Electronic device

Abstract

An electronic device includes a power amplifier, a power detector, and a bias circuit. The power amplifier amplifies a radio frequency signal from an input end. The power detector is electrically coupled to the input end, detects an input power of the radio frequency signal, and correspondingly outputs a driving voltage according to the input power. The bias circuit is electrically connected with the power amplifier and the power detector, and outputs a first driving current to the power amplifier according to the driving voltage. The power amplifier increases the power of the radio frequency signal from the input power to a target power according to the first driving current.

Description

Technical Field

[0001] The invention relates to an electronic device, and in particular to a power amplifier with an adaptive bias voltage adjustment function. Background Art

[0002] RF power amplifiers are often used in wireless communication products to amplify RF signals so that they can be radiated to receiving devices through antennas. However, in existing technologies, the configuration and design of the bias circuit of the power amplifier often determine the gain and efficiency of the power amplifier. In order to save power consumption of the power amplifier, how to increase the power conversion efficiency (Power Added Efficiency: PAE) of the power amplifier has become an important issue. Summary of the invention

[0003] To solve the above problems, the present invention discloses an electronic device, including a driving amplifier, a power amplifier, a power detector, and a bias circuit. The driving amplifier outputs a radio frequency signal. The power amplifier is electrically connected to the driving amplifier, and includes an input terminal, receives the radio frequency signal through the input terminal, and amplifies the radio frequency signal. The power detector is electrically coupled to the input terminal, detects an input power of the radio frequency signal, and outputs a driving voltage corresponding to the input power. The bias circuit is electrically connected to the power amplifier and the power detector, and outputs a first driving current to the power amplifier according to the driving voltage. The power amplifier increases the power of the radio frequency signal from the input power to a target power according to the first driving current. BRIEF DESCRIPTION OF THE DRAWINGS

[0004] Figure 1 FIG. 1 is a schematic diagram of an electronic device 100 according to an embodiment of the present invention.

[0005] Figure 2 FIG. 1 is a detailed circuit diagram of the power amplifier 102 and the bias circuit 106 in the electronic device 100 according to an embodiment of the present invention.

[0006] Figure 3 FIG. 1 is a detailed circuit diagram of the power amplifier 102 and the bias circuit 106 in the electronic device 300 according to an embodiment of the present invention.

[0007] Figure 4 FIG. 4 is a detailed circuit diagram of the power amplifier 102 and the bias circuit 106 in the electronic device 400 according to an embodiment of the present invention.

[0008] Figure 5A The figure is a graph showing the power conversion efficiency versus output power of a power amplifier in the prior art.

[0009] Figure 5B FIG. 1 is a graph showing power conversion efficiency versus output power of the power amplifier 102 in the electronic device 100 according to an embodiment of the present invention.

[0010]

Explanation of symbols

[0011] 100: Electronic devices

[0012] 102: Power Amplifier

[0013] 104: Power detector

[0014] 106: Bias circuit

[0015] 108: Driver Amplifier

[0016] 110: Bias circuit

[0017] 112: driving current

[0018] 120: driving voltage

[0019] 122: driving current

[0020] 130, 132, 134: RF signal

[0021] RFIN, IN: Input terminal

[0022] OUT: Output terminal

[0023] W: Input power

[0024] D1: First transistor

[0025] D2: Second transistor

[0026] D3: The third transistor

[0027] D4: The fourth transistor

[0028] R1: The first resistor

[0029] R2: Second resistor

[0030] R3: The third resistor

[0031] R4: The fourth resistor

[0032] R5: The fifth resistor

[0033] C1, C2: capacitors

[0034] L1: Inductor

[0035] 140: Coupling element

[0036] Vbias: first voltage

[0037] Vcc: Second voltage

[0038] G: Ground voltage

[0039] A, B: Point

[0040] 300: Electronic devices

[0041] 400: Electronic devices DETAILED DESCRIPTION

[0042] Figure 1 FIG. 1 is a schematic diagram of an electronic device 100 according to an embodiment of the present invention. Figure 1 As shown, the electronic device 100 includes a power amplifier 102, a power detector 104, a bias circuit 106, a driving amplifier 108, and a bias circuit 110. In some embodiments, the electronic device 100 is designed based on a Doherty power amplifier (Doherty PA) architecture of a heterojunction bipolar transistor (HBT) process, but the present invention is not limited thereto. In some embodiments, the power amplifier 102 includes an input terminal IN. The power amplifier 102 receives a radio frequency signal 132 through the input terminal IN and amplifies the radio frequency signal 132. The power of the radio frequency 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 radio frequency signal 132, and outputs a driving voltage 120 to the bias circuit 106 according to the input power W. For example, when the input power W of the radio frequency signal 132 is larger, the driving voltage 120 output by the power detector 104 is higher, but the present invention is not limited thereto. In some embodiments, the driving voltage 120 is a DC voltage, but the invention is not limited thereto.

[0043] 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 driving current 122 to the power amplifier 102 according to the driving voltage 120. In some embodiments, the driving current 122 is a DC current, but the present invention is not limited thereto. The power amplifier 102 increases the power of the RF signal 132 from the input power W to a target power according to the driving current 122, thereby generating a RF signal 134. The power amplifier 102 outputs the amplified RF signal 134 through an output terminal OUT. In some embodiments, the amplified RF signal 134 can be radiated to a receiving device via an antenna (not shown). In some embodiments, the driver amplifier 108 is electrically connected to the input terminal IN of the power amplifier 102. The driver amplifier 108 amplifies the RF signal 130 having an initial power to the RF signal 132 having an input power W. The driver amplifier 108 receives the RF signal 130 through an input terminal RFIN.

[0044] In some embodiments, the RF signal 130 may come from a RF transceiver (not shown). The RF transceiver may, for example, convert a digital signal into a baseband signal, convert the baseband signal into an intermediate frequency signal, and then convert the intermediate frequency signal into a RF signal, but the present invention is not limited thereto. Figure 1 In the embodiment of the present invention, the bias circuit 106 for driving the power amplifier 102 is different from the bias circuit 110 for driving the driving amplifier 108, but the present invention is not limited thereto. The driving amplifier 108 is used to perform the first stage amplification of the RF signal 130. The power amplifier 102 is used to perform the second stage amplification of the RF signal 130. In some embodiments, the power amplifier 102 is the last stage amplifier before the antenna, but the present invention is not limited thereto. In some embodiments, the power detector 104 can detect the input power W of the RF signal 132 in any form. For example, the power detector 104 can detect the voltage and current of the coupled signal of 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. Finally, the power of the coupled signal is converted into the input power W of the RF signal 132, but the present invention is not limited thereto. In some embodiments, the bias circuit 110 is electrically connected to the driving amplifier 108 to output a driving current 112 to the driving amplifier 108. In some embodiments, the driving current 112 is less than the driving current 122, but the present invention is not limited thereto. The driving current 112 and the driving current 122 are the same, and are also DC currents, but the present invention is not limited thereto.

[0045] Figure 2 FIG. 1 is a detailed circuit diagram of the power amplifier 102 and the bias circuit 106 in the electronic device 100 according to an embodiment of the present invention. Figure 2 As shown, 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. Figure 2 In the embodiment of the present invention, the first end of the first transistor D1 is electrically coupled to a first voltage Vbias through the third resistor R3, the second end of the first transistor D1 is electrically coupled to the second end of the fourth transistor D4 in the power amplifier 102 through the first resistor R1, and the third end of the first transistor D1 is electrically connected to a ground voltage G. The first end of the second transistor D2 is electrically connected to the first voltage Vbias, and the second end of the second transistor D2 is electrically coupled to the first end of the first transistor D1 through the second resistor R2. The 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, and 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.

[0046] 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. Figure 2 In an embodiment of the present invention, 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 bipolar junction transistors (Bipolar Junction Transistor: BJT), but the present invention is not limited thereto. In some embodiments, the first transistor D1, the second transistor D2, the third transistor D3, and the fourth transistor D4 are NPN bipolar junction transistors, but the present invention is not limited thereto.

[0047] In some embodiments, the power detector 104 detects the input power W of the RF signal 132, and outputs a driving 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 is larger, the driving voltage 120 output by the power detector 104 is higher, but the present invention is not limited thereto. The third transistor D3 outputs a driving current 122 from its third end to the second end of the fourth transistor D4 in the power amplifier 102 according to the driving voltage 120. For example, when the driving voltage 120 from the power detector 104 is higher, the driving current 122 output from the third end of the third transistor D3 to the second end of the fourth transistor D4 is larger. In some embodiments, the fourth resistor R4 can adjust a start-up voltage of the fourth transistor D4. For example, assuming 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. In the case where the fourth resistor R4 is not provided, the driving voltage 120 may need to be higher than 1.4V to enable the third transistor D3 to start outputting the driving current 122. In contrast, 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 terminal of the third transistor D3, the driving voltage 120 only needs to be higher than 0.7V to enable the third transistor D3 to start outputting the driving current 122.

[0048] exist Figure 2 In an embodiment of the present invention, the first transistor D1, the second transistor D2, the first resistor R1, the second resistor R2, the third resistor R3 in the bias circuit 106, and the fourth transistor D4 in the power amplifier 102 can be combined into a current mirror structure, but the present invention is not limited thereto. The fourth transistor D4 increases the power of the RF signal 132 from the input power W to a target power according to the driving current 122. In some embodiments, the fourth transistor D4 is driven by the driving current 122 from the third transistor D3 and the current from the second voltage Vcc at the same time. In detail, the first end of the fourth transistor D4 is electrically coupled to the second voltage Vcc through the inductor L1, the second end of the fourth transistor D4 is electrically connected to the third end of the third transistor D3 and the first resistor R1, and the third end of the fourth transistor D4 is electrically connected to the fourth resistor R4 and the ground voltage G. The capacitor C2 is electrically connected between the output end OUT and the first end of the fourth transistor D4. The inductor L1 is electrically connected between the second voltage Vcc and the first end of the fourth transistor D4. The fourth transistor D4 outputs the amplified RF signal 134 through the output terminal OUT.

[0049] In some embodiments, the first voltage Vbias may be the same as or different from the second voltage Vcc. Figure 2The electronic device 100 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 the 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 the 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.

[0050] Figure 3 FIG. 1 is a detailed circuit diagram of the power amplifier 102 and the bias circuit 106 in the electronic device 300 according to an embodiment of the present invention. Figure 3 As shown, 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. Figure 3 In the embodiment of the present invention, the first end of the first transistor D1 is electrically coupled to the first voltage Vbias through the third resistor R3, and the second end of the first transistor D1 is electrically connected to the third end of the second transistor D2 and the first end of the third transistor D3 through the first resistor R1. The third end of the first transistor D1 is electrically connected to the ground voltage G. The first end of the second transistor D2 is electrically connected to the first voltage Vbias, and the second end of the second transistor D2 is electrically coupled to the first end of the first transistor D1 through the second resistor R2. The 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, and 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.

[0051] Specifically, 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. On the other hand, 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. Figure 3 In the electronic device 300, since the setting of the resistor R1 is different from Figure 2 The configuration of the remaining components in the electronic device 300 is the same as that of the electronic device 100, and thus will not be described in detail.

[0052] Figure 4 FIG. 4 is a detailed circuit diagram of the power amplifier 102 and the bias circuit 106 in the electronic device 400 according to an embodiment of the present invention. Figure 4 As shown, 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. Figure 4 In the embodiment of the present invention, the first end of the first transistor D1 is electrically coupled to the first voltage Vbias through the third resistor R3, and the second end of the first transistor D1 is electrically connected to the third end of the second transistor D2 and the first end of the third transistor D3 through the first resistor R1. The third end of the first transistor D1 is electrically connected to the ground voltage G. The first end of the second transistor D2 is electrically connected to the first voltage Vbias, and the second end of the second transistor D2 is electrically coupled to the first end of the first transistor D1 through the second resistor R2. The 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, and 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 across 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, but the present invention is not limited to this. Figure 4 In the electronic device 400, since the setting of the resistor R5 is different from Figure 3 The configuration of the remaining components in the electronic device 400 is the same as that of the electronic device 300, and thus will not be described in detail.

[0053] Figure 5A The figure is a graph showing the power conversion efficiency versus output power of a power amplifier in the prior art. Figure 5A The horizontal axis is output power (dBm), and the vertical axis is power conversion efficiency (PAE) (%). The power amplifier in the prior art lacks the Figure 1 The power detector 104 in the electronic device 100 and its bias circuit are different from the bias circuit 106 of the present invention. In some embodiments, the power conversion efficiency is equal to the ratio of the RF signal output power to the consumed DC power, that is, PAE = (Pout-Pin) / Pdc. PAE is the power conversion efficiency, Pout is the RF signal output power, Pin is the RF signal input power, and Pdc is the consumed DC power. Figure 5A As shown, refer to Figure 5A At point A in FIG. 1 , when the output power of the power amplifier in the prior art is 28 dBm, the power conversion efficiency of the power amplifier in the prior art is 25%.

[0054] Figure 5B FIG. 1 is a graph showing power conversion efficiency versus output power of the power amplifier 102 in the electronic device 100 according to an embodiment of the present invention. Figure 5B The horizontal axis is output power (dBm), and the vertical axis is power conversion efficiency (PAE) (%). Figure 5B As shown, refer to Figure 5BAt point B in FIG. 1 , when the output power of the power amplifier 102 in the electronic device 100 is 28 dBm, the power conversion efficiency of the power amplifier 102 of the present invention is increased to 35% by the configuration of the bias circuit 106. In other words, under the same RF signal output power, compared with the power amplifier in the prior art, the power amplifier 102 in the electronic device 100 of the present invention can increase the power conversion efficiency by 10%, thereby achieving the purpose of effective power saving.

[0055] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meanings as commonly understood by those skilled in the art to which the present invention belongs. It is understood that these terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning consistent with the background or context of the relevant technology and the present disclosure, and should not be interpreted in an idealized or overly formal manner unless specifically defined in the embodiments of the present disclosure.

Claims

1. An electronic device, comprising: A driving amplifier for outputting a radio frequency signal; A power amplifier, electrically connected to the driving amplifier, comprising an input end, for receiving the radio frequency signal through the input end and amplifying the radio frequency signal; A power detector, electrically coupled to the input terminal, for detecting the input power of the radio frequency signal and outputting a driving voltage corresponding to the input power; A bias circuit, electrically connected to the power amplifier and the power detector, for outputting a first driving current to the power amplifier according to the driving voltage; The power amplifier increases the power of the radio frequency signal from the input power to the target power according to the first driving current.

2. The electronic device according to claim 1, wherein: The bias circuit includes: A first transistor, a first terminal of which is electrically coupled to a first voltage, a second terminal of which is electrically coupled to the power amplifier, and a third terminal of which is electrically connected to a ground voltage; a second transistor, a first terminal of which is electrically connected to the first voltage, and a second terminal of which is electrically coupled to the first terminal of the first transistor; and The third transistor has 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.

3. The electronic device as claimed in claim 2, wherein: 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 is electrically connected between the first end of the first transistor and the first voltage; and The fourth resistor is electrically connected between the third terminal of the third transistor and the ground voltage.

4. The electronic device as claimed in claim 3, wherein: The power amplifier includes: The fourth transistor has a first terminal electrically coupled to the second voltage, a second terminal electrically connected to the third terminal of the third transistor and the first resistor, and a third terminal electrically connected to the fourth resistor and the ground voltage.

5. The electronic device as claimed in claim 4, further comprising: The first capacitor is electrically connected between the input terminal and the third terminal of the third transistor.

6. The electronic device as claimed in claim 4, wherein: The power amplifier includes: A second capacitor electrically connected between the output terminal and the first terminal of the fourth transistor; and The first inductor is electrically connected between the second voltage and the first end of the fourth transistor.

7. The electronic device as claimed in claim 1, further comprising: The coupling element is electrically connected between the input end and the power detector and is used for coupling the radio frequency signal to the power detector.

8. The electronic device as claimed in claim 1, further comprising: A second bias circuit, electrically connected to the driving amplifier, for outputting a second driving current to the driving amplifier; The second driving current is smaller than the first driving current.

9. The electronic device as claimed in claim 4, wherein: The third transistor outputs the first driving current to the fourth transistor according to the driving voltage from the power detector.

10. The electronic device according to claim 4, wherein: The fourth resistor is used to adjust the start-up voltage of the fourth transistor.

11. The electronic device according to 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 structure.

12. The electronic device as claimed in claim 4, wherein: The first transistor, the second transistor, the third transistor, and the fourth transistor are bipolar junction transistors (Bipolar Junction Transistor: BJT).

13. The electronic device according to claim 12, wherein: The first transistor, the second transistor, the third transistor, and the fourth transistor are NPN bipolar junction transistors.

14. The electronic device as claimed in claim 4, wherein: The first voltage is the same as or different from the second voltage.

15. The electronic device according to claim 1, wherein: The driving amplifier amplifies the power of the radio frequency signal from the initial power to the input power.

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