WO2019047041A1 - Feedforward amplifier and intermodulation component detection method therefor - Google Patents

Abstract

Provided is a feedforward amplifier, comprising: a carrier cancellation loop (110) having an input end serving as an input end of the feedforward amplifier; a distortion cancellation loop (120) having an input end connected to an output end of the carrier cancellation loop (110) and an output end serving as an output end of the feedforward amplifier; and a control circuit (130) having a first input end connected to the output end of the distortion cancellation loop (120) and an output end connected to a control end of the distortion cancellation loop (120); wherein, the control circuit (130) comprises an intermodulation detection circuit (131) and a microprocessor (132). An input end of the intermodulation detection circuit (131) serves as the first input end of the control circuit (130). An output end of the intermodulation detection circuit (131) is connected to a first input end of the microprocessor (132). An output end of the microprocessor (132) serves as the output end of the control circuit (130). The feedforward amplifier described above has lower complexity and can achieve a better linearization effect.

Description

Feedforward amplifier and detection method of intermodulation component thereof

[Technical Field]

The present invention relates to the field of radio frequency communication technologies, and in particular, to a feedforward amplifier and a method for detecting intermodulation components thereof.

 【Background technique】

Modern mobile communication technology has higher and higher requirements on the linearity of power amplifiers. The linearization technology of power amplifiers has become the research focus in the field of wireless communication. Feedforward linearization technology has become the current research due to its good stability and linearization level. One of the hot spots.

At present, in order to obtain better linearization effect for feedforward, a pilot signal is usually coupled at the input end of the feedforward amplifier, and the amplitude and phase of the carrier cancellation loop and the distortion cancellation loop are controlled by detecting the pilot, thereby judging before The nonlinear cancellation effect of the feed, and then obtain a better linearization effect, but because of the increase of the pilot signal, the system complexity is high, increasing the power consumption of the system; or by detecting the two reference signals, that is, the amplitude reference signal and The phase reference signal controls the linearization capability of the feedforward, and thus obtains a better linearization effect. However, due to the addition of two reference signals, the system complexity is high, which increases the power consumption of the system.

 [Summary of the Invention]

The object of the present invention is to provide a feedforward amplifier and a method for detecting the intermodulation component thereof, in view of the problem that the feedforward amplifier in the prior art obtains better linearization.

The technical solution adopted by the present invention to solve the above technical problem is to provide a feedforward amplifier including: a carrier cancellation loop, an input terminal as an input end of the feedforward amplifier; a distortion cancellation loop, an input end and the carrier An output terminal of the cancellation loop, the output being the output of the feedforward amplifier; and a control circuit, the first input being coupled to the output of the distortion cancellation loop, the output being coupled to the distortion cancellation loop a control terminal connection; wherein: the control circuit includes an intermodulation detection circuit and a microprocessor, wherein an input end of the intermodulation detection circuit serves as a first input end of the control circuit, and the microprocessor is first An input end is connected to an output end of the intermodulation detection circuit, an output end of the microprocessor is used as an output end of the control circuit, and the microprocessor detects an intermodulation component detected by the intermodulation detection circuit Feedback to the distortion cancellation loop.

Another technical solution adopted by the present invention to solve the above technical problem is to provide a method for detecting an intermodulation component of a feedforward amplifier, wherein the feedforward amplifier includes a carrier cancellation loop and a distortion cancellation loop; The method includes: adjusting an amplitude and a phase of the carrier cancellation loop; performing, by the carrier cancellation loop, carrier cancellation according to the adjusted amplitude and phase of the carrier cancellation loop; determining a distortion output by the carrier cancellation loop Whether the carrier power in the component reaches a first preset value; adjusting the amplitude and phase of the distortion cancellation loop when the carrier power in the distortion component reaches the first preset value; The circuit performs distortion cancellation according to the amplitude and phase of the distortion cancellation loop that is adjusted; and determines whether the power of the intermodulation component in the second main signal output by the distortion cancellation loop reaches a second preset value, and if so, And acquiring an amplified first main signal output by the feedforward amplifier.

The beneficial effects of the present invention are: relative to the prior art, the intermodulation detection circuit is used to feed the intermodulation component to the distortion cancellation loop, so that the distortion cancellation loop can output a linearized better amplification signal, thereby eliminating the pilot. Circuits are generated to reduce the complexity of the system.

 [Description of the Drawings]

The present invention will be further described below in conjunction with the accompanying drawings and embodiments, in which:

1 is a circuit diagram of an embodiment of a feedforward amplifier of the present invention;

Fig. 2 is a schematic view showing the process of detecting the intermodulation component of the feedforward amplifier of the above embodiment.

【Detailed ways】

The technical solutions of the present invention are further described in detail below in conjunction with the accompanying drawings and specific embodiments.

1 shows a feedforward amplifier of the present invention. As shown in FIG. 1, the feedforward amplifier 100 includes a carrier cancellation loop 110, a distortion cancellation loop 120, and a control circuit 130, wherein the input of the carrier cancellation loop 110 As an input end of the feedforward amplifier 100, an input end of the distortion cancellation loop 120 is connected to an output end of the carrier cancellation loop 110, and an output end is used as an output end of the feedforward amplifier 100. The first input end of the control circuit 130 is The output of the distortion cancellation loop 120 is connected and the output is connected to the control terminal of the distortion cancellation loop 120.

The input end of the feedforward amplifier 100 inputs a first main signal including at least two carriers; the carrier cancellation loop 110 is configured to modulate and amplify the first main signal to obtain a second main signal, and the first main signal The signal and the second main signal are cancelled to extract a distortion component. The distortion cancellation loop 120 is configured to modulate, amplify, and perform carrier cancellation on the second main signal and the modulated and amplified distortion component to extract a carrier, such that by eliminating a nonlinear portion of the second main signal, The output end of the distortion cancellation loop 120 outputs a linear portion of the second main signal, thereby implementing an output of the feedforward amplifier 100 to output a linearized second main signal. The control circuit 130 is configured to detect intermodulation components included in the second main signal output by the distortion cancellation loop 120, and adaptively adjust parameters, such as amplitude and phase, of the distortion cancellation loop 120 according to the intermodulation components, thereby enabling feedforward Amplifier 100 achieves a better linear effect.

Specifically, as shown in FIG. 1, the control circuit 130 includes an intermodulation detection circuit 131 and a microprocessor 132. The input end of the intermodulation detection circuit 131 serves as the first input end of the control circuit 130, and the output end of the intermodulation detection circuit 131. Connected to the first input of microprocessor 132, the output of microprocessor 132 serves as the output of control circuit 130. The intermodulation detection circuit 131 is configured to detect an intermodulation component included in the second main signal output by the distortion cancellation loop 120, and the microprocessor 132 is configured to feed the intermodulation component to the distortion cancellation loop 120, so that the adjustment is adaptive. The distortion cancels the loop 120 such that the distortion cancellation loop 120 outputs an amplified first main signal having a better linear effect.

As further shown in FIG. 1, the second input of the control circuit 130 is coupled to the output of the carrier cancellation loop 120, and the output of the control circuit 130 is coupled to the control terminal of the carrier cancellation loop 110. The control circuit 130 is further configured to adaptively adjust parameters, such as amplitude and phase, of the carrier cancellation loop 110 according to the distortion component output by the carrier cancellation loop 120, thereby improving the accuracy of the distortion component output by the carrier cancellation loop 110, so that When the accuracy of the output distortion component of the carrier cancellation loop 110 is the greatest, that is, when the carrier power included in the distortion component is the smallest, the control circuit 130 adaptively adjusts the distortion cancellation loop 120 according to the intermodulation component.

Further, the frequency of the intermodulation component detected by the intermodulation detection circuit 131 from the distortion cancellation loop is determined by a preset value of the inter-carrier frequency difference of the first main signal input from the input end of the feedforward amplifier 100, That is, the frequency of the intermodulation component has a frequency difference from the frequency of the first main signal. As shown in FIG. 1, the intermodulation detection circuit 131 includes a mixer 131a, a bandpass filter 131b, and a phase locked loop 131c, wherein the first input terminal of the mixer 131a serves as an input terminal of the intermodulation detection circuit 131. The second input end of the mixer 131a is connected to the output end of the phase locked loop 131c, the output end of the mixer 131a is connected to the input end of the band pass filter 131b, and the output end of the band pass filter 131b is used as the intermodulation detection. The output of circuit 131. Since there is a frequency difference between the intermodulation component detected by the intermodulation detection circuit 131 and the frequency of the first main signal, the matrix coefficient of the band pass filter therein is greatly reduced, and the hardware implementation difficulty of the intermodulation detection circuit 131 is reduced.

In this embodiment, compared with the prior art, in order to obtain a better linearization effect, the intermodulation component is directly used to control the adjustment distortion cancellation loop, thereby eliminating the pilot generation circuit, reducing the complexity of the system, and saving the pilot. The occupied spectrum resources.

Specifically, as shown in FIG. 1, the carrier cancellation loop 110 includes a first modulator 111, a main power amplifier 112, a first delay line 113, a first power combiner 114, and a power splitter 115, wherein the power splitter 115 The input end serves as an input end of the carrier cancellation loop 110, and the input end of the first modulator 111 and the input end of the first delay line 113 are respectively connected to the first output end and the second output end of the power splitter 115, first The output of the extension line 113 is connected to the first input of the first power combiner 114, the output of the first modulator 111 is connected to the input of the main power amplifier 112, and the output of the main power amplifier 112 is combined with the first power. The second input of the device 114 is connected. Further, the control terminal of the first modulator 111 serves as a control terminal of the carrier cancellation loop 110. The power splitter 115 divides a first main signal input by the input end of the feedforward amplifier 100 into two first main signals, wherein one of the first main signals is transmitted to the first modulator 111, and then passes through the first modulator 111 and The main power amplifier 112 outputs a second main signal to the first power synthesizer 114, and the other first main signal is transmitted to the first delay line 113, and simultaneously outputted to the first power synthesizer 114 simultaneously with the second main signal, thereby being first The power combiner 114 performs carrier cancellation on the first main signal and the second main signal, and outputs a distortion component, thereby implementing an extracted distortion component, wherein the distortion component is mainly reflected by the main power amplifier 112.

The distortion cancellation loop 120 includes a second modulator 121, a secondary power amplifier 122, a second delay line 123, and a second power combiner 124, wherein the input of the second modulator 121 and the output of the first power combiner 114 Connected, the output of the second modulator 121 is connected to the input of the auxiliary power amplifier 122, the control end of the second modulator 121 serves as the control terminal of the distortion cancellation loop 120, the input of the second delay line 123 and the main power amplifier The output end of the second delay line 123 is connected to the first input end of the second power combiner 124, and the second input end of the second power combiner 124 is connected to the output end of the auxiliary power amplifier 122. The output of the two power combiner 124 acts as the output of the distortion cancellation loop 120. The distortion component passes through the second modulator 121 and the auxiliary power amplifier 122, modulates, amplifies, and transmits the distortion component to the second power combiner 124, and simultaneously transmits the second main signal to the second power through the second delay line 123. The synthesizer 124, and further the second power combiner 124, performs distortion cancellation on the second main signal and the modulated amplified distortion component to implement the advanced carrier, eliminates nonlinear distortion of the main power amplifier 122, and thereby obtains the amplified first main signal. .

Further, as shown in FIG. 1, the control circuit 130 further includes a first detecting circuit 133. The output of the intermodulation detecting circuit 131 is connected to the first input terminal of the microprocessor 132 via the first detecting circuit 133. In one embodiment, the first detection circuit 133 includes a detector 133a and an analog to digital converter 133b that are sequentially connected. The first detecting circuit 133 is configured to detect the power of the intermodulation component detected by the intermodulation detecting circuit 131, and transmit the power of the intermodulation component to the microprocessor 132.

The control circuit 130 further includes a second detection circuit 134, the input of the second detection circuit 134 is connected to the second output of the carrier cancellation loop 110, and the output is connected to the second input of the microprocessor 132, wherein In an embodiment, the second detection circuit 134 includes a detector 134a and an analog to digital converter 134b that are sequentially connected. The second detecting circuit 134 is configured to detect the carrier power included in the distortion component output by the carrier cancellation loop 110, and transmit the carrier power to the microprocessor 132.

As further shown in FIG. 1, the carrier cancellation loop 110 further includes a first directional coupler 116 and a second directional coupler 117, wherein the output of the main power amplifier 112 passes through the input of the first directional coupler 116 and The first output is coupled to the second input of the first power combiner 114, and the output of the main power amplifier 112 also passes through the input and the second output of the first directional coupler 116 as an output of the carrier cancellation loop 110. end. The output of the first power combiner 114 passes through the second directional coupler 117 and also serves as the output of the carrier cancellation loop 110.

The distortion cancellation loop 120 further includes a third directional coupler 125, wherein the output of the second power combiner 124 also passes through the input of the third directional coupler 125 and the first output as the output of the distortion cancellation loop 120. .

In the following, in conjunction with FIG. 1 and FIG. 2, in order to achieve optimal linearization of the feedforward amplifier 100, the intermodulation component detection of the feedforward amplifier 100 will be described in detail.

As shown in FIG. 2, the process of detecting the intermodulation component of the feedforward amplifier 100 includes the following steps:

First, starting from step S201: adjusting the amplitude and phase of the carrier cancellation loop 110. Specifically, the amplitude and phase of the first modulator 111 in the carrier cancellation loop 110 are adjusted.

Subsequently, step S202: the carrier cancellation loop 110 performs carrier cancellation according to the amplitude and phase in step S201.

Subsequently, step S203: detecting the carrier power in the distortion component output by the carrier cancellation loop 110.

Then, in step S204, it is determined whether the carrier power reaches the preset value. If yes, step S205 is performed. If no, step S201 is performed, which is equivalent to re-execution of step S201 to step S204 until the carrier power does not reach the preset value. The power reaches the preset value.

Subsequently, step S205: adjusting the amplitude and phase of the distortion cancellation loop 120. Specifically, the amplitude and phase of the second modulator 121 in the distortion cancellation loop 120 are adjusted.

Subsequently, step S206: the distortion cancellation loop 120 performs distortion cancellation according to the amplitude and phase in step S205.

Subsequently, step S207: detecting the power of the intermodulation component in the second main signal output by the distortion cancellation loop 120. In this step, the power of the intermodulation component in the second main signal is directly detected without using the pilot signal, thereby reducing system complexity.

Then, in step S208, it is determined whether the power of the intermodulation component reaches a preset value. If yes, the amplified first main signal output by the feedforward amplifier 100 is obtained, and the process ends. If not, step S205 is performed, which is equivalent to When the power of the intermodulation component does not reach the preset value, step S205 to step S208 are performed again until the power of the intermodulation component reaches a preset value.

Further, the process of detecting the intermodulation component of the feedforward amplifier 100 further includes: after the predetermined time interval, re-executing the above steps S201 to S208 to adjust the carrier cancellation loop 110 and the distortion cancellation loop 120 in real time, further improving the feedforward amplifier The linearity of the output of 100.

After experimental testing, when the first main signal SNR of the two carriers input by the feedforward amplifier 100 is 80 dB, the ACLR of the two carrier signals is detected by the above intermodulation component detection (Adjacent). Channel Leakage Ratio, adjacent channel leakage power ratio) is less than -76.3dBc, which indicates that the output of the feedforward amplifier 100 can achieve better linearization by the above-mentioned intermodulation component detection.

The above is only the embodiment of the present invention, and is not intended to limit the scope of the invention, and the equivalent structure or equivalent process transformations made by the description of the invention and the drawings are directly or indirectly applied to other related technologies. The fields are all included in the scope of patent protection of the present invention.

Claims (13)

1. A feedforward amplifier, including:

   a carrier cancellation loop having an input as an input of the feedforward amplifier;

   a distortion cancellation loop having an input coupled to an output of the carrier cancellation loop and an output serving as an output of the feedforward amplifier;

   a control circuit, the first input is coupled to the output of the distortion cancellation loop, and the output is coupled to the control end of the distortion cancellation loop;

   The control circuit includes an intermodulation detection circuit and a microprocessor, wherein an input end of the intermodulation detection circuit serves as a first input end of the control circuit, and a first input end of the microprocessor and the mutual An output of the detection circuit is connected, an output of the microprocessor is used as an output of the control circuit, and the microprocessor feeds back an intermodulation component detected by the intermodulation detection circuit to the distortion cancellation Loop.
2. A feedforward amplifier according to claim 1, wherein

   The second input end of the control circuit is connected to the output end of the carrier cancellation loop, and the output end of the control circuit is further connected to the control end of the carrier cancellation loop.
3. A feedforward amplifier according to claim 2, wherein a frequency of the intermodulation component detected by said intermodulation detecting circuit is determined by a preset value of an inter-carrier frequency difference of an input signal of an input terminal of said feedforward amplifier .
4. A feedforward amplifier according to claim 2, wherein

   The intermodulation detection circuit includes a mixer, a band pass filter, and a phase locked loop, wherein a first input end of the mixer serves as an input end of the intermodulation detection circuit, and the mixer a second input terminal is connected to an output end of the phase locked loop, an output end of the mixer is connected to an input end of the band pass filter, and an output end of the band pass filter is used as the intermodulation detection circuit The output.
5. A feedforward amplifier according to claim 2, wherein

   The carrier cancellation loop includes a first modulator, a main power amplifier, a first delay line, a first power combiner, and a power splitter, wherein an input of the power splitter acts as the carrier cancellation loop Input, the input end of the first modulator and the input end of the first delay line are respectively connected to the first output end and the second output end of the power splitter, the output of the first extension line a terminal is coupled to the first input of the first power combiner, an output of the first modulator is coupled to an input of the main power amplifier, and a control end of the first modulator is used as the carrier offset a control end of the loop, the output of the main power amplifier being connected to the second input of the first power combiner;

   The distortion cancellation loop includes a second modulator, a secondary power amplifier, a second delay line, and a second power combiner, wherein an input of the second modulator is coupled to an output of the first power combiner An output end of the second modulator is connected to an input end of the auxiliary power amplifier, a control end of the second modulator is used as a control end of the distortion cancellation loop, and an input end of the second delay line Connected to an output of the main power amplifier, an output of the second delay line is coupled to a first input of the second power combiner, and a second input of the second power combiner is An output of the auxiliary power amplifier is connected, and an output of the second power combiner serves as an output of the distortion cancellation loop.
6. A feedforward amplifier according to claim 2, wherein

   The control circuit further includes a first detecting circuit, and an output end of the intermodulation detecting circuit is connected to a first input end of the microprocessor via the first detecting circuit, wherein the first detecting circuit includes Connected detector and analog to digital converter.
7. A feedforward amplifier according to claim 2, wherein

   The control circuit further includes a second detecting circuit, an input end of the second detecting circuit is connected to an output end of the carrier cancellation loop, and an output end is connected to a second input end of the microprocessor, wherein The second detection circuit includes a detector and an analog to digital converter that are sequentially connected.
8. A feedforward amplifier according to claim 2, wherein said carrier cancellation loop further comprises a first directional coupler, wherein an output of said main power amplifier passes through an input of said first directional coupler The terminal and the first output are coupled to the second input of the first power combiner, and the output of the primary power amplifier also passes through the input and the second output of the first directional coupler.
9. A feedforward amplifier according to claim 2, wherein said carrier cancellation loop further comprises a second directional coupler, wherein the output of said first power combiner passes through a second directional coupler.
10. A feedforward amplifier according to claim 2, wherein said distortion cancellation loop further comprises a third directional coupler, wherein an output of said second power combiner further passes through said third directional coupler The input and the first output serve as outputs of the distortion cancellation loop.
11. A method for detecting an intermodulation component of a feedforward amplifier, wherein the feedforward amplifier includes a carrier cancellation loop and a distortion cancellation loop;

    The method includes:

    Adjusting the amplitude and phase of the carrier cancellation loop;

    Performing carrier cancellation according to the amplitude and phase of the adjusted carrier cancellation loop by the carrier cancellation loop;

    Determining whether the carrier power in the distortion component output by the carrier cancellation loop reaches a first preset value;

    Adjusting the amplitude and phase of the distortion cancellation loop when the carrier power in the distortion component reaches the first preset value;

    Distortion cancellation by the distortion cancellation loop according to the amplitude and phase of the adjusted distortion cancellation loop;

    Determining whether the power of the intermodulation component in the second main signal output by the distortion cancellation loop reaches a second preset value, and if so, acquiring the amplified first main signal output by the feedforward amplifier.
12. The method of claim 11 further comprising:

    Re-adjusting the amplitude and phase of the carrier cancellation loop when the carrier power does not reach the first preset value, and performing carrier cancellation according to the adjusted amplitude and phase of the carrier cancellation loop, until The carrier power is up to the first preset value.
13. The method of claim 12, further comprising:

    Re-adjusting the amplitude and phase of the distortion cancellation loop when the power of the intermodulation component does not reach the second preset value, and performing distortion cancellation according to the adjusted amplitude and phase of the distortion cancellation loop Until the power of the intermodulation component reaches the second preset value.