High frequency amplifier

Abstract

To suppress an unnecessary signal while suppressing a circuit scale.SOLUTION: A high-frequency amplifier includes a first amplifier having at least one stage of amplifiers, an output portion of which is electrically connected to an output terminal of the high-frequency amplifier and an input portion of which is input with a high-frequency signal, and an inductor having one end electrically connected to an output portion of the first amplifier and the other end electrically connected to an input portion of the first amplifier.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to high frequency amplifiers. [Background technology]

[0002] The following Patent Document 1 describes a pre-distortion compensation circuit that is provided in the preceding stage of an amplifier and generates an intermodulation distortion component that can substantially cancel out the intermodulation distortion component generated in the amplifier. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-292039 Summary of the Invention [Problem to be solved by the invention]

[0004] The pre-distortion compensation circuit described in Patent Document 1 has a large number of circuit components and is large in circuit scale.

[0005] The present disclosure has been made in view of the above, and aims to suppress unnecessary signals while reducing the circuit size. [Means for solving the problem]

[0006] A high-frequency amplifier according to one aspect of the present disclosure is a high-frequency amplifier having at least one amplifier stage, and includes: a first amplifier having an output section electrically connected to an output terminal of the high-frequency amplifier and having an input section to which a high-frequency signal is input; and an inductor having one end electrically connected to the output section of the first amplifier and the other end electrically connected to the input section of the first amplifier. [Effects of the Invention]

[0007] The high-frequency amplifier of the present disclosure can suppress unnecessary signals while reducing the circuit size. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing the configuration of a high-frequency amplifier of a comparative example. [Figure 2] FIG. 2 is a diagram showing the circuit configuration of the high-frequency amplifier according to the first embodiment. [Figure 3] FIG. 3 is a diagram showing circuit simulation models of the high-frequency amplifiers of the comparative example and the first embodiment. [Figure 4] FIG. 4 is a diagram showing the results of a circuit simulation of the high-frequency amplifier of the comparative example. [Figure 5] FIG. 5 is a diagram showing the results of a circuit simulation of the high-frequency amplifier according to the first embodiment. [Figure 6] FIG. 6 is a diagram showing a circuit configuration of a high-frequency amplifier according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. However, the present invention is not limited to these embodiments. Each embodiment is an example, and it goes without saying that partial substitution or combination of the configurations shown in different embodiments is possible. From the second embodiment onwards, a description of matters common to the first embodiment will be omitted, and only the differences will be described. In particular, similar effects resulting from similar configurations will not be mentioned in each embodiment.

[0010] First Embodiment To facilitate understanding of the first embodiment, a comparative example will be described before describing the first embodiment.

[0011] (Configuration of Comparative Example) FIG. 1 is a diagram showing the configuration of a high-frequency amplifier of a comparative example.

[0012] The high-frequency amplifier 100 amplifies a high-frequency input signal RFin and outputs an amplified high-frequency output signal RFout.

[0013] The frequency of the carrier wave of the radio frequency input signal RFin and the radio frequency output signal RFout is set to frequency F_Tx.

[0014] High-frequency amplifier 100 is a three-stage amplifier including a first-stage amplifier 110, a middle-stage amplifier 120, and a final-stage amplifier .

[0015] In this example, the number of stages in the high-frequency amplifier 100 is three, but the present disclosure is not limited to this. The number of stages in the high-frequency amplifier 100 may be one or two, or may be four or more.

[0016] The amplifier 110 includes a capacitor 112 , a resistor 114 , and a transistor 116 .

[0017] One end of the capacitor 112 is electrically connected to the terminal 201. A radio frequency input signal RFin is input to the terminal 201. The other end of the capacitor 112 is electrically connected to the base of the transistor 116. The capacitor 112 is a DC blocking capacitor that blocks the DC component of the radio frequency input signal RFin.

[0018] A bias current IB1 is input to one end of the resistor 114. The other end of the resistor 114 is electrically connected to the base of the transistor 116. The bias current IB1 is input to the base of the transistor 116 via the resistor 114.

[0019] The emitter of transistor 116 is electrically connected to a reference potential. The reference potential is exemplified by a ground potential, but the present disclosure is not limited thereto. In other words, the emitter of transistor 116 is grounded. A power supply voltage VCC is supplied to the collector of transistor 116 via a choke coil 221. The power supply voltage VCC is stabilized by a capacitor 224.

[0020] The transistor 116 amplifies a radio frequency input signal RFin input to the base, and outputs the amplified radio frequency signal RF1 from the collector.

[0021] The amplifier 120 includes a capacitor 122 , a resistor 124 , and a transistor 126 .

[0022] One end of the capacitor 122 is electrically connected to the collector of the transistor 116. The other end of the capacitor 122 is electrically connected to the base of the transistor 126. The capacitor 122 is a DC blocking capacitor that cuts the DC component of the high frequency signal RF1.

[0023] A bias current IB2 is input to one end of the resistor 124. The other end of the resistor 124 is electrically connected to the base of the transistor 126. The bias current IB2 is input to the base of the transistor 126 via the resistor 124.

[0024] The emitter of the transistor 126 is electrically connected to the reference potential, that is, the emitter of the transistor 126 is grounded. The power supply voltage VCC is supplied to the collector of the transistor 126 via the choke coil 222.

[0025] The transistor 126 amplifies the radio frequency signal RF1 input to the base, and outputs the amplified radio frequency signal RF2 from the collector.

[0026] The amplifier 130 includes a capacitor 132 , a resistor 134 , and a transistor 136 .

[0027] One end of the capacitor 132 is electrically connected to the collector of the transistor 126. The other end of the capacitor 132 is electrically connected to the base of the transistor 136. The capacitor 132 is a DC blocking capacitor that blocks the DC component of the high frequency signal RF2.

[0028] A bias current IB3 is input to one end of the resistor 134. The other end of the resistor 134 is electrically connected to the base of the transistor 136. The bias current IB3 is input to the base of the transistor 136 via the resistor 134.

[0029] The emitter of the transistor 136 is electrically connected to the reference potential. That is, the emitter of the transistor 136 is grounded. The power supply voltage VCC is supplied to the collector of the transistor 136 via the choke coil 223.

[0030] The transistor 136 amplifies the radio frequency signal RF2 input to the base, and outputs the amplified radio frequency output signal RFout from the collector.

[0031] The collector of the transistor 136 is electrically connected to the terminal 202 through a matching circuit 210 .

[0032] The transistor 136 has a parasitic capacitance 138 between the base and collector.

[0033] (Issues in Comparative Examples) For example, the frequency F_Tx is 1910 MHz. Also, consider a case where a high-frequency signal S11 in the ISM band (Industrial Scientific and Medical Band) propagates from a load (not shown) to the terminal 202. For example, the frequency F_ISM of the carrier wave of the high-frequency signal S11 is 2400 MHz.

[0034] The high-frequency signal S11 propagated to the terminal 202 propagates to the collector of the transistor 136 via the matching circuit 210. The high-frequency signal S11 propagated to the collector of the transistor 136 propagates to the base of the transistor 136 via the parasitic capacitance 138. In addition, the high-frequency signal RF2 is input to the base of the transistor 136.

[0035] Therefore, the high frequency signal RF2 and the high frequency signal S11 are mixed and amplified by the transistor 136.

[0036] That is, the output signal RF of the high-frequency amplifier 100 includes a component of the high-frequency output signal RFout and a component of the high-frequency signal S12 obtained after the high-frequency signal RF2 and the high-frequency signal S11 are mixed and amplified. The frequency of the high-frequency signal S12 is, for example, frequency 2·F_Tx−F_ISM.

[0037] For example, if the frequency F_Tx is 1910 MHz and the frequency F_ISM is 2400 MHz, the frequency of the high-frequency signal S12 is 2·1910−2400=1420 MHz.

[0038] It is undesirable for the component of the high frequency signal S12 to be included in the output signal RF of the high frequency amplifier 100. It is desirable to suppress the component of the high frequency signal S12 in the output signal RF of the high frequency amplifier 100.

[0039] (Configuration of the first embodiment) FIG. 2 is a diagram showing the configuration of the high-frequency amplifier according to the first embodiment.

[0040] The high-frequency amplifier 1 further includes an inductor 140 in comparison with the high-frequency amplifier 100 of the comparative example.

[0041] One end of inductor 140 is electrically connected to the output of amplifier 130 (the collector of transistor 136), and the other end of inductor 140 is electrically connected to the output of amplifier 120 (the collector of transistor 126) and the input of amplifier 130 (one end of capacitor 132).

[0042] The amplifier 130 corresponds to an example of a "first amplifier" in the present disclosure. The capacitor 132 corresponds to an example of a "first capacitor" in the present disclosure. The transistor 136 corresponds to an example of a "transistor" in the present disclosure. The inductor 140 corresponds to an example of an "inductor" in the present disclosure.

[0043] The inductor 140 , the capacitor 132 , and the parasitic capacitance 138 connected in series form an LC parallel resonant circuit 150 .

[0044] The LC parallel resonant circuit 150 corresponds to an example of a "first parallel resonant circuit" of the present disclosure.

[0045] The inductance value of the inductor 140 is set so that the resonant frequency of the LC parallel resonant circuit 150 is equal to the frequency F_ISM, but the present disclosure is not limited to this.

[0046] This allows the high-frequency amplifier 1 to increase the impedance at the frequency F_ISM when looking from the collector of the transistor 136 to the base of the transistor 136 .

[0047] Therefore, the high-frequency amplifier 1 can suppress the amplitude of the high-frequency signal S11 (frequency F_ISM) at the base terminal of the transistor 136, and can therefore suppress the component of the high-frequency signal S12 (frequency 2·F_Tx−F_ISM) in the output signal.

[0048] Since the high-frequency amplifier 1 can be realized by adding one inductor 140, the number of circuit components can be reduced compared to the pre-distortion compensation circuit described in Patent Document 1, and the circuit size can be reduced.

[0049] (Circuit Simulation) FIG. 3 is a diagram showing a circuit simulation model of the comparative example and the first embodiment.

[0050] The circuit simulation model 300 includes the high-frequency amplifier 1 or 100, an impedance circuit Zs, a capacitor C, and an impedance circuit ZL.

[0051] One end of the impedance circuit Zs is electrically connected to the input terminal of the high-frequency amplifier 1 or the high-frequency amplifier 100. The other end of the impedance circuit Zs is electrically connected to the reference potential.

[0052] One end of the capacitor C is electrically connected to the output terminal of the high-frequency amplifier 1 or the high-frequency amplifier 100. The other end of the capacitor C is electrically connected to the reference potential.

[0053] One end of the impedance circuit ZL is electrically connected to the output terminal of the high-frequency amplifier 1 or the high-frequency amplifier 100. The other end of the impedance circuit ZL is electrically connected to the reference potential.

[0054] In this circuit simulation model 300, a high-frequency signal S21 (frequency F_Tx) was input to the input terminal of the high-frequency amplifier 1 or the high-frequency amplifier 100, and a high-frequency signal S31 (frequency F_ISM) was input to the output terminal of the high-frequency amplifier 1 or the high-frequency amplifier 100. In addition, the phase of the high-frequency signal S31 relative to the phase of the high-frequency signal S21 was changed.

[0055] The high-frequency output signal S41 of the high-frequency amplifier 1 or the high-frequency amplifier 100 includes a component of a high-frequency signal S22 (frequency F_Tx) obtained by amplifying the high-frequency signal S21, and a component of a high-frequency signal S32 (frequency 2·F_Tx−F_ISM) obtained by mixing and amplifying the high-frequency signal S21 and the high-frequency signal S31.

[0056] FIG. 4 is a diagram showing the results of a circuit simulation of the high-frequency amplifier of the comparative example.

[0057] In FIG. 4, the horizontal axis represents the intensity Pout (dBm) of the high frequency signal S22 (frequency F_Tx), and the vertical axis represents the intensity (dBm) of each signal.

[0058] A line 411 indicates the intensity of the second harmonic (frequency 2·F_Tx) of the high-frequency signal S21 generated in the high-frequency amplifier 100.

[0059] A group of lines 412 indicates the intensity of high frequency signal S31 (frequency F_ISM) after amplification by high frequency amplifier 100. Each line in group of lines 412 indicates the intensity of high frequency signal S31 after amplification when the phase of high frequency signal S31 is changed.

[0060] A group of lines 413 indicates the intensity of high-frequency signal S32 (frequency 2·F_Tx−F_ISM) output from high-frequency amplifier 100. Each line in group of lines 412 indicates the intensity of high-frequency signal S32 when the phase of high-frequency signal S31 is changed.

[0061] The high frequency signal S32 (frequency 2·F_Tx−F_ISM) reaches a maximum when the strength of the high frequency signal S22 (frequency F_Tx) is approximately 35 dBm, as shown by point 414. The signal strength of the high frequency signal S32 (frequency 2·F_Tx−F_ISM) at point 414 is approximately −3 dBm.

[0062] FIG. 5 is a diagram showing the results of a circuit simulation of the high-frequency amplifier according to the first embodiment.

[0063] In FIG. 5, the horizontal axis represents the intensity Pout (dBm) of the high frequency signal S22 (frequency F_Tx), and the vertical axis represents the intensity (dBm) of each signal.

[0064] A line 421 indicates the intensity of the second harmonic (frequency 2·F_Tx) of the high-frequency signal S 21 generated in the high-frequency amplifier 1 .

[0065] A group of lines 422 indicates the intensity of high frequency signal S31 (frequency F_ISM) after amplification by high frequency amplifier 1. Each line in group of lines 422 indicates the intensity of high frequency signal S31 after amplification when the phase of high frequency signal S31 is changed.

[0066] A group of lines 423 indicates the intensity of high-frequency signal S32 (frequency 2·F_Tx−F_ISM) output from high-frequency amplifier 1. Each line in group of lines 422 indicates the intensity of high-frequency signal S32 when the phase of high-frequency signal S31 is changed.

[0067] The high frequency signal S32 (frequency 2·F_Tx−F_ISM) reaches a maximum when the strength of the high frequency signal S22 (frequency F_Tx) is approximately 32 dBm, as shown by point 424. The signal strength of the high frequency signal S32 (frequency 2·F_Tx−F_ISM) at point 424 is approximately −13 dBm.

[0068] The high-frequency amplifier 1 can make the maximum intensity of the high-frequency signal S32 (approximately -13 dBm, see point 424) smaller than the maximum intensity of the high-frequency signal S32 of the high-frequency amplifier 100 (approximately -3 dBm, see point 414).

[0069] (effect) The high-frequency amplifier 1 can increase the impedance at frequency F_ISM when looking from the collector of the transistor 136 to the base of the transistor 136. Therefore, the high-frequency amplifier 1 can suppress the amplitude of the high-frequency signal S11 (frequency F_ISM) at the base end of the transistor 136, and can suppress the component of the high-frequency signal S12 (frequency 2·F_Tx−F_ISM) in the output signal RF.

[0070] 4 and 5, the high-frequency amplifier 1 can make the maximum intensity of the high-frequency signal S32 (approximately -13 dBm, see point 424) smaller than the maximum intensity of the high-frequency signal S32 of the high-frequency amplifier 100 (approximately -3 dBm, see point 414).

[0071] Furthermore, since the high-frequency amplifier 1 can be realized by adding one inductor 140, the number of circuit components can be reduced compared to the pre-distortion compensation circuit described in Patent Document 1, and the circuit size can be reduced.

[0072] <Second embodiment> (composition) FIG. 6 is a diagram showing the configuration of a high-frequency amplifier according to the second embodiment.

[0073] Compared to the high-frequency amplifier 1 of the first embodiment (see FIG. 2), the high-frequency amplifier 1A further includes a capacitor 142.

[0074] The capacitor 142 corresponds to an example of the "second capacitor" of the present disclosure.

[0075] One end of the capacitor 142 is electrically connected to the other end of the inductor 140. The other end of the capacitor 142 is electrically connected to the base of the transistor 136.

[0076] The capacitor 142 is a DC blocking capacitor that blocks the current flowing through the inductor 140 due to the collector-base voltage of the transistor 136 .

[0077] The inductor 140 and capacitor 142 connected in series, and the parasitic capacitance 138 form an LC parallel resonant circuit 160 .

[0078] The LC parallel resonant circuit 160 corresponds to an example of a "second parallel resonant circuit" of the present disclosure.

[0079] The inductance value of the inductor 140 and the capacitance value of the capacitor 142 are set so that the resonant frequency of the LC parallel resonant circuit 160 is equal to the frequency F_ISM, but the present disclosure is not limited to this.

[0080] (effect) The high-frequency amplifier 1A can increase the impedance at frequency F_ISM when looking from the collector of the transistor 136 to the base of the transistor 136. Therefore, the high-frequency amplifier 1A can suppress the amplitude of the high-frequency signal S11 (frequency F_ISM) at the base end of the transistor 136, and can suppress the component of the high-frequency signal S12 (frequency 2·F_Tx−F_ISM) in the output signal RF.

[0081] Furthermore, since the high-frequency amplifier 1A can be realized by adding one inductor 140 and one capacitor 142, the number of circuit components can be reduced compared to the pre-distortion compensation circuit described in Patent Document 1, and the circuit size can be reduced.

[0082] <Configuration Example of the Present Disclosure> The present disclosure may also have the following configurations.

[0083] (1) A high frequency amplifier having at least one amplifier stage, a first amplifier having an output section electrically connected to the output terminal of the high-frequency amplifier and having an input section to which a high-frequency signal is input; an inductor having one end electrically connected to the output of the first amplifier and the other end electrically connected to the input of the first amplifier; Including, High frequency amplifier.

[0084] (2) The high-frequency amplifier according to (1) above, The first amplifier is a first capacitor to one end of which a high frequency signal is input; a transistor having an emitter grounded, a base electrically connected to the other end of the first capacitor, and outputting an amplified high-frequency signal from a collector; Including, one end of the inductor is electrically connected to the collector of the transistor; The other end of the inductor is electrically connected to one end of the first capacitor. High frequency amplifier.

[0085] (3) The high-frequency amplifier according to (2) above, The transistor is It has a parasitic capacitance between the base and collector. the inductor, the parasitic capacitance connected in series with the first capacitor, and the first parallel resonant circuit are configured; High frequency amplifier.

[0086] (4) The high-frequency amplifier according to (3) above, The inductance value of the inductor is The resonant frequency of the first parallel resonant circuit is set to be the frequency of a signal propagating to the output terminal of the first amplifier. High frequency amplifier.

[0087] (5) The high-frequency amplifier according to (1) above, Second Capacitor Further comprising: The first amplifier is A transistor in which the emitter is grounded, a high-frequency signal is input to the base, and the amplified high-frequency signal is output from the collector. Including, one end of the inductor is electrically connected to the collector of the transistor; the other end of the inductor is electrically connected to one end of the second capacitor; the other end of the second capacitor is electrically connected to the base of the transistor; High frequency amplifier.

[0088] (6) The high-frequency amplifier according to (5) above, The transistor is It has a parasitic capacitance between the base and collector. the parasitic capacitance, the inductor connected in series with the second capacitor, and the second parallel resonant circuit are configured; High frequency amplifier.

[0089] (7) The high-frequency amplifier according to (6) above, The inductance value of the inductor and the capacitance value of the second capacitor are The resonant frequency of the second parallel resonant circuit is set to be the frequency of a signal propagating to the output terminal of the first amplifier. High frequency amplifier.

[0090] The above-described embodiment is intended to facilitate understanding of the present invention, and is not intended to limit the present invention. The present invention may be modified or improved without departing from the spirit and scope of the present invention, and equivalents thereof are also included in the present invention. [Explanation of symbols]

[0091] 1, 1A, 100 High Frequency Amplifier 110, 120, 130 Amplifier 112, 122, 132, 142, 224 capacitors 114, 124, 134 Resistor 116, 126, 136 transistors 140 Inductor 150, 160 LC parallel resonant circuit 210 Matching circuit 221, 222, 223 Choke coils

Claims

1. A high frequency amplifier having at least one amplifier stage, a first amplifier having an output section electrically connected to the output terminal of the high-frequency amplifier and having an input section to which a high-frequency signal is input; an inductor having one end electrically connected to the output of the first amplifier and the other end electrically connected to the input of the first amplifier; Including, High frequency amplifier.

2. 2. The high-frequency amplifier according to claim 1, The first amplifier is a first capacitor to one end of which a high frequency signal is input; a transistor having an emitter grounded, a base electrically connected to the other end of the first capacitor, and outputting an amplified high-frequency signal from a collector; Including, one end of the inductor is electrically connected to the collector of the transistor; The other end of the inductor is electrically connected to one end of the first capacitor. High frequency amplifier.

3. 3. The high-frequency amplifier according to claim 2, The transistor is It has a parasitic capacitance between the base and the collector, the inductor, the parasitic capacitance connected in series with the first capacitor, and the first parallel resonant circuit are configured; High frequency amplifier.

4. 4. The high-frequency amplifier according to claim 3, The inductance value of the inductor is a resonant frequency of the first parallel resonant circuit is set to be equal to the frequency of a signal propagating to an output terminal of the first amplifier; High frequency amplifier.

5. 2. The high-frequency amplifier according to claim 1, Second Capacitor Further comprising: The first amplifier is A transistor in which the emitter is grounded, a high-frequency signal is input to the base, and the amplified high-frequency signal is output from the collector. Including, one end of the inductor is electrically connected to the collector of the transistor; the other end of the inductor is electrically connected to one end of the second capacitor; the other end of the second capacitor is electrically connected to the base of the transistor; High frequency amplifier.

6. 6. The high-frequency amplifier according to claim 5, The transistor is It has a parasitic capacitance between the base and the collector, the parasitic capacitance, the inductor, and the second capacitor connected in series form a second parallel resonant circuit; High frequency amplifier.

7. 7. The high-frequency amplifier according to claim 6, The inductance value of the inductor and the capacitance value of the second capacitor are The resonant frequency of the second parallel resonant circuit is set to be equal to the frequency of a signal propagating to the output terminal of the first amplifier. High frequency amplifier.

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