阅读说明：本技术 用于全双工或半双工收发器的射频前端 (RF front-end for full-duplex or half-duplex transceivers ) 是由 德罗尔·雷格夫 希米·西隆 根纳季·特所迪克 多伦·埃兹里 于 2019-03-27 设计创作，主要内容包括：本发明涉及用于无线通信的射频(RF)前端,特别地,用于半双工、全双工和/或频分双工收发器。本发明的RF前端尤其是基于正交平衡功率放大器(QBPA)。RF前端包括天线端口,用于向天线输出发射信号以及从天线接收接收信号；接收端口,用于向信号处理部分输出接收信号。进一步地,RF前端包括消除输入信号发生器,用于生成消除输入信号并向QBPA输出消除输入信号；并且,包括QBPA,配置为：在第一端口或第四端口处接收发射输入信号,从消除输入信号发生器接收消除输入信号,以及在与天线端口连接的第二端口处接收接收信号。(The present invention relates to Radio Frequency (RF) front ends for wireless communication, in particular for half-duplex, full-duplex and/or frequency-division-duplex transceivers. The RF front-end of the invention is based in particular on a Quadrature Balanced Power Amplifier (QBPA). The RF front end includes an antenna port for outputting a transmit signal to an antenna and receiving a receive signal from the antenna; and a receiving port for outputting the received signal to the signal processing section. Further, the RF front end includes a cancellation input signal generator for generating a cancellation input signal and outputting the cancellation input signal to the QBPA; and, includes a QBPA configured to: the method includes receiving a transmit input signal at a first port or a fourth port, receiving a cancel input signal from a cancel input signal generator, and receiving a receive signal at a second port connected to an antenna port.)

1. Radio frequency, RF, front end (100) for wireless communication, comprising:

an antenna port (101) for outputting a transmit signal (102) to an antenna (200) and receiving a receive signal (103) from the antenna (200);

a reception port (104) for outputting the reception signal (103) to a signal processing section (300);

a cancellation input signal generator (105) for generating a cancellation input signal (106) and outputting the cancellation input signal (106) to a Quadrature Balanced Power Amplifier (QBPA) (107); and

the QBPA (107) comprising first, second, third and fourth ports (108, 109, 110, 111), wherein the QBPA (107) is configured to:

receiving a transmit input signal (112) at the first port (108) or the fourth port (111);

-receiving the receive signal (103) at the second port (109) connected to the antenna port (101);

-receiving the cancellation input signal (106) from the cancellation input signal generator (105);

amplifying the transmit input signal (112) and the cancel input signal (106);

generating the transmit signal (102) from the transmit input signal (112) and outputting the transmit signal (102) at the second port (109);

generating a cancellation signal (113) from the cancellation input signal (106) and outputting the cancellation signal (113) and the reception signal (103) at the third port (110) connected to the reception port (104).

2. The RF front-end (100) of claim 1, wherein

The cancellation input signal generator (105) comprises a self-interference cancellation, SIC, filter.

3. The RF front-end (100) of claim 1 or 2, wherein

The cancellation input signal generator (105) is configured to generate the cancellation input signal (106) based on the transmit input signal (112) and/or SIC signal received at the first or fourth port (108, 111).

4. The RF front-end (100) of any of claims 1 to 3, wherein

The cancellation input signal generator (105) is configured to generate the cancellation input signal (106) in the following manner: the cancellation signal (113) cancels a leakage signal caused at the third port (110) when the transmission signal (102) is output from the second port (109).

5. The RF front-end (100) of any of claims 1 to 4, wherein

The QBPA (107) comprises:

a first coupler (1071) configured to split an input signal received from the first or the fourth port (108, 111) of the QBPA (107) into a first part and a second part with a phase difference of 90 ° between them, wherein the input signal is the transmit input signal (112) or the cancel input signal (106);

a first amplifier (1072a) configured to amplify the first portion of the input signal and output the amplified first portion of the input signal to a second coupler (1073);

a second amplifier (1072b) configured to amplify the second portion of the input signal and output the amplified second portion of the input signal to the second coupler (1073);

the second coupler (1073) configured to combine the amplified first and second portions of the input signal to form first and second output signals at the second and third ports (109, 110) of the QBPA (107), respectively.

6. The RF front-end (100) of claim 5, wherein the input signal of the first coupler (1071) comprises the transmit input signal (112), wherein

The second coupler (1073) is configured to combine the amplified first and second portions of the transmit input signal (112) such that they constructively form the transmit signal (102) at the second port (109) and destructively cancel each other at the third port (110).

7. The RF front-end (100) of claim 5 or 6, wherein

The cancellation input signal generator (105) comprises a first SIC filter (1051) arranged between the first coupler (1071) and the first amplifier (1072a), and a second SIC filter (1052) arranged between the first coupler (1071) and the second amplifier (1072b),

wherein the first SIC filter (1051) is configured to:

receiving the first portion of the input signal from the first coupler (1071),

generating a first cancellation input signal, an

Outputting the first cancellation input signal to the first amplifier (1072 a);

and, the second SIC filter (1052) is configured to:

receiving the second portion of the input signal from the first coupler (1071),

generating a second cancellation input signal, an

Outputting the second cancellation input signal to the second amplifier (1072 b).

8. The RF front-end (100) of claim 7, wherein

The second coupler (1073) is further configured to combine the amplified first and second cancellation input signals such that they constructively form the cancellation signal (113) at the third port (110) and destructively cancel each other at the second port (109).

9. The RF front-end (100) of claim 5 or 6, wherein

The RF front-end (100) further comprises a splitter (114), the cancellation input signal generator (105) comprises a third SIC filter (1053),

wherein the splitter (114) is configured to:

-receiving the transmit input signal (112),

splitting the transmit input signal (112) into third and fourth portions,

-outputting the third part of the transmit input signal (112) to the third SIC filter (1053) and the fourth part of the transmit input signal (112) to the fourth port (111) of the QBPA (107) connected to the first coupler (1071); and

the third SIC filter (1053) is configured to:

receiving the third portion of the transmit input signal (112) from the splitter (114),

generating said cancellation input signal (106), an

Outputting the cancellation input signal (106) to the first port (108) of the QBPA (107) connected with the first coupler (1071).

10. The RF front-end (100) of claim 5 or 6, wherein

The RF front-end (100) further comprises an in-phase-quadrature digital-to-analog converter, IQ DAC (115), an IQ baseband processing component, IQ BB (116), a first and a second mixer (117a, 117b), and

the cancellation input signal generator (105) comprises a BB SIC filter (1054),

wherein the IQ DAC (115) is configured to receive a digital signal, convert the digital signal to an analog signal, and output the analog signal to the IQ BB (116);

the IQ BB (116) is configured to receive the analog signal from the IQ DAC (115), generate a BB signal from the analog signal, and output the BB signal to the BB SIC filter (1054) and the first mixer (117 a);

the BB SIC filter (1054) is configured to receive the BB signal from the IQ BB (116), generate a BB cancellation input signal from the BB signal, and output the BB cancellation input signal to the second mixer (117 b);

the first mixer (117a) is configured to receive the BB signal from the IQ BB (116), mix the BB signal with a low frequency signal to form the transmit input signal (112), and output the transmit input signal (112) to the fourth port (111) of the QBPA (107);

the second mixer (117b) is configured to receive the BB cancellation input signal from the BB SIC filter (1054), mix the BB cancellation input signal with the low frequency signal to form the cancellation input signal (106), and output the cancellation input signal (106) to the first port (108) of the QBPA (107).

11. The RF front-end (100) of any of claims 1 to 6, wherein

The QBPA (107) is configured to:

receiving the cancellation input signal (106) from the cancellation input signal generator (105) at the first port (108), an

Receiving the transmit input signal (112) at the fourth port (111).

12. The RF front end (100) of any of claims 9 to 11, wherein

The second coupler (1073) is further configured to combine the amplified first and second portions of the cancellation input signal (106) such that they constructively form the cancellation signal (113) at the third port (110) and destructively cancel each other at the second port (109).

13. A full-duplex or half-duplex (700) transceiver, comprising

The radio frequency, RF, front end (100) according to any one of claims 1 to 12, and

a transmit and receive antenna (200) connected to the antenna port (101) of the RF front end (100).

14. The full-duplex or half-duplex transceiver (1000) of claim 13, wherein the RF front-end (100) is the RF front-end (100) of claim 11,

the transceiver (700) further comprises a digital baseband processing module (701), a digital front end (702) and an analog baseband and RF processing module (703),

wherein the digital baseband processing module (701) is configured to:

a frequency-domain signal is received and,

generating a first and a second sequence from said frequency domain signal, an

Outputting the first and second sequences to the digital front end (702);

the digital front end (702) is configured to:

receiving the first and second sequences from the digital baseband processing module (701),

converting the received first and second sequences, an

Outputting the converted first and second sequences to the analog baseband and RF processing module (703); and the analog baseband and RF processing module (703) is configured to:

receiving the converted first and second sequences from the digital front end (702),

generating a cancellation input signal (106) from the converted first sequence and outputting the cancellation input signal (106) to a first port (108) of a QBPA (107) in the RF front end (100), and

generating a transmit input signal (112) from the converted second sequence and outputting the transmit input signal (112) to a fourth port (111) of the QBPA (107) in the RF front end (100).

15. The full-duplex or half-duplex transceiver (700) of claim 14, in which

The digital baseband processing module (701) is further configured to convert the mixture of frequency domain signals and SIC coefficients to form the first sequence.

16. The full-duplex or half-duplex transceiver (700) of claim 14, in which

The first sequence is identical to the second sequence, and

the digital front end (702) is further configured to filter the received first sequence prior to converting it.

17. A method (1000) for performing wireless communication using a radio frequency, RF, front end, the method (1000) comprising:

providing (1001) a transmit signal to an antenna and receiving a receive signal from the antenna via an antenna port of the RF front-end,

using (1002) a cancellation input signal generator to: generating a cancellation input signal and outputting the cancellation input signal to a quadrature balanced power amplifier, QBPA, the QBPA comprising first, second, third and fourth ports,

using the QBPA to:

receiving (1003) a transmit input signal at the first port or the fourth port,

receiving (1004) the receive signal at the second port connected to the antenna port,

receiving (1005) the cancellation input signal from the cancellation input signal generator,

amplifying (1006) the transmit input signal and the cancel input signal,

generating (1007) the transmit signal from the transmit input signal and outputting the transmit signal at the second port,

generating (1008) the cancellation signal from the cancellation input signal, an

Outputting (1009) the cancellation signal and the reception signal at the third port; and

outputting (1010) the reception signal to a signal processing section via a reception port connected to the third port.

Technical Field

The present invention relates to Radio Frequency (RF) front ends for wireless communication, in particular for Half Duplex (HD), Full Duplex (FD) and/or Frequency Division Duplex (FDD) transceivers. Accordingly, the present invention also relates to a transceiver having a multimode RF front end. The RF front-end of the present invention is based on, inter alia, a Quadrature Balanced Power Amplifier (QBPA).

Background

In transmit and receive (T/R) antenna wireless communication scenarios, it is desirable to protect a Low Noise Amplifier (LNA) in the receive path from transmit signal leakage (TX leakage). In most scenarios, the minimum T/R isolation required to protect the LNA is about 30 dB. For Simultaneous Transmit Receive (STR) antenna wireless communication scenarios, such as FD or FDD without a duplexer, a minimum T/R isolation of 50-60dB is required. Therefore, a Self Interference Cancellation (SIC) mechanism is needed for STR wireless systems.

Conventional implementations of such SIC are implemented at the output of a Power Amplifier (PA), i.e., between the Transmit (TX) output and the Receive (RX) input, so that they "load" the TX and RX channels, causing power efficiency and signal-to-noise ratio losses. Figure 11 conceptually illustrates an example of a conventional SIC implementation, as is common in wireless communication applications. The SIC unit is implemented at the PA output (i.e., "after PA"). In particular, the input signal of the SIC unit is the output signal from the PA. Such an implementation causes both power efficiency losses and reduces the signal-to-noise ratio.

Fig. 12 shows a first example of an improved Quadrature Balanced Power Amplifier (QBPA) RF front end (RF front end, RFFE). In particular, this example is based on having unequal transmission paths (unequal PAs)_AAnd PA_B) Improved QBPA. This three-port version of the RFFE includes a TX input port, an RX output port, and an antenna TR/RX port. This improvement allows flexibility to create a feed-forward TX cancellation signal in the receive path that has the proper amplitude and is in anti-phase with the TX signal reflected from the antenna. Thus, the first example implements a dual mode RF front-end with built-in SIC functionality, thereby increasing isolation between the transmit and receive ports.

However, the first example requires simultaneous control of the PAs_AAnd PA_BThe amplitude and phase of the two PA paths, which adds considerable complexity to the front-end design. Also, the first example is limited in isolation of broadband signals, but the use of such broadband signals is of high interest.

Fig. 13 thus shows a second example of an improved QBPA RFFE. This four-port version adds a SIC input port. It uses QBPA structure and adopts two identical transmission Paths (PA)_A＝PA_B). In this way, after normalization by the gains of the two identical paths, the feed forward cancellation signal is injected from the fourth port, which was not previously used. The cancellation signal will be reconstructed at the receive port to cancel the transmitted signal reflected from the antenna.

Disclosure of Invention

In view of the above disadvantages and examples, embodiments of the present invention aim to provide an improved multi-mode RF front-end. In particular, it is an object to design a multimode RF front-end with improved power efficiency of SIC implementations. The multi-mode RF front-end should be easy to integrate, e.g., on a chip and/or PCB, and should have low SIC signal-to-noise ratio degradation.

This object is achieved by the embodiments provided in the appended independent claims. Advantageous implementations of the embodiments are further defined in the dependent claims.

In particular, embodiments may generate one or more SIC signals for any version and primarily for a 4-port improved QBPA. All new embodiments generate the SIC signal in a "pre-PA (pre-PA)" manner and reuse the QBPA power amplifier to amplify the SIC signal as well as the TX signal. This greatly improves the efficiency of SIC implementation and minimizes signal-to-noise ratio loss.

A first aspect of the invention provides an RF front end for wireless communication, comprising: an antenna port for outputting a transmit signal to an antenna and receiving a receive signal from the antenna; a reception port for outputting the reception signal to the signal processing section; a cancellation input signal generator for generating a cancellation input signal and outputting the cancellation input signal to the QBPA; and a QBPA comprising first, second, third and fourth ports, wherein QBPA is configured to: the method includes receiving a transmit input signal at a first port or a fourth port, receiving a receive signal at a second port connected to an antenna port, receiving a cancel input signal from a cancel input signal generator, amplifying the transmit input signal and the cancel input signal, generating the transmit signal from the transmit input signal and outputting the transmit signal at the second port, generating the cancel signal from the cancel input signal and outputting the cancel signal and the receive signal at a third port connected to the receive port.

The cancellation input signal is generated by a cancellation input signal generator in a "before PA" manner. In particular, the cancellation input signal is output to the QBPA, which therefore amplifies the SIC signal(s) and the TX signal(s) together. The cancellation signal is reconstructed at the third port so that leakage signals (TX leakage) caused at the third port when operating in the transmit mode can be cancelled. In particular, the cancellation signal may cancel the transmit signal reflected by the antenna (TX antenna reflection). The four-port RF front-end of the first aspect enables multi-mode operation by reusing amplifiers, in particular reducing SIC power consumption.

In an implementation form of the first aspect, the cancellation input signal generator comprises a SIC filter.

Optionally, the SIC filter can be used to suppress TX interference, i.e., TX leakage, and TX signal antenna reflections.

In an implementation form of the first aspect, the cancellation input signal generator is configured to generate the cancellation input signal based on the transmission input signal and/or the SIC signal received at the first or fourth port.

In this way, no additional signals need to be provided to construct the cancellation input signal. Alternatively, additional SIC signals may also be injected into the cancellation input signal generator to form the cancellation input signal.

In an implementation form of the first aspect, the cancellation input signal generator is configured to generate the cancellation input signal in the following manner: the cancellation signal cancels a leakage signal caused at the third port when the transmission signal is output from the second port.

Accordingly, the T/R isolation characteristics of the RF front-end of the first aspect are improved. Further, by adjusting the cancellation input signal, the T/R isolation can accommodate different leakage mechanisms. Thus, the RF front-end of the first aspect provides great flexibility.

In a further implementation form of the first aspect, the QBPA comprises a first coupler configured to split an input signal received from the first or fourth port of the QBPA into a first part and a second part with a phase difference of 90 ° between them, wherein the input signal is a transmit input signal or a cancel input signal; a first amplifier configured to amplify a first portion of the input signal and output the amplified first portion of the input signal to the second coupler; a second amplifier configured to amplify a second portion of the input signal and output the amplified second portion of the input signal to the second coupler; and a second coupler configured to combine the amplified first and second portions of the input signal and form first and second output signals at second and third ports of the QBPA, respectively.

The QBPA includes two power amplifiers. Alternatively, the first amplifier and the second amplifier may provide different gains. Alternatively, the amplification of the first amplifier may be the same as the amplification of the second amplifier.

In a further implementation form of the first aspect, the input signal of the first coupler comprises a transmit input signal, wherein the second coupler is configured to combine the amplified first and second portions of the transmit input signal such that they constructively form the transmit signal at the second port and destructively cancel each other at the third port.

Thus, the leakage of the transmission signal to the third port, i.e. towards the signal processing section for processing the reception signal, is reduced or even absent (it is noted that antenna reflections of the transmission signal are (yet) not taken into account).

In a further implementation form of the first aspect, the cancellation input signal generator comprises a first SIC filter arranged between the first coupler and the first amplifier, and a second SIC filter arranged between the first coupler and the second amplifier, wherein the first SIC filter is configured to: receiving a first portion of the input signal from the first coupler, generating a first cancellation input signal, and outputting the first cancellation input signal to the first amplifier; the second SIC filter is configured to: the second cancellation input signal is generated by receiving a second portion of the input signal from the first coupler, and outputting the second cancellation input signal to the second amplifier.

Maximum SIC freedom can be obtained by implementing two independent analog SIC filters at each PA input. But this may not provide a minimum form factor or efficiency, especially for passive delay lines SIC, or may generate noise and non-linearity for active SIC filters.

In a further implementation form of the first aspect, the second coupler is further configured to combine the amplified first and second cancellation input signals such that they constructively form a cancellation signal at the third port and destructively cancel each other at the second port.

The cancellation signal at the third port may cancel any T/R leakage, such as reflection of the transmitted signal at the antenna, which is reconstructed at the third port.

In a further implementation form of the first aspect, the RF front-end further comprises a splitter, the cancellation input signal generator comprising a third SIC filter, wherein the splitter is configured to: receiving a transmit input signal, splitting the transmit input signal into third and fourth portions, outputting the third portion of the transmit input signal to a third SIC filter and the fourth portion of the transmit input signal to a fourth port of the QBPA connected to the first coupler; and, the third SIC filter is configured to: the method further includes receiving a third portion of the transmit input signal from the splitter, generating a cancellation input signal, and outputting the cancellation input signal to the first coupler.

Alternatively, the TX input signal may be split into two different QBPA inputs. The TX signal may be higher in power and may be fed to other inputs after the SIC signal passes through the analog SIC filter. This alternative design may be more suitable for active SIC filtering.

In a further implementation form of the first aspect, the RF front-end further comprises an in-phase quadrature digital-to-analog converter (IQ DAC), an IQ baseband processing component (IQ BB), and the first and second mixers, and the cancellation input signal generator comprises a BB SIC filter, wherein the IQ DAC is configured to receive a digital signal, convert the digital signal to an analog signal, and output the analog signal to the IQ BB; the IQBB is configured to receive an analog signal from the IQDAC, generate a BB signal from the analog signal, and output the BB signal to the BB SIC filter and the first mixer; the BB SIC filter is configured to receive a BB signal from the IQ BB, generate a BB cancellation input signal from the BB signal, and output the BB cancellation input signal to the second mixer; the first mixer is configured to receive a BB signal from the IQ BB, mix the BB signal with a low frequency signal to form a transmit input signal, and output the transmit input signal to the fourth port of the QBPA; the second mixer is configured to receive a BB cancellation input signal from the BB SIC filter, mix the BB cancellation input signal with the low frequency signal to form a cancellation input signal, and output the cancellation input signal to the first port of the QBPA.

The implementation of an RF SIC filter may be physically too large and/or overly complex in some applications. Thus, as described in this implementation form, the implementation of a simple analog baseband (BB) SIC can be up-converted to RF. The complex low frequency signal is used to generate a transmit input signal and a cancel input signal.

In a further implementation form of the first aspect, the QBPA is configured to: a cancellation input signal is received at the first port from the cancellation input signal generator and a transmit input signal is received at the fourth port.

The TX chain and the SIC chain may be separate. In particular, the cancellation input signal may be fed to one port of the QBPA and the transmit input signal may be fed to the other port of the QBPA.

In a further implementation form of the first aspect, the second coupler is further configured to combine the amplified first and second portions of the cancellation input signal such that they constructively form a cancellation signal at the third port and destructively cancel each other at the second port.

A second aspect of the invention provides an FD or HD transceiver comprising an RF front-end according to the first aspect or any of its implementation forms, and a transmit and receive antenna connected to an antenna port of the RF front-end.

Accordingly, the transceiver of the second aspect achieves the advantages and effects of the RF front-end of the first aspect.

In an implementation form of the second aspect, if the TX chain and the SIC chain are separate, the transceiver further comprises a digital baseband processing module, a digital front end, and an analog baseband and RF processing module, wherein the digital baseband processing module is configured to: receiving the frequency domain signal, generating a first and a second sequence from the frequency domain signal, and outputting the first and the second sequence to a digital front end; the digital front end is configured to: receiving the first and second sequences from the digital baseband processing module, converting the received first and second sequences, and outputting the converted first and second sequences to the analog baseband and RF processing module; and, the analog baseband and RF processing module is configured to: the converted first and second sequences are received from the digital front end, a cancellation input signal is generated from the converted first sequence and output to a first port of the QBPA in the RF front end, and a transmit input signal is generated from the converted second sequence and output to a fourth port of the QBPA in the RF front end.

The implementation of analog SIC filters may be physically too large and/or complex in some applications. Thus, a simple digital BB SIC implementation can be up-converted to RF as described in this implementation. After the digital signal processing process, the digital signal may be converted to an RF signal including a transmit input signal and a cancel input signal.

In an implementation form of the second aspect, the digital baseband processing module is further configured to convert a mixture of the frequency domain signal and the SIC coefficients to form a first sequence.

In another implementation form of the second aspect, the first sequence is identical to the second sequence, and the digital front end is further configured to filter the received first sequence before converting it.

A third aspect of the present invention provides a method for performing wireless communication using an RF front end, the method comprising: providing a transmit signal to an antenna and receiving a receive signal from the antenna via an antenna port of an RF front end, using a cancellation input signal generator to: generating a cancellation input signal and outputting the cancellation input signal to a Quadrature Balanced Power Amplifier (QBPA), using the QBPA to: receiving a transmit input signal at the first port or the fourth port, receiving a receive signal at the second port connected to the antenna port, receiving a cancel input signal from a cancel input signal generator, amplifying the transmit input signal and the cancel input signal, generating a transmit signal from the transmit input signal and outputting the transmit signal at the second port, generating a cancel signal from the cancel input signal, and outputting the cancel signal and the receive signal at the third port; and outputting the reception signal to the signal processing section via a reception port connected to the third port.

The method of the third aspect may be developed in an implementation form according to the implementation form described for the first aspect above. By the method of the third aspect and its implementation forms, the advantages and effects of the RF front-end of the first aspect and its various implementation forms are achieved.

It has to be noted that all devices, elements, units and means described in the present application may be implemented in software or hardware elements or any kind of combination thereof. All steps performed by the various entities described in this application, as well as the functions described as being performed by the various entities, are intended to mean that the various entities are adapted or configured to perform the various steps and functions. Even if in the following description of specific embodiments specific functions or steps to be performed by an external entity are not reflected in the description of specific detailed elements of the entity performing the specific steps or functions, it should be clear to a person skilled in the art that these methods and functions can be implemented in corresponding software elements or hardware elements, or any kind of combination thereof.

Drawings

The above aspects and implementations of the invention are explained in the following description of specific embodiments with reference to the drawings, in which:

fig. 1 illustrates a multi-mode RF front-end according to an embodiment of the present invention.

Fig. 2 illustrates a multi-mode RF front end according to an embodiment of the present invention.

Fig. 3 illustrates a multi-mode RF front end according to an embodiment of the present invention.

Fig. 4 illustrates a multi-mode RF front end according to an embodiment of the present invention.

Fig. 5 illustrates a multi-mode RF front end according to an embodiment of the present invention.

Fig. 6 illustrates a multi-mode RF front end according to an embodiment of the present invention.

Fig. 7 shows a transceiver (FD, FDD or HD) according to an embodiment of the present invention.

Fig. 8 shows a transceiver (FD, FDD or HD) according to an embodiment of the present invention.

Fig. 9 shows a transceiver (FD, FDD or HD) according to an embodiment of the present invention.

FIG. 10 illustrates a method according to an embodiment of the invention.

Figure 11 conceptually illustrates an example of a conventional SIC implementation.

Figure 12 shows an example of an improved QBPA RF front-end.

Figure 13 shows another example of an improved QBPA RF front-end.

Detailed Description

Fig. 1 shows an RF front end 100 according to an embodiment of the invention. The RF front-end 100 is particularly a multi-mode RF front-end, suitable for HD, FD and FDD wireless communication, e.g. in an HD, FD or FDD transceiver.

The RF front end 100 has an antenna port 101 and an antenna 200 may be connected to the antenna port 101. The antenna port 101 is used to output a transmit signal 102 to the antenna 200 (in transmit mode) and to receive a receive signal 103 from the antenna 200 simultaneously or not (in receive mode).

The RF front end 100 also has a receiving port 104, and a receiving path including the signal processing part 300 may be connected to the receiving port 104. The reception port 104 is used to output a reception signal 103 received from the antenna 200 via the antenna port 101 to the signal processing section 300.

The RF front end 100 also has a cancellation input signal generator 105. The cancellation input signal generator 105 generates a cancellation input signal 106 and outputs the cancellation input signal 106 to the QBPA 107 of the RF front end 100.

Thus, the RF front end 100 further has a QBPA 107. The QBPA 107 acts as a T/R isolation stage and allows STR. QBPA 107 includes four ports, namely a first port 108, a second port 109, a third port 110 and a fourth port 111. The second port 109 is connected to the antenna port 101, i.e. it is used for providing the transmit signal 102 to the antenna 200 and for receiving the receive signal 103 from the antenna 200. The third port 110 is connected with the receiving port 104, i.e. it is used to provide the received signal 103 to the signal processing part 300.

The QBPA 107 is in particular configured to receive the transmit input signal 112 at the first port 108 or at the fourth port 111 and to receive the cancellation input signal 106 from the cancellation input signal generator 105. The cancellation input signal 106 may be received at the first port 108 or at the fourth port 111, or may be received at other ports in the QBPA 107. For example, the cancellation input signal 106 may be injected into the internal elements of the QBPA 107. In addition, QBPA 107 is configured to receive received signal 103 at second port 110.

QBPA 107 is configured to amplify transmit input signal 112 and cancel input signal 106. It should be appreciated that the cancellation input signal 106 is generated before the PA input and may therefore be amplified along with the transmit input signal 112.

QBPA 107 is further configured to generate and output transmit signal 102 at second port 109 from transmit input signal 112; generating a cancellation signal 113 from the cancellation input signal 106 and outputting it at the third port 110; and outputting at the third port the received signal 103 received at the second port 110.

Accordingly, in the transmit mode, a transmit signal 102 is generated (indicated by dashed line 112 → 102) and provided to the antenna 200. In addition, a cancel signal 113 is generated (indicated by a broken line 106 → 113) and supplied to the signal processing section. Optionally, a SIC filter may be used to generate the cancellation input signal 106. Optionally, the cancellation input signal generator 105 may be configured to generate the cancellation input signal 106 based on the transmit input signal 112 and/or the SIC signal received at the first port 108 or at the fourth port 111. In particular, cancellation signal 113 may cancel any leakage caused by transmit signal 102 output to antenna 200, such as reflections of transmit signal 102 at antenna 200 that are reflected back to antenna port 101/second port 109, or any other defect that causes other TX signal "leakage" phenomena between second port 109 and third port 110. In the receiving mode, the reception signal 103 is transmitted from the second port 109 to the third port 110 (indicated by dotted lines), and is supplied to the signal processing section 300. As described above, the transmission mode and the reception mode may be set simultaneously.

Fig. 2 shows a multi-mode RF front-end 100 according to an embodiment of the invention, which is based on the RF front-end 100 shown in fig. 1. Accordingly, like elements are provided with like reference numerals. In particular, fig. 2 shows how the transmit signal 102 is generated from the transmit input signal 112, and the cancellation signal 111 is generated from the "before PA" cancellation input signal. To this end, the QBPA 107 includes a first coupler 1071, a first amplifier 1072a, a second amplifier 1072b, and a second coupler 1073. The first coupler 1071, the first amplifier 1072a, and the second coupler 1073 constitute at least a part of a first signal path, and the first coupler 1071, the second amplifier 1072b, and the second coupler 1073 constitute at least a part of a second signal path. Accordingly, the first amplifier 1072a is disposed in the first signal path and the second amplifier 1072b is disposed in the second signal path.

The first coupler 1071 is configured to divide an input signal received from the first port 108 or the fourth port 111 into a first part and a second part. In particular, the input signal is the transmit input signal 112 or the cancel input signal 106. For either of the signals 112 or 106, a phase difference of 90 ° is thereby generated between the first portion and the second portion. The first amplifier 1072a is configured to amplify the first portion and the second amplifier 1072b is configured to amplify the second portion. The second coupler 1073 is further configured to combine the amplified first and second portions of the input signal to form first and second output signals at the second port 109 and the third port 110, respectively. Thus, the amplified first and second transmit input signal portions are combined such that they constructively form the transmit signal 102 at the second port 109 and destructively cancel each other at the third port 110. In this way, the transmission signal 102 is generated from the transmission input signal 112, and the transmission signal 102 is output to the antenna 200 only at the second port 109.

Fig. 3 shows a multimode RF front-end 100 according to an embodiment of the invention, which is based on the RF front-end 100 shown in fig. 1 and/or fig. 2. The cancellation input signal generator 105 may include a first SIC filter 1051 disposed between the first coupler 1071 and the first amplifier 1072a, and a second SIC filter 1052 disposed between the first coupler 1071 and the second amplifier 1072 b.

In particular, first SIC filter 1051 is configured to receive a first portion of an input signal from first coupler 1071. The first SIC filter 1051 is further configured to generate a first cancellation input signal and output the first cancellation input signal to the first amplifier 1072 a. Similarly, second SIC filter 1052 is configured to receive a second portion of the input signal from first coupler 1071. The second SIC filter 1052 is further configured to generate a second cancellation input signal and output the second cancellation input signal to the second amplifier 1072 b.

In this way, the first and second cancellation input signals are fed to the first and second amplifiers 1072a and 1072b, respectively. The amplified first and second cancellation input signals are then combined in a second coupler 1073. In particular, the second coupler 1073 is further configured to combine the amplified first and second cancellation input signals such that they constructively form a cancellation signal 113 at the third port 110 and destructively cancel each other at the second port 109. Further, also in this way, the cancellation signal 113 is generated from the first and second cancellation input signals and is output to the signal processing section 300 (here including the LNA 201) only at the third port 110. It should be understood that 1051 and 1052 each generate a different signal and both include TX and cancellation signals. Each amplifier ratio amplifies a different "mixed" version of the TX and SIC signals, as in all other cases. As can be seen from fig. 2, the inputs of PA1 and PA2 include the two mentioned TX and SIC signals but in combination with different phases, such that TX summation (subtraction at 109) is achieved at 109 by 1073, while SIC summation (subtraction at 109, of course) is achieved at 110 by 1073. This is true for all embodiments herein.

Maximum SIC freedom can be achieved by implementing two independent SIC filters (e.g., analog SIC filters) at each PA input. But this may not provide a minimum physical size or efficiency, especially for passive delay lines SIC. Noise and non-linearity may also be generated for active SIC filters.

Fig. 4 shows a multimode RF front-end 100 according to an embodiment of the invention, which is also based on the RF front-end 100 shown in fig. 1 and/or fig. 2. Optionally, the RF front-end 100 further comprises a splitter 114 and the cancellation input signal generator 105 comprises a third SIC filter 1053. The splitter 114 is configured to receive the transmit input signal 112 and split it into third and fourth portions. The splitter 114 is further configured to output a third portion of the transmit input signal 112 to a third SIC filter 1053. The splitter 114 is further configured to output a fourth portion of the transmit input signal 112 to a fourth port of the QBPA 107 coupled to the first coupler 1071.

A fourth part of the transmit input signal 112 is fed to QBPA 107. Accordingly, the transmit signal 102 will be constructed based on the fourth portion of the transmit input signal 112.

The third SIC filter 1053 is configured to receive a third portion of the transmit input signal 112 from the splitter 114. The third SIC filter 1053 is further configured to generate and output the cancellation input signal 106 to the first port 108 of the QBPA 107 connected to the first coupler 1071. In this way, the cancellation input signal 106 is also fed to QBPA 107. Accordingly, a cancellation signal 113 will be constructed based on the cancellation input signal 106.

It should be understood that the TX signal may alternatively be split into two different QBPA inputs. The TX signal is higher in power and the SIC signal will be fed to other inputs after passing through the analog SIC filter. This alternative approach may be more suitable for active SIC filter designs.

Fig. 5 shows a multimode RF front-end 100 according to an embodiment of the invention, which is also based on the RF front-end 100 shown in fig. 1 and/or fig. 2. Optionally, the RF front-end 100 further comprises an IQ DAC 115, an IQ BB 116, and a first mixer 117a and a second mixer 117 b. The cancellation input signal generator 105 includes a BB SIC filter 1054. The IQ DAC 115 is configured to receive and convert a digital signal into an analog signal and output the analog signal to the IQ BB. Accordingly, the IQ BB 116 is configured to receive the analog signal from the IQ DAC 115. The IQ BB 116 is further configured to generate a BB signal from the analog signal and output the BB signal to a BB SIC filter 1054 and a first mixer 117 a. The BB SIC filter 1054 is configured to receive the BB signal from the IQ BB 116, generate a BB cancellation input signal from the BB signal, and output the BB cancellation input signal to the second mixer 117 b.

In addition, a complex low frequency signal is provided in the present embodiment. The first mixer 117a is configured to receive BB signals from the IQ BB 116. The first mixer 117a is further configured to mix the BB signal with the low frequency signal to form the transmit input signal 112, and to output the transmit input signal 112 to the fourth port 111 of the QBPA 107. The second mixer 117b is configured to receive the BB cancellation input signal from the BB SIC filter 1054. The second mixer 117b is further configured to mix the BB cancellation input signal with the low frequency signal to form the cancellation input signal 106 and to output the cancellation input signal 106 to the first port 108 of the QBPA 107.

Accordingly, the transmit signal 102 and the cancellation signal 113 will be constructed based on the transmit input signal 112 and the cancellation input signal 106 fed to the QBPA 107, respectively.

Notably, the implementation of the RF SIC filter may be physically too large and/or in some applications too complex. In this way, a simple analog baseband SIC implementation can be up-converted to RF as described herein.

Fig. 6 shows a multimode RF front-end 100 according to another embodiment of the invention, which is also based on the RF front-end 100 shown in fig. 1 and/or fig. 2. In particular, the SIC chain and the TX chain may be implemented separately.

QBPA 107 is configured to receive the cancellation input signal 106 from the cancellation input signal generator 105 at the first port 108. QBPA 107 is also configured to receive a transmit input signal 112 at a fourth port 111.

The implementation of analog SIC filters may be physically too large and/or complex in some applications. Thus, a simple digital BB SIC implementation can be designed to up-convert a digital signal to an RF signal.

Optionally, according to previous embodiments, the cancellation input signal 106 is fed to the QBPA 107. In this scenario, the cancellation input signal 106 passes through the first coupler 1071 and is split into first and second portions of the cancellation input signal. The first and second amplifiers 1072a and 1072b will further amplify the first and second portions of the cancellation input signal, respectively. Accordingly, the second coupler 1073 is further configured to combine the amplified first and second portions of the cancellation input signal such that they constructively form the cancellation signal 113 at the third port 110 and destructively cancel each other at the second port 109. Further, also in this way, the cancel signal 113 is generated by canceling the first and second parts of the input signal and is output to the signal processing section only at the third port 110.

Fig. 7 shows a transceiver 700(FD, FDD or HD) according to an embodiment of the invention, the transceiver 700 comprising an RF front end 100 according to an embodiment of the invention, in particular one of the RF front ends 100 of fig. 1 to 6. The transceiver 700 further comprises a transmit receive antenna 200 connected to the antenna port 101 of the RF front end 100. Transceiver 700 is capable of operating in HD, FD, and/or FDD modes because RF front-end 100 is a multi-mode RF front-end, and in particular, can simultaneously transmit and receive signals via antenna 200. Due to the use of the RF front end 100, the transmit signal leakage in the transceiver 700 is greatly reduced.

Both fig. 8 and fig. 9 show a digital full TX chain implementation for a separate TX/SIC implementation. In particular, the RF front end 100 is the RF front end 100 of fig. 6.

The transceiver 700 further comprises a digital baseband processing module 701, a digital front end 702 and an analog baseband and RF processing module 703. The digital baseband processing module 701 is configured to receive a frequency domain signal and generate first and second time domain sequences from the frequency domain signal. In particular, the digital baseband processing module 701 may perform an Inverse Fast Fourier Transform (IFFT) on the frequency domain signal.

The digital baseband processing module 701 is further configured to output the first and second sequences to a digital front end 702. The digital front end 702 is configured to receive the first and second sequences from the digital baseband processing module 701. The digital front end 702 is further configured to convert the received first and second sequences and output the converted first and second sequences to the analog baseband and RF processing module 703. Optionally, the digital front end 702 may include an IQ DAC.

Accordingly, the analog baseband and RF processing module 703 is configured to receive the converted first and second sequences from the digital front end 702. The analog baseband and RF processing module 703 is configured to generate a cancellation input signal 106 from the converted first sequence and output the cancellation input signal 106 to the first port 108 of the QBPA 107 in the RF front end 100. The analog baseband and RF processing module 703 is then further configured to generate a transmit input signal 112 from the converted second sequence and output the transmit input signal 112 to the fourth port 111 of the QBPA 107 in the RF front end 100. In this way, the transmit input signal 112 and the cancel input signal 106 are each constructed from digital signals. At the next stage, the transmit input signal 112 and the cancel input signal 106 are fed to the RF front end 100 and processed accordingly as discussed in the previous embodiments.

As shown in fig. 8, the digital baseband processing module 701 is further configured to convert the mixture of frequency domain signals and SIC coefficients to form a first sequence. Specifically, IFFT is performed on the frequency domain signal to generate a second sequence. Meanwhile, IFFT is performed on the mixture of the frequency domain signal and the SIC coefficient to generate a first sequence. Accordingly, the first sequence is used to form the SIC signal, while the second sequence is used to form the TX signal.

In another digital implementation as shown in fig. 9, the first sequence may optionally be the same as the second sequence. In other words, the time domain signal is fed to the digital front end 702 after being IFFT-processed. The digital front end 702 is further configured to filter the received IFFT-processed time domain signal before converting it. In this way, the application of SIC coefficients replaces the filter applied to the time domain signal using only a single IFFT.

FIG. 10 shows a method 1000 according to an embodiment of the invention. The method 1000 is for performing wireless communications using an RF front end 100, in particular the RF front end 100 shown in one of fig. 1 to 6. The method 1000 comprises the step 1001 of providing a transmit signal 102 to the antenna 200 via the antenna port 101 of the RF front end 100 and receiving a receive signal 103 from the antenna 200. Further, the method 1000 includes step 1002 generating a cancellation input signal using a cancellation input signal generator and outputting the cancellation input signal to QBPA 107, the QBPA 107 including first, second, third and fourth ports. The method 1000 further includes using QBPA 107 to: step 1003 is executed, receiving the transmission input signal 112 at the first port 108 or the fourth port 111; step 1004 is executed to receive the received signal 103 at the second port 109 connected to the antenna port 101; step 1005 is executed to receive the cancellation input signal 106 from the cancellation input signal generator 105; step 1006 is performed, amplifying the transmit input signal 112 and the cancel input signal 106; step 1007 is executed, generating a transmission signal 102 from the transmission input signal 112 and outputting the transmission signal 102 at the second port 109; step 1008 is performed to generate a cancellation signal 113 from the cancellation input signal 106; step 1009 is performed to output the cancellation signal 113 and the reception signal 103 at the third port 110. Finally, the method 1000 comprises outputting the received signal 103 to the signal processing part 201 via a port 104 connected to the third port 110.

In summary, the embodiments of the present invention achieve a plurality of advantages. The advantages are that:

the RF front end can be integrated on chip, especially in a digital to RF configuration.

Broadband cancellation of antenna reflections is possible.

A very power efficient SIC implementation is achieved.

Low SIC signal-to-noise ratio degradation is achieved.

The present invention has been described in connection with various embodiments by way of example and implementation. However, other variations will be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure and the independent claims. In the claims as well as in the description, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. A single element or other unit may fulfill the functions of several entities or items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.