combines them after amplification to reproduce amplitude changes.

F.H.Raab, “Efficiency of outphasing RF power-amplifier systems,” IEEE Trans.Commun., Vol.COM-33, pp. 1094-1099, Oct. 1985.

  The transmission signal is divided into two constant envelope signals having different phases, and is synthesized after amplification, and the amplification circuit using the conventional technique related to the amplification circuit that reproduces the amplitude change (hereinafter, the amplification circuit according to the conventional technique is referred to as “ LINC (Linear Amplification with Nonlinear Components) amplifier circuit) can be used for non-linear, high-efficiency amplifiers to amplify constant envelope signals, thus reducing the linearity and power efficiency of amplification. It is possible to achieve both.

  However, the LINC amplifier circuit must have two λ / 4 transmission lines that require an electrical length that is a quarter wavelength of the wavelength λ at the frequency used for communication (hereinafter referred to as “used frequency”). Therefore, it is very difficult to reduce the size of the amplifier circuit.

  On the other hand, in recent years, communication devices have been downsized, and an amplifier circuit applied to the communication device is required to be further downsized in addition to a function of amplifying a signal with low distortion and power efficiency. However, since the LINC amplifier circuit is very difficult to downsize as described above, the LINC amplifier circuit is an amplifier circuit that can achieve both amplification linearity and power efficiency. Even so, it cannot be applied to a communication device (not realistic).

  Therefore, there has been a demand for an amplifier circuit that can be reduced in size while achieving both amplification linearity and power efficiency.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a new and improved amplification capable of reducing the size while achieving both amplification linearity and power efficiency. It is to provide a circuit and a communication device.

  To achieve the above object, according to a first aspect of the present invention, a first amplifying unit that receives a first constant envelope signal and outputs a first input signal obtained by amplifying the first constant envelope signal. A second amplifying unit that receives a second constant envelope signal having a phase different from that of the first constant envelope signal, outputs a second input signal obtained by amplifying the second constant envelope signal, and the first input. A magnetic coupling transformer for inputting a signal and the second input signal to the primary side, and outputting an amplitude-modulated output signal by combining the first input signal and the second input signal on the secondary side; The magnetic coupling transformer includes: a primary side first inductor and a primary side first capacitor constituting a first primary side to which the first input signal is input; and the first primary side; The secondary side first inductor and the secondary side first capacitor constituting the corresponding first secondary side , A primary second inductor and a primary second capacitor constituting a second primary side to which the second input signal is input, and a second 2 corresponding to the second primary side. An amplifier circuit comprising: a secondary side second inductor and a secondary side second capacitor constituting a secondary side; and a synthesis unit that synthesizes the first input signal and the second input signal and outputs the output signal. Provided.

  With this configuration, it is possible to reduce the size while achieving both amplification linearity and power efficiency.

  The combining unit includes an output capacitor having a predetermined capacitance, and the primary side first inductor and the primary side first capacitor, the secondary side first inductor, and the secondary side first capacitor. 1 capacitor, the primary side second inductor and the primary side second capacitor, the secondary side second inductor and the secondary side second capacitor are respectively connected in parallel, and the secondary side second capacitor One capacitor, the second secondary capacitor, and the output capacitor may be connected in series.

  With this configuration, it is possible to reduce the size while achieving both amplification linearity and power efficiency.

  The absolute values of the reactances of the secondary side first capacitor and the secondary side second capacitor are approximately twice the absolute values of the reactances of the secondary side first inductor and the secondary side second inductor, respectively. There may be.

  With this configuration, both amplification linearity and power efficiency can be achieved.

  The combining unit includes an output inductor having a predetermined inductance, the primary side first inductor and the primary side first capacitor, the primary side second inductor, and the primary side second capacitor. Are connected in parallel, and the secondary side first inductor and the secondary side first capacitor are connected in series to the secondary side second inductor and the secondary side second capacitor, respectively. A secondary first capacitor, the secondary second capacitor, and a first terminal of the output inductor may be connected, and the output signal may be output from a second terminal of the output inductor.

  With this configuration, it is possible to reduce the size while achieving both amplification linearity and power efficiency.

  The absolute values of the reactances of the secondary side first capacitor and the secondary side second capacitor are approximately twice the absolute values of the reactances of the secondary side first inductor and the secondary side second inductor, respectively. In addition, the inductance of the output inductor may be approximately ½ of the inductance of the secondary side first inductor and the secondary side second inductor.

  With this configuration, both amplification linearity and power efficiency can be achieved.

  The primary side first inductor and the primary side first capacitor, the primary side second inductor and the primary side second capacitor, the secondary side first inductor and the secondary side first The capacitor, the secondary side second inductor, and the secondary side second capacitor are respectively connected in series, and the output from the connection point of the secondary side first capacitor and the secondary side second capacitor. A signal may be output.

  With this configuration, it is possible to reduce the size while achieving both amplification linearity and power efficiency.

  Further, the inductances of the primary side first inductor and the secondary side first inductor and the capacitances of the primary side first capacitor and the secondary side first capacitor are the primary side 1 inductor and the primary side first capacitor, and the secondary side first inductor and the secondary side first capacitor are set to resonate at the frequency of the first constant envelope signal, and the primary side The inductances of the second inductor and the secondary second inductor and the capacitances of the primary second capacitor and the secondary second capacitor are the primary second inductor and the primary, respectively. The second side capacitor, the secondary side second inductor, and the secondary side second capacitor may be set to resonate at the frequency of the second constant envelope signal.

  With this configuration, both amplification linearity and power efficiency can be achieved.

  Moreover, you may further provide the switching part which switches the impedance of the output side of the said 2nd amplification part.

  With this configuration, the rate of increase in impedance can be controlled. Here, for example, the switching unit may switch the operation of the second amplifier so as to selectively input the second input signal to the magnetic coupling transformer, and turns off the second amplification unit. In this case, the impedance on the output side of the second amplifying unit can be switched.

  The first amplifying unit includes a plurality of first amplifiers to amplify the first constant envelope signal, and the second amplifying unit includes a plurality of second amplifiers to convert the second constant envelope signal. A plurality of primary side first inductors and primary side first capacitors, a plurality of secondary side first inductors and secondary side first capacitors respectively corresponding to the first amplifiers; A plurality of primary side second inductors and primary side second capacitors corresponding to each of the second amplifiers, and a plurality of secondary side second inductors and secondary side second capacitors may be provided.

  With this configuration, the output voltage of each amplifier can be reduced.

  The first amplifying unit receives a first positive phase constant envelope signal as a differential signal and a first negative phase constant envelope signal whose phase is inverted from that of the first positive phase constant envelope signal. The second amplification unit receives a second positive phase constant envelope signal as a differential signal and a second negative phase constant envelope signal whose phase is inverted with respect to the second positive phase constant envelope signal. The first amplifying unit causes the primary side first inductor to function as a power supply inductor that supplies power to the first amplifying unit, and the second amplifying unit includes the primary side second inductor as the second power inductor. You may make it function as a power supply inductor which supplies power to an amplification part.

  With this configuration, the circuit configuration can be simplified.

  The first amplifying unit receives a first positive phase constant envelope signal as a differential signal and a first negative phase constant envelope signal whose phase is inverted from that of the first positive phase constant envelope signal. The second amplification unit receives a second positive phase constant envelope signal as a differential signal and a second negative phase constant envelope signal whose phase is inverted with respect to the second positive phase constant envelope signal. The first amplifying unit causes an output capacitance component of a transistor constituting the first amplifying unit to function as the primary first capacitor, and the second amplifying unit outputs an output of the transistor constituting the second amplifying unit. The capacitance component may function as the primary side second capacitor.

  With this configuration, the circuit configuration can be simplified.

  In order to achieve the above object, according to the second aspect of the present invention, the first constant envelope signal and the first constant envelope signal are different in phase based on the input transmission signal. A signal distributor that distributes the signal to two constant envelope signals, an amplifier that receives the first constant envelope signal and the second constant envelope signal, and outputs an amplitude-modulated output transmission signal; A communication unit that transmits the output transmission signal output from the amplifying unit to an external device, wherein the amplifying unit receives the first constant envelope signal and amplifies the first constant envelope signal. A first amplifying unit that outputs an input signal; a second amplifying unit that receives the second constant envelope signal; outputs a second input signal obtained by amplifying the second constant envelope signal; and the first input signal. And the second input signal are respectively input to the primary side, and the first input is input to the secondary side. Communication device is provided which issue and by synthesizing the said second input signal and a magnetically-coupled transformer for outputting the output transmission signal.

  With this configuration, it is possible to reduce the size while achieving both amplification linearity and power efficiency.

  According to the present invention, downsizing can be achieved while achieving both amplification linearity and power efficiency.

  Exemplary embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In the present specification and drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

(Construction of the conventional amplifier circuit and problems in the conventional amplifier circuit)
Before describing the amplifier circuit according to the embodiment of the present invention, first, the configuration of a conventional amplifier circuit (LINC-type amplifier circuit) and its problems will be described.

[Configuration of conventional amplifier circuit]
FIG. 1 is an explanatory diagram showing the configuration of a LINC type amplifier circuit 10 (conventional amplifier circuit). The amplifying circuit 10 converts the modulation signal (transmission signal) Si (t) with information on the input phase and amplitude, the first constant envelope signal S1 (t) having the constant amplitude and the phase different from the second constant signal It is decomposed into a constant envelope signal S2 (t). Then, the amplifier circuit 10 applies the amplified signal to the load Ro by amplifying the first constant envelope signal S1 (t) and the second constant envelope signal S2 (t) and then combining them. .

  Referring to FIG. 1, the amplifier circuit 10 includes a signal distribution circuit 12 (called a Signal Component Separator in a LINC type amplifier circuit), a first class B amplifier circuit 14, a second class B amplifier circuit 16, and a combining circuit 18 ( The LINC amplifier circuit is called “Chirex Combiner”). In FIG. 1, a load Ro to which an amplified signal output from the amplifier circuit 10 is applied is also shown.

  The signal distribution circuit 12 decomposes the input modulation signal Si (t) into a first constant envelope signal S1 (t) and a second constant envelope signal S2 (t). FIG. 2 is a diagram illustrating the relationship between the input modulation signal (transmission signal) Si (t), the first constant envelope signal S1 (t), and the second constant envelope signal S2 (t) as a vector. FIG.

  As shown in FIG. 2, the first constant envelope signal S1 (t) and the second constant envelope signal S2 (t) are signals obtained by decomposing the modulation signal Si (t), and Si (t ) = S1 (t) + S2 (t).

  Here, the modulation signal Si (t) is a signal in which information is placed on the phase and amplitude, and the modulation signal Si (t) is expressed by Equation 1 below. In addition, the first constant envelope signal S1 (t) and the second constant envelope signal S2 (t) are signals having constant amplitude and different phases, and the following formulas 2, 3, and 4 can be expressed.

・・・（数式１）

... (Formula 1)

・・・（数式２）

... (Formula 2)

・・・（数式３）

... (Formula 3)

・・・（数式４）

... (Formula 4)

  Referring to FIG. 1 again, components of the conventional amplifier circuit 10 will be described. The first class B amplifier circuit 14 and the second class B amplifier circuit 16 are each configured by a class B amplifier, and the first class B amplifier circuit 14 amplifies the first constant envelope signal S1 (t). The second class B amplifier circuit 16 amplifies the second constant envelope signal S2 (t). Here, when the first class B amplifier circuit 14 and the second class B amplifier circuit 16 are driven with an optimum load impedance, a maximum efficiency of π / 4 is obtained.

  The synthesis circuit 18 includes a first λ / 4 transmission line 20, a second λ / 4 transmission line 22, a first reactance circuit 24, and a second reactance circuit 26. The amplified first constant envelope signal S1 (t) output and the amplified second constant envelope signal S2 (t) output from the second class B amplifier circuit 16 are combined to generate a modulated signal. A signal obtained by amplifying Si (t) is output.

  Here, the output voltage applied to the load Ro is Vout (t), the maximum voltage is Vmax, the susceptance of the first reactance circuit 24 is −Bs, the susceptance of the second reactance circuit 26 is + Bs, and the first λ / 4 transmission. Assuming that the characteristic impedance of the line 20 is RT, the admittance Y1 viewed from the output of the first class B amplifier circuit 14 on the load Ro side can be expressed by the following Equation 5. Further, the power efficiency η of the amplifier circuit 10 can be expressed by the following Equation 6.

・・・（数式５）

... (Formula 5)

・・・（数式６）

... (Formula 6)

  FIG. 3 is an explanatory diagram showing an example of power efficiency with respect to the output voltage Vout (t) in the conventional amplifier circuit 10. Here, FIG. 3 shows the power efficiency with respect to the output voltage Vout (t) when the amplifier circuit 10 includes the first reactance circuit 24 and the second reactance circuit 26 and when the amplifier circuit 10 does not.

  When the values of the first reactance circuit 24 and the second reactance circuit 26 are optimized so that the imaginary part of the admittance Y1 becomes 0 (zero) at a certain output voltage, the amplifier circuit 10 is wide as shown in FIG. It can be seen that high power efficiency can be maintained over the output voltage range. Even if the amplifier circuit 10 does not include the first reactance circuit 24 and the second reactance circuit 26, the amplifier circuit 10 can have a linear relationship between the output voltage and the power efficiency. Since the above is the same as the characteristics of the class B amplifier, it means that the communication apparatus including the amplifier circuit 10 can use the amplitude-modulated wave used for communication with the efficiency of class B. Here, the above-described effect in the amplifier circuit 10 is an effect of the λ / 4 transmission line, as the load amplitude seen from the output side of the class B amplifier circuit appears larger (that is, the load admittance appears smaller) as the output amplitude becomes lower. .

  FIG. 4 is an explanatory diagram showing an example of load admittance as viewed from the output side of the class B amplifier circuit with respect to the output voltage in the conventional amplifier circuit 10 (when no reactance circuit is provided). Here, in FIG. 4, the real part (“real (Yin)” in FIG. 4), the imaginary part (“imag (Yin)” in FIG. 4), and the absolute value ( FIG. 4 shows “mag (Yin)”).

  As shown in FIG. 4, it can be seen that the relationship between the output voltage in the amplifier circuit 10 and the absolute value of the load admittance is a proportional relationship.

  The LINC-type amplifier circuit 10 includes two lines corresponding to the first constant envelope signal S1 (t) and the second constant envelope signal S2 (t) obtained by decomposing the input modulation signal Si (t). By providing the λ / 4 transmission line, the output voltage and the power efficiency can be in a linear relationship (when no reactance circuit is provided), or high power efficiency is maintained over a wide output voltage range. (When a reactance circuit is provided). Therefore, it can be said that the LINC-type amplifier circuit 10 can achieve both amplification linearity and power efficiency.

[Problems of the conventional amplifier circuit 10]
As described above, the LINC-type amplifier circuit 10 includes two λ / 4 transmission lines (a first λ / 4 transmission line 20 and a second λ / 4 transmission line 22). And power efficiency. However, the amplifier circuit 10 must include a first λ / 4 transmission line 20 and a second λ / 4 transmission line 22 that each require an electrical length that is ¼ of the wavelength λ at the operating frequency. In other words, in the amplifier circuit 10, the lower the frequency used, the greater the electrical length and the greater the physical length (assuming the shortening rate is constant). That is, in the amplifier circuit 10, the electrical length and physical length depend on the operating frequency. Therefore, it is very difficult for the amplifier circuit 10 to reduce the size of the amplifier circuit (and even if the amplifier circuit 10 can be reduced in size, the cost for downsizing is further required).

  Therefore, the LINC-type amplifier circuit 10 is applied to a recent communication apparatus that is required to be further downsized even if it is an amplifier circuit that can achieve both amplification linearity and power efficiency. That is practically difficult.

(Amplifier circuit approach according to an embodiment of the present invention)
As described above, the LINC-type amplifier circuit 10 can achieve both the linearity of amplification and power efficiency by including the synthesis circuit 18 having two λ / 4 transmission lines. Although it has a transmission line, it cannot be downsized. Therefore, in the amplification circuit according to the embodiment of the present invention, the amplification signal linearity and power are obtained by amplifying each of the signals obtained by decomposing the modulation signals (transmission signals) and then combining them without using the λ / 4 transmission line. It is possible to reduce the size while achieving both efficiency. More specifically, in the amplifier circuit according to the embodiment of the present invention, a magnetic coupling transformer (transformer) that can be significantly reduced in size as compared with the λ / 4 transmission line instead of the λ / 4 transmission line. Hereinafter, by using a "transformer"), it is possible to reduce the size while satisfying both linearity of amplification and power efficiency.

  Also, the transformer can widen the band compared to the λ / 4 transmission line. Therefore, the amplifier circuit according to the embodiment of the present invention can achieve a wider band than the LINC amplifier circuit 10 by using a transformer.

  However, just because the combining circuit 18 of the amplifier circuit 10 shown in FIG. 1 is configured by a general transformer, the same power efficiency as that of the LINC amplifier circuit 10 is not always obtained.

[Problem of the amplifier circuit in which the synthesis circuit 18 of the amplifier circuit 10 is configured with a general transformer]
FIG. 5 is an explanatory diagram showing an amplifier circuit 50 in which the synthesis circuit 18 of the conventional amplifier circuit 10 according to the embodiment of the present invention is configured by a general transformer.

  Referring to FIG. 5, the amplifier circuit 50 includes a first class B amplifier circuit 14, a second class B amplifier circuit 16, and a synthesis circuit 52. In FIG. 5, for comparison with the LINC amplifier circuit 10 shown in FIG. 1, the first constant envelope signal S 1 (t) shown in FIG. ) And the second constant envelope signal S2 (t) shown in FIG. 2 is input to the second class B amplifier circuit 16. FIG. 5 also shows the load impedance RL.

  The first class B amplifier circuit 14 and the second class B amplifier circuit 16 have the same configuration as the first class B amplifier circuit 14 and the second class B amplifier circuit 16 shown in FIG. The constant envelope signal S1 (t) is amplified, and the second class B amplifier circuit 16 amplifies the second constant envelope signal S2 (t).

  The synthesis circuit 52 is composed of two transformers corresponding to the first class B amplifier circuit 14 and the second class B amplifier circuit 16, respectively. Each transformer has the same configuration, and on the primary side, a primary side capacitor 54 (60) having a capacitance C11 and a primary side inductor 56 (60) having an inductance L11 are connected in parallel. The secondary side is composed of a secondary inductor 58 (64) having an inductance L12. The secondary side has a common secondary capacitor 66 connected in parallel with the load impedance RL and having a capacitance CL.

  Here, for simplification of description, the inductance L11 of each primary inductor and the inductance L12 of each secondary inductor are equal, the inductance Q is infinite, and the coupling coefficient k of each transformer is 1. To do. When the transformer conversion efficiency is maximized at the operating frequency (angular frequency ωo), the output resistance of the first class B amplifier circuit 14 and the second class B amplifier circuit 16 is Rs, and the primary side inductance L11 and secondary side of each transformer The relationship between the inductance L12, the primary side capacitance C11, and the secondary side capacitance CL can be expressed by the following Equations 7-9. When the first constant envelope signal S1 (t) and the second constant envelope signal S2 (t) having different phases are input to the first class B amplifier circuit 14 or the second class B amplifier circuit 16 In this case, the load impedance Z1 viewed from the output side of the first class B amplifier circuit 14 is j × RL / 2.

・・・（数式７）

... (Formula 7)

・・・（数式８）

... (Formula 8)

・・・（数式９）

... (Formula 9)

  FIG. 6 shows an example of load admittance as seen from the output side of the class B amplifier circuit with respect to the output voltage in the amplifier circuit 50 in which the synthesis circuit 18 of the conventional amplifier circuit 10 according to the embodiment of the present invention is configured by a general transformer. It is explanatory drawing. Here, in FIG. 6, the real part (“real (Yin)” in FIG. 6), the imaginary part (“imag (Yin)” in FIG. 6), and the absolute value ( FIG. 6 shows “mag (Yin)”).

  As shown in FIG. 6, the relationship between the output voltage in the amplifier circuit 50 and the absolute value of the load admittance is different from the case of the LINC-type amplifier circuit 10 shown in FIG.

  FIG. 7 is an explanatory diagram showing an example of the power efficiency with respect to the output voltage in the amplifier circuit 50 in which the synthesis circuit 18 of the conventional amplifier circuit 10 according to the embodiment of the present invention is configured by a general transformer.

  As shown in FIG. 7, the amplifier circuit 50 cannot make the output voltage and the power efficiency have a linear relationship (in the case of no reactance circuit) like the LINC-type amplifier circuit 10 shown in FIG. When the output voltage is low, the power efficiency is deteriorated. This is because, for example, when the output voltage is low, the amplifier circuit 50 cannot sufficiently reduce the admittance viewed from the amplifier circuit on the load side.

  Therefore, the amplifier circuit 50 in which the synthesis circuit 18 of the conventional amplifier circuit 10 is configured by a general transformer can be more easily reduced in size than the conventional amplifier circuit 10, but the first constants having different phases are different from each other. When the envelope signal S1 (t) and the second constant envelope signal S2 (t) are input, it is impossible to achieve both amplification linearity and power efficiency.

  Then, next, the amplifier circuit which concerns on embodiment of this invention is demonstrated. In the following, for comparison with the LINC amplifier circuit 10 shown in FIG. 1, the first constant envelope signal S1 (t) obtained by decomposing the modulation signal Si (t) shown in FIG. The description will be made assuming that the constant envelope signal S2 (t) is input to the amplifier circuit according to the embodiment of the present invention. Hereinafter, the first constant envelope signal S1 (t) is referred to as a first input signal S1, and the second constant envelope signal S2 (t) is referred to as a second input signal S2.

(Amplifier circuit according to the first embodiment)
FIG. 8 is an explanatory diagram showing the amplifier circuit 100 according to the first embodiment of the present invention. Referring to FIG. 8, the amplification circuit 100 includes a first amplification circuit 102 (first amplification unit), a second amplification circuit 104 (second amplification unit), and a synthesis circuit 106 (synthesis unit). FIG. 8 also shows the load impedance RL.

  The first amplifier circuit 102 is composed of, for example, a class B amplifier, and amplifies the input first constant envelope signal S1 (t). The second amplifier circuit 104 is configured by, for example, a class B amplifier, and amplifies the input second constant envelope signal S2 (t). In the following description, the first amplifier circuit 102 and the second amplifier circuit 104 are described as class B amplifier circuits, but the first amplifier circuit 102 and the second amplifier circuit 104 according to the embodiment of the present invention are class B amplifier circuits. For example, various types of amplifiers such as a class AB amplifier can be applied.

  The synthesis circuit 106 synthesizes two transformers corresponding to the first amplification circuit 102 and the second amplification circuit 104 respectively, and the amplified first input signal S1 and second input signal S2 output from each of the transformers. And an output capacitor Co that outputs an output signal.

  The primary side of a transformer corresponding to the first amplifier circuit 102 (hereinafter referred to as “first transformer”) is a primary side first inductor 108 having an inductance L1 and a primary side first capacitor having a capacitance C1. The primary side first inductor 108 and the primary side first capacitor 112 are connected in parallel. The secondary side of the first transformer includes a secondary side first inductor 110 having an inductance L2 and a secondary side first capacitor 114 having a capacitance C2. The secondary first capacitor 114 is connected in parallel. Here, the reactance value of the secondary-side first capacitor 114 can be, for example, approximately twice that of the secondary-side first inductor 110, but is not limited thereto.

  The primary side of a transformer (hereinafter referred to as “second transformer”) corresponding to the second amplifier circuit 104 is a primary side second inductor 116 having an inductance L1 and a primary side second capacitor having a capacitance C1. The primary side second inductor 116 and the primary side second capacitor 120 are connected in parallel. The secondary side of the second transformer includes a secondary side second inductor 118 having an inductance L2 and a secondary side second capacitor 122 having a capacitance C2. The secondary second capacitor 122 is connected in parallel. Here, the reactance value of the secondary side second capacitor 122 can be, for example, approximately twice that of the secondary side second inductor 118, but is not limited thereto.

  The output capacitor 124 has a capacitance Co, and the secondary-side second capacitor 122 of the second transformer, the secondary-side first capacitor 114 of the first transformer, and the output capacitor 124 are connected in series. As described above, the secondary side second capacitor 122 of the second transformer, the secondary side first capacitor 114 of the first transformer, and the output capacitor 124 are connected in series, so that the output capacitor 124 becomes the first transformer. Amplified first input signal S1 (hereinafter referred to as “first amplified signal S1 ′”) output from the second transformer and an amplified second input signal S2 output from the second transformer (hereinafter referred to as “second amplified signal”). S2 ′ ”) can be combined (for example, added).

  Here, the output signal output from the output capacitor 124 is a first amplified signal S1 ′ obtained by amplifying the first input signal S1 and the second input signal S2 obtained by decomposing the modulation signal Si (t) shown in FIG. The second amplified signal S2 ′ is synthesized. That is, the output signal output from the output capacitor 124 is a signal obtained by amplifying the modulation signal Si (t) shown in FIG.

  Further, the primary side inductance L1, the secondary side inductance L2, and the primary side capacitance C1 of each of the first transformer and the second transformer constituting the synthesis circuit 106 are, for example, a use frequency (angular frequency ωo). ) Is set to a value that maximizes the conversion efficiency of the transformer. For example, when the conversion ratio of each of the first transformer and the second transformer is 1: 1, L1 = L2 can be set. Here, the Q value for the primary side inductance L1 is Q1, the Q value for the secondary side inductance L2 is Q2, and the coupling coefficient of each transformer is k. For simplicity of explanation, for example, L1 = L2, Q1 = Q2. In the above, when the conversion efficiency of the transformer is maximized at the used frequency (angular frequency ωo), the output impedance of the first amplifier circuit 102 and the second amplifier circuit 104 is Rs, the load impedance RL, and the inductance on the primary side of each transformer The relationship between L1, the secondary side inductance L2, the primary side capacitance C1, the secondary side capacitance C2, and the capacitance Co of the output capacitor 124 can be expressed by the following equations 10-14. .

・・・（数式１０）

(Equation 10)

・・・（数式１１）

... (Formula 11)

・・・（数式１２）

... (Formula 12)

・・・（数式１３）

... (Formula 13)

・・・（数式１４）

... (Formula 14)

  When the coupling coefficient k of each of the first transformer and the second transformer is k = 1, Expressions 10 to 14 are expressed as Expressions 15 to 19 below.

・・・（数式１５）

... (Formula 15)

・・・（数式１６）

... (Formula 16)

・・・（数式１７）

... (Formula 17)

・・・（数式１８）

... (Formula 18)

・・・（数式１９）

(Equation 19)

  Here, when the first input signal S1 and the second input signal S2 are, for example, signals having the same phase (that is, when θ (t) in Equations 2 to 4 is 0 (zero)), the first The load impedance Z1 viewed from the output of the amplifier circuit 102 (or the second amplifier circuit 102) is RL / 2. When the first input signal S1 and the second input signal S2 are, for example, signals having opposite phases and the amplitude of the output voltage at the load end is 0 (zero), the first amplifier circuit 102 (or An equivalent circuit of the load impedance Z1 viewed from the output of the second amplifier circuit 102) can be shown as in FIG. Therefore, in the above case, the load impedance Z1 viewed from the output of the first amplifier circuit 102 (or the second amplifier circuit 102) is infinite, and the admittance is 0 (zero).

  Therefore, the amplification circuit 100 is configured to have the two λ / 4 transmission lines shown in FIG. 1 by setting each value as shown in Expressions 10 to 14 (or Expressions 15 to 19). 10, as the amplitude of the output signal decreases, the impedance viewed from the output side of the first amplifier circuit 102 and the output side of the second amplifier circuit 104 can be increased.

  FIG. 10 is an explanatory diagram illustrating an example of load admittance as viewed from the output side of the class B amplifier circuit with respect to the output voltage in the amplifier circuit 100 according to the first embodiment of the present invention. Here, in FIG. 6, the real part (“real (Yin)” in FIG. 10) and the imaginary part (“imag (Yin in FIG. 10)) of the load admittance viewed from the output side of the first amplifier circuit 102 or the second amplifier circuit 104. ) ") And the absolute value (" mag (Yin) "in FIG. 10).

  As shown in FIG. 10, it can be seen that the relationship between the output voltage in the amplifier circuit 100 and the absolute value of the load admittance is close to a proportional relationship as compared to FIG. 6 showing the case of the amplifier circuit 50 using a transformer. .

  FIG. 11 is an explanatory diagram showing an example of the power efficiency with respect to the output voltage in the amplifier circuit 100 according to the first embodiment of the present invention.

  As shown in FIG. 11, the relationship between the output voltage and the power efficiency in the amplifier circuit 100 is linear as in the conventional LINC-type amplifier circuit 10 (without the reactance circuit) shown in FIG. The power efficiency of the amplifier circuit 100 is the same as that of the conventional amplifier circuit 10 of the LINC method.

  As described above, the amplifier circuit 100 according to the first embodiment includes the first amplifier circuit 102 and the second amplifier circuit 104, and receives the first input signal S1 and the second input signal S2 having different phases to be input. Amplify each. The amplifier circuit 100 also includes a combining circuit 106, which combines the first amplified signal S1 ′ amplified by the first amplifier circuit 102 and the second amplified signal S2 ′ amplified by the second amplifier circuit 104 to generate an output signal. Output. Here, the synthesis circuit 106 does not include two λ / 4 transmission lines unlike the synthesis circuit 18 of the LINC-type amplifier circuit 10 (conventional amplifier circuit), and includes a first transformer corresponding to the first amplifier circuit 102, A second transformer corresponding to the second amplifier circuit 104 and an output capacitor 124 are included. As described above, the amplifier circuit 100 is different from the LINC amplifier circuit 10 in the configuration of the synthesis circuit 106. However, as shown in FIGS. 3 and 11, the relationship between the output voltage and the power efficiency is proportional, and The same power efficiency as that of the LINC amplifier circuit 10 can be obtained. Therefore, the amplifier circuit 100 can achieve both amplification linearity and power efficiency.

  In addition, unlike the LINC-type amplifier circuit 10, the amplifier circuit 100 is configured by using a magnetic coupling transformer that can significantly reduce the size of the synthesis circuit 106 as compared with the λ / 4 transmission line. Therefore, the amplifier circuit 100 can be reduced in size easily and without cost compared with the LINC-type amplifier circuit 10.

  Therefore, the amplifier circuit 100 can be reduced in size while achieving both amplification linearity and power efficiency.

  In addition, the magnetic coupling transformer included in the amplifier circuit 100 can have a wider band than the λ / 4 transmission line. Therefore, the amplifier circuit 100 can achieve a wider band than the LINC amplifier circuit 10 by using a magnetically coupled transformer.

  Further, the amplifier circuit 100 can easily change the resonance frequency by changing the capacitance of the capacitor constituting the magnetic coupling transformer. Therefore, the amplifier circuit 100 can easily switch the used frequency band.

[Modification of Amplifier Circuit 100]
[1] First Modification In the amplifier circuit 100 shown in FIG. 8, a configuration is shown in which the first input signal S1 and the second input signal S2 are each amplified by one class B amplifier circuit. The amplifier circuit 100 according to the embodiment is not limited to the above configuration.

  FIG. 12 is an explanatory diagram showing an amplifier circuit 150 according to a first modification of the first embodiment of the present invention. The amplifier circuit 150 has a configuration in which the first amplifier circuit 102 shown in FIG. 8 is divided into two first divided amplifier circuits 102a and 102b, and the second amplifier circuit 104 is divided into two second divided amplifier circuits 104a and 104b. Have. The amplifier circuit 150 includes transformers corresponding to the first divided amplifier circuits 102a and 102b and the second divided amplifier circuits 104a and 104b.

  Here, the first input signal S1 is input to the first divided amplifier circuits 102a and 102b, and the amplified signals having the same phase are added on the secondary side of the transformer corresponding to the first divided amplifier circuits 102a and 102b. Similarly, the second input signal S2 is input to the second divided amplifier circuits 104a and 104b, and amplified signals having the same phase are added on the secondary side of the transformer corresponding to the second divided amplifier circuits 104a and 104b.

  Similarly to the amplifier circuit 100 shown in FIG. 8, the amplifier circuit 150 has a configuration in which the secondary side second capacitor 122, the secondary side first capacitor 114, and the output capacitor 124 are connected in series. In the capacitor 124, two signals having different phases are combined.

  Therefore, the amplifier circuit 150 can achieve the same effect as the amplifier circuit 100 shown in FIG.

  Further, the impedances of the first divided amplifier circuits 102a and 102b and the second divided amplifier circuits 104a and 104b of the amplifier circuit 150 viewed from the load are respectively the first amplifier circuit 102 and the second amplifier circuit 104 of the amplifier circuit 100 shown in FIG. It becomes 1/2 of the impedance seen from each. Therefore, the amplifier circuit 150 uses the output voltages of the first divided amplifier circuits 102a and 102b and the second divided amplifier circuits 104a and 104b as the output voltages of the first amplifier circuit 102 and the second amplifier circuit 104 shown in FIG. The output voltage can be reduced by half (the output voltage can be reduced).

  FIG. 12 illustrates a configuration in which the first amplifier circuit 102 and the second amplifier circuit 104 illustrated in FIG. 8 are each divided into two amplifier circuits as the amplifier circuit according to the first modification of the first embodiment. However, the amplifier circuit according to the embodiment of the present invention is not limited to the configuration of FIG. For example, the amplifier circuit according to the first modification of the first embodiment can also divide the first amplifier circuit 102 and the second amplifier circuit 104 shown in FIG. 8 into three or more amplifier circuits. That is, the amplifier circuit according to the embodiment of the present invention can be divided into a plurality of amplifier circuits. In addition, the inductance of the inductor and the capacitance of the capacitor constituting the transformer corresponding to each first divided amplifier circuit are, for example, the sum of the inductance of the inductor and the capacitance of the capacitor constituting the transformer corresponding to the first amplifier circuit 102. It can be set to be equal to the electric capacity. Similarly, the inductance of the inductor and the capacitance of the capacitor constituting the transformer corresponding to each second divided amplifier circuit are, for example, the sum of the inductance of the inductor and the capacitor constituting the transformer corresponding to the second amplifier circuit 104, for example. It can be set to be equal to the capacitance.

[2] Second Modification FIG. 13 is an explanatory diagram showing an amplifier circuit 160 according to a second modification of the first embodiment of the present invention. In the amplifier circuit 160, the first amplifier circuit 102 and the second amplifier circuit 104 shown in FIG. 8 are each shown as a differential amplifier circuit using transistors. In FIG. 13, the first input signal S1 is input as differential signals S1p and S1n, and the second input signal S2 is input as differential signals S2p and S2n.

  As shown in FIG. 13, each of the first amplifier circuit 102 and the second amplifier circuit 104 is a differential amplifier circuit, so that the amplifier circuit 160 has an inductor L1 on the primary side of the transformer and a collector power supply of the transistor that constitute the synthesis circuit. An inductor for supplying Vcc (power supply inductor) can be shared. In addition, the amplifier circuit 160 can share the capacitor C1 on the primary side of the transformer constituting the synthesis circuit and the collector-emitter capacitance (output capacitance component) of the transistor. Therefore, the amplifier circuit 160 can simplify the circuit configuration.

  Further, in the amplifier circuit 160 according to the second modification, each of the first amplifier circuit 102 and the second amplifier circuit 104 is configured by a differential amplifier circuit, which is basically the same as the amplifier circuit 100 shown in FIG. It has a configuration. Therefore, the amplifier circuit 160 can achieve the same effect as the amplifier circuit 100 shown in FIG.

(Amplifier circuit according to the second embodiment)
In the above, the amplifier circuit 100 using the transformer as the synthesis circuit is shown as the amplifier circuit according to the embodiment of the present invention. However, the configuration of the amplifier circuit using the transformer as the synthesis circuit according to the embodiment of the present invention is not limited to the configuration of the amplifier circuit 100 shown in FIG. Then, the other structure of the amplifier circuit which uses a transformer as a synthetic | combination circuit based on embodiment of this invention is shown next.

  FIG. 14 is an explanatory diagram showing an amplifier circuit 200 according to the second embodiment of the present invention. Referring to FIG. 14, the amplification circuit 200 includes a first amplification circuit 102 (first amplification unit), a second amplification circuit 104 (second amplification unit), and a synthesis circuit 202 (synthesis unit). FIG. 14 also shows the load impedance RL.

  The first amplifier circuit 102 has the same configuration as the first amplifier circuit 102 according to the first embodiment shown in FIG. 8, and amplifies the first input signal S1. The second amplifier circuit 104 has the same configuration as the second amplifier circuit 104 according to the first embodiment shown in FIG. 8, and amplifies the second input signal S2.

  The synthesizing circuit 202 includes two transformers (first transformer and second transformer) corresponding to the first amplifier circuit 102 and the second amplifier circuit 104, the first amplified signal S1 ′ output from each of the transformers, and the second transformer. An output inductor Lo that outputs the output signal by combining the amplified signal S2 ′.

  The primary side of the first transformer is composed of a primary side first inductor 108 having an inductance L1 and a primary side first capacitor 112 having a capacitance C1, and the primary side first inductor 108 and the primary side first capacitor. One capacitor 112 is connected in parallel. The secondary side of the first transformer includes a secondary side first inductor 110 having an inductance L2 and a secondary side first capacitor 204 having a capacitance C4. The secondary first capacitor 204 is connected in series. Here, the reactance value of the secondary-side first capacitor 204 can be, for example, approximately twice that of the secondary-side first inductor 110, but is not limited thereto.

  The primary side of the second transformer includes a primary side second inductor 116 having an inductance L1 and a primary side second capacitor 120 having an electrostatic capacitance C1, and the primary side second inductor 116 and the primary side second inductor. The two capacitors 120 are connected in parallel. The secondary side of the second transformer includes a secondary side second inductor 118 having an inductance L2 and a secondary side second capacitor 206 having a capacitance C4. The secondary second capacitor 206 is connected in series. Here, the reactance value of the secondary side second capacitor 206 can be, for example, approximately twice that of the secondary side second inductor 118, but is not limited thereto.

  The output inductor 208 has an inductance Lo, and the connection point A between the secondary side second capacitor 206 of the second transformer and the secondary side first capacitor 204 of the first transformer and the output inductor 208 are connected in series. The As described above, when the connection point A and the output inductor 208 are connected in series, the first amplified signal S1 ′ output from the first transformer and the second amplified signal S2 ′ output from the second transformer Can be synthesized. Here, the inductance of the output inductor 208 can be, for example, substantially ½ of the secondary side first inductor 110 and the secondary side second inductor 118, but is not limited thereto.

  The primary-side inductance L1, the secondary-side inductance L2, and the primary-side capacitance C1 of each of the first transformer and the second transformer constituting the synthesis circuit 202 are, for example, at a use frequency (angular frequency ωo). It is set to a value that maximizes the conversion efficiency of the transformer. For example, when the conversion ratio of each of the first transformer and the second transformer is 1: 1, L1 = L2 can be set. Here, the Q value for the primary side inductance L1 is Q1, the Q value for the secondary side inductance L2 is Q2, and the coupling coefficient of each transformer is k. For simplicity of explanation, for example, L1 = Let L2, Q1 = Q2, and k = 1. In the above, when the conversion efficiency of the transformer is maximized at the used frequency (angular frequency ωo), the output impedance of the first amplifier circuit 102 and the second amplifier circuit 104 is Rs, the load impedance RL, and the inductance on the primary side of each transformer The relationship among L1, the secondary side inductance L2, the primary side capacitance C1, the secondary side capacitance C4, and the inductance Lo of the output inductor 208 can be expressed by the following equations 20-24.

・・・（数式２０）

(Equation 20)

・・・（数式２１）

... (Formula 21)

・・・（数式２２）

... (Formula 22)

・・・（数式２３）

(Equation 23)

・・・（数式２４）

... (Formula 24)

  Here, when the first input signal S1 and the second input signal S2 are signals having the same phase, for example, the load impedance Z1 viewed from the output of the first amplifier circuit 102 (or the second amplifier circuit 102) is 2 XRL. When the first input signal S1 and the second input signal S2 are, for example, signals having opposite phases and the amplitude of the output voltage at the load end is 0 (zero), the first amplifier circuit 102 (or The load impedance Z1 viewed from the output of the second amplifier circuit 102) is infinite, and the admittance is 0 (zero).

  Therefore, in the amplifier circuit 200, as each value is set as shown in Equations 20 to 24, as the amplitude of the output signal becomes smaller, similarly to the amplifier circuit 100 according to the first embodiment shown in FIG. Thus, it is possible to increase the impedance when the load side is viewed from the output side of the first amplifier circuit 102 and the output side of the second amplifier circuit 104.

  As described above, the amplifier circuit 200 according to the second embodiment differs from the amplifier circuit 100 according to the first embodiment shown in FIG. As the signal amplitude decreases, the impedance viewed from the output side of the first amplifier circuit 102 and the output side of the second amplifier circuit 104 from the load side can be increased. Therefore, the amplifier circuit 200 can achieve the same effect as the amplifier circuit 100.

[Modification of Amplifier Circuit 200]
The amplifying circuit according to the second embodiment can take a modification similar to the aforesaid modification of the amplifying circuit according to the first embodiment.

(Amplifier circuit according to the third embodiment)
Next, still another configuration of an amplifier circuit using a transformer as a synthesis circuit according to the embodiment of the present invention will be described.

  FIG. 15 is an explanatory diagram showing an amplifier circuit 300 according to the third embodiment of the present invention. Referring to FIG. 15, the amplifier circuit 300 includes a first amplifier circuit 102 (first amplifier), a second amplifier circuit 104 (second amplifier), and a synthesis circuit 302 (synthesis unit). FIG. 15 also shows the load impedance RL.

  The first amplifier circuit 102 has the same configuration as the first amplifier circuit 102 according to the first embodiment shown in FIG. 8, and amplifies the first input signal S1. The second amplifier circuit 104 has the same configuration as the second amplifier circuit 104 according to the first embodiment shown in FIG. 8, and amplifies the second input signal S2.

  The combining circuit 302 includes two transformers (first transformer and second transformer) corresponding to the first amplifier circuit 102 and the second amplifier circuit 104, respectively, and a first amplified signal S1 ′ output from each of the transformers. The second amplified signal S2 ′ is synthesized at the connection point B. That is, in the synthesis circuit 302, the connection point B serves as the synthesis unit 312 and an output signal is output from the connection point B.

  The primary side of the first transformer includes a primary side first inductor 108 having an inductance L1 and a primary side first capacitor 304 having a capacitance C3. The primary side first inductor 108 and the primary side first inductor One capacitor 304 is connected in series. The secondary side of the first transformer includes a secondary side first inductor 110 having an inductance L2 and a secondary side first capacitor 306 having a capacitance C5. The secondary first capacitor 306 is connected in series. Here, the primary-side inductance L1 and the electrostatic capacitance C3, and the secondary-side inductance L2 and the electrostatic capacitance C5 are set so as to resonate at a use frequency (frequency of the first input signal S1), for example. However, it is not limited to the above.

  The primary side of the second transformer includes a primary side second inductor 116 having an inductance L1 and a primary side second capacitor 308 having a capacitance C3. The primary side second inductor 116 and the primary side Two capacitors 308 are connected in series. The secondary side of the second transformer includes a secondary side second inductor 118 having an inductance L2 and a secondary side second capacitor 310 having a capacitance C5. The secondary second capacitor 310 is connected in series. Here, the primary-side inductance L1 and the capacitance C3, and the secondary-side inductance L2 and the capacitance C5 are set so as to resonate at, for example, a use frequency (frequency of the second input signal S2). However, it is not limited to the above.

  The secondary-side first capacitor 306 of the first transformer and the secondary-side second capacitor 310 of the second transformer are connected at a connection point B, and the first amplified signal S1 ′ output from the first transformer and the second transformer The second amplified signal S2 ′ to be output is synthesized (added) at the connection point B. That is, the secondary side first capacitor 306 and the secondary side second capacitor 310 are connected as shown in FIG.

  The primary-side inductance L1, the secondary-side inductance L2, and the primary-side capacitance C3 of each of the first transformer and the second transformer constituting the synthesis circuit 302 are, for example, at a use frequency (angular frequency ωo). It is set to a value that maximizes the conversion efficiency of the transformer. For example, when the conversion ratio of each of the first transformer and the second transformer is 1: 1, L1 = L2 can be set. Here, the Q value for the primary side inductance L1 is Q1, the Q value for the secondary side inductance L2 is Q2, and the coupling coefficient of each transformer is k. For simplicity of explanation, for example, L1 = Let L2, Q1 = Q2, and k = 1. In the above, when the conversion efficiency of the transformer is maximized at the used frequency (angular frequency ωo), the output impedance of the first amplifier circuit 102 and the second amplifier circuit 104 is Rs, the load impedance RL, and the inductance on the primary side of each transformer The relationship between L1, the secondary-side inductance L2, the primary-side capacitance C3, and the secondary-side capacitance C5 can be expressed by the following equations 25-28.

・・・（数式２５）

... (Formula 25)

・・・（数式２６）

... (Formula 26)

・・・（数式２７）

... (Formula 27)

・・・（数式２８）

(Equation 28)

  The amplifier circuit 200 is set to the first value as the amplitude of the output signal becomes smaller, as in the amplifier circuit 100 according to the first embodiment shown in FIG. The impedance seen from the output side of the amplifier circuit 102 and the output side of the second amplifier circuit 104 from the load side can be made large.

  As described above, the amplifier circuit 300 according to the third embodiment differs from the amplifier circuit 100 according to the first embodiment shown in FIG. As the amplitude decreases, the impedance viewed from the output side of the first amplifier circuit 102 and the output side of the second amplifier circuit 104 to the load side can be increased. Therefore, the amplifier circuit 300 can achieve the same effect as the amplifier circuit 100.

[Modification of Amplifier Circuit 300]
The amplifier circuit according to the third embodiment can take a modification similar to the modification of the amplifier circuit according to the first embodiment described above.

(Amplifier circuit according to the fourth embodiment)
In the amplifier circuit according to the first to third embodiments, the first amplifier circuit 102 and the second amplifier circuit 104 are provided and both the first amplifier circuit 102 and the second amplifier circuit 104 operate. However, the amplifier circuit according to the embodiment of the present invention is not limited to the above configuration. For example, the amplifier circuit of the present invention includes three or more amplifier circuits, and “when the output power is small, the amplifier circuit is operated in class A or class AB to amplify the modulation signal, for example, by turning off the power. It is also possible to perform an operation of “reducing power consumption by not using an unnecessary amplifier circuit”. Then, next, the amplifier circuit which concerns on the 4th Embodiment of this invention is demonstrated. In the following, for comparison with the amplifier circuit 300 according to the third embodiment shown in FIG. 15, a configuration including two amplifier circuits of the first amplifier circuit 102 and the second amplifier circuit 104 will be described as an example. To do.

  FIG. 16 is an explanatory diagram showing an amplifier circuit 400 according to the fourth embodiment of the present invention. Referring to FIG. 16, the amplifier circuit 400 basically has the same configuration as the amplifier circuit 300 according to the third embodiment shown in FIG. 15. Compared with the amplifier circuit 300, the amplifier circuit 400 includes a switch 404 (switching unit). It has more. FIG. 16 also shows the load impedance RL. The amplifier circuit according to the fourth embodiment of the present invention is basically the same as the amplifier circuit 100 according to the first embodiment shown in FIG. 8, the amplifier circuit 200 according to the second embodiment shown in FIG. It goes without saying that a similar configuration can be provided.

  The first amplifier circuit 102, the second amplifier circuit 104, and the synthesis circuit 302 have the same configuration as that of the amplifier circuit 300 according to the third embodiment shown in FIG.

  For example, the second amplifier circuit 104 turns on / off the power of the second amplifier circuit 104 based on a control signal transmitted from a control unit of a communication device (not shown) provided with the amplifier circuit 400. The amplification operation of the second amplifier circuit 104 is turned ON / OFF.

  In the amplifying circuit 50 configured with a general transformer shown in FIG. 6, when a part of the amplifying circuits is turned off, the impedance viewed from the output side of the remaining amplifying circuits becomes small, and it is difficult to improve the efficiency. In the amplifier circuit 300 shown in FIG. 15, for example, even when the switch 402 remains OFF, the load is applied from the output side of each amplifier circuit when the first amplifier circuit 102 and the second amplifier circuit 104 are operating in the same phase. The impedance Z1 of the above is Z1 = 2 × RL, where L1 = L2, Q1 = Q2, and k = 1. Here, when the second amplifier circuit 104 is turned OFF with the output impedance of the second amplifier circuit 104 unchanged, the impedance Z1 ′ viewed from the output side of the first amplifier circuit 102 is Z1 ′ = 6 × RL. The impedance viewed from the output side of the first amplifier circuit 102 is three times that when the second amplifier circuit 104 is ON.

  On the other hand, the amplifier circuit 400 shorts the output of the second amplifier circuit 104 to the ground GND by turning on the switch 402 when the second amplifier circuit 104 is OFF. In the above case, the impedance Z1 ″ viewed from the output side of the first amplifier circuit 102 is Z1 ″ = 4 × RL, and the impedance viewed from the output side of the first amplifier circuit 102 is the second impedance. This is twice that when the amplifier circuit 104 is ON. As described above, the amplifier circuit 400 can control the rate of increase in impedance by selectively turning the switch 402 ON / OFF.

  In FIG. 16, the configuration including the two amplifier circuits of the first amplifier circuit 102 and the second amplifier circuit 104 is taken as an example. However, as described above, the amplifier circuit according to the fourth embodiment of the present invention is 3 The above amplifier circuit can also be provided. In the above case, the amplifier circuit according to the fourth embodiment of the present invention outputs (for example, simultaneously) the output of the amplifier circuit operating in synchronism with selectively turning off some of the amplifier circuits. Since the impedance viewed from the side can be increased to an optimum value, it is possible to increase the power efficiency.

  As described above, the amplifier circuit 400 according to the fourth embodiment basically has the same configuration as the amplifier circuit 300 according to the third embodiment shown in FIG. Therefore, the amplifier circuit 400 can achieve the same effect as the amplifier circuit 300.

  In addition, the amplifier circuit 400 includes a switch 404 that controls the output impedance of some of the amplifier circuits that are selectively turned off, thereby increasing the impedance viewed from the output side of the operating amplifier circuit to an optimum value. Therefore, power efficiency can be improved.

[Modification of Amplifier Circuit 400]
The amplifier circuit according to the fourth embodiment can take a modification similar to the modification of the amplifier circuit according to the first embodiment described above.

(Amplifier circuit according to the fifth embodiment)
In the above, as the amplifier circuit according to the first to fourth embodiments, as shown in FIGS. 3 and 11, the output voltage and the power are the same as those of the conventional LINC-type amplifier circuit 10 (without the reactance circuit). A configuration is shown in which the relationship with efficiency is a proportional relationship, and power efficiency similar to that of the LINC-type amplifier circuit 10 can be obtained. However, the amplifier circuit according to the embodiment of the present invention is not limited to the above. For example, as in the conventional LINC-type amplifier circuit 10 (with a reactance circuit) shown in FIG. High power efficiency can also be maintained.

  FIG. 17 is an explanatory diagram showing an amplifier circuit 500 according to the fifth embodiment of the present invention. Referring to FIG. 17, the amplification circuit 500 includes a first amplification circuit 102 (first amplification unit), a second amplification circuit 104 (second amplification unit), and a synthesis circuit 502 (synthesis unit). FIG. 17 also shows the load impedance RL.

  The synthesizing circuit 502 includes two transformers (first transformer and second transformer) corresponding to the first amplifier circuit 102 and the second amplifier circuit 104, the first amplified signal S1 ′ output from each of the transformers, and the second transformer. The output capacitor Co is configured to combine the amplified signal S2 ′ and output an output signal.

  The first amplifier circuit 102 has the same configuration as the first amplifier circuit 102 according to the first embodiment shown in FIG. 8, and amplifies the first input signal S1. The second amplifier circuit 104 has the same configuration as the second amplifier circuit 104 according to the first embodiment shown in FIG. 8, and amplifies the second input signal S2.

  The combining circuit 502 includes two transformers corresponding to the first amplifier circuit 102 and the second amplifier circuit 104, and the amplified first amplified signal S1 ′ and the second amplified signal S2 ′ output from the transformers, respectively. An output capacitor Co that combines and outputs an output signal.

  The primary side of the first transformer includes a primary side first inductor 108 having an inductance L1 and a primary side first capacitor 504 having a capacitance C6. The primary side first inductor 108 and the primary side first capacitor One capacitor 504 is connected in parallel. The secondary side of the first transformer includes a secondary side first inductor 110 having an inductance L2 and a secondary side first capacitor 114 having a capacitance C2. The secondary first capacitor 114 is connected in parallel.

  The primary side of the second transformer includes a primary side second inductor 116 having an inductance L1 and a primary side second capacitor 506 having a capacitance C7, and the primary side second inductor 116 and the primary side second inductor. Two capacitors 506 are connected in parallel. The secondary side of the second transformer includes a secondary side second inductor 118 having an inductance L2 and a secondary side second capacitor 122 having a capacitance C2. The secondary second capacitor 122 is connected in parallel.

  The output capacitor 124 has a capacitance Co and, like the synthesis circuit 102 according to the first embodiment shown in FIG. 8, the secondary side second capacitor 122 of the second transformer, the secondary side of the first transformer. The first capacitor 114 and the output capacitor 124 are connected in series.

  As shown in FIG. 17, the amplifier circuit 500 basically has the same configuration as the amplifier circuit 100 according to the first embodiment shown in FIG. 8, but the primary side first capacitor 504 and the primary side second capacitor. The difference is that the capacitances of the capacitor 506 are different from each other. The above difference is synonymous with the addition of circuits corresponding to reactance circuits 24 and 26 in the LINC-type amplifier circuit 10 shown in FIG. 1, for example, to the amplifier circuit according to the embodiment of the present invention. Here, the capacitance C6 of the primary side first capacitor 504 and the capacitance C7 of the primary side second capacitor 506 can be set to values indicated by the following mathematical expressions 29 and 30.

・・・（数式２９）

(Equation 29)

・・・（数式３０）

(Equation 30)

  Here, Bs shown in Equations 29 and 30 is the same as the susceptance in the LINC amplifier circuit 10 shown in Equation 5. In other words, the amplifier circuit 500 can optimize the Bs so that the imaginary part of the admittance seen from the output side of the amplifier circuit to the load side becomes 0 at a certain output voltage, and the conventional amplifier circuit 10 of the LINC system shown in FIG. Similar to (with a reactance circuit), high efficiency can be maintained over a wide output voltage range.

  As described above, the amplifier circuit 400 according to the fifth embodiment basically has the same configuration as the amplifier circuit 100 according to the first embodiment shown in FIG. Therefore, the amplifier circuit 500 can achieve the same effect as the amplifier circuit 100.

  In addition, the amplifier circuit 500 determines the electrostatic capacitance of the primary side first capacitor 504 so that the capacitances of the primary side first capacitor 504 and the primary side second capacitor 506 are different from each other based on Expressions 29 and 30. By setting the capacitance C6 and the capacitance C7 of the primary-side second capacitor 506, a wide output voltage range can be obtained in the same manner as the conventional LINC-type amplifier circuit 10 (with a reactance circuit) shown in FIG. High efficiency can be maintained across.

[Modification of Amplifier Circuit 500]
The amplifier circuit according to the fifth embodiment can take a modification similar to the modification of the amplifier circuit according to the first embodiment described above.

(Communication apparatus according to an embodiment of the present invention)
Next, a communication device to which the amplifier circuit according to the embodiment of the present invention is applied will be described.

  FIG. 18 is an explanatory diagram showing a communication device 900 according to the embodiment of the present invention. 18 is an embodiment of the communication apparatus according to the embodiment of the present invention, and it goes without saying that the embodiment of the present invention is not limited to the configuration of FIG. In the following description, it is assumed that the modulation signal (transmission signal) Si (t) shown in FIG.

  Referring to FIG. 18, the communication device 900 includes a signal distribution circuit 902 (signal distribution unit), an amplification circuit 904 (amplification unit), and a communication unit 906.

  In addition, the communication device 900 includes, for example, a control unit (not shown) configured by an MPU (Micro Processing Unit) or the like that can control the entire communication device 900, a program used by the control unit, an operation parameter, Various types of data such as a ROM (Read Only Memory) (not shown) in which control data is recorded, a RAM (Random Access Memory (not shown)) that primarily stores a program executed by the control unit, display data for a user interface, etc. You may provide the memory | storage part (not shown) which can memorize | store data, an application, etc., the operation part (not shown) which a user can operate, a display part (not shown), etc. The communication device 900 connects the above-described constituent elements by, for example, a bus as a data transmission path.

  Here, as the storage unit (not shown), for example, a magnetic recording medium such as a hard disk, an EEPROM (Electronically Erasable and Programmable Read Only Memory), a flash memory, a MRAM (Magnetoresistive Random Access) Non-volatile memory such as Memory (RAM), FeRAM (Ferroelectric Random Access Memory), PRAM (Phase change Random Access Memory), and the like, but is not limited thereto.

  Examples of the operation unit (not shown) include an operation input device such as a keyboard and a mouse, a rotary selector such as a button, a direction key, and a jog dial, or a combination thereof. I can't. Examples of the display unit (not shown) include an LCD (Liquid Crystal Display), an organic EL display (Organic Light Emitting Diode display), and the like. However, it is not limited to the above.

  The signal distribution circuit 902 decomposes the input modulation signal Si (t) into the first input signal S1 and the second input signal S2, and outputs the first input signal S1 and the second input signal S2, respectively. Here, the signal distribution circuit 902 can decompose the modulation signal Si (t), for example, as shown in FIG. The modulation signal Si (t) input to the signal distribution circuit 902 is generated by, for example, a control unit (not shown) and transmitted from the control unit, but is not limited thereto.

  The amplification circuit 902 receives the first input signal S1 and the second input signal S2 output from the signal distribution circuit 902, and the amplification circuit 902 amplifies the first input signal S1 and the second input signal S2, respectively. The output signal synthesized later is output.

  Here, as the amplifier circuit 902, the amplifier circuits according to the first to fifth embodiments of the present invention described above can be applied. FIG. 18 shows an example in which the amplifier circuit 100 according to the first embodiment is applied.

  The communication unit 906 includes an impedance matching circuit 908, an isolator 910, a bandpass filter 912, and a communication antenna 914.

  The impedance matching circuit 908 matches the output impedance of the amplifier circuit 902 and the input impedance of the communication unit 906. By including the impedance matching circuit 908, the communication unit 906 can further increase the transmission efficiency of the modulated signal, for example.

  The isolator 910 passes the modulated signal in the transmission direction (from the amplification circuit 906 to the communication antenna 914) and prevents transmission in the direction opposite to the transmission direction. By providing the isolator 910, the communication unit 906 can suppress, for example, load fluctuation on the communication unit 906 side as viewed from the amplifier circuit 902.

  The band-pass filter 912 passes only the modulation signal in a specific frequency band and attenuates the modulation signals in other bands. The communication unit 906 includes the bandpass filter 912, so that noise included in the modulation signal output from the amplifier circuit 902 can be removed, for example.

  The communication antenna 914 transmits an amplitude-modulated wave based on the modulation signal output from the bandpass filter 912.

  The communication apparatus 900 according to the embodiment of the present invention amplifies the modulation signal Si (t) as a transmission signal with the configuration shown in FIG. 18, and generates an amplitude-modulated wave to the external apparatus based on the amplified modulation signal. Can be sent. Although not shown in FIG. 18, the communication antenna 914 can also function as a reception unit that receives an amplitude-modulated wave transmitted from an external device, and the communication device 900 can receive the amplitude received by the communication antenna 914. A demodulator that demodulates the received signal based on the modulated wave can also be provided.

  Further, since the communication device 900 can include the amplifier circuit according to the first to fifth embodiments described above as the amplifier circuit 904, a desired amplification effect can be obtained while reducing the size of the amplifier circuit 904. Furthermore, power efficiency can be improved.

  Although the communication apparatus 900 has been described as an embodiment of the present invention, the embodiment of the present invention is not limited to such a form. For example, a computer such as a UMPC (Ultra Mobile Personal Computer) or a portable communication such as a cellular phone is used. The present invention can be applied to a portable game machine such as a device or PlayStation Portable (registered trademark).

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to the example which concerns. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.

It is explanatory drawing which shows the structure of the amplifier circuit (conventional amplifier circuit) of a LINC system. It is explanatory drawing which shows the relationship between the input modulation signal (transmission signal) which concerns on the LINC type amplifier circuit, and the 1st constant envelope signal and the 2nd constant envelope signal by a vector. It is explanatory drawing which shows an example of the power efficiency with respect to the output voltage in the conventional amplifier circuit. It is explanatory drawing which shows an example of the load admittance seen from the output side of the class B amplifier circuit with respect to the output voltage in the conventional amplifier circuit. It is explanatory drawing which shows the amplifier circuit which comprised the synthetic | combination circuit of the conventional amplifier circuit which concerns on embodiment of this invention with the common transformer. It is explanatory drawing which shows an example of the load admittance seen from the output side of the class B amplifier circuit with respect to the output voltage in the amplifier circuit which comprised the synthetic | combination circuit of the conventional amplifier circuit which concerns on embodiment of this invention with the general transformer. It is explanatory drawing which shows an example of the power efficiency with respect to the output voltage in the amplifier circuit which comprised the synthetic | combination circuit of the conventional amplifier circuit which concerns on embodiment of this invention with the common transformer. It is explanatory drawing which shows the amplifier circuit which concerns on the 1st Embodiment of this invention. It is explanatory drawing which shows the equivalent circuit of the load circuit seen from the output side of each class B amplifier circuit in case the output voltage in the amplifier circuit which concerns on the 1st Embodiment of this invention is 0. It is explanatory drawing which shows an example of the load admittance seen from the output side of the class B amplifier circuit with respect to the output voltage in the amplifier circuit which concerns on the 1st Embodiment of this invention. It is explanatory drawing which shows an example of the power efficiency with respect to the output voltage in the amplifier circuit which concerns on the 1st Embodiment of this invention. It is explanatory drawing which shows the amplifier circuit which concerns on the 1st modification of the 1st Embodiment of this invention. It is explanatory drawing which shows the amplifier circuit which concerns on the 2nd modification of the 1st Embodiment of this invention. It is explanatory drawing which shows the amplifier circuit which concerns on the 2nd Embodiment of this invention. It is explanatory drawing which shows the amplifier circuit which concerns on the 3rd Embodiment of this invention. It is explanatory drawing which shows the amplifier circuit which concerns on the 4th Embodiment of this invention. It is explanatory drawing which shows the amplifier circuit which concerns on the 5th Embodiment of this invention. It is explanatory drawing which shows the communication apparatus which concerns on embodiment of this invention.

Explanation of symbols

10, 100, 150, 160, 200, 300, 400, 500 Amplifier circuit 12, 902 Signal distribution circuit 18, 106, 156, 202, 302, 502 Composite circuit 102 First amplifier circuit 104 Second amplifier circuit 108 Primary side First inductor 110 Secondary side first inductor 112 Primary side first capacitor 114 Secondary side first capacitor 116 Primary side second inductor 118 Secondary side second inductor 120 Primary side second capacitor 122 Secondary side first 2-capacitor 900 communication device 904 amplifier circuit 906 communication unit

Claims (12)

A first amplification unit that receives a first constant envelope signal and outputs a first input signal obtained by amplifying the first constant envelope signal;
A second amplifying unit that receives a second constant envelope signal having a phase different from that of the first constant envelope signal and outputs a second input signal obtained by amplifying the second constant envelope signal;
The first input signal and the second input signal are respectively input to the primary side, and the first input signal and the second input signal are combined on the secondary side to output an amplitude-modulated output signal. A magnetically coupled transformer;
With
The magnetic coupling transformer is
A primary-side first inductor and a primary-side first capacitor constituting a first primary side to which the first input signal is input;
A secondary-side first inductor and a secondary-side first capacitor constituting a first secondary side corresponding to the first primary side;
A primary-side second inductor and a primary-side second capacitor constituting a second primary side to which the second input signal is input;
A secondary second inductor and a secondary second capacitor constituting a second secondary side corresponding to the second primary side;
A combining unit that combines the first input signal and the second input signal and outputs the output signal;
An amplifying circuit comprising: The combining unit is composed of an output capacitor having a predetermined capacitance,
The primary side first inductor and the primary side first capacitor, the secondary side first inductor and the secondary side first capacitor, the primary side second inductor and the primary side second capacitor, The secondary side second inductor and the secondary side second capacitor are respectively connected in parallel,
2. The amplifier circuit according to claim 1, wherein the secondary side first capacitor, the secondary side second capacitor, and the output capacitor are connected in series.   The absolute value of the reactance of each of the secondary side first capacitor and the secondary side second capacitor is approximately twice the absolute value of the reactance of each of the secondary side first inductor and the secondary side second inductor. The amplifier circuit according to claim 2, wherein: The combining unit is composed of an output inductor having a predetermined inductance,
The primary side first inductor and the primary side first capacitor, and the primary side second inductor and the primary side second capacitor are respectively connected in parallel;
The secondary side first inductor and the secondary side first capacitor, and the secondary side second inductor and the secondary side second capacitor are connected in series, respectively.
The secondary side first capacitor, the secondary side second capacitor, and a first terminal of the output inductor are connected, and the output signal is output from a second terminal of the output inductor. The amplifier circuit according to claim 1. The absolute value of the reactance of each of the secondary side first capacitor and the secondary side second capacitor is approximately twice the absolute value of the reactance of each of the secondary side first inductor and the secondary side second inductor,
5. The amplifier circuit according to claim 4, wherein an inductance of the output inductor is substantially ½ of an inductance of the secondary side first inductor and a secondary side second inductor. The primary side first inductor and the primary side first capacitor, the primary side second inductor and the primary side second capacitor, the secondary side first inductor and the secondary side first capacitor, The secondary side second inductor and the secondary side second capacitor are respectively connected in series,
2. The amplifier circuit according to claim 1, wherein the output signal is output from a connection point between the secondary side first capacitor and the secondary side second capacitor. The inductances of the primary side first inductor and the secondary side first inductor and the capacitances of the primary side first capacitor and the secondary side first capacitor are the primary side first inductor. And the primary side first capacitor, the secondary side first inductor and the secondary side first capacitor are set to resonate at the frequency of the first constant envelope signal,
The inductances of the primary side second inductor and the secondary side second inductor and the capacitances of the primary side second capacitor and the secondary side second capacitor are the primary side second inductor. And the primary side second capacitor, the secondary side second inductor and the secondary side second capacitor are set to resonate at the frequency of the second constant envelope signal, The amplifier circuit according to claim 6.   The amplifier circuit according to claim 1, further comprising a switching unit that switches an impedance on an output side of the second amplifying unit. The first amplifying unit includes a plurality of first amplifiers to amplify the first constant envelope signals,
The second amplifying unit includes a plurality of second amplifiers to amplify the second constant envelope signals,
The magnetic coupling transformer is
A plurality of primary side first inductors and primary side first capacitors corresponding to each of the first amplifiers; a plurality of secondary side first inductors and secondary side first capacitors;
A plurality of primary side second inductors and primary side second capacitors corresponding to each of the second amplifiers, a plurality of secondary side second inductors and secondary side second capacitors;
The amplifier circuit according to claim 1, further comprising: A first positive phase constant envelope signal as a differential signal and a first negative phase constant envelope signal in which the phase of the first positive phase constant envelope signal is inverted are input to the first amplification unit,
A second positive phase constant envelope signal as a differential signal and a second negative phase constant envelope signal whose phase is inverted from that of the second positive phase constant envelope signal are input to the second amplifier.
The first amplifying unit causes the primary-side first inductor to function as a power supply inductor that supplies power to the first amplifying unit,
2. The amplifier circuit according to claim 1, wherein the second amplifying unit causes the primary-side second inductor to function as a power supply inductor that supplies power to the second amplifying unit. 3. A first positive phase constant envelope signal as a differential signal and a first negative phase constant envelope signal in which the phase of the first positive phase constant envelope signal is inverted are input to the first amplification unit,
A second positive phase constant envelope signal as a differential signal and a second negative phase constant envelope signal whose phase is inverted from that of the second positive phase constant envelope signal are input to the second amplifier.
The first amplifying unit causes an output capacitance component of a transistor constituting the first amplifying unit to function as the primary first capacitor,
2. The amplifier circuit according to claim 1, wherein the second amplifying unit causes an output capacitance component of a transistor constituting the second amplifying unit to function as the primary-side second capacitor. A signal distributor for distributing a first constant envelope signal and a second constant envelope signal having a phase different from that of the first constant envelope signal based on the input transmission signal;
An amplifying unit that receives the first constant envelope signal and the second constant envelope signal and outputs an amplitude-modulated output transmission signal;
A communication unit that transmits the output transmission signal output from the amplification unit to an external device;
With
The amplification unit is
A first amplification unit that receives the first constant envelope signal and outputs a first input signal obtained by amplifying the first constant envelope signal;
A second amplifying unit that receives the second constant envelope signal and outputs a second input signal obtained by amplifying the second constant envelope signal;
Magnetic coupling in which the first input signal and the second input signal are respectively input to a primary side, and the first input signal and the second input signal are combined on the secondary side to output the output transmission signal With a transformer;
A communication apparatus comprising:

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