阅读说明：本技术 高频放大器 (High frequency amplifier ) 是由 木元雄资 于 2020-04-09 设计创作，主要内容包括：本发明涉及高频放大器。一种高频放大器(1),其包括：输入端子P<Sub>IN</Sub>；输出端子P<Sub>OUT</Sub>；晶体管(5),其被配置为放大施加到输入端子P<Sub>IN</Sub>的RF信号；匹配电路(9)和反射电路(7),该匹配电路(9)用于RF信号的基波,该反射电路(7)用于相对于基波的谐波,匹配电路(9)和反射电路(7)被串联连接在晶体管(5)和输出端子P<Sub>OUT</Sub>之间；提取电路(13),其被配置为提取出现在输出端子P<Sub>OUT</Sub>处的谐波；处理电路(15、17),其被配置为调整由提取电路(13)提取的谐波的相位和强度；以及多路复用电路(19),其被配置为将由处理电路(15、17)处理的谐波多路复用到由反射电路(7)反射的谐波并将被多路复用的谐波提供给晶体管(5)。(The present invention relates to a high frequency amplifier. A high frequency amplifier (1), comprising: input terminal P IN (ii) a Output terminal P OUT (ii) a A transistor (5) configured to amplify the voltage applied to the input terminal P IN The RF signal of (1); a matching circuit (9) for a fundamental wave of the RF signal and a reflection circuit (7) for a harmonic wave with respect to the fundamental wave, the matching circuit (9) and the reflection circuit (7) being connected in series between the transistor (5) and the output terminal P OUT To (c) to (d); an extraction circuit (13) configured to extract the presence at the output terminal P OUT A harmonic of (d); a processing circuit (15, 17) configured to adjust the phase and intensity of the harmonics extracted by the extraction circuit (13); and a multiplexing circuit (19) Configured to multiplex the harmonics processed by the processing circuit (15, 17) to the harmonics reflected by the reflection circuit (7) and to provide the multiplexed harmonics to the transistor (5).)

1. A high frequency amplifier comprising:

an input terminal;

an output terminal;

a transistor configured to amplify an input high frequency signal applied to the input terminal;

a matching circuit for a fundamental wave of the input high-frequency signal and a reflection circuit for a harmonic with respect to the fundamental wave, the matching circuit and the reflection circuit being connected in series between the transistor and the output terminal;

an extraction circuit configured to extract harmonics appearing at the output terminal;

a processing circuit configured to adjust a phase and intensity of the harmonic extracted by the extraction circuit; and

a multiplexing circuit configured to multiplex the harmonic processed by the processing circuit to the harmonic reflected by the reflection circuit and to provide the multiplexed harmonic to the transistor.

2. The high frequency amplifier according to claim 1,

the harmonic is a second harmonic of the fundamental.

3. The high-frequency amplifier according to claim 1 or claim 2,

the reflection circuit is a transmission line having one end connected to a transmission line extending between the transistor and the matching circuit and the other end opened, and has a length equal to one quarter of the wavelength of the harmonic.

4. The high frequency amplifier according to any one of claim 1 through claim 3,

the extraction circuit includes: :

one transmission line which is open at one end and has a length equal to one quarter of the wavelength of the fundamental wave; and

another transmission line having a length equal to one-fourth of the wavelength of the fundamental wave, and one end of which is connected to the other end of the one transmission line and the other end of which is connected to the output terminal.

5. The high frequency amplifier according to any one of claim 1 through claim 3,

the multiplexing circuit includes:

one transmission line which is open at one end and has a length equal to one quarter of the wavelength of the fundamental wave; and

another transmission line having a length equal to one-fourth of the wavelength of the fundamental wave and having one end connected to the other end of the one transmission line and the other end connected to a transmission line extending between the transistor and the matching circuit.

6. The high frequency amplifier according to any one of claim 1 to claim 5,

the processing circuit includes:

another transistor configured to amplify or attenuate the extracted harmonics; and

a transmission line configured to shift a phase of the extracted harmonic, and the other transistor and the transistor are the same size.

7. The high frequency amplifier according to claim 6,

the processing circuit further includes a filter disposed between the extraction circuit and the another transistor, the filter configured to remove the fundamental wave.

Technical Field

The present disclosure relates to a high frequency amplifier that amplifies a high frequency signal.

Background

Conventional high frequency amplifiers that amplify high frequency waves such as microwaves have been used for various purposes such as radio communication and radar. Examples of such high-frequency amplifiers include class-F amplifiers and inverse class-F amplifiers that can operate efficiently to suppress power loss. For example, an amplifier disclosed in japanese unexamined patent publication No.2005-204208 includes an odd harmonic signal generating circuit that generates an odd harmonic signal with respect to a fundamental wave signal to be amplified, and a rectangular wave signal generating circuit that multiplexes the odd harmonic signal to the fundamental wave signal. Further, the amplifier disclosed in WO2017/122271a includes a harmonic supply circuit that supplies a harmonic contained in an RF signal amplified by a first transistor to a second transistor, and a fundamental wave supply circuit that supplies a fundamental wave contained in the RF signal to the second transistor.

However, the structure disclosed in japanese unexamined patent publication No.2005-204208 described above requires a signal source that generates a harmonic signal that causes an increase in power consumption. Further, in the structure disclosed in the above-mentioned WO2017/122271a, harmonics are attenuated toward the end face of the intrinsic transistor due to parasitic components on the output side of the transistor, and the impedance of the harmonics on the end face of the intrinsic transistor cannot be set to a true optimum impedance, which makes it impossible to sufficiently improve the power efficiency of the entire amplifier by matching only using passive elements. The present disclosure provides a high frequency amplifier capable of sufficiently improving power efficiency.

Disclosure of Invention

A high frequency amplifier according to an aspect of the present disclosure includes: an input terminal; an output terminal; a transistor configured to amplify an input high frequency signal applied to an input terminal; a matching circuit for inputting a fundamental wave of a high-frequency signal and a reflection circuit for a harmonic wave with respect to the fundamental wave, the matching circuit and the reflection circuit being connected in series between the transistor and the output terminal; an extraction circuit configured to extract harmonics appearing at the output terminal; a processing circuit configured to adjust a phase and intensity of the harmonic extracted by the extraction circuit; and a multiplexing circuit configured to multiplex the harmonics processed by the processing circuit to the harmonics reflected by the reflection circuit and supply the multiplexed harmonics to the transistor.

Drawings

Fig. 1 is a block diagram showing a schematic structure of a high-frequency amplifier according to an embodiment;

fig. 2 is a circuit diagram showing the structure of the high frequency amplifier shown in fig. 1;

fig. 3A is a graph showing output power when the high frequency amplifier does not multiplex the second harmonic and Power Added Efficiency (PAE) for the input power; and

fig. 3B is a graph showing output power when the high frequency amplifier multiplexes the second harmonic and Power Added Efficiency (PAE) for the input power.

Detailed Description

A description will be given below of embodiments of the present disclosure with reference to the accompanying drawings. Note that in the description of the drawings, the same components are denoted by the same reference numerals, and redundant description will be omitted.

[ Structure of high-frequency Amplifier ]

Fig. 1 is a block diagram showing the structure of a high-frequency amplifier 1 according to the embodiment. The high frequency amplifier 1 is used for radio communication or radar, for example, to amplify a high frequency signal. As shown in FIG. 1, the high frequency amplifier 1 includes an input terminal P_INAnd an output terminal P_OUTThe input matching circuit 3, the transistor 5, the harmonic reflection circuit 7, the fundamental wave matching circuit 9, the harmonic extraction circuit 13, and the phase shifter 15, the amplifier 17, and the multiplexing circuit 19. Input terminal P_INA high-frequency signal (RF signal) is received from the high-frequency signal source 21 via a transmission line 23 having a characteristic impedance Z0. On the other hand, the output terminal P_OUTIs connected to a load 25 having a characteristic impedance Z0. The harmonic reflection circuit 7, the fundamental wave matching circuit 9, and the harmonic extraction circuit 13 are provided at an input terminal P_INAnd an output terminal P_OUTAre connected in series.

The input matching circuit 3 matches the input impedance of the transistor 5 with the characteristic impedance of the transmission line 23. Specifically, the input matching circuit 3 matches the impedance when the transistor 5 is viewed from the control terminal (gate terminal) of the transistor 5 with the characteristic of the transmission line 23 when the transistor is viewed from the terminal of the input matching circuit 3 connected to the transmission line 23.

For example, the transistor 5 is a field effect crystal for amplifying the RF signalA transistor (FET). The following description will be given with FETs used as transistors, but the same description applies to bipolar transistors. An RF signal is input to the gate serving as an input of the transistor 5 via the transmission line 23 and the input matching circuit 3. The source of the transistor 5 is grounded and the drain thereof is connected to the output terminal P via the harmonic reflection circuit 7 and the fundamental wave matching circuit 9_OUT。

The harmonic reflection circuit 7 and the fundamental wave matching circuit 9 are each formed of a transmission line and have a specific impedance and a specific length. The harmonic reflection circuit 7 transmits a fundamental component contained in the output of the transistor 5 and reflects the harmonic component toward the transistor 5. The fundamental wave matching circuit 9 is to observe the output terminal P from the end face of the drain of the transistor 5_OUTThe impedance in time is matched to an optimum load impedance that allows optimization of design parameters such as output power and power added efficiency of the transistor 5.

Usually, the slave input terminal P_INThe input RF signal contains not only fundamental waves but also harmonic components. Further, the input and output characteristics of the transistor 5 are nonlinear, and even when an RF signal containing no distortion (no harmonic component) is input, a significant harmonic component appears in the signal resulting from amplifying the RF signal. The harmonic reflection circuit 7 reflects this harmonic component toward the transistor 5 and transmits only the fundamental wave. The fundamental wave matching circuit 9 performs impedance matching on the optimum load impedance on the fundamental wave thus transmitted.

The harmonic extraction circuit 13 extracts the harmonic component having passed through the fundamental wave matching circuit 9 and outputs the harmonic component at the output terminal P_OUTAnd (c) occurs. The harmonic reflection circuit 7 reflects most of the harmonic components appearing at the output of the transistor 5; however, it is in principle impossible to make the transmission amount zero. Further, the fundamental wave matching circuit 9 transmits only the fundamental wave and also reflects or absorbs harmonic components other than the fundamental wave; however, it is not possible to make the harmonic component at the output of the fundamental wave matching circuit 9 zero. At the output terminal P_OUTA small but significant harmonic component will be present. The harmonic extraction circuit 13 extracts the harmonic appearing at the output terminal P_OUTThe phase shifter (processing circuit) 15 adjusts the phase of the harmonic component by rotating the phase, and the amplifier (processing) is operatedCircuit) 17 adjusts the intensity of the harmonic component by amplifying or attenuating the harmonic component. Then, the harmonic components processed as described above are multiplexed to the harmonic reflected by the harmonic reflecting circuit 7 by the multiplexing circuit 19 for harmonic, and the multiplexed harmonic is supplied to the drain of the transistor 5.

As described above, the output signal of the transistor 5 always contains such harmonic components. When the harmonic component is supplied to the load 25 via an external circuit such as an output transmission line, extra power is consumed in the drain resistance of the transistor 5 or the external circuit. Therefore, it is preferable that the reflection intensity to be used for the harmonic is set higher when the load 25 is viewed from the drain output of the transistor 5. This is equivalent to the case where no harmonic component is output to the external circuit. Further, the reflected harmonics enable suppression of power loss by causing waveform shaping at the end face of the drain of the transistor 5.

However, the conventional output matching circuit including only the fundamental wave matching circuit cannot sufficiently improve the reflection intensity of the harmonic component. Even if the optimum matching is performed with the fundamental wave, the harmonic component is not necessarily given the optimum reflection condition. Further, the structure in which the harmonic reflection circuit and the fundamental wave matching circuit are connected in series can cause the harmonic reflection circuit to shift the matching condition for the fundamental wave from an optimum value. One of the harmonic reflection circuit and the fundamental wave matching circuit may become an element that deteriorates the optimum condition of the other.

Further, the transistor 5 generally includes an element portion (a portion included in the semiconductor element) and a portion (a bonding wire, a bonding pad, a lead terminal, or the like) which extends outward as a part of the element portion and connects the element portion to an external circuit. With the element portion, even when the matching condition and the reflection condition are satisfied for both the fundamental wave and the harmonic wave, using a circuit formed as an actual device including a bonding wire, a bonding pad, a lead terminal, and the like makes it difficult to obtain a satisfactory combination of the matching condition and the reflection condition.

According to the present embodiment, it is provided that the signal appears at the output terminal P_OUTIs amplified or attenuated and then supplied to the structure of the drain output of the transistor 5, thereby improvingThe harmonic reflection intensity of the transistor 5 is increased and the output terminal P is increased_OUTThe fundamental component present.

A description will be given of a specific circuit configuration of the high-frequency amplifier 1 with reference to fig. 2.

As shown in fig. 2, the high-frequency amplifier 1 includes a main transmission line including transmission lines 21a to 21d and a planar waveguide 31 represented by a parallel circuit of an inductor and a capacitor, and a sub-transmission line, and is connected between a transistor 5 and an output terminal P_OUTThe secondary transmission line extends from the node C2 of the primary transmission line to the node C4 of the primary transmission line via the transistor 17 a.

The harmonic reflection circuit 7 is connected to a node C1 of the main transmission line between the fundamental wave matching circuit 9 and the multiplexing circuit 19, and includes a transmission line 7a having a length equal to λ/8. Here, λ denotes the wavelength of the fundamental wave, and λ/8 is equal to one quarter of the wavelength of the second harmonic. One end of the transmission line 7a is open; therefore, it can be said that the node C1 on the main transmission line is short-circuited for the second harmonic component and thus forms a reflection circuit of the second harmonic propagating through the main transmission line.

The harmonic extraction circuit 13 includes two transmission lines 13a, 13b having a length equal to λ/4 of the fundamental wave. One end of the transmission line 13b is open and the other end is connected to one end of the transmission line 13a, and the other end of the transmission line 13a is connected to the output terminal P via a node C2 on the main transmission line_OUT. As a result, the node C3 between the two transmission lines 13a, 13b on the sub-transmission line can be regarded as short-circuited for the fundamental wave. On the other hand, the node C3 is open to the second harmonic. Since the length of the transmission line 13a is equal to λ/4 of the fundamental wave, the node C2 connected to the other end of the transmission line 13a on the main transmission line is open to both the fundamental wave and the second harmonic wave.

The transmission line 13a and the two transmission lines 21c and 21d form a fundamental wave matching circuit 9. In particular, since the transmission line 7a forming the reflection circuit for the second harmonic is inserted into the main transmission line, the characteristic impedance of the main transmission line disturbed by the transmission line 7a is required to match the fundamental wave from the downstream side of the main transmission line of the transmission line 7 a. Since the lengths of the two transmission lines 13a, 13b are equal to half the wavelength of the second harmonic, the transmission lines 13a, 21c, 21d forming the fundamental wave matching circuit 9 do not affect the second harmonic. As a result, some of the second harmonic that leaks without being reflected by the transmission line 7a flows from the node C2 into the sub-transmission line.

The second harmonic flowing into the sub transmission line through the node C3 reaches the transistor 17a, which amplifies or attenuates the second harmonic, via the transmission lines 15a, 17b, and then reaches the multiplexing circuit 19 via the transmission lines 17C, 15 b. The transistor 17a is the same in type and size as the transistor 5. The transmission lines 15a, 15b form a phase shifter 15 that shifts the phase of the second harmonic flowing into the sub-transmission line. Further, one end of the transmission line 15a is connected to a filter circuit 29 including a resistor, an inductor, and a capacitor. A filter circuit 29 is interposed between the harmonic extraction circuit 13 and the transistor 17a to remove the fundamental component flowing into the sub-transmission line to prevent the transistor 17a from being affected by the fundamental component. Typically, the fundamental component is overwhelmingly larger in magnitude than the second harmonic component. Although the transmission lines 21c, 21d, 13a forming the fundamental wave matching circuit 9 suppress the inflow of the fundamental wave to the sub-transmission line, the filter circuit 29 prevents the fundamental wave component flowing into the sub-transmission line from reaching the transistor 17 a. Therefore, it is desirable that the filter circuit 29 have a filter structure having excellent frequency cutoff characteristics. The other end of the transmission line 17c is connected to one end of the transmission line 15b forming the phase shifter 15.

The multiplexing circuit 19 comprises two transmission lines 19a, 19b, each having a length equal to λ/4 of the fundamental wave. I.e. the length of the transmission lines 19a, 19b is equal to half the wavelength of the second harmonic. One end of the transmission line 19b is open and the other end is connected to one end of the transmission line 19 a. The other end of the transmission line 19a is connected to a node C4 between the transistor 5 on the main transmission line and the transmission line 7 a. Since one end of the transmission line 19b is open, the node C5 located between the two transmission lines 19a, 19b can be considered as short-circuited for the fundamental wave and open for the second harmonic. As a result, the node C4 on the main transmission line can be considered open to both fundamental and second harmonics. That is, the multiplexing circuit 19 exhibits the same effect as that exhibited by the two transmission lines 13a, 13b included in the harmonic extraction circuit 13. That is, the transmission lines 21a, 21b and the transmission line 19a on the main transmission line function as a matching circuit for the fundamental wave, and have no influence on the second harmonic.

The above-described high-frequency amplifier 1 is capable of extracting the second harmonic from the output of the transistor 5 after adjusting the amplitude and phase of the second harmonic and feeding back the second harmonic to the drain of the transistor 5. This makes it possible to make the intensity of the second harmonic at the drain of the transistor 5 higher and to make it appear at the output terminal P_OUTThe fundamental wave of (a) is relatively higher, which in turn can improve the power efficiency of the high frequency amplifier 1 as a whole. More specifically, this enables the reflection intensity of the second harmonic to be higher and reduces heat loss due to waveform shaping, which in turn enables the power efficiency of the high-frequency amplifier 1 to be improved, as compared with a structure in which the harmonic processing circuit is formed of only a passive circuit.

Fig. 3A and 3B show the evaluation results of the output power and the Power Added Efficiency (PAE) for the input power in the high-frequency amplifier 1. Fig. 3A is the evaluation results of the output power and PAE when the second harmonic is not multiplexed in the present embodiment, and fig. 3B is the evaluation results of the output power and PAE when the second harmonic is multiplexed in the present embodiment. In each graph, a curve G1 represents the change in output power with respect to input power, and a curve G2 represents PAE with respect to input power. As shown in the graphs, although the output power when the input power is 20dBm is approximately equal to 31dBm in each graph, the maximum power added efficiency is improved from 62% of the conventional efficiency to about 73% in the present embodiment including the multiplexing circuit for the second harmonic.

According to the present embodiment, returning the second harmonic to the drain of the transistor 5 enables the second harmonic reflected by the harmonic reflection circuit 7 to be equivalently amplified to be returned to the transistor 5, which in turn enables the efficiency for the fundamental wave to be improved. That is, in the high-frequency amplifier 1, the harmonic reflected by the transmission line 7a and the harmonic extracted and adjusted in amplitude and phase by the harmonic extracting circuit 13, the phase shifter 15, the amplifier 17, and the multiplexing circuit 19 are multiplexed to the output at the drain of the transistor 5. This makes it possible to sufficiently increase the voltage reflection coefficient of the harmonic wave at the end face of the intrinsic portion of the transistor 5.

Further, in the high-frequency amplifier 1, the harmonic extraction circuit 13 includes transmission lines 13a, 13b, and the multiplexing circuit 19 includes transmission lines 19a, 19 b. This configuration allows the harmonic extraction circuit 13 and the multiplexing circuit 19 to extract and multiplex the harmonics to the output without affecting the propagation characteristics of the fundamental wave of the output of the transistor 5.

The high frequency amplifier 1 further includes a filter circuit 29. This enables harmonics to be efficiently extracted from the output of the transistor 5 and fed back to the output.

Further, according to the present embodiment, the second harmonic corresponding to twice the fundamental frequency is extracted from the drain of the transistor 5 and fed back. This structure can efficiently generate a voltage signal converted into a pseudo rectangular wave at the drain of the transistor 5.

Further, according to the present embodiment, the amplifier 17 includes a transistor 17a having the same size as the transistor 5. This structure allows the design parameters of the two transistors to have commonality.

Having described and illustrated the principles of the present invention in accordance with a preferred embodiment, it should be apparent to those skilled in the art that the invention may be modified in arrangement and detail without departing from such principles. The present invention is not limited to the specific structure disclosed according to the present embodiment. Accordingly, all modifications and changes coming within the scope and spirit of the claims are claimed.

According to the above-described embodiment, the second harmonic is extracted from the output of the transistor 5 by the harmonic extraction circuit 13, and the second harmonic thus extracted is multiplexed to the output of the transistor; however, the second harmonic may be any harmonic such as a third harmonic or a fourth harmonic. Further, another structure may be used in which a plurality of harmonic processing circuits such as the secondary transmission lines according to the above-described embodiments are provided, and each processing corresponds to one of different harmonics. Even with such a structure, the voltage reflection coefficient of the harmonic at the end face of the intrinsic portion of the transistor 5 can be sufficiently increased to improve power efficiency.