Differential amplification device

Abstract

Provided is a differential amplification device that enables downsizing of the device. A differential amplification device (1) includes: an input matching circuit (MN1) that is an input balun of a signal input at an input terminal; an output matching circuit (MN2) that is an output balun of a signal output to an output terminal; a first amplifier (11) and a second amplifier (12) that are connected in parallel between the input balun and the output balun and output a differential signal; a first diode (D1) that is provided between a path between the input balun and the first amplifier and a reference potential; a second diode (D2) that is provided between a path between the input balun and the second amplifier and the reference potential; and a bias circuit (21) that applies a bias to the first diode and the second diode, with the cathode of the first diode and the cathode of the second diode connected to the reference potential side.

Description

TECHNICAL FIELD

[0001] The present application relates to a differential amplification device. BACKGROUND

[0002] A differential amplification device used as a power amplification device for wireless communication or the like is known (for example, Patent Literature 1). The differential amplification device disclosed in Patent Literature 1 is provided with an amplification circuit for a low power mode (hereinafter referred to as LPM) and an amplification circuit for a high power mode (hereinafter referred to as HPM). Depending on the power mode, the amplification circuit for LPM and the amplification circuit for HPM are switched.

[0003] PRIOR ART LITERATURE

[0004] PATENT LITERATURE

[0005] Patent Literature 1: Japanese Patent Application Publication No. 2014-155171 SUMMARY

[0006] PROBLEMS TO BE SOLVED BY THE INVENTION

[0007] However, according to Patent Literature 1, in addition to the amplification circuit for HPM, the amplification circuit for LPM is also required, and it is difficult to achieve miniaturization of the differential amplification device.

[0008] The present disclosure was made in view of the above circumstances, and aims to provide a differential amplification device capable of switching power modes and achieving miniaturization of the device.

[0009] MEANS FOR SOLVING PROBLEMS

[0010] In order to solve the above problems and achieve the object, a differential amplification device according to one embodiment of the present disclosure includes: an input terminal; an input balun that is input with a signal input at the input terminal; an output terminal; an output balun that outputs a signal to the output terminal; a first amplifier and a second amplifier that are provided in parallel between the input balun and the output balun, and output a differential signal; a first diode that is provided between a path between the input balun and the first amplifier and a reference potential; a second diode that is provided between a path between the input balun and the second amplifier and the reference potential; and a bias circuit that applies a bias to the first diode and the second diode, a cathode of the first diode and a cathode of the second diode being connected to the reference potential.

[0011] EFFECT OF THE INVENTION

[0012] According to the present disclosure, miniaturization of a differential amplification device can be achieved. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 is a diagram showing an example of a differential amplification device of Embodiment 1 of the present disclosure.

[0014] Figure 2 is a diagram shown focusing on an input matching circuit, an amplifier, and the like of Embodiment 1 of the present disclosure.

[0015] Figure 3 is a diagram showing an example of a differential amplification device of Embodiment 2 of the present disclosure.

[0016] Figure 4 is a diagram showing an example of a differential amplification device of Embodiment 3 of the present disclosure.

[0017] Figure 5 is a diagram showing an example of a differential amplification device of Embodiment 4 of the present disclosure.

[0018] Figure 6 is a diagram showing an example of a differential amplification device of Embodiment 5 of the present disclosure.

[0019] Figure 7 is a diagram showing an example of a differential amplification device of Embodiment 6 of the present disclosure.

[0020] Figure 8 is a diagram showing an example of a differential amplification device of Embodiment 7 of the present disclosure.

[0021] REFERENCE SIGNS

[0022] 1, 1a to 1f Differential amplification device

[0023] 11, 12 Amplifier

[0024] 21, 22 Bias circuit

[0025] 30, 31, 32, 33, 330, 331, 332 Capacitor

[0026] 40, 41, 42 Parallel resonance circuit

[0027] 51, 52, 53 Resistive element

[0028] 61, 111, 112, 121, 122, 141-1 to 141-N, 142-1 to 142-N, 340, 341, 342 Inductor

[0029] 70, 71, 72, 73 Bias line

[0030] 110, 120, TR1, TR2 transformer

[0031] 200 matching circuit

[0032] 201 input terminal

[0033] 202 output terminal

[0034] D1, D2 diode

[0035] GND reference potential

[0036] MN1 input matching circuit

[0037] MN2 output matching circuit

[0038] P21 midpoint DETAILED DESCRIPTION

[0039] Hereinafter, embodiments of the present application will be described in detail based on the drawings. In the description of each of the embodiments below, the same reference numerals are assigned to the same or equivalent structural parts, and the description thereof is simplified or omitted. The present application is not limited by each of the embodiments. In addition, in the structural elements of each of the embodiments, parts that can be easily substituted by those skilled in the art or substantially the same parts are included. Note that the structures described below can be appropriately combined. In addition, omission, substitution, or alteration of the structures can be made within a range that does not depart from the gist of the present application.

[0040] [1st Embodiment]

[0041] [Structure]

[0042] Figure 1 is a diagram illustrating an example of a differential amplification device of the 1st embodiment of the present disclosure. Figure 1 The differential amplification device 1 illustrated includes an input terminal 201, an input matching circuit MN1, a 1st amplifier, i.e., an amplifier 11 and a 2nd amplifier, i.e., an amplifier 12, which constitute a differential amplification circuit, an output matching circuit MN2, and an output terminal 202. The input matching circuit MN1 includes a capacitor 30, an inductor 111, and an inductor 112. The output matching circuit MN2 includes an inductor 121, an inductor 122, and a matching circuit 200.

[0043] One end of the capacitor 30 is connected to the input terminal 201. The other end of the capacitor 30 is connected to one end of the inductor 111. The capacitor 30 is a capacitor for cutting off direct current. The other end of the inductor 111 is connected to a reference potential. The reference potential exemplifies a ground potential, but the present disclosure is not limited thereto. The same is true in the following description. Note that the capacitor 30 is provided on the amplifier 11, 12 side with respect to the input terminal 201, but the present disclosure is not limited thereto. The capacitor 30 may, for example, also be provided on the side opposite to the amplifier 11, 12 side with respect to the input terminal 201.

[0044] The inductor 111 is electromagnetically field-coupled to the inductor 112, constituting a transformer 110. Here, one end of the inductor 111 is connected to the input terminal 201, and the other end of the inductor 111 is connected to the reference potential. In addition, one end of the inductor 112 is connected to the input of the amplifier 11, and the other end of the inductor 112 is connected to the input of the amplifier 12. The transformer 110 functions as an input balun that performs unbalanced-to-balanced conversion on a signal for the primary winding, i.e., the inductor 111. The signal input to the inductor 111 is converted by the transformer 110, causing the inductor 112 to generate a differential signal. Electromagnetic field coupling is defined as coupling of either or both of magnetic field coupling and electric field coupling.

[0045] The output of the input matching circuit MN1 is connected to one end of a capacitor 31 and one end of a capacitor 32. The other end of the capacitor 31 is connected to the input of the amplifier 11. The capacitor 31 is a capacitor for cutting off direct current. The other end of the capacitor 32 is connected to the input of the amplifier 12. The output of the amplifier 11 is connected to one end of an inductor 121. The output of the amplifier 12 is connected to the other end of the inductor 121. The capacitor 32 is a capacitor for cutting off direct current.

[0046] The inductor 121 is electromagnetically field-coupled to an inductor 122, constituting a transformer 120. One end of the inductor 122 is connected to the input of the matching circuit 200. The other end of the inductor 122 is connected to the reference potential. The transformer 120 functions as an output balun that performs balanced-to-unbalanced conversion. The output of the matching circuit 200 is connected to the output terminal 202.

[0047] Figure 2 is a diagram illustrating the input matching circuit MN1, the amplifiers 11 and 12, and the like of the first embodiment of the present disclosure. As shown in FIG. 1, the input matching circuit MN1 is connected to the input terminal 201. The input matching circuit MN1 is connected to the input of the amplifier 11 and the input of the amplifier 12. The input matching circuit MN1 is connected to the output of the amplifier 11 and the output of the amplifier 12. The input matching circuit MN1 is connected to the input of the matching circuit 200. The input matching circuit MN1 is connected to the output of the matching circuit 200. The input matching circuit MN1 is connected to the output terminal 202. Figure 2As shown, a diode Dl as a first diode is provided in a path between the transformer 110 as an input balun and the amplifier 11. The diode Dl is connected between one end of the inductor 112 and a reference potential GND. The cathode of the diode Dl is connected to the reference potential GND. Further, a diode D2 as a second diode is provided in a path between the transformer 110 as an input balun and the amplifier 12. The diode D2 is connected between the other end of the inductor 112 and the reference potential GND. The cathode of the diode D2 is connected to the reference potential GND. The diodes Dl and D2 are connected in parallel with respect to the amplifiers 11 and 12. Note that the reference potential GND is a reference potential of the amplifiers 11 and 12.

[0048] The bias bll output from the bias circuit 21 is applied to the anode of the diode Dl. The bias bll output from the bias circuit 21 is applied via a bias line 71. The bias line 71 is connected to the secondary-side winding of the transformer 110 as an input balun. A parallel resonance circuit 41 is connected to the bias line 71. The parallel resonance circuit 41 includes a capacitor 331 and an inductor 341 connected in parallel with each other. Note that two diodes Dl can be provided to be a two-stage structure. However, from the viewpoint of miniaturization of the device, it is desirable that the diode Dl be only one (i.e., a one-stage structure). The bias bll is a voltage for turning on one diode Dl.

[0049] The bias b22 output from the bias circuit 22 is applied to the input of the amplifier 12. The bias b22 output from the bias circuit 22 is applied to the input of the amplifier 12 via a resistance element 52. Thereby, a bias is applied to a transistor in the amplifier 12.

[0050] The bias b22 output from the bias circuit 22 is applied to the input of the amplifier 12. The bias b22 output from the bias circuit 22 is applied to the input of the amplifier 12 via a resistance element 52. Thereby, a bias is applied to a transistor in the amplifier 12.

[0051] The bias b22 output from the bias circuit 22 is applied to the input of the amplifier 12. The bias b22 output from the bias circuit 22 is applied to the input of the amplifier 12 via a resistance element 52. Thereby, a bias is applied to a transistor in the amplifier 12.

[0052] [Action]

[0053] The signal input to the input terminal 201, for example, an input signal RFin of RF (Radio Frequency), is distributed as two signals that are approximately 180° out of phase with each other after passing through the transformer 110, and is input to the amplifiers 11 and 12. The two signals amplified by the amplifiers 11 and 12 are combined as an output signal RFout via the output matching circuit MN2 and output to the output terminal 202.

[0054] Here, the gain of the differential amplification device 1 can be adjusted by making the diode Dl connected to the input side of the amplifier 11 and the diode D2 connected to the input side of the amplifier 12 conductive or non-conductive.

[0055] Specifically, the diodes Dl and D2 are made conductive by the bias bll and b12 applied from the bias circuit 21, and thus a part of the input signal flows to the reference potential GND through the diodes Dl and D2. Thereby, the gain can be lowered, and LPM can be achieved.

[0056] On the other hand, the diodes Dl and D2 are made non-conductive by the bias bll and b12 applied from the bias circuit 21. At this time, the parallel resonant circuits 41 and 42 are adjusted in advance to be open (i.e., impedance is infinite) in the operating frequency. Therefore, the gain is not affected. Thereby, HPM can be achieved without lowering the gain.

[0057] As described above, by the applied bias, LPM can be achieved by making the diodes Dl and D2 conductive, and HPM can be achieved by making the diodes Dl and D2 non-conductive.

[0058] When the diodes are connected at the front stage of the transformer 110 as the input balun (specifically, between the input terminal 201 and the transformer 110), the impedance of the front stage of the transformer 110 is relatively high, and the voltage amplitude of the signal becomes large, and thus the diodes can be unexpectedly conductive. In contrast, by connecting the diodes Dl and D2 at the rear stage of the transformer 110 as the input balun (specifically, between the transformer 110 and the amplifiers 11 and 12) as in the first embodiment, by using the feature that the impedance of the rear stage of the transformer 110 is lower than that of the front stage of the transformer 110, the input voltage amplitude of the signal can be reduced, and the diodes can be prevented from being unexpectedly conductive.

[0059] As described above, by adding the diodes and making the diodes conductive or non-conductive by the applied bias, LPM and HPM can be achieved even without providing a structure dedicated to LPM. Therefore, the differential amplification device can be miniaturized.

[0060] [2nd Embodiment]

[0061] [Structure]

[0062] Figure 3 is a diagram showing an example of a differential amplification device la of the 2nd embodiment of the present disclosure. Figure 3 is a diagram showing the input matching circuit MN1, the amplifiers 11 and 12, and the like, focusing on the 2nd embodiment. In the 2nd embodiment, diodes D1 and D2 are connected at the stage subsequent to the transformer 110 as an input balun as well.

[0063] As shown in Figure 3 , in the 2nd embodiment, unlike the 1st embodiment, the bias line 70 is connected to the midpoint P21 of the inductor 112 as a secondary winding of the input balun. The midpoint P21 is a virtual ground point of the high-frequency signal. The midpoint in the present disclosure is not a position that becomes half of the inductance value of the secondary winding of the transformer, but is defined as half of the primary winding within the range of manufacturing deviation of the secondary winding of the transformer. Note that the bias line 70 can be connected to any part of the inductor 112, and does not necessarily have to be connected to the midpoint P21 of the inductor 112.

[0064] The midpoint P21 of the secondary winding of the transformer 110 is connected to the bias circuit 21 via the parallel resonance circuit 40. The parallel resonance circuit 40 includes a capacitor 330 and an inductor 340 connected in parallel to each other. The parallel resonance circuit 40 is adjusted in advance to become an open circuit (i.e., impedance is infinitely large) in the operating frequency.

[0065] [Operation]

[0066] In the 2nd embodiment as well, the bias is applied to the diodes D1 and D2 via the parallel resonance circuit 40. Figure 3 As with the differential amplification device of the 2nd embodiment described with reference to Figure 2 , by the applied bias, LPM can be realized by making the diodes D1 and D2 conductive, and HPM can be realized by making the diodes D1 and D2 non-conductive. In particular, by connecting the diodes D1 and D2 at the stage subsequent to the transformer 110 as an input balun, it is possible to become a low impedance and reduce the input voltage amplitude.

[0067] As described above, by the applied bias, LPM can be realized by making the diodes D1 and D2 conductive, and HPM can be realized by making the diodes D1 and D2 non-conductive.

[0068] As described above, by adding diodes and making the diodes conductive or non-conductive by the applied bias, it is possible to realize LPM and HPM even without providing a structure dedicated to LPM. Therefore, it is possible to realize a small differential amplification device.

[0069] In addition, in the differential amplification device of the second embodiment described above, the bias is applied via the parallel resonance circuit 40. In contrast, in the differential amplification device of the third embodiment, the parallel resonance circuit is not used. Figure 2 In the differential amplification device of the second embodiment described above, the parallel resonance circuit is provided for each of the two diodes D1 and D2. In the third embodiment, one parallel resonance circuit is provided. Therefore, compared with the second embodiment, the circuit scale can be further reduced.

[0070] [Third Embodiment]

[0071] [Structure]

[0072] Figure 4 Fig. 1 is a diagram showing an example of the differential amplification device 1b of the third embodiment of the present disclosure. Figure 4 Fig. 2 is a diagram shown focusing on the input matching circuit MN1, the amplifiers 11 and 12, and the like of the third embodiment. As shown in Fig. 2, in the third embodiment, the diodes D1 and D2 are connected at the stage subsequent to the transformer 110 as the input balun. Figure 4 As shown in Fig. 2, in the third embodiment, the diodes D1 and D2 are connected at the stage subsequent to the transformer 110 as the input balun. As with the second embodiment, the bias line 70 is connected to the midpoint P21 of the inductor 112.

[0073] In the differential amplification device of the second embodiment described above, the bias is applied via the parallel resonance circuit 40. In contrast, in the differential amplification device of the third embodiment, the parallel resonance circuit is not used. Figure 2 In the differential amplification device of the second embodiment described above, the bias is applied via the parallel resonance circuit 40. In contrast, in the differential amplification device of the third embodiment, the parallel resonance circuit is not used.

[0074] In the differential amplification device of the second embodiment described above, the bias is applied via the parallel resonance circuit 40. In contrast, in the differential amplification device of the third embodiment, the parallel resonance circuit is not used.

[0075] [Operation]

[0076] By making the diodes D1 and D2 conductive by the bias b1 applied from the bias circuit 21, a part of the input signal flows to the reference potential GND through the diodes D1 and D2. Thereby, the gain can be made to drop, and LPM can be realized.

[0077] On the other hand, by making the diodes D1 and D2 non-conductive by the bias b1 applied from the bias circuit 21, a part of the input signal does not flow to the reference potential GND through the diodes D1 and D2, and HPM can be realized without making the gain drop.

[0078] As described above, by the bias applied, LPM can be realized by making the diodes D1 and D2 conductive, and HPM can be realized by making the diodes D1 and D2 non-conductive.

[0079] As above, by adding diodes and making the diodes conductive or non-conductive by the applied bias, LPM and HPM can be achieved even without providing a structure dedicated to LPM. Thus, the differential amplification device can be miniaturized.

[0080] [4th Embodiment]

[0081] [Structure]

[0082] Figure 5 is a diagram showing an example of a differential amplification device 1c of the 4th embodiment of the present disclosure. Figure 5 is a diagram showing the input matching circuit MN1, the amplifiers 11 and 12, and the like of the 4th embodiment.

[0083] In the 4th embodiment shown in Figure 5 , the cathodes of the diodes D1 and D2, which are shunt diodes, are connected to each other and connected to a reference potential via a resistance element 53. At this time, when the resistance value of the resistance element 53 is made large to some extent, the second-order distortion input to the amplifiers 11 and 12, which are a differential pair, can be alleviated. Figure 5 The other structures of the 4th embodiment shown in Figure 2 are the same as those of the 1st embodiment described with reference to

[0084] [Operation]

[0085] By making the diodes D1 and D2 conductive by the bias b11, b12 applied from the bias circuit 21, a part of the input signal flows to the reference potential GND through the diodes D1 and D2. Thus, the gain can be made to drop, and LPM can be achieved.

[0086] On the other hand, the diodes D1 and D2 are made non-conductive by the bias b11, b12 applied from the bias circuit 21. Thus, a part of the input signal does not flow to the reference potential GND through the diodes D1 and D2, and HPM can be achieved without making the gain drop.

[0087] As above, by the applied bias, LPM can be achieved by making the diodes D1 and D2 conductive, and HPM can be achieved by making the diodes D1 and D2 non-conductive.

[0088] As above, by adding diodes and making the diodes conductive or non-conductive by the applied bias, LPM and HPM can be achieved even without providing a structure dedicated to LPM. Thus, the differential amplification device can be miniaturized.

[0089] [5th Embodiment]

[0090] [Structure]

[0091] Figure 6 This is a diagram illustrating an example of the differential amplifier device 1d according to the fifth embodiment of this disclosure. Figure 6 This diagram focuses on the input matching circuit MN1, amplifiers 11 and 12, etc., of the fifth embodiment. In the fifth embodiment, diodes D1 and D2 are also connected after the transformer 110, which serves as an input balun.

[0092] exist Figure 6 In the fifth embodiment shown, the bias line 73 is connected to the midpoint P21 of the inductor 112. The midpoint P21 is a virtual ground point for high-frequency signals. A series resonant circuit including an inductor 61 and a capacitor 33 is provided on the bias line 73. One end of the inductor 61 is connected in series with one end of the capacitor 33. The other end of the inductor 61 is connected to the midpoint of the secondary winding of the transformer 110, i.e., the inductor 112. The other end of the capacitor 33 is connected to the primary winding, i.e., the inductor 111, and the reference potential. A bias b1 is applied to the connection point of the inductor 61 and the capacitor 33. It should be noted that the inductor 61 can also be replaced by a signal line.

[0093] [action]

[0094] By utilizing the bias b1 applied from the bias circuit 21 to turn on diodes D1 and D2, a portion of the input signal flows to the reference potential GND through diodes D1 and D2. This allows for a decrease in gain, enabling LPM (Limited Power Management).

[0095] On the other hand, diodes D1 and D2 are turned off by applying a bias b1 from the bias circuit 21. As a result, a portion of the input signal will not flow to the reference potential GND through diodes D1 and D2, thus achieving HPM without loss of gain.

[0096] As described above, by applying a bias, LPM can be achieved by turning on diodes D1 and D2, and HPM can be achieved by turning off diodes D1 and D2.

[0097] Furthermore, the midpoint of the secondary winding of the input matching circuit MN1 is connected to the reference potential of the primary winding via a series resonant circuit. By pre-setting the resonant frequency of the series resonant circuit to match the frequency to be removed, for example, it is possible to remove the double-wave component with twice the fundamental frequency.

[0098] As described above, by adding a diode and using an applied bias to make the diode conduct or cut off, both LPM and HPM can be implemented without a dedicated LPM structure. Therefore, the miniaturization of differential amplifier devices is possible.

[0099] [Sixth Implementation]

[0100] [Structure]

[0101] Figure 7 is a diagram showing an example of the differential amplification device 1e of Embodiment 6 of the present disclosure. Figure 7 is an example of a structure of an amplifier between the input matching circuit MN1 and the output matching circuit MN2 of Embodiment 1 including two stages. The amplifier of the two-stage structure is connected in cascade via electromagnetic field coupling based on a transformer, so that the output of the front stage becomes the input of the rear stage.

[0102] As shown in Figure 7 , the differential amplification device 1e of Embodiment 6 has the transformer TR1 at the rear stage of the amplifiers 11-1 and 12-1. In addition, the differential amplification device 1e of Embodiment 6 has the amplifiers 11-2 and 12-2 at the rear stage of the transformer TR1. Furthermore, the differential amplification device 1e of Embodiment 6 has the output matching circuit MN2 at the rear stage of the amplifiers 11-2 and 12-2. The transformer TR1 includes the inductor 141-1 as a primary-side winding and the inductor 142-1 as a secondary-side winding.

[0103] The differential amplification device 1e of Embodiment 6 has the capacitors 31-1 and 31-2. The capacitors 31-1 and 31-2 correspond to the capacitors 31 in Figure 2 . The differential amplification device 1e of Embodiment 6 has the capacitors 32-1 and 32-2. The capacitors 32-1 and 32-2 correspond to the capacitors 32 in Figure 2 .

[0104] The differential amplification device 1e of Embodiment 6 has the resistance elements 51-1 and 51-2. The resistance elements 51-1 and 51-2 correspond to the resistance elements 51 in Figure 2 . The differential amplification device 1e of Embodiment 6 has the resistance elements 52-1 and 52-2. The resistance elements 52-1 and 52-2 correspond to the resistance elements 52 in Figure 2 .

[0105] The differential amplification device 1e of Embodiment 6 has the diodes D1 and D2 only at the first stage. The bias b11 output from the bias circuit 21 is applied to the anode of the diode D1. The bias b11 output from the bias circuit 21 is applied via the bias line 71. The parallel resonance circuit 41 is connected to the bias line 71. The parallel resonance circuit 41 includes the capacitor 331 and the inductor 341.

[0106] The bias b12 output from the bias circuit 21 is applied to the anode of the diode D2. The bias b12 output from the bias circuit 21 is applied via the bias line 72. The bias line 72 is connected to the parallel resonant circuit 42. The parallel resonant circuit 42 includes the capacitor 332 and the inductor 342.

[0107] Note that the bias b21 output from the bias circuit 22 is applied to the input side of the amplifier 11-1 via the resistive element 51-1. The bias b22 output from the bias circuit 22 is applied to the input side of the amplifier 12-1 via the resistive element 52-1. The bias b31 output from the bias circuit 22 is applied to the input side of the amplifier 11-2 via the resistive element 51-2. The bias b32 output from the bias circuit 22 is applied to the input side of the amplifier 12-3 via the resistive element 52-3.

[0108] [Action]

[0109] The output of the differential amplification circuit based on the amplifiers 11-1 and 12-1 is input to the differential amplification circuit based on the amplifiers 11-2 and 12-2 via the transformer TR1. The output of the differential amplification circuit based on the amplifiers 11-2 and 12-2 is output to the output terminal 202 via the output matching circuit MN2.

[0110] In the 6th embodiment, also by making the diodes D1 and D2 conductive by the biases b11 and b12 applied from the bias circuit 21, a part of the input signal flows to the reference potential GND through the diodes D1 and D2. By this, it is possible to make the gain drop, and it is possible to realize LPM.

[0111] On the other hand, by making the diodes D1 and D2 non-conductive by the biases b11 and b12 applied from the bias circuit 21. At this time, the parallel resonant circuits 41 and 42 are adjusted in advance to become open (i.e., impedance infinite) in the operation frequency. Therefore, there is no influence on the gain. By this, it is possible to realize HPM without making the gain drop.

[0112] As above, by the biases applied, it is possible to realize LPM by making the diodes D1 and D2 conductive, and it is possible to realize HPM by making the diodes D1 and D2 non-conductive.

[0113] Note that in the 7th embodiment, although the amplifiers are provided in two stages in the structure of the 1st embodiment, it is also possible to provide the amplifiers in two stages in any of the structure of the 2nd embodiment, the structure of the 3rd embodiment, the structure of the 4th embodiment, and the structure of the 5th embodiment.

[0114] As above, by adding a diode and making the diode conductive or non-conductive by an applied bias, LPM and HPM can be achieved even without providing a structure dedicated to LPM. Thus, the differential amplification device can be miniaturized.

[0115] [7th Embodiment]

[0116] [Structure]

[0117] Figure 8 is a diagram showing an example of the differential amplification device 1f of the 7th embodiment of the present disclosure. Figure 8 is an example of a structure of an amplifier between an input matching circuit MN1 and an output matching circuit MN2 employing the 1st embodiment including N stages (N is an integer of 2 or more, the same applies hereinafter). The amplifier of the N-stage structure is connected in cascade via electromagnetic field coupling based on a transformer, so that the output of the preceding stage becomes the input of the succeeding stage.

[0118] As shown in Figure 8 , the differential amplification device 1f of the 7th embodiment has a transformer TR1 in the succeeding stage of the amplifiers 11-1 and 12-1 of the 1st stage. In addition, the differential amplification device 1f of the 7th embodiment has amplifiers 11-2 and 12-2 of the 2nd stage in the succeeding stage of the transformer TR1. Furthermore, the differential amplification device 1f of the 7th embodiment has a transformer TR2 in the succeeding stage of the amplifiers 11-2 and 12-2. Hereinafter, the same applies to the differential amplification device 1f of the 7th embodiment, which has amplifiers 11-N and 12-N of the Nth stage in the succeeding stage of the transformer TR2. The differential amplification device 1f of the 7th embodiment has an output matching circuit MN2 in the succeeding stage of the amplifiers 11-N and 12-N of the Nth stage. The transformer TR1 includes an inductor 141-1 as a primary-side winding and an inductor 142-1 as a secondary-side winding. The transformer TR2 includes an inductor 141-2 as a primary-side winding and an inductor 142-2 as a secondary-side winding.

[0119] The differential amplification device 1f of the 7th embodiment has capacitors 31-1, 31-2,..., 31-N. The capacitors 31-1, 31-2,..., 31-N correspond to the capacitors 31 in Figure 2 . The differential amplification device 1f of the 7th embodiment has capacitors 32-1, 32-2,..., 32-N. The capacitors 32-1, 32-2,..., 32-N correspond to the capacitors 32 in Figure 2 .

[0120] The differential amplification device 1f of the 7th embodiment has resistance elements 51-1, 51-2,..., 51-N. The resistance elements 51-1, 51-2,..., 51-N correspond to the resistance elements 51 in Figure 2The differential amplification device 1f of the seventh embodiment has the resistive element 52-1, 52-2,..., 52-N. The resistive element 52-1, 52-2,..., 52-N corresponds to the resistive element 51 in the differential amplification device 1 of the first embodiment. Figure 2 The resistive element 52 in the differential amplification device 1f of the seventh embodiment.

[0121] The differential amplification device 1f of the seventh embodiment has the diodes D1 and D2 only at the first stage. The bias b11 output from the bias circuit 21 is applied to the anode of the diode D1. The bias b11 output from the bias circuit 21 is applied via the bias line 71. The bias line 71 is connected to the parallel resonant circuit 41. The parallel resonant circuit 41 includes the capacitor 331 and the inductor 341.

[0122] The bias b12 output from the bias circuit 21 is applied to the anode of the diode D2. The bias b12 output from the bias circuit 21 is applied via the bias line 72. The bias line 72 is connected to the parallel resonant circuit 42. The parallel resonant circuit 42 includes the capacitor 332 and the inductor 342.

[0123] Note that the bias b21 output from the bias circuit 22 is applied to the input side of the amplifier 11-1 via the resistive element 51-1. The bias b22 output from the bias circuit 22 is applied to the input side of the amplifier 12-1 via the resistive element 52-1. The bias b31 output from the bias circuit 22 is applied to the input side of the amplifier 11-2 via the resistive element 51-2. The bias b32 output from the bias circuit 22 is applied to the input side of the amplifier 12-3 via the resistive element 52-3. Hereinafter, similarly, the bias bn1 output from the bias circuit 22 is applied to the input side of the amplifier 11-N via the resistive element 51-N. The bias bn2 output from the bias circuit 22 is applied to the input side of the amplifier 12-N via the resistive element 52-N.

[0124] [Operation]

[0125] The output of the differential amplification circuit based on the amplifiers 11-1 and 12-1 is input to the differential amplification circuit based on the amplifiers 11-2 and 12-2 of the next stage via the transformer TR1. The output of the differential amplification circuit based on the amplifiers 11-2 and 12-2 is input to the differential amplification circuit based on the amplifiers of the next stage via the transformer TR2. Hereinafter, similarly, the output is sequentially input to the differential amplification circuit based on the amplifiers of the next stage. The output of the differential amplification circuit based on the amplifiers 11-N and 12-N of the Nth stage as the final stage is output to the output terminal 202 via the output matching circuit MN2.

[0126] In the seventh embodiment, the diodes Dl and D2 are made to be conductive by the bias bll and b12 applied from the bias circuit 21, and thus a part of the input signal flows to the reference potential GND through the diodes Dl and D2. Thus, the gain can be made to decrease, and the LPM can be realized.

[0127] On the other hand, the diodes Dl and D2 are made to be non-conductive by the bias bll and b12 applied from the bias circuit 21. At this time, the parallel resonance circuits 41 and 42 are previously adjusted to be open circuits (i.e., the impedance is infinite) in the operation frequency. Thus, the gain is not affected. Thus, the HPM can be realized without making the gain decrease.

[0128] As described above, by the applied bias, the LPM can be realized by making the diodes Dl and D2 to be conductive, and the HPM can be realized by making the diodes Dl and D2 to be non-conductive.

[0129] Note that, in the seventh embodiment, although the amplifier is made to be N stages in the structure of the first embodiment, the amplifier can be made to be N stages in any of the structure of the second embodiment, the structure of the third embodiment, the structure of the fourth embodiment, and the structure of the fifth embodiment.

[0130] As described above, by adding the diodes and making the diodes to be conductive or non-conductive by the applied bias, the LPM and the HPM can be realized even without providing a structure dedicated to the LPM. Thus, the differential amplification device can be made to be small in size.

Claims

1. A differential amplifier, comprising: Input terminals; An input balun is used to input the signal to the input terminal. Output terminals; A balun that outputs a signal to the output terminal; The first amplifier and the second amplifier are connected in parallel between the input balun and the output balun to output a differential signal. A first diode is disposed between the path between the input balun and the first amplifier and the reference potential; A second diode is disposed between the path between the input balun and the second amplifier and the reference potential; as well as A biasing circuit that applies a bias to the first diode and the second diode. The cathodes of the first diode and the second diode are connected to the reference potential. The differential amplifier includes a parallel resonant circuit, which is disposed between the first diode and the second diode and the bias circuit. The parallel resonant circuit includes an inductor and a capacitor connected in parallel.

2. The differential amplifier device according to claim 1, wherein, The input balun includes a primary winding and a secondary winding. The bias line used to apply the bias is connected to the secondary winding of the input balun.

3. The differential amplifier device according to claim 2, wherein, The bias line used to apply the bias is connected to the midpoint of the secondary winding of the input balun.

4. The differential amplifier according to any one of claims 1 to 3, wherein, The differential amplifier also includes a resistive element disposed between the cathode and the reference potential. The cathode is connected to the reference potential via the resistive element.

5. The differential amplifier device according to claim 3, wherein, The differential amplifier also includes a series resonant circuit disposed on the bias line. The series resonant circuit includes an inductor and a capacitor, and one end of the inductor is connected in series with one end of the capacitor. The other end of the inductor is connected to the midpoint of the secondary winding of the input balun. The other end of the capacitor is connected to the primary winding and the reference potential. The bias is applied to the connection point between the inductor and the capacitor.

6. The differential amplifier according to any one of claims 1 to 3, wherein, The differential amplifier includes multiple stages of the first amplifier and the second amplifier, which are cascaded together.

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