Power amplifier device and method with digital pre-distortion mechanism

Abstract

The present application provides a power amplifier device and method with a digital predistortion mechanism, the power amplifier device comprising: a digital predistortion circuit and a power amplifier. The digital predistortion circuit receives a source digital signal comprising a source real part and a source imaginary part, and when the first and the second of the source real part and the source imaginary part are respectively low level and high level, the first and the second levels are alternately outputted as the first predistortion component, which is equivalent to the low level, and the second is directly outputted as the second predistortion component, thereby generating an input signal comprising an input real part and an input imaginary part, wherein the first and the second predistortion components are respectively one of the input real part and the input imaginary part. The power amplifier receives the input signal, performs power amplification, and generates an output signal.

Description

Technical Field

[0001] The present invention relates to power amplification technology, and in particular to a power amplification device and method with a digital predistortion mechanism. Background Art

[0002] A power amplifier usually requires a lower load impedance to generate a higher output power. Generally speaking, the load impedance is fixed so that the power of the output signal has nothing to do with the load impedance and only has a one-to-one correspondence with the voltage and current of the input signal.

[0003] However, for a power amplifier implemented with multiple RF digital-to-analog converters, for example, the constant load will deviate from the ideal load in the actual working state and change dynamically, and at the same time, it will cause a nonlinear relationship between the input signal and the output signal. When one of the real component and the imaginary component of the input signal of the power amplifier is in a low state and the other is in a high state, the load will deviate from the ideal load, and the high state will be affected by the low state and cannot output at full amplitude. The output signal cannot reach the maximum power, which reduces the efficiency. Summary of the invention

[0004] In view of the problems in the prior art, one object of the present invention is to provide a power amplifier device and method with a digital pre-distortion mechanism to improve the prior art.

[0005] The present invention includes a power amplifier device with a digital pre-distortion mechanism (digital pre-distortion; DPD), including: a digital pre-distortion circuit and a power amplifier. The digital pre-distortion circuit is configured to receive a source digital signal including a source real component and a source imaginary component, and perform digital pre-distortion when it is determined that the first of the source real component and the source imaginary component is at a low level and the second is at a high level, and alternately outputs a low level equivalent to the first as a first pre-distortion component with the first level and the second level, and directly outputs the second as a second pre-distortion component, thereby generating an input signal including an input real component and an input imaginary component, wherein the first pre-distortion component and the second pre-distortion component are respectively one of the input real component and the input imaginary component. The power amplifier is configured to receive the input signal, perform power amplification, and generate an output signal.

[0006] The present invention further includes a power amplification method with a digital predistortion mechanism, which is applied to a power amplification device, comprising: enabling a digital predistortion circuit to receive a source digital signal including a source real component and a source imaginary component; enabling the digital predistortion circuit to perform digital predistortion when determining that the first of the source real component and the source imaginary component is at a low level and the second is at a high level, enabling the digital predistortion circuit to alternately output a low level equivalent to the first as a first predistortion component with a first level and a second level, and directly output the second as a second predistortion component, thereby generating an input signal including an input real component and an input imaginary component, wherein the first predistortion component and the second predistortion component are respectively one of the input real component and the input imaginary component; and enabling a power amplifier to receive the input signal for power amplification to generate an output signal.

[0007] The features, implementation and effects of the present invention are described in detail below with reference to the accompanying drawings for preferred embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 A block diagram showing a power amplifier device with a digital pre-distortion mechanism according to an embodiment of the present invention;

[0009] Figure 2A as well as Figure 2B The figure shows a waveform diagram of a signal outputted by the digital pre-distortion circuit 110 after performing digital pre-distortion in one embodiment of the present invention;

[0010] Figure 3A as well as Figure 3B A waveform diagram showing a signal output by the digital pre-distortion circuit 110 after digital pre-distortion in one embodiment of the present invention; and

[0011] Figure 4 The flowchart of a power amplification method according to an embodiment of the present invention is shown.

[0012]

Explanation of symbols

[0013] 100: Power amplifier

[0014] 110: Digital Pre-Distortion Circuit

[0015] 120: Power Amplifier

[0016] 400: Power Amplification Method

[0017] S410~S450: Steps

[0018] DP1: first predistortion component

[0019] DP2: Second predistortion component

[0020] IN: Input signal

[0021] INI: Input real part

[0022] INQ: Input the imaginary component

[0023] OS: Source signal

[0024] OSI: Source Integer

[0025] OSQ: Source Imaginary Quantity

[0026] OUT: Output signal

[0027] VH: High level

[0028] VL: Low level DETAILED DESCRIPTION

[0029] An object of the present invention is to provide a power amplifier device and method with a digital pre-distortion mechanism.

[0030] Please refer to Figure 1 . Figure 1 A block diagram of a power amplifier device 100 with a digital pre-distortion mechanism according to an embodiment of the present invention is shown.

[0031] In one embodiment, the power amplifier device 100 is, for example, but not limited to, a plurality of IQ-based radio frequency analog-to-digital converters (RF DACs) for receiving a digital source signal OS and generating a simulated output signal OUT after power amplification.

[0032] The power amplifier device 100 includes a digital pre-distortion circuit 110 and a power amplifier 120 .

[0033] The digital predistortion circuit 110 is configured to receive a source signal OS including a source real component OSI and a source imaginary component OSQ. In one embodiment, the digital predistortion circuit 110 processes the source real component OSI and the source imaginary component OSQ to generate an input signal IN including an input real component INI and an input imaginary component INQ.

[0034] In more detail, when the low level is represented by a logical value of 0 and the high level is represented by a logical value of 1, the levels of the source real component OSI and the source imaginary component OSQ will have four possible states represented by logical values, namely (0,0), (0,1), (1,0) and (1,1).

[0035] When the first of the source real component OSI and the source imaginary component OSQ is at a low level and the second is at a high level, ie, the logic value represents a combination of (0, 1) or (1, 0), the digital pre-distortion circuit 110 is configured to perform a digital pre-distortion process.

[0036] Please also refer to Figure 2A as well as Figure 2B . Figure 2A as well as Figure 2B The figure shows a waveform diagram of a signal outputted by the digital pre-distortion circuit 110 after digital pre-distortion in one embodiment of the present invention, wherein the horizontal axis represents time and the vertical axis represents voltage.

[0037] When the source real component OSI is at a low level VL (eg, 0 volts) and the source imaginary component OSQ is at a high level VH (eg, 3 volts), the digital pre-distortion circuit 110 will Figure 2A As shown, the first level X and the second level -Y are alternately outputted as a low level equivalent to the source real component OSI as the first predistortion component DP1. Figure 2B As shown, the source real component OSQ directly outputted as the high level VH is used as the second pre-distortion component DP2.

[0038] Among them, the first predistortion component DP1 is Figure 1 The second predistortion component DP2 is Figure 1 , the input imaginary component INQ of the input signal IN.

[0039] In one embodiment, the digital pre-distortion circuit 110 can selectively output the first level X and the second level -Y alternately at the same frequency as the first pre-distortion component DP1. After averaging, it is equivalent to the low level VL of XY.

[0040] For example, the digital predistortion circuit 110 may make X and Y equal, such as 3. Therefore, the digital predistortion circuit 110 will alternately output a first level of 3 volts and a second level of -3 volts as the first predistortion component DP1, which is equivalent to a low level VL of 0 volt (3-3=0).

[0041] In one embodiment, when outputting at the same fixed frequency, the input signal IN generated eventually will have unnecessary spikes at the fixed frequency on the spectrum. Therefore, in another embodiment, the digital pre-distortion circuit 110 can output the first level X and the second level -Y at different frequencies.

[0042] Please also refer to Figure 3A as well as Figure 3B . Figure 3A as well as Figure 3B FIG. 1 is a diagram showing a waveform of a signal output by the digital pre-distortion circuit 110 after performing digital pre-distortion in one embodiment of the present invention.

[0043] When the source real component OSI is at a high level VH (eg, 3 volts) and the source imaginary component OSQ is at a low level VL (eg, 1 volt), the digital pre-distortion circuit 110 will Figure 3A As shown in FIG. 1 , the source real component OSI directly outputted as the high level VH is used as the second predistortion component DP2. In addition, the digital predistortion circuit 110 can be as follows: Figure 3B As shown, the first level X and the second level -Y are alternately outputted as a low level VL equivalent to the source imaginary component OSQ as the first predistortion component DP1.

[0044] Among them, the first predistortion component DP1 is Figure 1 The second predistortion component DP2 is Figure 1 , the input real component INI of the input signal IN.

[0045] The digital pre-distortion circuit 110 can selectively output N times of the first level X and M times of the second level -Y alternately in one cycle as the first pre-distortion component DP1. After averaging, the output voltage will be equivalent to a low level VL of (NX-MY) / (NM).

[0046] For example, when the low level of the source real component OSI is 1 volt, the digital pre-distortion circuit 110 can make X and Y be, for example, 1.5 volts and 2 volts, respectively. Therefore, the digital pre-distortion circuit 110 will alternately output a first level of 1.5 volts 4 times and a second level of -2 volts 2 times as the first pre-distortion component DP1, which is equivalent to a low level VL of 1 volt ((4×1.5-2×2) / (4-2)=1).

[0047] Therefore, when the first level X and the second level -Y are output alternately at different frequencies, the occurrence of the burst will be determined by the corresponding occurrence times M and N, and will be smaller in intensity and more dispersed in the frequency spectrum.

[0048] On the other hand, when the source real component OSI and the source imaginary component OSQ are both high or low, that is, the logic value represents a combination of (0,0) or (1,1), the digital pre-distortion circuit 110 is configured not to perform the digital pre-distortion process. The digital pre-distortion circuit 110 directly outputs the source real component OSI and the source imaginary component OSQ as the input real component INI and the input imaginary component INQ of the input signal IN.

[0049] Next, the power amplifier 120 is configured to receive the input signal IN to perform power amplification and generate an output signal OUT.

[0050] In common applications, a power amplifier is configured to transmit an output signal OUT to a load (not shown) electrically coupled thereto. For example, for a power amplifier device implemented with a plurality of RF digital-to-analog converters, the constant load deviates from the ideal load of the actual working state of the power amplifier and no longer has a one-to-one relationship with the input signal.

[0051] In more detail, the change of ideal load caused by different working conditions will cause a nonlinear relationship between the input signal and the output signal. When one of the real component and the imaginary component of the input signal is at a low level and the other is at a high level, the one with the high level will be affected by the low level due to load deviation and cannot reach full-scale output. In the constellation diagram drawn based on the real component and the imaginary component, the original values ​​of the real component and the imaginary component can fall evenly in the range of -1 to 1, which should make the constellation diagram present an ideal square. However, due to the influence of the above-mentioned dynamic load changes, the shape of the constellation diagram will be distorted, with corner compression or corner expansion.

[0052] Therefore, the power amplifier device of the present invention uses a digital pre-distortion mechanism to simulate a low level with an alternately output voltage level, so that a high level can be output at full amplitude without being affected by the low level when the load changes, thereby increasing the overall power of the output signal.

[0053] It should be noted that the values ​​of each voltage and the output times of the first level and the second level in the above embodiment are only examples. In other embodiments, the values ​​of each voltage and the output times of the first level and the second level can be adjusted according to actual needs and are not limited to the above implementation.

[0054] Please refer to Figure 4 . Figure 4 A flow chart of a power amplification method 400 according to an embodiment of the present invention is shown.

[0055] In addition to the aforementioned device, the present invention further discloses a power amplification method 400, which is applied to, for example, but not limited to Figure 1 An embodiment of the power amplification method 400 is as follows: Figure 4 As shown, it includes the following steps:

[0056] In step S410 : the digital pre-distortion circuit 110 receives a source signal OS including a source real component OSI and a source imaginary component OSQ.

[0057] In step S420 , the digital pre-distortion circuit 110 determines whether the first of the source real component OSI and the source imaginary component OSQ is at a low level and the second of the source imaginary component OSQ is at a high level.

[0058] In step S430: when the first one of the source real component OSI and the source imaginary component OSQ is at a low level and the second one is at a high level, the digital pre-distortion circuit 110 alternately outputs a low level equivalent to the first one as the first pre-distortion component DP1 with the first level and the second level, and directly outputs the second one as the second pre-distortion component DP2, thereby generating an input signal IN including an input real component INI and an input imaginary component INQ, wherein the first pre-distortion component DP1 and the second pre-distortion component DP2 are respectively one of the input real component INI and the input imaginary component INQ.

[0059] In step S440 , when the source real component OSI and the source imaginary component OSQ are both high or low, the digital pre-distortion circuit 110 directly outputs the source real component OSI and the source imaginary component OSQ as the input real component INI and the input imaginary component INQ of the input signal IN.

[0060] In step S450: after step S430 or step S440 is completed, the power amplifier 120 receives the input signal to perform power amplification and generate an output signal.

[0061] It should be noted that the above implementation is only an example. In other embodiments, those skilled in the art may make changes without violating the spirit of the present invention.

[0062] In summary, the present invention provides a power amplifier device and method with a digital pre-distortion mechanism.

[0063] Although the embodiments of the present invention are described above, these embodiments are not intended to limit the present invention. A person having ordinary knowledge in the technical field may make changes to the technical features of the present invention according to the explicit or implicit contents of the present invention. All these changes may fall within the scope of patent protection sought by the present invention. In other words, the scope of patent protection of the present invention shall be subject to that defined in the claims of this application.

Claims

1. A power amplifier device with a digital pre-distortion (DPD) mechanism, characterized in that: Include: a digital predistortion circuit configured to receive a source digital signal including a source real component and a source imaginary component, and perform digital predistortion when determining that a first one of the source real component and the source imaginary component is a low level and a second one of the source real component and the source imaginary component is a high level, and alternately output the low level equivalent to the first one as a first predistortion component with a first level and a second level, and directly output the second one as a second predistortion component, thereby generating an input signal including an input real component and an input imaginary component, wherein the first predistortion component and the second predistortion component are one of the input real component and the input imaginary component respectively; and A power amplifier is configured to receive the input signal, perform power amplification, and generate an output signal.

2. The power amplifier device according to claim 1, characterized in that: The value of the first level is X and the value of the second level is -Y. The digital pre-distortion circuit outputs the first level and the second level alternately at the same frequency as the first pre-distortion component to equivalently output the low level with a value of XY.

3. The power amplifier device according to claim 2, characterized in that: The values ​​of X and Y are equal, so the equivalent output value is 0.

4. The power amplifier device according to claim 1, characterized in that: The value of the first level is X and the value of the second level is -Y. The digital pre-distortion circuit alternately outputs the first level N times and the second level M times as the first pre-distortion component in one cycle, with the low level having an equivalent output value of (NX-MY) / (NM).

5. The power amplifier device according to claim 1, characterized in that: The digital predistortion circuit is also configured to determine that the source real component and the source imaginary component are both low voltage components. When the source real component and the source imaginary component are both at the high level, the source real component and the source imaginary component are directly output as the input real component and the input imaginary component of the input signal respectively.

6. A power amplification method with a digital predistortion mechanism, applied to a power amplification device, characterized in that: Include: A digital predistortion circuit is configured to receive a source digital signal including a source real component and a source imaginary component; The digital predistortion circuit performs digital predistortion when it is determined that a first one of the source real component and the source imaginary component is at a low level and a second one of the source imaginary component is at a high level, so that the digital predistortion circuit alternately outputs the low level equivalent to the first one as a first predistortion component at a first level and a second level, and directly outputs the second one as a second predistortion component, thereby generating an input signal including an input real component and an input imaginary component, wherein the first predistortion component and the second predistortion component are respectively one of the input real component and the input imaginary component; as well as A power amplifier receives the input signal to perform power amplification and generate an output signal.

7. The power amplification method according to claim 6, characterized in that: The value of the first level is X and the value of the second level is -Y, and the power amplification method further comprises: The digital pre-distortion circuit is made to alternately output the first level and the second level at the same frequency as the first pre-distortion component, with the equivalent output value being the low level of XY.

8. The power amplification method according to claim 7, characterized in that: The values ​​of X and Y are equal, so the equivalent output value is 0.

9. The power amplification method according to claim 6, characterized in that: The value of the first level is X and the value of the second level is -Y, and the power amplification method further comprises: The digital pre-distortion circuit is made to alternately output the first level N times and the second level M times as the first pre-distortion component in one cycle, with the low level having an equivalent output value of (NX-MY) / (NM).

10. The power amplification method according to claim 6, characterized in that: Also includes: When the digital predistortion circuit determines that the source real component and the source imaginary component are both at the low level or both at the high level, the digital predistortion circuit directly outputs the source real component and the source imaginary component as the input real component and the input imaginary component of the input signal.

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