WO2008050440A1

WO2008050440A1 - Power amplifier

Info

Publication number: WO2008050440A1
Application number: PCT/JP2006/321425
Authority: WO
Inventors: Katsuhiro Sakai; Shinji Ueda; Takashi Enoki
Original assignee: Panasonic Corporation
Priority date: 2006-10-26
Filing date: 2006-10-26
Publication date: 2008-05-02

Abstract

A power amplifier wherein a simple circuit arrangement is used to prevent the output power level and distortion from degrading due to the variation of a load. In this power amplifier, if the impedance of an antenna (114) varies, a VSWR determining means (112) determines a VSWR value of the output stage of an amplifying element (111). When the VSWR value determined by the VSWR determining means (112) is small, it can be estimated that the matched impedance is in the vicinity of 50 ohms, so that it can be determined that the output power level is stable and the distortion level satisfies a permissible value, with the result that a current control means (113) performs no current control of the amplifying element (111). When the VSWR value determined by the VSWR determining means (112) is large, it can be estimated that the output power level and distortion degrade for a small current value of the amplifying element (111), so that the current control means (113) performs a current control such that the current of the amplifying element (111) becomes large.

Description

Specification

Power amplifier

Technical field

TECHNICAL FIELD [0001] The present invention relates to a power amplifier used for a portable wireless device and the like, and more particularly to a power amplifier that supplies stable power when a load changes.

Background art

Conventionally, as an example of a power amplifier whose load may fluctuate, a power amplifier that is mounted on a portable radio device and amplifies a transmission signal is known. In portable radios, the impedance of the antenna always varies depending on the surrounding environment.

[0003] This type of power amplifier is typically impedance matched to provide the maximum gain or output power level for a particular load value. However, when the impedance of the antenna, which is the load of this type of power amplifier, fluctuates, impedance mismatch may occur at the output stage of the power amplifier, and the desired power may not be transmitted for the antenna force. Furthermore, there is a risk that power efficiency and distortion will deteriorate. As a conventional technique for solving such a problem, a method is known in which an isolator is provided at the output stage of a power amplifier and the load is not varied.

[0004] As another method for suppressing the degradation of the output power level that occurs when the load fluctuates, if the degradation of the power level output from the power amplifier is detected, the load fluctuation is detected. A technique is also disclosed in which impedance adjustment is performed so that an optimum output power level is always obtained by switching the matching circuit of the output stage of the power amplifier to a matching circuit of a different impedance (for example, Patent Documents). 1). According to this technology, deterioration of the output power level of the power amplifier is always detected, and when the output power level deteriorates, it is determined that the load has changed, and the impedance of the matching circuit of the output stage in the power amplifier is switched. In order to obtain a more optimal output power level. In addition, according to this technique, a configuration for detecting the level of reflected power from a load is disclosed as means for detecting deterioration of the output power level.

Patent Document 1: Japanese Patent Laid-Open No. 9-83403 Disclosure of the invention

Problems to be solved by the invention

[0005] However, in the conventional power amplifier, the load is not changed by using the isolator! /, And the output power level and the distortion are not degraded. Since the shape of the device becomes larger than that of other components, problems such as the inability to make a portable wireless device small and light can occur.

[0006] Further, in the method of switching the matching circuit of the output stage of the power amplifier to a matching circuit having a different impedance when the load fluctuates, as in the power amplifier described in Patent Document 1 described above, the impedance of the different impedance is reduced. Since it is necessary to provide multiple matching circuits, the entire matching circuit may become large. In addition, even if the impedance is matched and the output power level is relatively improved by switching the matching circuit, there is no means for preventing distortion degradation. Therefore, there is a possibility that the power amplifier cannot be used. In addition, the power amplifier described in Patent Document 1 describes a configuration in which the matching circuit is selected so that the reflected power is minimized, but in this configuration, all the matching circuits are compared. As a result, if the minimum value of the reflected power itself is large, there is a problem that the effect of improving the output power level cannot be obtained.

[0007] Further, in the power amplifier described in Patent Document 1 above, since there are many combinations of matching circuits to be switched, the power amplifier itself is provided with a matching circuit corresponding to all impedance matching. Problems such as enlargement also occur. Furthermore, since the matching process of the matching circuit to be switched according to the load variation is performed, there is a problem that it takes time to perform the process of selecting the optimum matching circuit. Although a configuration using a variable matching circuit as a matching circuit is also described, depending on the range in which the impedance can be varied, as a result of comparison for all matching circuits, the minimum reflected power is the same as described above. If the value itself is large, the output power level may not be improved much. As for the combinations for selecting the values of the variable elements of the variable matching circuit, there are various combinations of variable elements as described above, so that the matching circuit is compared to select the optimum matching circuit. Long processing time There is also a risk.

[0008] An object of the present invention is to provide a power amplifier such as a single amplifier or a Doherty amplifier that can prevent deterioration of output power level and distortion against load fluctuations with a simple circuit configuration.

Means for solving the problem

[0009] The power amplifier according to the present invention has an amplifying element for amplifying power, and a degree of reflection by a standing wave generated by interference between a traveling wave output from the amplifying element and a reflected wave input to the amplifying element. VSWR detection means for detecting the VSWR value, and a current flowing through the amplifying element based on the VSWR value detected by the VSWR detection means so that the power level exceeds the first threshold value and the distortion level becomes the second threshold value or less. And a current control means for controlling.

[0010] A power amplifier according to the present invention includes a reflection element that detects a reflection coefficient that is a ratio of an amplification element that multiplies power and a traveling wave output from the amplification element and a reflected wave input to the amplification element. And current control for controlling the current flowing through the amplifying element so that the power level exceeds the first threshold and the distortion level is equal to or lower than the second threshold based on the reflection coefficient detected by the reflection coefficient detecting means. Means.

The invention's effect

[0011] According to the power amplifier of the present invention, the VSWR value or reflection coefficient indicating the degree of signal reflection is monitored, and the current value of the power amplifier is always controlled to an appropriate value or range according to these values. Therefore, it is possible to prevent the output power level and distortion from being deteriorated even when the load of the power amplifier fluctuates. In addition, since it becomes possible to prevent deterioration of distortion, it can also be applied to portable radio devices that are used under ambient environment conditions where antenna impedance is severe, which has been impossible until now. Furthermore, even when the power supply voltage of the power amplifier drops, distortion can be prevented from being deteriorated, so that it can be used even when the battery voltage of the portable radio device is reduced. The time can be extended.

Brief Description of Drawings

[0012] [FIG. 1] In order to introduce the present invention, the output power level and distortion level in the Doherty amplifier Schematic characteristic diagram showing the characteristics of the

[Fig. 2] Diagram showing measurement points measured to obtain the approximate characteristics of output power level and distortion shown in Fig. 1.

[3] Basic configuration diagram of a typical Doherty amplifier

[Fig.4] Equivalent circuit showing the impedance at each node when the peak amplifier is OFF in the low power region in the Doherty amplifier shown in Fig.3

[Fig.5] Equivalent circuit showing the impedance at each node when the peak amplifier is ON in the high power region in the Doherty amplifier shown in Fig.3

6] Block diagram showing the basic configuration of the single-configuration power amplifier according to Embodiment 1 of the present invention.

[7] A first block diagram in which the single-configuration power amplifier according to Embodiment 2 of the present invention is used in a two-stage non-configuration.

8] A second block diagram in which the single-configuration power amplifier according to Embodiment 2 of the present invention is used in a two-stage non-configuration.

[9] A third block diagram in which the single-configuration power amplifier according to Embodiment 2 of the present invention is used in a two-stage non-configuration.

FIG. 10 is a block diagram showing the first configuration of the VSWR detection means in Embodiment 3 of the present invention.

FIG. 11 is a block diagram showing the second configuration of the VSWR detection means in the third embodiment of the present invention.

FIG. 12 is a block diagram showing the third configuration of the VSWR detection means in the third embodiment of the present invention.

[13] Block diagram showing the configuration of the current control means for controlling the power supply of the amplifying element in the fourth embodiment of the present invention

14] Block diagram showing the configuration of the current control means for controlling the bias voltage of the amplifying element in the fourth embodiment of the present invention.

15] Block diagram showing the configuration of the current control means for controlling the current source of the amplifying element in the fourth embodiment of the present invention. FIG. 16 is a block diagram showing a configuration of current control means for controlling the matching circuit of the output stage of the amplifier element in the fourth embodiment of the present invention.

FIG. 17 is a block diagram showing a configuration of current control means for performing variable phase control in Embodiment 4 of the present invention.

FIG. 18 is a block diagram showing a configuration of current control means for controlling the distribution ratio of the current of the amplifying element in the fourth embodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

The power amplifier of the present invention includes a VSWR detection means for detecting a VSWR value of a standing wave generated by interference between a traveling wave output from the power amplifier camera and a reflected wave reflected at the antenna end, and a VSWR detection means And a current control means for controlling the current flowing through the power amplifier based on the detected value (that is, the VSWR value) detected. Instead of the VS WR detection means, a configuration including a reflection coefficient detection means for detecting a reflection coefficient that is a ratio of a traveling wave and a reflected wave may be adopted.

[0014] The VSWR value (voltage standing wave ratio) is the degree to which a part of the signal is reflected on the circuit when a high-frequency signal passes through the device (that is, the degree of signal reflection). It is widely used as an indicator of high frequency characteristics. When this VSWR value is 1, it is an ideal state where there is no reflection at all. The larger the reflection, the larger the VSWR value, and the larger the signal loss. A standing wave is a wave in which the reflected wave interferes with the original traveling wave and does not change the node or belly of the wave, but only the amplitude changes. The state of reflection depends on the magnitude of this amplitude. (For example, the impedance of the antenna) can be known. For example, the degree of impedance matching between the cable and antenna is indicated by the V SWR value.

[0015] With the configuration of the power amplifier as described above, the current control means flows to the power amplifier based on the VSWR value detected by the VSWR detection means or the reflection coefficient detected by the reflection coefficient detection means. By appropriately controlling the current, it is possible to prevent deterioration of the output power level and distortion of the power amplifier.

<Introduction process of the present invention> As a result of the present invention, the inventors of the present invention conducted an experiment using a Dono and Tee amplifier in a current ratio (IcZlp) of the carrier current Ic to the peak current Ip of the peak amplifier and the reflection coefficient γ of the power. Was found to be related to the deterioration of the output power level and distortion of the power amplifier. As a result, by monitoring the VSWR value or reflection coefficient and appropriately controlling the current value of the power amplifier, it will not cause degradation of output power level and distortion even if load fluctuation occurs in the power amplifier. The conclusion was reached that this is possible. The introduction process of the invention having such a process will be described below.

FIG. 1 is a schematic characteristic diagram showing characteristics of output power level and distortion level in a Doherty amplifier in order to introduce the present invention. The horizontal axis represents the current ratio (IcZlp) between the carrier current Ic of the carrier amplifier and the peak current Ip of the peak amplifier (IcZlp), and the left vertical axis represents the distortion level ACLR (Adjacent Channel Leakage power Ratio) [dBc] The right vertical axis represents Pout [dBm] indicating the output power level. The horizontal axis shows the current ratio threshold A, the left vertical axis shows the ACLR threshold (ie, distortion threshold) B, and the right vertical axis shows the Pout threshold (ie, power threshold). In addition, the characteristic diagram of the lower solid line in Fig. 1 shows the ACLR characteristics (that is, the distortion level characteristics) when the reflection coefficient γ is varied. In addition, the characteristic diagram of the upper dashed line in Fig. 1 shows the Pout characteristic (that is, the output power level characteristic) when the reflection coefficient γ is changed.

FIG. 2 is a diagram showing measurement points measured to obtain the approximate characteristics of output power level and distortion shown in FIG. In Fig. 2, the points 0.1, 0.3, 0.6, 0.7, and 1.0 of the circles are concentric circles indicating the reflection coefficients Ί. Note that Re (γ) on the horizontal axis represents the real axis of the reflection coefficient, and ιπι (γ) on the vertical axis represents the imaginary axis of the reflection coefficient. In addition, 1 to 12 on the circumference show the measurement points when the load phase (that is, the impedance of the antenna) is changed 360 ° at 30 ° intervals. That is, this figure shows each measurement point when the phase of the reflection coefficient γ is changed by 30 ° by 0.1, 0.3, 0.6, 0.7, and 1.0.

[0019] The schematic characteristic diagram of FIG. 1 will be described with reference to the measurement points in FIG. 2. In the measurement of the output power level (Pout) and distortion level (ACLR) in FIG. 1, the reflection coefficient γ is small. When the reflection coefficient γ is slightly large (for example, γ = 0. 6) ) And when the reflection coefficient γ is large (for example, when γ = 0.7), the measurement points on the circumference of Fig. 2 are phased at 90 ° intervals of 1, 4, 7, and 10. The measurement data when measuring 4 points at is shown.

[0020] In FIG. 1, when Pout (output power level) on the right vertical axis is higher than the power threshold C, the output power level is good, and ACLR (distortion level) on the left vertical axis is the distortion threshold B. A lower V indicates that the distortion level is good!

In the characteristic of the output power level indicated by the broken line on the upper side of FIG. 1, when the reflection coefficient γ is small, the output power level is above the power threshold C, and therefore the output power level characteristic is good. However, as the reflection coefficient γ increases, the output power level decreases, and when the reflection coefficient 0 becomes very large, the output power level falls below the power threshold C (allowable value) and can be tolerated as power deterioration increases. Disappear. In other words, when the reflection coefficient γ increases, the power reflection increases, so the output power decreases. However, if the current ratio (IcZlp) on the horizontal axis is increased, the output power level is improved, and if the current ratio (IcZlp) is greater than the current ratio threshold A, the output power is increased even if the reflection coefficient γ is very large. The power level exceeds the power threshold C and the power degradation falls within the allowable range.

[0022] Further, in the distortion characteristic of the solid line on the lower side of Fig. 1, when the reflection coefficient γ is small, the distortion level is lower than the distortion threshold value で, so the distortion characteristic is good. However, as the reflection coefficient y increases, the distortion level (ACLR) increases, and when the distortion level (ACLR) exceeds the distortion threshold value Β (allowable value), the deterioration of the distortion increases and becomes unacceptable. However, if the current ratio (IcZlp) on the horizontal axis is increased, the distortion level (ACLR) decreases, and if the current ratio (IcZlp) is greater than the current ratio threshold A, the reflection coefficient γ becomes very large. However, the distortion level (ACLR) is below the distortion threshold B, and the distortion degradation falls within the allowable range.

[0023] From the above, when the reflection coefficient γ is large (for example, when γ = 0.6 or γ = 0.7), both the output power level and distortion are good when the current ratio (IcZlp) is large. I can see that This means that as the carrier current Ic increases, the linearity of the carrier amplifier becomes better and the distortion becomes better. Or, by reducing the peak current Ip, the influence of distortion of the peak amplifier means that the distortion has improved due to the short period. Alternatively, the sum Ids (= Ic + Ip) of the carrier current Ic and peak current Ip is large. It can be seen that both the output power level and the distortion characteristics are good. This is because the characteristics of the carrier amplifier are mainly seen in the case of the Doherty amplifier. Therefore, if the carrier current Ic is increased, the linearity of the Dono and Tee amplifiers is improved and the distortion characteristics are improved. Means.

[0024] In other words, the current ratio (IcZlp) contributes to the performance improvement of the Dono and Tee amplifiers, and is considered to be a large ratio. Since the peak amplifier is biased with class C bias, the peak current Ip of the peak amplifier This means that when the ratio is large, the ratio of contribution to the performance improvement of the Doherty amplifier becomes smaller and the distortion characteristics worsen. However, if the peak current Ip is small, the distortion characteristics can be improved by taking the optimum value of the peak current Ip when the load is 50 Ω.

[0025] Next, in the above data, we found a clue to improve the output power level and distortion characteristics in a Doherty amplifier in which both a carrier amplifier and a peak amplifier are operating. Let us consider whether it is possible to improve the output power level and distortion characteristics by decreasing the current and increasing the current value. For this reason, some matters related to the present invention regarding the Doherty amplifier will be described.

In recent years, Dono and Tee amplifiers have attracted attention as power amplifiers that amplify transmission signals with high efficiency. The Doherty amplifier, which is favorably used for power amplifiers such as portable radios, was first devised by W.H. Doherty in 1936, and is introduced, for example, in Non-Patent Document 1 below.

[0027] Non-Patent Document 1: W.H.Doherty, "A New High Efficiency Power Amplifier For Modular ed Wave", Proceeding of the Institude of Radio Engineers, Vol. 24, No. 9, September 193 6, ppl l63-1182

FIG. 3 is a basic configuration diagram of a general Doherty amplifier. The Doherty amplifier includes two amplifiers called a carrier amplifier 101 and a peak amplifier 102 and three λλ4 lines A, B, and C forces. Only the carrier amplifier 101 operates in the low power region, and the carrier amplifier 101 and the peak amplifier 102 are biased to operate together in the high power region. Next, the principle of how the Doherty amplifier operates with high efficiency will be schematically described. FIG. 4 is an equivalent circuit showing the impedance at each node when the peak amplifier 102 is OFF in the low power region in the Dono / Tee amplifier shown in FIG. In other words, this figure is an equivalent circuit diagram showing the impedance seen from the load 103 side from each node when the Dono and Tee amplifiers shown in FIG. 3 operate in the low power region, and the impedance Z is connected to the load 103.

0

In this case, the impedance when the load 103 side is viewed from each node when the peak amplifier 102 is OFF is expressed.

FIG. 5 shows an equivalent circuit showing the impedance at each node when the peak amplifier 102 is ON in the high power region in the Dono / Tee amplifier shown in FIG. In other words, this figure is an equivalent circuit diagram showing the impedance as seen from the load 103 side from each node when the Dono / Ty amplifier shown in FIG. 3 operates in the high power region. When connected, the negative from each node when the peak amplifier 102 is turned on.

0

It represents the impedance when looking at the load 103 side.

[0031] λ Ζ4 line C directly connected to load 103 causes impedance Z of load 103 to be Ζ /

0 0

Converted to 2. Since the peak amplifier 102 is turned off at low power, the output impedance of the peak amplifier 102 is opened as shown in FIG. Therefore, λ Ζ 4 lines Α Force is the same impedance as seen from the load 103 side Ζ

0 Z2. Furthermore, impedance Z Z2 is converted in impedance by λ Z4 line A, and the load is loaded from carrier amplifier 101.

0 1

The impedance of the 03 side is 2Z.

0

On the other hand, at the time of high power, as shown in FIG. 5, the peak amplifier 102 is turned on, and the peak amplifier 102 supplies power to the load 103. At this time, both the impedance of the λ 力 4 line A force viewed from the load 103 side and the impedance viewed from the peak amplifier 102 toward the load 103 side are Z. Also, the impedance when looking at the load 103 side from λ Ζ4 line Α

0

And λ Ζ4 line Α have the same characteristic impedance, the impedance of the carrier amplifier 101 viewed from the load 103 side is also Z. From the above, load 1 from carrier amplifier 101

0

The impedance seen in 03 is 2Z at low power operation and at high power operation.

0

Is powerful to become Z.

0

[0033] Therefore, when the load impedance of the carrier amplifier 101 is 2Z, the saturation power is reduced. However, when the load impedance is Z, the saturation power is high.

0

This design makes it possible to achieve high-efficiency operation over a high dynamic range.

[0034] In the operation mode of the Doherty amplifier as described above, the result of Fig. 1 shows that the carrier amplifier 101 and the peak amplifier 102 are operating in the high power region as shown in Fig. 5. Is. At this time, the impedance Z seen from the output stage of the carrier amplifier 101 becomes equal to the impedance Z of the load 103. Thus, carrier amplifier 1

0 0

The characteristics of 01 are considered to be similar to those of Doherty amplifier. Therefore, the output power level and distortion characteristics of the Doherty amplifier obtained in Fig. 1 can be extended to a single amplifier.

Therefore, in order to facilitate the explanation of a specific embodiment of the power amplifier according to the present invention, a single amplifier having a single power amplifier is taken as an example, and deterioration and distortion of the output power level are taken as an example. A method for preventing the deterioration of the material will be described in detail. Note that in the drawings used in the following embodiments, the same constituent elements are denoted by the same reference numerals, and redundant description is omitted as much as possible. In the following explanation, the embodiment will be described in the case of using the VSWR detection means for detecting the VSWR value indicating the reflection degree of the signal, but the reflection coefficient for detecting the reflection coefficient instead of the VSWR detection means. Detection means may be used. When the reflection coefficient detection means is used, the VSWR detection means should be read as the reflection coefficient detection means.

In the first embodiment, a method for preventing deterioration of output power level and distortion when a single configuration power amplifier is used will be described. FIG. 6 is a block diagram showing a basic configuration of a single-configuration power amplifier according to Embodiment 1 of the present invention. This power amplifier includes an amplifying element 111, a VSWR detection means 112, and a current control means 113, and an antenna 114 is connected to the output of the VSWR detection means 112. The VSWR detection means 112 has a function of detecting the VSWR value of the amplification element 111, and the current control means 113 controls the current value of the amplification element 111 based on the VSWR value detected by the VSWR detection means 112. . Instead of the VSWR detection means 112, the antenna 114 Reflection coefficient detection means for detecting a reflection coefficient, which is the ratio of the traveling wave and the reflected wave from the antenna 114, may be provided.Hereinafter, in each embodiment, the VSWR detection means 112 is provided, and the reflection coefficient detection means is provided. When equipped, the VSWR detection means 112 is replaced with the reflection coefficient detection means 112.

First, detection of load fluctuation performed by the VSWR detection unit 112 will be described. The VSWR detection means 112 at the output stage of the amplifying element 111 detects the load fluctuation. That is, if the value of VSWR detected by the VSWR detection means 112 has changed, it is determined that the impedance of the antenna 114 has changed. Of course, when the reflection coefficient detecting means 112 is provided at the output stage of the amplifying element 111, if the reflection coefficient detected by the reflection coefficient detecting means 112 changes, the impedance of the antenna 114 changes. Judge.

Next, the current control of the amplification element 111 performed by the current control unit 113 will be described. If the VSWR value detected by the VS WR detection means 112 is small, the matching impedance is considered to be close to 50 Ω, so it is determined that the distortion is satisfied at the same time as the stability of the output power level. The control means 113 does not control the current of the amplification element 111. In addition, when the VSWR value detected by the VSWR detection means 112 is large, it is considered that the output power level and distortion are degraded when the current value of the amplification element 111 is small. Current control is performed so that the current increases. Of course, when the reflection coefficient detecting means 112 is provided at the output stage of the amplifying element 111, the current control means 113 determines the current of the amplifying element 111 when the reflection coefficient detected by the reflection coefficient detecting means 112 is small. Control is not performed, but when the reflection coefficient is large, it is considered that the output power level and distortion have deteriorated when the current value of the amplifying element 101 is small. Therefore, the current control means 113 has a large current in the amplifying element 111. Current control is performed so that

In the second embodiment, a method for preventing deterioration of output power level and distortion when a single-configuration power amplifier is used in a two-stage balanced configuration will be described. FIG. 7 is a first block diagram in which a single-configuration power amplifier according to Embodiment 2 of the present invention is used in a two-stage balance configuration. The configuration of the power amplifier in Fig. 7 is shown in Fig. 6. The configuration is basically the same as that of the power amplifier, but the amplification device 11 la and the amplification device 11 lb having the same capacity are balanced in two stages. Note that the two-stage configuration of the amplifying elements ll la and 11 lb may be a Dono and tee amplifier, but the circuit in that case may be configured as shown in FIG. In addition, the present invention can be realized even if a single-configuration power amplifier has a balanced configuration of three or more stages.

The VSWR detection means 112 of the second embodiment shown in FIG. 7 is provided after the output of the amplification element 11 la and the output of the amplification element 111b are combined. Since the VSWR detecting means 112 performs the same method as in FIG. The reflection coefficient detection means 112 may be used instead of the VSWR detection means 112.

[0041] For the current control of the amplifying element 11 la and the amplifying element 11 lb performed by the current control means 113, if the VSWR value detected by the VSWR detection means 112 is small, a balanced configuration of two or more stages in a single configuration In addition, since the matching impedance is considered to be close to 50 Ω in both the Doherty configuration, it is judged that the distortion level also satisfies the allowable value at the same time, and current control is not performed.

[0042] On the other hand, regarding the current control of the amplifying element 11 la and the amplifying element 11 lb performed by the current control means 113, when the VSWR value is large, the balance configuration of two or more stages in the single configuration and the donut configuration The current control method is different. In other words, in a balance configuration with two or more stages in a single configuration, when the VSWR value is large, it is considered that the output power level and distortion are degraded when the current value of each amplifier element llla, 111b is small. Current control is performed by the current control means 1 13 so as to increase the current value of each amplification element 11 la, 11 lb.

[0043] In the Doherty configuration, when the VSWR value is large, it is considered that the output power level and distortion are degraded due to the current value of each of the amplifying elements ll la and 11 lb. Thus, the current value of each amplification element 11 la, 11 lb is appropriately controlled.

That is, in FIG. 7, the amplifying element 11 la is regarded as a carrier amplifier, the amplifying element 11 lb is regarded as a peak amplifier, Ic is the carrier current of the carrier amplifier, Ip is the peak current of the peak amplifier, and Ic + When Ip = Ids, the current control unit 113 performs the following current control.

[0045] The current ratio (IcZlc) between the carrier current Ic and the peak current Ip is small! Therefore, the current control means 113 controls the current of the carrier amplifier (amplifying element 11 la) and the peak amplifier (amplifying element 11 lb) and sets the current ratio (IcZlc) to a desired value or more to prevent distortion deterioration. . Further, since the distortion is degraded when the carrier current Ic is small, the current control means 113 controls the current of the carrier amplifier (amplifying element 11 la), and the carrier current Ic is set to a desired value or more to distort the carrier current Ic. Prevent deterioration. If the peak current Ip is large, the distortion deteriorates. Therefore, the current control means 113 controls the current of the peak amplifier (amplifier element 1 ib) so that the current value of the peak current Ip is not more than a desired value. To prevent distortion degradation.

[0046] When Ids (= Ic + Ip) obtained by adding the carrier current Ic and the peak current Ip is small, the distortion deteriorates! /, So the current control means 113 causes the carrier amplifier (amplifying element 11 la) to And control the current of the peak amplifier (amplifier element 11 lb) to prevent distortion degradation by setting Ids to a desired value or more. In the case of the Dono and Tee amplifiers, since most of the current normally flows through the carrier amplifier (amplifying element 1 11a), the current control means 113 controls the current of the carrier amplifier (amplifying element 11 la). By increasing the carrier current Ic, Ids is set to a desired value or more to prevent distortion degradation.

FIG. 8 is a second block diagram in which the single-configuration power amplifier according to Embodiment 2 of the present invention is used in a two-stage balance configuration. The configuration of the power amplifier in FIG. 8 is basically the same as that of the power amplifier in FIG. 6, but the amplification element 111a and the amplification element 111b have a two-stage non-lance configuration. Further, the second configuration of the second embodiment shown in FIG. 8 is different from the first configuration of the second embodiment shown in FIG. 7, and the VSWR detecting means 112 is provided on the output side of the amplifying element 111a. It has been.

Therefore, in this case, the VSWR detection means 112 detects the VSWR value due to load fluctuation on the output side of the amplification element 11 la and transmits the VSWR value to the current control means 113. The current control means 113 performs current control of the amplifying element 11 la and the amplifying element 11 lb based on the VSW R value in which the output side force of the amplifying element 11 la is also detected. At this time, since the currents flowing through the amplifying element 11 la and the amplifying element 11 lb are almost the same, based on the VSWR value detected from the output side of the amplifying element 11 la! /, The two amplifying elements 11 la, Even if the current control of 111b is performed, the current of amplifier 11 la and the current of amplifier 11 lb are balanced. I can do it.

Note that the reflection coefficient detecting means 112 may be used instead of the VSWR detecting means 112. In addition, the current control method by the current control means 113 is the same as that in FIG. Further, the two-stage single configuration shown in FIG. 8 may be a Dono and Tee amplifier, but the circuit in that case may be configured as shown in FIG. In addition, the present invention can be realized even if a single-configuration power amplifier has a balanced configuration of three or more stages.

FIG. 9 is a third block diagram in which the single-configuration power amplifier according to Embodiment 2 of the present invention is used in a two-stage balance configuration. The difference between the third configuration of the second embodiment shown in FIG. 9 and the second configuration of the second embodiment shown in FIG. 8 is that the VSWR detection means 112 force amplifying element is not connected to the output side of the amplifying element 111a. It is only a point provided on the output side of 111b. Therefore, the detection operation of the VSWR value due to the load change is performed by the VSWR detection means 112 by the same method as in FIG. The current control method by the current control means 113 is also the same as that described in the second part of the second embodiment in FIG.

In the third embodiment, some specific configuration examples of the VSWR detection unit 112 will be described. FIG. 10 is a block diagram showing a first configuration of the VSWR detection means 112 according to Embodiment 3 of the present invention. Note that the VSWR detection means 112 may be replaced with the reflection coefficient detection means 112, but in the following description, the configuration of the VSWR detection means 112 will be described. Note that the input / output terminals r, s, t of the VSWR detection means 112 in the third embodiment correspond to the input / output terminals r, s, t of the VSWR detection means 112 in the power amplifier shown in FIG. However, since the TPC setting level terminal u shown in FIG. 10 may or may not be provided, it is indicated by the VSWR detection means 112 in FIG.

[0052] As shown in FIG. 10, the VSWR detection means 112 includes an output level detection unit 121, and the output level detection unit 121 is an amplifying element output side terminal! : Connected to load side terminal s, VSWR detection terminal t, and TPC setting level terminal u. The TPC setting level terminal u is TPC (Transmit Power Control) information indicating the power information that is actually desired to be output. This terminal is used to input the information setting level.

[0053] In such a configuration, the reflected power level can be predicted based on the TPC setting level input from the TPC setting level terminal u to the output level detection unit 121 and the output power level of the amplification element output terminal! Then, the VSWR value is detected from the VSWR detection terminal t based on the TPC setting level of the TPC setting level terminal u and the output power level of the amplifying element output side terminal r. For example, if the power to be actually transmitted set at the TPC setting level terminal u is 23 dBm (200 mW) and the output power level at the amplifier output terminal r is 20 dBm (10 OmW), it is attenuated by 3 dB. The reflected power is also 20dBm (100mW). Therefore, the reflection coefficient is 100Z200 = 0.5, and the VSWR value of (1 + 0.5) / (1-0.5) = 3 is detected from the VSWR detection terminal t.

Note that the detection of the output power level of the amplifier element output side terminal r can be performed by, for example, a combination of a directional coupler and a detector. That is, a minute power (for example, lZioo power) out of the power output from the amplifying element by the directional coupler is extracted.

The micro power signal is received by the detector and the output power level is measured.

FIG. 11 is a block diagram showing the second configuration of the VSWR detection means 112 according to Embodiment 3 of the present invention. As shown in FIG. 11, the VSWR detection means 112 includes a reflection level detection unit 122. The reflection level detection unit 122 is amplifying element output side terminal!:, Load side terminal s, VSWR detection terminal t, and TPC setting level. Connected to terminal u.

[0056] In such a configuration, the reflection level can be predicted from the TPC setting level input from the TPC setting level terminal u to the reflection level detection unit 122 and the reflected power level input to the load side terminal s. Then, the VSWR detection terminal beam VSWR value is detected based on the TPC setting level of the TPC setting level terminal u and the reflected power level of the load side terminal s. The reflected power level of the load side terminal s can be detected by a combination of a directional coupler and a detector, for example.

FIG. 12 is a block diagram showing a third configuration of the VSWR detection means 112 according to Embodiment 3 of the present invention. As shown in FIG. 12, the VSWR detection means 112 includes an incident / reflection level detection unit 123. The incident / reflection level detection unit 123 is connected to the output terminal of the amplification element!:, The load side terminal s, and the VSWR detection terminal t. It is connected. In such a configuration, the amplification element By detecting the output power level of the child output side terminal r (that is, equivalent to the incident wave power level) and the reflected wave power level of the load side terminal s and calculating the detection result (that is, incident wave power level force reflection) By dividing the wave power level), the VS WR value is detected from the VSWR detection pin t. When performing detection with such a configuration, the TPC setting level is not required. The detection of the output power level at the amplifier output terminal r (corresponding to the incident wave power level) and the reflected wave power level at the load terminal s is performed by a combination of a directional coupler and a detector. be able to.

In the fourth embodiment, some specific configuration examples of the current control means 113 will be described. FIG. 13 is a block diagram showing a configuration of current control means for controlling the power supply of the amplifying element in the fourth embodiment of the present invention. The current control unit 113 includes a current value detection unit 131 and a power supply setting unit 132. The current value detector 131 detects the output current of the amplifying element 111. Based on the output current of the amplifying element 111 detected by the current value detecting unit 131 and the VSWR value to which the VSWR detecting means force is also input, the power setting unit 132 determines the voltage of the power supply E 101 of the amplifier 111. To control.

[0059] In such a configuration of current control means 113, power supply setting section 132 controls the voltage of power supply E101 based on current detection information from current value detection section 131 and a VSWR value from a VSWR detection means (not shown). By doing so, the output current of the amplifying element 111 is substantially controlled. Instead of the VSWR value, a reflection coefficient having a reflection coefficient detecting means (not shown) may be used. Also, the amplification element controlled by the current control means 113 may be two or more stages in a single configuration! / Or a Doherty amplifier.

FIG. 14 is a block diagram showing a configuration of current control means for performing bias voltage control of the amplification element in the fourth embodiment of the present invention. The current control unit 113 includes a current value detection unit 131 and a bias setting unit 133. The noise setting unit 133 is based on the output current of the amplifying element 111 detected by the current value detecting unit 131 and the VSWR value of the VSWR detecting means (not shown)! Controls the voltage of lb.

In such a configuration of the current control means 113, current detection from the current value detection unit 131 is performed. By controlling the bias setting unit 133 based on the information and the VSWR value from the VSWR detection means (not shown), the bias setting unit 133 changes the voltage of the bias power supply E 101b of the amplifying element 111. Thereby, the output current of the amplifying element 111 is substantially controlled. Note that a reflection coefficient from a reflection coefficient detecting means (not shown) may be used instead of the VSWR value. In addition, the amplification element controlled by the current control means 113 may be a single configuration of two or more stages! /, And a Dono or Tee amplifier! /.

FIG. 15 is a block diagram showing a configuration of current control means for controlling the current source of the amplifying element in the fourth embodiment of the present invention. The current control unit 113 includes a current value detection unit 131 and a current source setting unit 134. The current source setting unit 134 is based on the output current of the amplifying element 111 detected by the current value detecting unit 131 and the VSWR value input from the VSWR detecting means (not shown)! /, And from the current source A101 to the amplifying element 111. To control the current flowing to

[0063] In such a configuration of the current control means 113, the current source setting unit 134 uses the current source V based on the current detection information from the current value detection unit 131 and the VSWR value from the VSWR detection unit (not shown). By controlling the current flowing from A101 to the amplifying element 111, the current of the amplifying element 111 is substantially controlled. In place of the VSWR value, a reflection coefficient from a reflection coefficient detection means (not shown) may be used. In addition, the amplification element controlled by the current control means 113 may be a single configuration of two or more stages, or a Dono or Tee amplifier! /.

FIG. 16 is a block diagram showing a configuration of current control means 113 that controls the matching circuit of the output stage of the amplification element in the fourth embodiment of the present invention. The current control unit 113 includes a current value detection unit 131 and a matching network control unit 135. Based on the current detection information from the current value detection unit 131 and the VSWR value input from the VSWR detection means (not shown), the matching network control unit 135 matches a matching circuit (not shown) at the output stage of the amplification element 111. Change the matching network.

In such a configuration of the current control unit 113, the matching network control unit 135 is not illustrated based on the current detection information from the current value detection unit 131 and the VSWR value input by the VSWR detection unit force (not illustrated). The current of the amplifying element 111 is substantially controlled by changing the matching network of the matching circuit. That is, the matching network control unit 135 sets the impedance of the antenna (not shown) on the output side of the amplification element 111. For example, a matching circuit (not shown) is switched so as to match. In place of the VSWR value, a reflection coefficient having a reflection coefficient detecting means power (not shown) may be used. Also, the amplifying element can be two or more stages in a single configuration, or it can be a dono or tee amplifier! /.

FIG. 17 is a block diagram showing a configuration of current control means for performing variable phase control in Embodiment 4 of the present invention. The current control unit 113 includes a current value detection unit 131 and a variable phase shifter control unit 136. Based on the current detection information from the current value detection unit 131 and the VSWR value that is also input with the VSWR detection means force (not shown), the variable phase shifter control unit 136 sets the amplification element 111 so that the reflection coefficient is minimized. Shift the output phase.

In such a configuration of the current control unit 113, a variable phase shifter control unit 136 is provided at the output stage of the amplifying element 111, and the variable phase shifter control unit 136 includes a current from the current value detection unit 131. The current of the amplifying element 111 is substantially controlled by changing the phase based on the detection information and the VSWR value (not shown) based on the input VSWR value. Instead of the VSWR value, a reflection coefficient having a reflection coefficient detecting means power (not shown) may be used. Also, the amplifier element can be a single stage with two or more stages, or it can be a dono or tee amplifier! /.

FIG. 18 is a block diagram showing a configuration of current control means for controlling the distribution ratio of the current of the amplifying element in the fourth embodiment of the present invention. The current control means 113 is configured to include current value detection units 131 a and 13 lb and a distribution ratio control unit 137. The distribution ratio control unit 137 is based on the current detection information from the current value detection units 131a and 131b and the VSWR value that is also input with the VSWR detection means force (not shown)! Distribute the current value of element 11 lb appropriately.

[0069] In such a configuration of the current control means 113, the current value detection unit 131a detects the current value of the amplification element 11la, and the current value detection unit 131b detects the current value of the amplification element 11lb. Then, based on the current detection information of the current value detection unit 131a and the current value detection unit 131b, the distribution ratio control unit 137 calculates the distribution ratio between the current value of the amplification element 11 la and the current value of the amplification element 11 lb. By controlling appropriately, the current of the amplifying element 11 la and the amplifying element 11 lb is substantially controlled. In other words, in an amplifying element having a two-stage balanced configuration or more, the current of each amplifying element 111a, 111b can be appropriately controlled by changing the current distribution ratio (or absolute distribution amount) of the input stage. it can. Note that the reflection coefficient (not shown) is used instead of the VSWR value. The reflection coefficient from the detection means may be used. The amplification element may be a Doherty amplifier Industrial applicability

The power amplifier according to the present invention can prevent deterioration of output power level and distortion caused by load fluctuations with a simple circuit configuration, so that it can be effectively used for mobile phones having severe antenna directivity conditions. It becomes possible to do.

Claims

The scope of the claims

[1] an amplifying element for amplifying power;

VSWR detection means for detecting a VSWR value indicating a degree of reflection by a standing wave generated by interference between the traveling wave output to the amplification element and the reflected wave input to the amplification element;

Current control means for controlling the current flowing through the amplifying element based on the VSWR value detected by the VSWR detection means so that the power level exceeds the first threshold and the distortion level is equal to or less than the second threshold; Power amplifier provided.

[2] The power amplifier according to [1], wherein the VSWR detection means detects the VSWR value based on a traveling wave power output from the amplifying element and a TPC set value indicating a transmission power target value. .

[3] The electric power according to claim 1, wherein the VSWR detection unit detects the VSWR value based on a reflected wave power input to the amplifying element and a TPC setting value indicating a transmission power target value. Power amplifier.

4. The power amplifier according to claim 1, wherein the VSWR detection means detects the VSWR value based on a traveling wave power output from the amplification element and a reflected wave power input to the amplification element. .

[5] an amplifying element for increasing power;

Reflection coefficient detection means for detecting a reflection coefficient that is a ratio of a traveling wave output from the amplification element and a reflected wave input to the amplification element;

Current control means for controlling the current flowing through the amplifying element so that the power level exceeds the first threshold and the distortion level is equal to or lower than the second threshold based on the reflection coefficient detected by the reflection coefficient detection means. amplifier.

6. The power amplifier according to claim 5, wherein the reflection coefficient detection means detects the reflection coefficient based on a traveling wave power output from the amplification element and a TPC set value indicating a transmission power target value. .

7. The reflection coefficient detection unit according to claim 5, wherein the reflection coefficient detection means detects the reflection coefficient based on a reflected wave power input to the amplifying element and a TPC set value indicating a transmission power target value. Power amplifier.

6. The power amplifier according to claim 5, wherein the reflection coefficient detection means detects the reflection coefficient based on traveling wave power output from the amplification element and reflected wave power input to the amplification element.