Electronic device

Abstract

To provide an electronic device that can efficiently save power by increasing the power added efficiency (PAE) of a power amplifier.SOLUTION: An electronic device 100 includes a driver amplifier, a power amplifier, a power detector, and a bias circuit. The driver amplifier outputs a radio frequency (RF) signal. The power amplifier is electrically connected to the driver amplifier. The power amplifier has an input terminal IN, and receives an RF signal 132 through the input terminal and amplifies the RF signal. The power detector is electrically coupled to the input terminal and detects an input power W of the RF signal. The power detector outputs a driving voltage 120 according to the input power. The bias circuit 106 is electrically connected to the power amplifier and the power detector. The bias circuit outputs a driving current 122 to the power amplifier according to the driving voltage. The power amplifier amplifies the power of the RF signal from the input power to a target power according to the driving current 122.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to electronic devices, and more particularly to a power amplifier having adaptive bias adjustment. [Background technology]

[0002] RF power amplifiers are often used in wireless communication products to amplify RF signals, which are then radiated to a receiving device by an antenna. However, in the existing technology, the layout and design of the bias circuit of the power amplifier often determines the gain and effectiveness of the power amplifier. In order to save the power consumption of the power amplifier, how to improve the power added efficiency (PAE) of the power amplifier has become an important issue. Summary of the Invention [Problem to be solved by the invention]

[0003] An object of the present invention is to provide an electronic device capable of increasing the power added efficiency (PAE) of a power amplifier and thereby enabling efficient power saving. [Means for solving the problem]

[0004] An electronic device according to an embodiment of the present invention includes a driver amplifier, a power amplifier, a power detector, and a bias circuit. The driver amplifier outputs a radio frequency (RF) signal. The power amplifier is electrically connected to the driver amplifier. The driver amplifier has an input end. The driver amplifier receives an RF signal via the input end. The driver amplifier amplifies the RF signal. The power detector is electrically coupled to the input end. The power detector detects an input power of the RF signal and outputs a drive voltage according to the input power. The bias circuit is electrically connected to the power amplifier and the power detector. The bias circuit outputs a first drive current to the power amplifier according to the drive voltage. The power amplifier amplifies the power of the RF signal from the input power to a target power according to the first drive current. Effect of the Invention

[0005] The present invention increases the PAE and achieves efficient power saving. [Brief description of the drawings]

[0006] The present invention can be more fully understood from the following detailed description and examples, taken in conjunction with the accompanying drawings.

[0007] [Figure 1] 1 illustrates an electronic device 100 according to some embodiments of the present invention. [Diagram 2] 1 is a detailed circuit diagram of a power amplifier 102 and a bias circuit 106 in an electronic device 100 according to some embodiments of the present invention. [Diagram 3] 3 is a detailed circuit diagram of a power amplifier 102 and a bias circuit 106 in an electronic device 300 according to some embodiments of the present invention. [Figure 4] 4 is a detailed circuit diagram of a power amplifier 102 and a bias circuit 106 in an electronic device 400 according to some embodiments of the present invention. [Figure 5A] 1 is a graph of power added efficiency (PAE) versus output power for a prior art power amplifier. [Figure 5B] 1 is a graph of power added efficiency (PAE) versus output power of a power amplifier 102 in an electronic device 100 according to some embodiments of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] In order to make the above objects, features and advantages of certain embodiments of the present specification more comprehensible, the following detailed description is given in conjunction with the accompanying drawings.

[0009] Certain terms are used throughout this specification and the following claims to refer to certain components. As one skilled in the art will appreciate, electronics manufacturers may refer to components by different names. This specification does not intend to distinguish between components that have different names but not different functions. It is understood that the words "have" and "include" are used in an open-ended manner and should be interpreted to mean "including, but not limited to." Thus, the terms "have," "include," and / or "comprise" as used herein are used to indicate the presence of certain technical features, values, method steps, operations, units, and / or components. However, they do not exclude the possibility that more technical features, values, method steps, operations, units, components, or any combination thereof may be added.

[0010] Directional terms used throughout this specification and the following claims, such as: "top", "upper", "lower", "lower", "front", "rear", "back", "left", "right", etc., are directions with reference to the drawings. Thus, the directional terms are used for purposes of explanation and not for purposes of limiting the invention. With reference to the drawings, the drawings illustrate general features of methods, structures, and / or materials used in certain embodiments. However, the drawings should not be construed as defining or limiting the scope or characteristics encompassed by these embodiments. For example, the relative size, thickness, and location of each layer, region, and / or structure may be reduced or enlarged for clarity.

[0011] When corresponding components, such as layers or areas, are described as being "on another component," they may be directly on the other component, or there may be other components between them. On the other hand, when a corresponding component is "directly on the other component (or a variation thereof)," there is no component between them. Furthermore, when a corresponding component is referred to as being "on another component," the corresponding component and the other component have a top-view / vertical relationship, and the corresponding component may be below or above the other component, with the top-view / vertical relationship being determined by the device orientation.

[0012] When a component or layer is referred to as being "connected" to another component or layer, it should be understood that there may be a direct connection to the other component or layer, or there may be intervening components or layers. In contrast, when a component is referred to as being "directly connected" to another component or layer, there are no intervening components or layers.

[0013] An electrical connection or coupling as described in this disclosure may refer to a direct connection, where the endpoints of two circuit components are directly connected or connected to each other by a conductor line segment, and an indirect connection, where there is an intermediate component between the endpoints of the two circuit components, including but not limited to a switch, diode, capacitor, inductor, resistor, or other suitable component or combination of the above components.

[0014] The terms "first," "second," "third," "fourth," "fifth," and "sixth" are used to describe components. They are not used to indicate a priority or precedence relationship, but are used only to distinguish between components of the same name.

[0015] It should be noted that the technical features in the different embodiments described below can be replaced, recombined, or mixed with each other to configure other embodiments without departing from the spirit of the present invention.

[0016] FIG. 1 illustrates an electronic device 100 according to some embodiments of the present invention. As shown in FIG. 1, the electronic device 100 includes a power amplifier 102, a power detector 104, a bias circuit 106, a driver amplifier 108, and a bias circuit 110. In some embodiments, the electronic device 100 is designed based on the architecture of a Doherty power amplifier manufactured by a heterojunction bipolar transistor (HBT) process, but the present invention is not limited thereto. In some embodiments, the power amplifier 102 has an input terminal IN. The power amplifier 102 receives a radio frequency (RF) signal 132 through the input terminal IN and amplifies the RF signal 132. The power of the RF signal 132 is the same as an input power W. The power detector 104 is electrically coupled to the input terminal IN. The power detector 104 detects the input power W of the RF signal 132 and outputs a driving voltage 120 to the bias circuit 106 according to the input power W. For example, although the invention is not so limited, a higher input power W of the RF signal 132 will result in a higher driving voltage 120 output by the power detector 104. In some embodiments, the driving voltage 120 is a DC voltage.

[0017] In some embodiments, the bias circuit 106 is electrically connected to the power amplifier 102 and the power detector 104. The bias circuit 106 outputs a drive current 122 to the power amplifier 102 according to the drive voltage 120. In some embodiments, the drive current 122 is a DC current, but the present invention is not limited thereto. The power amplifier 102 amplifies the power of the RF signal 132 from an input power W to a target power according to the drive current 122 to generate an RF signal 134. The power amplifier 102 outputs the amplified RF signal 134 via an output terminal OUT. In some embodiments, the amplified RF signal 134 can be radiated to a receiving device by an antenna (not shown). In some embodiments, the driver amplifier 108 is electrically connected to an input terminal IN of the power amplifier 102. The driver amplifier 108 amplifies the RF signal 130 of the initial power to the RF signal 132 of the input power W. The driver amplifier 108 receives the RF signal 130 via an input terminal RFIN.

[0018] In some embodiments, the RF signal 130 may be a signal from a radio frequency transceiver (not shown). The radio frequency transceiver may, for example, convert a digital signal to a baseband signal, convert a baseband signal to an intermediate frequency signal, and convert an intermediate frequency signal to a radio frequency signal, but this is not a limitation of the present invention. In some embodiments of FIG. 1, the bias circuit 106 used to drive the power amplifier 102 is different from the bias circuit 110 used to drive the driver amplifier 108, but this is not a limitation of the present invention. The driver amplifier 108 is used to amplify the RF signal 130 in a first stage. The power amplifier 102 is used to amplify the RF signal 130 in a second stage. In some embodiments, the power amplifier 102 is a final stage amplifier before the antenna, but this is not a limitation of the present invention. In some embodiments, the power detector 104 may detect the input power W of the RF signal 132 in any manner. For example, the power detector 104 may detect the voltage and current of the coupled signal from the RF signal 132 coupled to the power detector 104, and calculate the power of the coupled signal based on the voltage and current of the coupled signal. The power detector 104 finally converts the power of the combined signal to an input power W of the RF signal 132, although this is not the sole limitation of the present invention. In some embodiments, the bias circuit 110 is electrically connected to the driver amplifier 108 and outputs a drive current 112 to the driver amplifier 108. In some embodiments, the drive current 112 is less than the drive current 122, although this is not the sole limitation of the present invention. The drive current 112 is the same as the drive current 122 and is a DC current, although this is not the sole limitation of the present invention.

[0019] FIG. 2 is a detailed circuit diagram of the power amplifier 102 and the bias circuit 106 in the electronic device 100 according to some embodiments of the present invention. As shown in FIG. 2, the bias circuit 106 includes a first transistor D1, a second transistor D2, a third transistor D3, a first resistor R1, a second resistor R2, a third resistor R3, and a fourth resistor R4. The power amplifier 102 includes a fourth transistor D4, a capacitor C2, and an inductor L1. In some embodiments of FIG. 2, a first end of the first transistor D1 is electrically coupled to a first voltage Vbias by the third resistor R3. A second end of the first transistor D1 is electrically coupled to a second end of the fourth transistor D4 in the power amplifier 102 by the first resistor R1. A third end of the first transistor D1 is electrically connected to a ground voltage G. A first end of the second transistor D2 is electrically connected to the first voltage Vbias. A second end of the second transistor D2 is electrically coupled to the first end of the first transistor D1 by the second resistor R2. A first end of the third transistor D3 is electrically connected to a third end of the second transistor D2. A second end of the third transistor D3 is electrically connected to the power detector 104. A third end of the third transistor D3 is electrically connected to a second end of the fourth transistor D4 in the power amplifier 102.

[0020] In detail, the first resistor R1 is electrically connected between the second end of the first transistor D1 and the second end of the fourth transistor D4 in the power amplifier 102. The second resistor R2 is electrically connected between the second end of the second transistor D2 and the first end of the first transistor D1. The third resistor R3 is electrically connected between the first end of the first transistor D1 and the first voltage Vbias. The fourth resistor R4 is electrically connected between the third end of the third transistor D3 and the ground voltage G. In some embodiments of FIG. 2, the electronic device 100 further includes a coupling element 140. The coupling element 140 is electrically connected between the input terminal IN and the power detector 104 to couple the RF signal 132 to the power detector 104. In some embodiments, the coupling element 140 is electrically coupled to the ground voltage G, but the present invention is not limited thereto. The power detector 104 is electrically connected to the second end of the third transistor D3 in the bias circuit 106. In some embodiments, the first transistor D1, the second transistor D2, the third transistor D3, and the fourth transistor D4 are each a bipolar junction transistor (BJT), although the invention is not so limited. In some embodiments, the first transistor D1, the second transistor D2, the third transistor D3, and the fourth transistor D4 are each an NPN-type BJT, although the invention is not so limited.

[0021] In some embodiments, the power detector 104 detects the input power W of the RF signal 132 and outputs the drive voltage 120 to the second end of the third transistor D3 in the bias circuit 106 according to the input power W. For example, when the input power W of the RF signal 132 becomes higher, the drive voltage 120 output by the power detector 104 becomes higher, but the present invention is not limited to this. The third transistor D3 outputs a drive current 122 from its third end to the second end of the fourth transistor D4 in the power amplifier 102 according to the drive voltage 120. For example, when the drive voltage 120 from the power detector 104 becomes higher, the drive current 122 output from the third end of the third transistor D3 to the second end of the fourth transistor D4 becomes higher. In some embodiments, the fourth resistor R4 can adjust the turn-on voltage of the fourth transistor D4. For example, assume that the forward bias voltage from the second end to the third end of the third transistor D3 is 0.7V, and the forward bias voltage from the second end to the third end of the fourth transistor D4 is 0.7V. When the fourth resistor R4 is not provided, the driving voltage 120 must be higher than 1.4 V to cause the third transistor D3 to start outputting the driving current 122. On the other hand, in the bias circuit 106 of the present invention, since the fourth resistor R4 is electrically connected between the ground voltage G and the third end of the third transistor D3, the driving voltage 120 must be higher than 0.7 V to cause the third transistor D3 to start outputting the driving current 122.

[0022] In some embodiments of FIG. 2, the first transistor D1, the second transistor D2, the first resistor R1, the second resistor R2, and the third resistor R3 in the bias circuit 106, and the fourth transistor D4 in the power amplifier 102 are combined into a current mirror, but the present invention is not limited thereto. The fourth transistor D4 amplifies the power of the RF signal 132 from the input power W to a target power according to the drive current 122. In some embodiments, the fourth transistor D4 is simultaneously driven by the drive current 122 from the third transistor D3 and a current from the second voltage Vcc. In particular, a first end of the fourth transistor D4 is electrically coupled to the second voltage Vcc by an inductor L1. A second end of the fourth transistor D4 is electrically connected to the third end of the third transistor D3 and the first resistor R1. A third end of the fourth transistor D4 is electrically connected to the fourth resistor R4 and the ground voltage G. A capacitor C2 is electrically connected between the output terminal OUT and the first end of the fourth transistor D4. The inductor L1 is electrically connected between the second voltage Vcc and a first end of the fourth transistor D4, which outputs the amplified RF signal 134 through an output terminal OUT.

[0023] In some embodiments, the first voltage Vbias is the same as or different from the second voltage Vcc. In some embodiments, the electronic device 100 in FIG. 2 further includes a capacitor C1. The capacitor C1 is electrically connected between the input terminal IN and the third terminal of the third transistor D3. In some embodiments, the capacitor C1 is used to block a DC component from the first voltage Vbias to prevent the DC component of the first voltage Vbias from entering the input terminal IN. The capacitor C2 is used to block a DC component from the second voltage Vcc to prevent the DC component of the second voltage Vcc from entering the output terminal OUT. The inductor L1 is used to block the amplified RF signal 134 to prevent the RF signal 134 from interfering with the second voltage Vcc.

[0024] FIG. 3 is a detailed circuit diagram of the power amplifier 102 and the bias circuit 106 in the electronic device 300 according to some embodiments of the present invention. As shown in FIG. 3, the bias circuit 106 includes a first transistor D1, a second transistor D2, a third transistor D3, a first resistor R1, a second resistor R2, a third resistor R3, and a fourth resistor R4. In some embodiments of FIG. 3, a first end of the first transistor D1 is electrically coupled to a first voltage Vbias by the third resistor R3. A second end of the first transistor D1 is electrically connected to a third end of the second transistor D2 and a first end of the third transistor D3 by the first resistor R1. A third end of the first transistor D1 is electrically connected to a ground voltage G. A first end of the second transistor D2 is electrically connected to the first voltage Vbias. A second end of the second transistor D2 is electrically coupled to the first end of the first transistor D1 by the second resistor R2. A first end of the third transistor D3 is electrically connected to the third end of the second transistor D2. The second end of the third transistor D3 is electrically connected to the power detector 104. The third end of the third transistor D3 is electrically connected to the second end of the fourth transistor D4 in the power amplifier 102.

[0025] In detail, the first resistor R1 is electrically connected between the second end of the first transistor D1 and the third end of the second transistor D2. Meanwhile, the first resistor R1 is also electrically connected between the second end of the first transistor D1 and the first end of the third transistor D3. Except for the arrangement of the resistor R1 in the electronic device 300 in FIG. 3 being different from that of the electronic device 100 in FIG. 2, the arrangement of other components of the electronic device 300 is the same as that of the electronic device 100, and will not be described.

[0026] FIG. 4 is a detailed circuit diagram of the power amplifier 102 and the bias circuit 106 in the electronic device 400 according to some embodiments of the present invention. As shown in FIG. 4, the bias circuit 106 includes a first transistor D1, a second transistor D2, a third transistor D3, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, and a fifth resistor R5. In some embodiments of FIG. 4, a first end of the first transistor D1 is electrically coupled to a first voltage Vbias by the third resistor R3. A second end of the first transistor D1 is electrically connected to a third end of the second transistor D2 and a first end of the third transistor D3 by the first resistor R1. A third end of the first transistor D1 is electrically connected to a ground voltage G. A first end of the second transistor D2 is electrically connected to the first voltage Vbias. A second end of the second transistor D2 is electrically coupled to the first end of the first transistor D1 by the second resistor R2. A first end of the third transistor D3 is electrically connected to the third end of the second transistor D2. The second end of the third transistor D3 is electrically connected to the power detector 104. The third end of the third transistor D3 is electrically connected to the second end of the fourth transistor D4 in the power amplifier 102. The fifth resistor R5 is connected to bridge between the first end of the third transistor D3 and the third end of the third transistor D3. In some embodiments, the fifth resistor R5 is used to prevent reverse bias voltage, but the present invention is not limited thereto. In the electronic device 400 in FIG. 4, except that the arrangement of the resistor R5 is different from that of the electronic device 300 in FIG. 3, the arrangement of other components of the electronic device 400 is the same as that of the electronic device 300, and will not be described.

[0027] FIG. 5A is a graph of power added efficiency (PAE) versus output power of a power amplifier of the prior art. The horizontal axis of FIG. 5A is output power (dBm), and the vertical axis is PAE (%). The power amplifier of the prior art does not have the power detector 104 in the electronic device 100 of FIG. 1 of the present invention, and its bias circuit is different from the bias circuit 106 of the present invention. In some embodiments, the power added efficiency is equal to the ratio of the output power of the RF signal to the DC power consumption, that is, PAE=(Pout-Pin) / Pdc. PAE is the power added efficiency, Pout is the output power of the RF signal, Pin is the input power of the RF signal, and Pdc is the DC power consumption. As shown in FIG. 5A, referring to point A of FIG. 5A, when the output power of the power amplifier of the prior art is 28 dBm, the PAE of the power amplifier of the prior art is 25%.

[0028] FIG. 5B is a graph of power added efficiency (PAE) versus output power of the power amplifier 102 in the electronic device 100 according to some embodiments of the present invention. The horizontal axis of Fig. 5B is output power (dBm), and the vertical axis is PAE (%). As shown in Fig. 5B, referring to point B of Fig. 5B, when the output power of the power amplifier 102 in the electronic device 100 is 28 dBm, the PAE of the power amplifier 102 of the present invention is increased to 35% by setting the bias circuit 106. That is, under the same output power of the RF signal, compared with the power amplifier of the prior art, the PAE of the power amplifier 102 in the electronic device 100 of the present invention is increased by 10%, so that the purpose of efficient power saving can be achieved.

[0029] While the present invention has been described by way of example and in terms of the preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiment. On the contrary, the present invention is intended to cover various modifications and similar arrangements as would be apparent to those skilled in the art. Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements. [Explanation of symbols]

[0030] 100 Electronic equipment 102 Power Amplifier 104 Power Detector 106 Bias Circuit 108 Driver Amplifier 110 Bias circuit 112 Drive Current 120 Driving voltage 122 Drive Current 130, 132, 134 RF signal RFIN, IN input terminal OUT Output terminal W Input power D1 First transistor D2 Second transistor D3 Third transistor D4 Fourth transistor R1 First register R2 Second register R3 Third register R4 Fourth Register R5 Fifth Register C1, C2 capacitance L1 Inductor 140 Coupling element Vbias First voltage Vcc Second Voltage G Ground voltage A, B points 300 Electronic equipment 400 Electronic equipment

Claims

1. A driver amplifier that outputs a radio frequency (RF) signal; a power amplifier electrically connected to the driver amplifier, having an input terminal, receiving the RF signal through the input terminal and amplifying the RF signal; a power detector electrically coupled to the input end, for detecting an input power of the RF signal and outputting a driving voltage according to the input power; a bias circuit electrically connected to the power amplifier and the power detector, the bias circuit outputting a first drive current to the power amplifier in accordance with the drive voltage; The electronic device, wherein the power amplifier amplifies the power of the RF signal from the input power to a target power in accordance with the first drive current.

2. The bias circuit includes: a first transistor having a first end electrically coupled to a first voltage, a second end electrically coupled to the power amplifier, and a third end electrically connected to a ground voltage; a second transistor having a first end electrically connected to the first voltage and a second end electrically coupled to the first end of the first transistor; a third transistor having a first end electrically connected to the third end of the second transistor, a second end electrically connected to the power detector, and a third end electrically connected to the power amplifier; 2. The electronic device according to claim 1, further comprising:

3. The bias circuit includes: a first resistor electrically connected between the second end of the first transistor and the power amplifier; a second resistor electrically connected between the second end of the second transistor and the first end of the first transistor; a third resistor electrically connected between the first end of the first transistor and the first voltage; a fourth resistor electrically connected between the third end of the third transistor and the ground voltage; 3. The electronic device according to claim 2, further comprising:

4. The power amplifier is 4. The electronic device of claim 3, further comprising a fourth transistor having a first end electrically coupled to a second voltage, a second end electrically connected to the third end of the third transistor and to the first resistor, and a third end electrically connected to the fourth resistor and to the ground voltage.

5. 5. The electronic device of claim 4, further comprising a first capacitor electrically connected between the input and the third terminal of the third transistor.

6. The power amplifier is a second capacitor electrically connected between an output terminal and the first terminal of the fourth transistor; and a first inductor electrically connected between the second voltage and the first end of the fourth transistor; 5. The electronic device according to claim 4, further comprising:

7. 2. The electronic device of claim 1, further comprising a coupling element electrically connected between said input and said power detector for coupling said RF signal to said power detector.

8. moreover, a second bias circuit electrically connected to the driver amplifier and configured to output a second drive current to the driver amplifier; 2. The electronic device of claim 1, wherein the second drive current is less than the first drive current.

9. 5. The electronic device according to claim 4, wherein the third transistor outputs the first drive current to the fourth transistor according to the drive voltage from the power detector.

10. 5. The electronic device of claim 4, wherein the fourth resistor adjusts a turn-on voltage of the fourth transistor.

11. 5. The electronic device of claim 4, wherein the first transistor, the second transistor, the fourth transistor, the first resistor, the second resistor, and the third resistor are combined into a current mirror.

12. 5. The electronic device of claim 4, wherein the first transistor, the second transistor, the third transistor, and the fourth transistor are each a bipolar junction transistor (BJT).

13. 13. The electronic device of claim 12, wherein the first transistor, the second transistor, the third transistor, and the fourth transistor are each an NPN BJT.

14. 5. The electronic device of claim 4, wherein the first voltage and the second voltage are the same or different.

15. The electronic device of claim 1 , wherein the driver amplifier amplifies the power of the RF signal from an initial power to the input power.

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