CN114338312B - Apparatus and method for linearizing transmission signals - Google Patents
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Abstract
An apparatus and method for linearizing a transmission signal are disclosed. An embodiment method for linearizing a transmission signal generated by quadrature amplitude modulation and radio frequency amplification of an analog baseband signal, the method comprising: demodulating a feedback signal obtained from the transmission signal; comparing the demodulated feedback signal with the baseband signal; digitally calculating the predistortion control signal based on the comparison; and performing analog predistortion on the analog baseband signal controlled by the predistortion control signal.
Description
Cross Reference to Related Applications
The present application claims priority from French patent application number 2010321 filed on 10/9/2020, which is incorporated herein by reference.
Technical Field
Embodiments relate generally to wireless communications and, in particular, to linearization of transmission signals resulting from quadrature amplitude modulation and radio frequency amplification.
Background
Electronic wireless communication devices such as transceivers typically include high spectral efficiency signal transmission devices that transmit signals using numerical quadrature amplitude modulation ("M-ary quadrature amplitude modulation," M-QAM).
High spectral efficiency transmission devices typically use a linear modulation method for the transmission signal and include a quadrature modulation device and a radio frequency amplifier.
However, quadrature modulation devices and most radio frequency amplifiers are nonlinear electronic devices that introduce distortion to the transmitted signal.
Therefore, a signal linearization circuit in a high spectral efficiency transmission device is known to apply predistortion to a signal to be transmitted to compensate for distortion introduced by a radio frequency amplifier and a quadrature modulation device.
Furthermore, the nonlinear characteristics of the radio frequency amplifier may change over time, for example due to aging of the amplifier itself, temperature variations or power supply variations; accordingly, it is desirable to provide an adaptive linearization circuit.
Known adaptive linearization circuits are typically performed at transmission radio frequencies or intermediate frequencies and are efficient when the high spectral efficiency transmission device is incorporated into a wireless electronic communication device comprising a single transmission antenna.
In contrast, when an electronic communication device includes multiple transmission chains, each comprising a quadrature modulation device and a nonlinear radio frequency amplifier, such as an active phased array antenna system "APAAS" that may include tens of transmission chains, conventional adaptive linearization circuits and methods present functional problems because they should be provided locally for each transmission chain (i.e., each antenna segment).
In fact, local solutions present problems related to area consumption, power consumption and high design complexity of Integrated Circuits (ICs).
Thus, these IC designs for locally driving each antenna segment are pushing process integration capabilities to a limit and are not cost effective in the context of multiple transmission chain devices (e.g., APAAS).
Furthermore, a low energy and low cost single transmission chain device may benefit from lower area consumption, lower power consumption, and lower design complexity.
Accordingly, there is a need to provide a linearization technique for a transmission chain with high spectral efficiency that overcomes the drawbacks of the known techniques without degrading or degrading performance characteristics such as high transmission range, high efficiency, low bit error rate, and low adjacent channel interference. The values of these performance characteristics may typically be imposed by standards.
Disclosure of Invention
According to an embodiment, a solution combining analog and digital adaptive predistortion is proposed for a compact high spectral efficiency transmitter. Mixed signal (analog and digital) adaptive predistortion is applied directly to I and Q analog baseband waveforms and can be advantageously monitored based on a combination of intermodulation out-of-band power and an integrated symbol error digital signal obtained at a sampling rate well below the nyquist frequency.
According to one aspect, a method for linearizing a transmission signal generated by quadrature amplitude modulation and radio frequency amplification of an analog baseband signal is presented, the method comprising demodulating a feedback signal derived from the transmission signal, comparing between the demodulated feedback signal and the baseband signal, digitally calculating a predistortion control signal based on the comparison, and analog predistortion of the analog baseband signal controlled by the predistortion control signal.
Therefore, since predistortion is applied to a low frequency of an analog baseband signal, not an intermediate frequency signal or a radio frequency signal, difficulties and criticality of digital calculation and analog predistortion waveform design are low, and the structure can be simplified, and power and area consumption can be reduced.
According to one embodiment, the comparison is a digital comparison and the method comprises an analog-to-digital conversion of the demodulated feedback signal and an analog-to-digital conversion of the baseband signal.
Thus, analog-to-digital conversion is provided for low frequencies of the baseband signal with a simpler architecture and lower power consumption than conventional techniques that perform high sampling rates, which are typically more than twice the bandwidth of the baseband transmission signal (i.e., more than the nyquist frequency). In practice, the analog-to-digital conversion may be performed at a frequency well below the nyquist frequency of the baseband transmission signal, since the nonlinear characteristics of the radio frequency amplifier may change slowly over time, for example due to aging of the amplifier itself, ambient temperature changes, voltage supply changes or switching between transmission channels.
According to one embodiment, the method comprises symbol demapping of the digitally demodulated feedback signal, symbol demapping of the digital baseband signal, and the digital comparison comprises a comparison between the symbols of the feedback signal and the symbols of the baseband signal.
Symbol comparison provides a perception of the quality of the transmitted radio frequency signal according to this less complex solution and thus allows to reduce the error vector amplitude in the symbol constellation.
According to one embodiment, the digital calculation of the predistortion control signal is additionally based on out-of-band power detection of the analog demodulated feedback signal.
Out-of-band power detection prevents spectral regrowth from causing interference in adjacent channels of the spectrum.
Thus, double checking both out-of-band intermodulation power and symbol error rate ensures that the predistortion method does not affect the transmitted symbol integrity, while providing a third order intermodulation improvement of about 15 dB.
According to another aspect, a method for linearizing a plurality of transmit signals of an active phased array antenna system is presented, the method comprising the above-defined method for each transmit signal.
In fact, the high architectural simplicity, reduced power dissipation and area consumption, and high performance provided by the method for linearizing each transmitted signal, allows for a multiple increase in implementation in a single device (e.g., an active phased array antenna system).
According to another aspect, an integrated circuit is presented that includes a transmit driver configured to perform quadrature amplitude modulation and radio frequency amplification of an analog baseband signal. There is also proposed a linearization circuit comprising: a demodulator circuit configured to demodulate a feedback signal taken from the transmission signal; a comparator circuit configured to compare the demodulated feedback signal with the baseband signal; a digital calculation unit configured to calculate a predistortion control signal based on a comparison result provided by the comparator circuit; an analog predistorter circuit configured to predistort an analog baseband signal controlled by a predistortion control signal.
According to an embodiment, the comparator circuit is a digital comparator circuit and the integrated circuit comprises an analog-to-digital converter configured to convert the demodulated feedback signal and an analog-to-digital converter configured to convert the baseband signal.
According to one embodiment, the integrated circuit includes a symbol demapper configured to demap symbols of the digitally demodulated feedback signal and a symbol demapper configured to demap symbols of the digital baseband signal. Further, the digital comparator circuit is configured to compare the sign of the demodulated feedback signal with the sign of the baseband signal.
According to an embodiment, the integrated circuit further comprises an out-of-band power detection circuit configured to detect an out-of-band intermodulation power of the analog demodulated feedback signal, and the digital calculation unit is configured to additionally calculate the predistortion control signal based on the out-of-band power detection result.
According to another aspect, an active phased array antenna system is presented that includes a plurality of transmit drivers and an integrated circuit defined for each transmit driver as described above.
Drawings
Other advantages and features of the invention will appear from a review of the detailed description of non-limiting embodiments of the invention and the accompanying drawings, in which:
Fig. 1 shows a transmission device; and
Fig. 2 shows an active phased array antenna system.
Detailed Description
Fig. 1 shows an integrated circuit IC integrated in a high spectral efficiency transmission device DEV, in particular a transmission chain tx_drv, also called a transmission antenna driver. For example, the high spectral efficiency transmission device DEV may be a 5G backhaul transceiver or the like.
The processing unit PU generates digital baseband signals conveying data in digital quadrature amplitude modulation ("M-ary quadrature amplitude modulation", "M-QAM") on an in-phase channel I and a quadrature phase channel Q. Such M-QAM data is a binary word of log 2 (M) bits encoded according to a symbol constellation identified by the phase and amplitude of the signal in the complex plane.
The digital-to-analog converter DAC provides (in addition to the I/Q driver) an analog baseband signal BB TX converted from the digital output of the processing unit PU.
The processing unit PU, the digital-to-analog converter DAC and the I/Q driver are typically external to the high spectral efficiency transmission device DEV and typically belong to a digital baseband board.
The transmit antenna driver tx_drv comprises a mixer qam_mod configured to perform quadrature amplitude modulation on the baseband transmit signal bb_tx, outputting a radio frequency modulated signal rf_tx. The local oscillator rf_lo or another source provides a radio frequency carrier signal to the mixer qam_mod.
The term "radio frequency" is understood to mean the frequency of a carrier signal that depends on the application of the transmission device and may be used to define the ability of the element to operate at these frequencies. For example, in a possible 5G application ("5G NR" or "LTE" standard), the carrier signal radio frequency may be higher than 24GHz, or in a possible WiFi application ("ISO 802.11" standard), for example 2.4GHz or 5GHz.
The driver tx_drv includes a radio frequency amplifier RFPA configured to perform power amplification of a radio frequency modulated signal output from the mixer qam_mod.
The amplifier RFPA operates with very small back-off power relative to its saturation point to achieve high transmission range and efficiency. For example, the amplifier RFPA operates at approximately 90% saturation. The amplifier RFPA operates at this type of level with a non-linear power input to the power output characteristic, which results in a radio frequency transmission signal RF TX distortion at the antenna ANT.
The integrated circuit thus comprises a linearization circuit for linearizing the transmitter chain tx_drv of the high spectral efficiency wireless transmission device by applying a predistortion to the transmission signal amplified by the amplifier RFPA in order to compensate for the RFPA non-linearity characteristics of the amplifier.
The linearization circuit comprises a feedback loop circuit that retrieves the radio frequency transmission signal RF TX via a coupler CPL (e.g. an inductive coupler). The coupler CPL provides a radio frequency feedback signal rf_fb to the feedback loop, which is equal to the radio frequency transmission signal rf_tx. In the example shown, the coupler CPL may include a feedback signal amplifier.
To calculate the predistortion applied to the waveform, the linearization circuit therefore uses a feedback signal based on the actual transmission signal rf_tx at the output of the transmission chain tx_drv. Thus, the predistortion takes into account time variations of the transmission chain tx_drv, such as aging of the amplifier RFPA, temperature variations or power supply variations.
The linearization circuit comprises a demodulator circuit qam_demod configured to demodulate the feedback signal rf_fb, providing an analog baseband (demodulated) feedback signal bb_fb on feedback channels I and Q.
Advantageously, these feedback channels I and Q may be input to an out-of-band power detector circuit pwr_det, as will be discussed later. In the example shown, the input passes a band-pass pre-filter BPF. The out-of-band power detection circuit pwr_det is configured to detect out-of-band intermodulation power of the analog demodulation feedback signal bb_fb.
The analog demodulation feedback signal bb_fb is converted to a digital baseband feedback signal by analog-to-digital converters ADC on feedback channels I and Q.
Meanwhile, the "root" analog baseband transmission signal bb_tx is converted into a digital baseband transmission signal by an analog-to-digital converter ADC connected to the transmission channels I and Q.
It is emphasized here that the analog-to-digital converters ADC are designed for the low frequencies of the baseband signals bb_tx, bb_fb, so that the sampling rates they perform are defined in accordance with these low frequencies. Furthermore, as will be described later, the analog-to-digital converter ADC is designed such that the sampling rate can be well below the nyquist sampling frequency (i.e., below half the nyquist sampling frequency).
Thus, in practice, the analog-to-digital converter ADC of the present embodiment is greatly simplified and more compact and energy efficient than the commonly used converters with higher sampling rates.
The digitally converted baseband feedback signal and the digitally converted baseband transmission signal are demapped by respective symbol demapper circuits SYMP _demap. Accordingly, the symbol demapper circuit SYMP _demap is configured to DEMAP the symbols of the digitally demodulated feedback signal symbols of the digital baseband signal.
Demapping of the signal symbols means converting the phase and amplitude of the signal into corresponding binary coded values according to a reference mapping of the symbols in the complex plane.
The obtained binary value bb_fb_bin corresponding to the sign of the digitally demodulated feedback signal and the obtained binary value bb_tx_bin corresponding to the sign of the digitally converted baseband transmission signal are compared by means of a digital comparison circuit COMP. The result of this comparison provides the symbol error rate of the transmission signal RF TX.
For digital control problems, it is advantageous to provide the instantaneous value of the symbol error rate to an integrator circuit INTG configured to integrate the symbol error rate before providing it to the calculation unit dpd_cu. The digital integrator INTG zeroes the digital error signal.
In the feedback loop, the digital comparator circuit COMP is accordingly configured to compare the demodulated feedback signal rf_bb with the baseband transmission signal bb_tx, providing a basis for calculating the predistortion compensation nonlinearity of the transmission chain tx_drv.
The digital calculation unit dpd_cu is configured to calculate a predistortion control signal pd_ct based on the symbol error rate provided by the comparator circuit COMP.
In the example shown, the digital calculation unit dpd_cu also calculates the predistortion control signal pd_ct using the result of the out-of-band power detector circuit pwr_det.
The digital predistortion control signal pd_ct controls the analog predistorter circuit APD.
The analog predistorter circuit APD is configured to predistort the analog baseband signal bb_tx in the transmission chain tx_drv, i.e. the waveform of the analog baseband signal bb_tx is designed to be opposite to the distortion that the signal would undergo through the nonlinear elements (mainly the amplifier RFPA) in the transmission chain tx_drv.
For example, the predistortion control signal contains digital values of parameters such as coefficients for a cubic or penta polynomial solution for minimizing the symbol error rate (and for minimizing out-of-band intermodulation power).
The analog predistorter circuit APD is configured to convert the digital parameter values into an analog tuning signal. The analog tuning signal is combined with the analog baseband transmission signal bb_tx, for example, by a mixer element, in order to tune (or design) the waveform of the transmission signal bb_tx.
Thus, turning now to the sampling frequency of the analog-to-digital converter ADC, since the digital conversion signal is used for symbol comparison in order to adaptively adjust the predistortion control signal pd_ct, the digital conversion signal need not precisely contain all the information conveyed in the initial analog signals bb_tx, bb_fb. Thus, the sampling rate of the analog-to-digital converter ADC can be set well below the nyquist sampling frequency.
In other words, the linearization circuit designs the waveform of the analog baseband transmission signal bb_tx; it performs a digital comparison between the transmitted symbol and the received feedback symbol. The digital predistortion device then calculates predistortion coefficients from the integral of the out-of-band signal portion and the symbol error rate.
Since predistortion is applied to a low frequency analog baseband, the waveform design difficulty of processing and application of the analog predistortion circuit APD by the calculation unit dpd_cu is less critical than typical waveform designs performed in the radio frequency domain.
Furthermore, pre-distortion of the analog signal directly and processing the feedback in the digital domain prevents (compared to all-digital operation on the radio frequency domain): the analog baseband is reduced to digital by a high-end complex, power and area consuming analog-to-digital converter, the predistortion is performed digitally by a power and area consuming digital signal processor, and then the high-end complex, power and area consuming digital-to-analog converter returns to the analog domain.
In other words, the analog baseband signal is directly predistortion, and the feedback processing is performed in the digital domain, so that the architecture is greatly simplified, and the power consumption and the silicon area are reduced.
In addition, the out-of-band intermodulation power and symbol error rate are doubly checked to ensure that the predistortion process does not affect the integrity of the transmitted symbols, while providing a third order intermodulation frequency improvement of about 15 dB.
The high architecture simplicity, reduced power consumption and reduced area enable the implementation of high spectral efficiency transmission devices DEV in which the medium density digital gates are integrated with analog components in a single chip.
Technologies combining digital and analog on a single chip, commonly referred to as "BiCMOS" technology (referring to bipolar gate technology and complementary metal oxide semiconductor gate technology), are often subject to trade-offs between analog and digital parts due to the co-integration of the fabrication methods.
Thus, the channel length of the digital gate may be limited to, for example, 55 nanometers, which corresponds to a "medium density". Thus, these BiCMOS techniques are often disadvantageous for implementing conventional linearization techniques using high performance digital signal processing "DSP" units, high sampling frequency analog-to-digital converters, and high sampling frequency digital-to-analog converters.
In other words, the conventional all-digital linearization technique is not suitable for coordinating digital and analog component techniques, but rather affects the combination of analog and digital linearization circuits of the analog baseband waveform, as depicted in fig. 1, providing a solution for implementing a high spectral efficiency transmission device DEV in a medium density digital and analog co-integrated ("BiCMOS") single chip.
Furthermore, the solution provided allows low energy and low cost application systems in combination with such high spectral efficiency transmission devices DEV with a single transmission chain.
For example, wireless video recording drone devices for general consumer use may benefit from such a power-efficient linearization chain, e.g., allowing real-time broadcasting of high-definition video signals.
Furthermore, these advantages enable the implementation of multiple linearization circuits in a single integrated circuit for linearizing a large number of transmitter chains tx_drv, for example in a high spectral efficiency wireless transmission device comprising an active phased array antenna system.
Reference is made to fig. 2.
Fig. 2 shows an active phased array antenna system SYS comprising an antenna array APAA.
The antenna APAA is used to transmit the same transmission signal, however, with a separate phase shift (not shown) to superimpose separate spherical wave fronts to produce a planar beam traveling in a particular directional direction.
Each antenna is driven by a respective transmission chain tx_drv1, tx_drv2, tx_drv3, …, tx_drvn, which may for example be numbered in tens of.
The transmission chains tx_drv1-tx_drvn are each of the same type as the transmission chains tx_drv described above in connection with fig. 1 and each comprise in particular a quadrature amplitude modulator qam_mod and a radio frequency amplifier PA1-PAN.
Conventional adaptive linearization techniques are complex and expensive to implement in such antenna arrays because they require the provision of some high performance digital signal processing "DSP" units, high sampling frequency analog-to-digital converters, and high sampling frequency digital-to-analog converters for each transmission chain tx_drv1-tx_drvn.
Thus, the conventional linearization technique currently used in such antenna arrays is performed upstream of the digital processing unit PU, generating a predistorted digital baseband signal for only one transmission chain tx_drv. This conventional digital linearization method becomes proportionally inefficient as the number of transmission chains increases, just like the APAA system.
As previously mentioned, each transmission chain tx_drv1-tx_drvn of the active phased array antenna system SYS is provided with its separate linearization circuit, namely a digital feedback loop FDB and an analog predistorter APD, as described in connection with fig. 1, due to the simple architecture, low power consumption and low area consumption of the linearization circuit described above in connection with fig. 1.
Thus, the specific distortion on each transmission signal rf_tx1-rf_txn caused by the non-linearities of the radio frequency amplifiers PA1, PA2, PA3, …, PAn, respectively, is adaptively compensated by the corresponding linearization circuit FDB, APD provided for each transmission chain tx_drv1-tx_ DRVN.
Furthermore, since the linearization circuits FDB, APD use a feedback mechanism based on the actual transmission signal RF_TX1-RF_TXn at the output of the transmission chain TX_DRV1-TX_ DRVN, as described in FIG. 1, the predistortion is adaptive to changes in the transmission chain TX_DRV1-TX_ DRVN over time, such as aging, temperature changes, or power supply changes of the amplifiers PA 1-PAn.
The service life and reliability of the system SYS are improved.
Various embodiments and modifications have been described. Those skilled in the art will appreciate that certain features of these various embodiments and variants can be combined and that other variants will occur to those skilled in the art.
Finally, based on the functional indications given above, the practical implementation of the described embodiments and variants is within the reach of a person skilled in the art.
Claims (20)
1. A method for linearizing a transmission signal generated by quadrature amplitude modulation and radio frequency amplification of an analog baseband signal, the method comprising:
analog demodulation of a feedback signal derived from the transmission signal;
Comparing the demodulated feedback signal with the baseband signal;
Digitally calculating a predistortion control signal based on the comparison; and
And based on the predistortion control signal, predistortion is carried out on the analog baseband signal.
2. The method of claim 1, wherein the comparison is a digital comparison, the method further comprising:
performing analog-to-digital conversion of the demodulated feedback signal; and
Analog-to-digital conversion of the baseband signal is performed.
3. The method of claim 2, wherein the method further comprises:
Demapping the digitally demodulated feedback signal into feedback signal symbols; and
Demapping the analog-to-digital converted baseband signal into baseband symbols;
The digital comparison includes comparing the feedback signal symbol with the baseband symbol.
4. The method of claim 2, wherein each analog-to-digital conversion comprises a sampling frequency that is less than half a nyquist sampling frequency of the corresponding signal.
5. The method of claim 1, wherein the pre-distortion control signal is digitally calculated and is additionally based on out-of-band power detection of an analog demodulated feedback signal.
6. An active phased array antenna method for linearizing a plurality of transmission signals generated by quadrature amplitude modulation and radio frequency amplification of an analog baseband signal, the method comprising, for each transmission signal:
analog demodulation of a feedback signal derived from the transmission signal;
Comparing the demodulated feedback signal with the baseband signal;
Digitally calculating a predistortion control signal based on the comparison; and
And based on the predistortion control signal, predistortion is carried out on the analog baseband signal.
7. The method of claim 6, wherein the comparison is a digital comparison, the method further comprising:
performing analog-to-digital conversion of the demodulated feedback signal; and
Analog-to-digital conversion of the baseband signal is performed.
8. The method of claim 7, wherein the method further comprises:
Demapping the digitally demodulated feedback signal into feedback signal symbols; and
Demapping the analog-to-digital converted baseband signal into baseband symbols;
The digital comparison includes comparing the feedback signal symbol with the baseband symbol.
9. The method of claim 7, wherein each analog-to-digital conversion comprises a sampling frequency that is less than half a nyquist sampling frequency of the corresponding signal.
10. The method of claim 6, wherein the pre-distortion control signal is digitally calculated based on out-of-band power detection of an additionally analog demodulated feedback signal.
11. An integrated circuit, comprising:
a transmission antenna driver configured to perform quadrature amplitude modulation and radio frequency amplification of the analog baseband signal; and
A linearization circuit, comprising:
an analog demodulator circuit configured to demodulate a feedback signal derived from the output transmission signal;
A comparator circuit configured to compare the demodulated feedback signal with the baseband signal;
A digital calculation unit configured to calculate a predistortion control signal based on a comparison result provided by the comparator circuit; and
An analog predistorter circuit configured to predistort the analog baseband signal controlled by the predistortion control signal.
12. The integrated circuit of claim 11, wherein,
The comparator circuit is a digital comparator circuit; and
The integrated circuit includes:
A first analog-to-digital converter configured to convert the demodulated feedback signal; and
A second analog-to-digital converter configured to convert the baseband signal.
13. The integrated circuit of claim 12, wherein the integrated circuit further comprises:
A first symbol demapper circuit configured to demap symbols of the digitally demodulated feedback signal; and
A second symbol demapper circuit configured to demap symbols of the analog-to-digital converted baseband signal;
wherein the digital comparator circuit is configured to compare the sign of the feedback signal with the sign of the baseband signal.
14. The integrated circuit of claim 12, wherein each analog-to-digital converter operates at a sampling frequency that is less than half a nyquist sampling frequency of the corresponding signal.
15. The integrated circuit of claim 11, further comprising:
An out-of-band power detector circuit configured to detect out-of-band intermodulation power of the analog demodulated feedback signal;
wherein the digital calculation unit is configured to calculate the predistortion control signal additionally based on an out-of-band power detection result.
16. An active phased array antenna system comprising:
A plurality of transmit antenna drivers, each transmit antenna driver configured to perform quadrature amplitude modulation and radio frequency amplification of the analog baseband signal; and
An integrated circuit for each transmit antenna driver, the integrated circuit comprising:
an analog demodulator circuit configured to demodulate a feedback signal derived from the output transmission signal;
A comparator circuit configured to compare the demodulated feedback signal with the baseband signal;
A digital calculation unit configured to calculate a predistortion control signal based on a comparison result provided by the comparator circuit; and
An analog predistorter circuit configured to predistort the analog baseband signal controlled by the predistortion control signal.
17. The active phased array antenna system of claim 16,
Wherein the comparator circuit is a digital comparator circuit; and
Wherein the integrated circuit comprises:
A first analog-to-digital converter configured to convert the demodulated feedback signal; and
A second analog-to-digital converter configured to convert the baseband signal.
18. The active phased array antenna system of claim 17, wherein the integrated circuit further comprises:
A first symbol demapper circuit configured to demap symbols of the digitally demodulated feedback signal; and
A second symbol demapper circuit configured to demap symbols of the analog-to-digital converted baseband signal;
wherein the digital comparator circuit is configured to compare the sign of the feedback signal with the sign of the baseband signal.
19. The active phased array antenna system of claim 17, wherein each analog-to-digital converter operates at a sampling frequency that is less than half the nyquist sampling frequency of the corresponding signal.
20. The active phased array antenna system of claim 16, further comprising:
An out-of-band power detector circuit configured to detect out-of-band intermodulation power of the analog demodulated feedback signal;
wherein the digital calculation unit is configured to calculate the predistortion control signal additionally based on an out-of-band power detection result.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR2010321A FR3115179B1 (en) | 2020-10-09 | 2020-10-09 | Method for linearizing a transmission signal and corresponding integrated circuit |
| FR2010321 | 2020-10-09 | ||
| US17/468,053 US12057869B2 (en) | 2020-10-09 | 2021-09-07 | Apparatus and method for linearizing a transmission signal |
| US17/468,053 | 2021-09-07 |
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| CN114338312A CN114338312A (en) | 2022-04-12 |
| CN114338312B true CN114338312B (en) | 2024-07-30 |
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| CN105978500A (en) * | 2016-04-29 | 2016-09-28 | 华为技术有限公司 | Analog predistortion system, transceiver and communication device |
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