WO2016006445A1

WO2016006445A1 - Doherty amplifier and radio communication device

Info

Publication number: WO2016006445A1
Application number: PCT/JP2015/068184
Authority: WO
Inventors: 英樹丹後
Original assignee: 住友電気工業株式会社
Priority date: 2014-07-07
Filing date: 2015-06-24
Publication date: 2016-01-14
Also published as: JP2016019094A

Abstract

A Doherty amplifier (1) is provided with a carrier amplifier (3), a peak amplifier (2), and a 90-degree hybrid coupler (4) which divides an input signal between the carrier amplifier (3) and the peak amplifier (2). The 90-degree hybrid coupler (4) is provided with an input port to which the input signal is given, a pair of output ports which output a pair of divided signals having different phases from each other to the carrier amplifier (3) and the peak amplifier (2), and a first port (4a) which is an isolation port. A terminating device (5) which terminates the first port (4a) at an impedance substantially different from the characteristic impedance of a signal transmission path is connected to the first port (4a).

Description

Doherty amplifier and radio communication apparatus

The present invention relates to a Doherty amplifier and a wireless communication apparatus using the Doherty amplifier.

In recent years, mobile wireless communication systems such as mobile phones have been widened, and power amplifiers have improved wideband amplification characteristics such as high efficiency and low distortion characteristics over a wide frequency band, and Δ gain suppression. Is more desirable.
Here, the Δ gain is a difference between the maximum value and the minimum value of the gain when an input signal in a predetermined frequency band is amplified.

As a power amplifier for realizing high efficiency, a Doherty type amplifier (hereinafter also referred to as “Doherty amplifier”) including a carrier amplifier and a peak amplifier is known (see, for example, Patent Document 1). .

The Doherty amplifier is configured so that the carrier amplifier operates in class AB or class B and the peak amplifier operates in class C. As a result, when the instantaneous power is low, the peak amplifier operation is stopped and only the carrier amplifier is operated to increase the efficiency. When the instantaneous power is high, both amplifiers operate, so the saturation power is increased while maintaining high efficiency. Can do.

JP 2013-26658 A

An amplifying element used for a Doherty amplifier or the like is generally configured to obtain optimum amplification characteristics in a predetermined frequency band. For this reason, when a signal having a frequency outside the frequency band where the optimum amplification characteristic is obtained in the amplification element is amplified, deterioration of the amplification characteristic is inevitable.

Therefore, in the conventional Doherty amplifier, even if it is intended to set the frequency band of the input signal to be wider, it is difficult to satisfy the required Δ gain due to the amplification characteristics of the amplification element, etc. There has been a problem that an optimum gain characteristic cannot be obtained.

The present invention has been made in view of such circumstances, and an object thereof is to provide a Doherty amplifier and a wireless communication apparatus capable of adjusting gain characteristics.

A Doherty amplifier according to an embodiment includes a carrier amplifier, a peak amplifier, and a hybrid coupler that distributes an input signal to the carrier amplifier and the peak amplifier, and the hybrid coupler includes an input port to which the input signal is supplied. A pair of output ports for outputting a pair of distributed signals having different phases to the carrier amplifier and the peak amplifier, and an isolation port, and a transmission path for transmitting the input signal to the isolation port A termination device for terminating the isolation port with an impedance substantially different from the characteristic impedance is connected.

In addition, a wireless communication device according to another embodiment includes the Doherty amplifier.

According to the present invention, the gain characteristic can be adjusted.

It is a block diagram which shows the Doherty amplifier which concerns on one Embodiment. It is a circuit diagram showing an example of a circuit pattern when a Doherty amplifier is formed on a substrate. It is a block diagram which shows the structure of a termination device. It is a block diagram which shows the Doherty amplifier which concerns on other embodiment. It is a block diagram which shows the structure of the termination | terminus apparatus which concerns on other embodiment. It is a block diagram which shows the structure of the termination | terminus apparatus which concerns on other embodiment. It is a graph which shows an example of the result of an evaluation test.

[Description of Embodiment]
In research on Doherty amplifiers that can obtain stable amplification characteristics for wideband input signals, we focused on hybrid couplers that distribute input signals to carrier amplifiers and peak amplifiers. The isolation port setting was studied.
As a result, by connecting a capacitive element to the isolation port and adjusting the characteristic impedance of the terminal part, the frequency deviates from the frequency band where the optimum amplification characteristic can be obtained as the amplification element used in the Doherty amplifier. It has been found that even if the above signal is input, it can be adjusted so as to obtain a good gain characteristic.
The following embodiments have been made based on the above findings.

First, the contents of the embodiment will be listed and described.
(1) A Doherty amplifier according to an embodiment includes a carrier amplifier, a peak amplifier, and a hybrid coupler that distributes an input signal to the carrier amplifier and the peak amplifier, and the hybrid coupler is provided with the input signal. An input port; a pair of output ports for outputting a pair of distributed signals having different phases to the carrier amplifier and the peak amplifier; and an isolation port; and transmitting the input signal to the isolation port A termination device for terminating the isolation port with an impedance substantially different from the characteristic impedance of the transmission line is connected.

According to the Doherty amplifier configured as described above, the load impedance of the carrier amplifier when viewed from the output side of the Doherty amplifier is obtained by terminating the isolation port of the hybrid coupler with an impedance substantially different from the characteristic impedance of the transmission line. The balance with the load impedance of the peak amplifier can be changed. As a result, the gain characteristic as the Doherty amplifier can be adjusted.
Note that “impedance substantially different from the characteristic impedance of the transmission line” differs from the gain characteristic when the isolation port is terminated with the characteristic impedance of the transmission line to the extent that the gain characteristic is changed. It is shown that the impedance is not equal to the impedance of the isolation port.

(2) In the Doherty amplifier, the terminator preferably includes a capacitive element having one end connected to the isolation port and the other end grounded.
(3) In this case, the capacitance element preferably has a variable capacitance. Thereby, the impedance that terminates the isolation port can be adjusted appropriately, and the gain characteristic as the Doherty amplifier can be adjusted appropriately.

(4) In the Doherty amplifier, the termination device may include a resistance element having one end connected to the isolation port and the other end grounded.
(5) The resistance value of the resistance element may be variable. Thereby, the impedance that terminates the isolation port can be adjusted appropriately, and the gain characteristic as the Doherty amplifier can be adjusted appropriately.

(6) In the Doherty amplifier, an acquisition unit that acquires state information indicating states of the carrier amplifier and the peak amplifier, and a capacitance of the capacitive element based on the state information, or a resistance value of the resistive element It is preferable to further include a control unit that adjusts.
In this case, the impedance for terminating the isolation port can be adjusted more appropriately according to the states of the carrier amplifier and the peak amplifier, and the gain characteristics as the Doherty amplifier can be adjusted more appropriately.
(7) It is preferable that the state information is information indicating the temperatures of the carrier amplifier and the peak amplifier, or information indicating a usage period of the carrier amplifier and the peak amplifier.

(8) Moreover, the radio | wireless communication apparatus which concerns on other embodiment is provided with the amplification apparatus as described in said (1).

[Details of the embodiment]
Hereinafter, preferred embodiments will be described with reference to the drawings.
[1. (Overall configuration)
FIG. 1 is a block diagram illustrating a Doherty amplifier 1 according to an embodiment. The Doherty amplifier 1 is used for a base station apparatus or the like in a mobile communication system, and is used for amplifying a communication signal.

The Doherty amplifier 1 includes a peak amplifier 2, a carrier amplifier 3, and a 90-degree hybrid coupler 4 that distributes an input signal to the

amplifiers

2 and 3.
The 90-degree hybrid coupler 4 includes an input port, a pair of output ports, and an isolation port.
A peak amplifier 2 and a carrier amplifier 3 are connected to both output ports of the 90-degree hybrid coupler 4. Further, the input terminal Pin of the Doherty amplifier 1 is connected to the input port. A termination device 5 for terminating the isolation port is connected to the isolation port. Thereby, the 90-degree hybrid coupler 4 distributes the input signal given from the input terminal Pin to the peak amplifier 2 and the carrier amplifier 3 with substantially equal power.
The signal distributed to the peak amplifier 2 is given a phase difference of about 90 degrees (λ / 4) with respect to the signal distributed to the carrier amplifier 3 by the 90-degree hybrid coupler 4.

The output signal of the peak amplifier 2 and the output signal of the carrier amplifier 3 are combined by the output combining unit 6 at the subsequent stage of these

amplifiers

2 and 3. The output combining unit 6 is connected to the output terminal Pout of the Doherty amplifier 1. Therefore, the signal combined by the output combining unit 6 is output from the output terminal Pout.

The peak amplifier 2 and the output combining unit 6 are connected by a line 7.
The carrier amplifier 3 and the output combining unit 6 are connected by a line 9.
The line 9 has a line length for providing a phase difference of λ / 4 between the output signal of the peak amplifier 2 passing through the line 7 and the output signal of the carrier amplifier 3 passing through the line 9. Yes.

The carrier amplifier 3 and the peak amplifier 2 are configured using LD-MOSFETs (Lateral Diffusion Metal Oxide Semiconductor Field Effect Transistors) as amplifying elements.

The carrier amplifier 3 is configured to operate as class AB or class B. The peak amplifier 2 is configured to operate as a class C.
Therefore, the carrier amplifier 3 always operates, and the peak amplifier 2 starts operating when the carrier amplifier 3 approaches the saturation state. As a result, when the instantaneous power is small, the operation of the peak amplifier 2 is stopped and only the carrier amplifier 3 is operated to increase the efficiency. When the instantaneous power is large, both amplifiers can be operated.

In this embodiment, the saturation output level of the peak amplifier 2 is higher than the saturation output level of the carrier amplifier 3, and the Doherty amplifier 1 of this embodiment constitutes a so-called asymmetric Doherty amplifier. .

FIG. 2 is a circuit diagram showing an example of a circuit pattern when the Doherty amplifier 1 is formed on a substrate.
In the figure, on the substrate B, the above-described peak amplifier 2, carrier amplifier 3, 90-degree hybrid coupler 4, output synthesis unit 6, line 7 and line 9 are provided.

The 90-degree hybrid coupler 4 includes four

ports

4a, 4b, 4c, and 4d. Among these ports, the second port 4b is an input port to which the input terminal Pin is connected. Of the four ports, the third port 4c and the fourth port 4d constitute a pair of output ports that output a pair of distributed signals having different phases to the carrier amplifier 3 and the peak amplifier 2.

A matching circuit 16 is provided on the line 15 that connects the fourth port 4 d of the 90-degree hybrid coupler 4 and the peak amplifier 2.
A line 7 is connected to the output terminal 2 a of the peak amplifier 2 via a matching circuit 17. Therefore, the line 7 connects the output combining unit 6 and the output terminal 2 a of the peak amplifier 2 via the matching circuit 17.
A matching circuit 19 is provided on the line 18 connecting the third port 4 c of the 90-degree hybrid coupler 4 and the carrier amplifier 3.
The line 9 is connected to the output terminal 3 a of the carrier amplifier 3 via the matching circuit 20. Therefore, the line 9 connects the output combining unit 6 and the carrier amplifier 3 via the matching circuit 20. As described above, the line 9 is a line for giving a phase difference of λ / 4 between the output signal of the peak amplifier 2 passing through the line 7 and the output signal of the carrier amplifier 3 passing through the line 9. The length is secured.

The output synthesizer 6 and the output terminal Pout are connected by an output line 21 that performs impedance conversion.

Further, in the 90-degree hybrid coupler 4, the first port 4a is an isolation port, to which the above-described termination device 5 is connected.

[2. (Terminating device)
FIG. 3 is a block diagram showing the configuration of the termination device 5.
As shown in the figure, the termination device 5 includes a resistor 5a and a capacitor 5b.
The resistor 5a has one end connected to the first port 4a of the 90-degree hybrid coupler 4 and the other end grounded. The resistor 5a is preferably set to have a resistance value equal to or higher than the characteristic impedance set for the signal transmission path for transmitting the input signal or higher than the impedance when viewed from the outside of the first port 4a. .
One end of the capacitor 5b is connected to the first port 4a of the 90-degree hybrid coupler 4, and the other end is grounded.

Here, normally, the first port 4a, which is an isolation port, is terminated by connecting a resistor having substantially the same resistance value as the characteristic impedance of the signal transmission path.
On the other hand, the termination device 5 of the Doherty amplifier 1 of the present embodiment connects the capacitor 5b as a capacitive element in addition to the resistor 5a, so that the first port 4a (isolation port) of the 90-degree hybrid coupler 4 is connected. ) Is terminated with an impedance substantially different from the characteristic impedance of the signal transmission line.
As a result, the balance between the load impedance of the carrier amplifier 3 and the load impedance of the peak amplifier 2 when viewed from the output side of the Doherty amplifier 1 can be changed. As a result, the gain characteristic of the Doherty amplifier 1 can be appropriately adjusted so that a stable gain can be obtained while the frequency band of the input signal is set to a wider band.
As a result, even if the frequency band of the input signal is set to a wider band, a stable gain can be obtained, and the maximum increase / decrease width of the gain change of the output signal when the input signal within the predetermined frequency band is amplified. The Δ gain that is a value can be suppressed.

The above-mentioned “impedance substantially different from the characteristic impedance of the signal transmission path” means that the gain characteristic changes with respect to the gain characteristic when the first port 4a is terminated with the characteristic impedance of the signal transmission path. It indicates that the impedances are different to the extent that they are generated, or impedances that do not match the impedance of the first port 4a.

In the present embodiment, if the capacitor 5b is connected to the first port 4a in addition to the resistor 5a, the Δ gain can be suppressed. However, the Δ gain can be more effective by appropriately setting the capacitance of the capacitor 5b. Can be suppressed. For example, the capacitance of the capacitor 5b is preferably set to 0.1 pF or more. Furthermore, in order to obtain a Δ gain suppression effect more effectively, the capacitance of the capacitor 5b is preferably set to 3 pF or less.

In addition, the resistor 5a is normally terminated with a resistor having the same resistance value as the characteristic impedance of the signal transmission line. Therefore, as described above, the resistance value of the resistor 5a is set to be equal to or higher than the characteristic impedance of the signal transmission line. Is done. Further, in order to effectively obtain the Δ gain suppression effect, the resistance value of the resistor 5a is set to 500Ω or less. Further, the resistance value of the resistor 5a is preferably set to 100Ω or less, a more stable gain can be obtained in a wide band, and the Δ gain can be more effectively suppressed.

[3. Regarding other embodiments]
FIG. 4 is a block diagram illustrating a Doherty amplifier 1 according to another embodiment, and FIG. 5 is a block diagram illustrating a configuration of a termination device 5 according to another embodiment.
The Doherty amplifier 1 according to the present embodiment includes

temperature sensors

31 and 32 for detecting the temperatures of the peak amplifier 2 and the carrier amplifier 3, and the termination device 5 includes a varactor diode 5c instead of the capacitor 5b. In addition, the present embodiment is different from the above-described embodiment in that a control unit 33 that applies a voltage to the varactor diode 5c is provided.

In FIG. 4, the temperature sensor 31 detects the temperature of the peak amplifier 2 and gives a detection signal indicating the detection result to the control unit 33.
The temperature sensor 32 detects the temperature of the carrier amplifier 3 and gives a detection signal indicating the detection result to the control unit 33.
These

temperature sensors

31 and 32 constitute an acquisition unit that acquires information (state information) indicating the temperature of each

amplifier

2 and 3, and the control unit 33 (FIG. 5) uses the acquired information as a detection signal. To give.

As shown in FIG. 5, the termination device 5 of the present embodiment includes the above-described varactor diode 5 c and a control unit 33 in addition to the resistor 5 a. The varactor diode 5c has a cathode side connected to the first port 4a of the 90-degree hybrid coupler 4 and an anode side grounded. A capacitor 5d is connected between the first port 4a and the varactor diode 5c.

The control unit 33 is connected to a line connecting the capacitor 5d and the varactor diode 5c, and has a function of applying a voltage to the cathode side of the varactor diode 5c. The capacitor 5d is provided so as to block the voltage applied by the control unit 33 from reaching the first port 4a, and is set to have a capacity that causes a short circuit in the frequency band of the input signal in the present embodiment. . Therefore, the capacitor 5d does not function as a capacitive element for the input signal.
In this embodiment, the capacitor 5d is set to have a short-circuit capacity. However, a capacitor having a smaller capacity can be used together with the varactor diode 5c to form a capacitor element.

The control part 33 can adjust the capacity | capacitance of the said varactor diode 5c by controlling the voltage applied to the varactor diode 5c.
The varactor diode 5 c constitutes a capacitive element provided in the termination device 5. The control unit 33 can adjust the impedance of the termination device 5 that terminates the first port 4a by making the capacitance of the varactor diode 5c variable.

The control unit 33 adjusts the capacitance of the varactor diode 5c according to the temperatures of the peak amplifier 2 and the carrier amplifier 3 indicated by the detection signals from the

temperature sensors

31 and 32.
The control unit 33 stores a table in which the temperatures of the peak amplifier 2 and the carrier amplifier 3 are associated with the voltage value applied to the varactor diode 5c.

The voltage value to be applied to the varactor diode 5c registered in this table is set based on the gain characteristics of the Doherty amplifier 1 with respect to changes in the temperature of the peak amplifier 2 and the carrier amplifier 3 that have been grasped in advance by experiments or the like. The value is set so as to suppress the Δ gain as much as possible at each temperature.

When the detection signal is given from the

temperature sensors

31 and 32, the control unit 33 refers to the table and sets a voltage value to be applied to the varactor diode 5c according to the contents registered in the table. The controller 33 applies the set voltage value to the varactor diode 5c.
Thereby, the control unit 33 adjusts the impedance of the termination device 5 that terminates the first port 4a by adjusting the capacitance of the varactor diode 5c according to the temperature of the peak amplifier 2 and the carrier amplifier 3, and the Δ gain is The gain characteristic of the Doherty amplifier 1 can be adjusted so as to be suppressed.

The gain characteristics of the peak amplifier 2 and the carrier amplifier 3 change according to the temperature. According to this embodiment, the temperature of the peak amplifier 2 and the carrier amplifier 3 is detected, and the Doherty amplifier 1 is detected according to the temperature. Therefore, even if the gain characteristics of the peak amplifier 2 and the carrier amplifier 3 change according to the temperature, the gain characteristics as the Doherty amplifier 1 can be adjusted appropriately.

In the present embodiment, information indicating temperature is acquired as information indicating the states of the peak amplifier 2 and the carrier amplifier 3, and the capacitance of the varactor diode 5c is adjusted based on this information so that the Δ gain is suppressed. As shown, when the control unit 33 can count the usage elapsed period, which is a period that has elapsed since the peak amplifier 2 and the carrier amplifier 3 are actually used, the control unit 33 As the information indicating the state of the amplifier 3, the impedance of the termination device 5 that terminates the first port 4a is adjusted by adjusting the capacitance of the varactor diode 5c based on the elapsed usage period, and the Doherty amplifier so that the Δ gain is suppressed. The gain characteristic as 1 can be adjusted.

The gain characteristics of the peak amplifier 2 and the carrier amplifier 3 may change over time according to the usage elapsed period. According to the above configuration, even if the peak amplifier 2 and the carrier amplifier 3 change over time, The gain characteristic of the Doherty amplifier 1 can be appropriately adjusted so that a gain characteristic that suppresses the Δ gain according to the change with time can be obtained.

In the present embodiment, the resistor 5a has a fixed resistance value, but a variable resistor having a variable resistance value may be used.
Further, when a variable resistor is used as the resistor 5a, the control unit 33 can be configured to control so as to adjust the resistance value of the resistor 5a.
With this configuration, the range of adjustment can be expanded, and the Δ gain can be more effectively suppressed.

In each of the above embodiments, the termination device 5 includes the resistor circuit 5a and the capacitor 5b or the varactor diode 5c, and the first port 4a is terminated. However, the termination device 5 includes the capacitor 5b. The first port 4a may be terminated with an impedance substantially different from the characteristic impedance of the transmission line.
Furthermore, as shown to Fig.6 (a), it can also be set as the structure which the termination | terminus device 5 is equipped with the varactor diode 5c, and terminates the 1st port 4a. Also in this case, the control unit 33 controls the varactor diode 5c in the same manner as in the above embodiment, and adjusts the impedance of the termination device 5 that terminates the first port 4a, so that the gain characteristic as the Doherty amplifier 1 is more appropriate. Can be adjusted.

Moreover, the termination | terminus device 5 can also be set as the structure which terminates the 1st port 4a by providing only the resistor 5a made into the impedance substantially different from the characteristic impedance of a transmission line.
Further, as shown in FIG. 6B, the termination device 5 may be configured to terminate the first port 4a only by the variable resistance circuit 5e. Even in this case, the control unit 33 controls the resistance value of the variable resistance circuit 5e in accordance with the information indicating the states of the peak amplifier 2 and the carrier amplifier 3, and terminates the first port 4a, as in the above embodiment. By adjusting the impedance of the termination device 5, the gain characteristic of the Doherty amplifier 1 can be adjusted appropriately.

In the present embodiment, the case where the Doherty amplifier 1 is configured by the peak amplifier 2 and the carrier amplifier 3 using an LD-MOSFET as an amplifying element is illustrated, but other amplifying elements such as GaN-HEMT (GaN-High) are exemplified. You may comprise the Doherty amplifier 1 using the amplifier which used Electron Mobility Transistor) as an amplification element.
Further, in the present embodiment, the case where the Doherty amplifier 1 is configured as an asymmetric type Doherty amplifier is illustrated, but even when the Doherty amplifier 1 is configured as a symmetric type Doherty amplifier, the above-described termination device 5 is used to suppress Δ gain. be able to.

[4. Evaluation test)
Next, an evaluation test related to the Doherty amplifier 1 having the above configuration will be described.
In the evaluation test, the Doherty amplifier 1 having the configuration described in the above embodiment is modeled by computer simulation, and the frequency of the input signal when the input signal of constant power is applied to the modeled Doherty amplifier 1 and the output signal The relationship with gain was obtained, and the change in gain when the frequency of the input signal was changed was evaluated.

As a modeled configuration, a configuration in which the termination device 5 shown in FIG. 3 is connected to the Doherty amplifier 1 is adopted. Moreover, it set as follows about the resistor 5a and the capacitor | condenser 5b which the termination | terminus apparatus 5 has.
Example 1: Resistance value of the resistor 5a = 50Ω, capacitance of the capacitor 5b = 1pF
Example 2: Resistance value of resistor 5a = 100Ω, capacitance of capacitor 5b = 1pF
Example 3: Resistance value of resistor 5a = 200Ω, capacitance of capacitor 5b = 1 pF
Example 4: Resistance value of resistor 5a = 100Ω, no capacitor 5b Comparative example 1: Resistance value of resistor 5a = 50Ω, no capacitor 5b

The resistor 5a of Comparative Example 1 was set to the same value as the characteristic impedance (50Ω) set for the signal transmission path of a general communication device.
In the first to fourth embodiments, as described above, the impedance at which the termination device 5 terminates the first port 4a by changing the resistance value of the resistor 5a or connecting the capacitor 5b is the transmission line. The impedance was set to be different from the characteristic impedance (50Ω).

FIG. 7 is a graph showing an example of the result of the evaluation test.
In the figure, the horizontal axis represents the frequency of the input signal, and the vertical axis represents the gain of the output signal.
In the figure, solid line A indicates Example 1, broken line B indicates Example 2, dashed-dotted line C indicates Example 3, broken line D indicates Example 4, and alternate long and two short dashes line E indicates Comparative Example 1.

In the figure, the output of the first embodiment at the position m4 where the frequency of the input signal is 2.5 GHz, the position m5 where the frequency of the input signal is 2.7 GHz, and the position m6 where the frequency of the input signal is 2.9 GHz. The signal gain was determined as follows.
Gain of output signal of embodiment 1 Position m4: 13.420 dB
Position m5: 12.513 dB
Position m6: 10.994 dB

Further, the gain of the output signal of Example 2 at each of the position m4, the position m5, and the position m6 was obtained as follows.
Gain of output signal of embodiment 2 Position m4: 14.634 dB
Position m5: 11.709 dB
Position m6: 12.176 dB

The gain of the output signal of Example 3 at each of the position m4, the position m5, and the position m6 was obtained as follows.
Gain of output signal of embodiment 3 Position m4: 15.403 dB
Position m5: 11.090 dB
Position m6: 13.099 dB

The gain of the output signal of Example 4 at each of the position m4, the position m5, and the position m6 was obtained as follows.
Output signal gain of Example 4 Position m4: 14.094 dB
Position m5: 11.979 dB
Position m6: 8.591 dB

The gain of the output signal of Comparative Example 1 at each of the position m4, the position m5, and the position m6 was obtained as follows.
Output signal gain of Comparative Example 1 Position m4: 12.5622 dB
Position m5: 12.626 dB
Position m6: 8.646 dB

As shown in FIG. 7 and the above numerical values, the gains appear to be larger than those of Comparative Example 1 in each of Examples 1 to 3 at a high frequency such as 2.9 GHz where the gain is decreased in Comparative Example 1. I can confirm.
From this, it can be seen that each of the first to third embodiments can adjust the gain characteristic of the Doherty amplifier so as to obtain a stable gain in a wide frequency range as compared with the first comparative example.

Further, in Example 4, the gain characteristic is different from that in Comparative Example 1. From this result, it can be seen that the Doherty amplifier of this embodiment can adjust the gain characteristic as the Doherty amplifier.

From the above results, according to the Doherty amplifier 1 according to the present embodiment, by terminating the first port 4a (isolation port) of the 90-degree hybrid coupler 4 with an impedance different from the characteristic impedance of the transmission line, the Doherty amplifier 1 The gain characteristics can be adjusted, and even if the frequency band of the input signal is set to a wider band, it can be adjusted to suppress the Δ gain, and it has been confirmed that a stable gain can be obtained. .
In the evaluation test, an input signal having a frequency ranging from 2.5 GHz to 2.9 GHz was evaluated. For example, an input signal having a frequency band different from that of the evaluation test such as a signal having a lower frequency band was amplified. Even so, the Doherty amplifier of the present embodiment can adjust the gain characteristics as described above.

[5. Others]
The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the meanings described above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

DESCRIPTION OF SYMBOLS 1 Doherty amplifier 2 Peak amplifier 2a Output terminal 3 Carrier amplifier 3a Output terminal 4 90 degree hybrid coupler 4a 1st port (isolation port)
4b Second port (input port)
4c 3rd port (output port)
4d 4th port (output port)
DESCRIPTION OF SYMBOLS 5 Termination apparatus 5a Resistor 5b Capacitor 5c Varactor diode 5d Capacitor 5e Variable resistance circuit 6 Output composition part 7 Line 9 Line 15 Line 16 Matching circuit 17 Matching circuit 18 Line 19 Matching circuit 20 Matching circuit 21 Output line 31 Temperature sensor 32 Temperature sensor 32 33 Controller B Board

Claims

A carrier amplifier;
A peak amplifier;
A hybrid coupler for distributing an input signal to the carrier amplifier and the peak amplifier,
The hybrid coupler includes an input port to which the input signal is given, a pair of output ports that output a pair of distributed signals having different phases to the carrier amplifier and the peak amplifier, and an isolation port,
A Doherty amplifier connected to the isolation port is a termination device that terminates the isolation port with an impedance substantially different from a characteristic impedance of a transmission path for transmitting the input signal.
The Doherty amplifier according to claim 1, wherein the terminator includes a capacitive element having one end connected to the isolation port and the other end grounded.
The Doherty amplifier according to claim 2, wherein the capacitance element has a variable capacitance.
The Doherty amplifier according to any one of claims 1 to 3, wherein the termination device includes a resistance element having one end connected to the isolation port and the other end grounded.
The Doherty amplifier according to claim 4, wherein the resistance element has a variable resistance value.
An acquisition unit for acquiring state information indicating a state of the carrier amplifier and the peak amplifier;
The Doherty amplifier according to claim 3, further comprising a control unit that adjusts the capacitance of the capacitive element or the resistance value of the resistive element based on the state information.
The Doherty amplifier according to claim 6, wherein the state information is information indicating a temperature of the carrier amplifier and the peak amplifier, or information indicating an elapsed usage period of the carrier amplifier and the peak amplifier.
A wireless communication apparatus comprising the Doherty amplifier according to claim 1.