Harmonic suppression circuit and transmitter

Abstract

The present invention provides a harmonic suppression circuit and a transmitter, wherein the harmonic suppression circuit comprises: a differential amplifier module, for amplifying an input differential signal to output an amplified signal; a first adjustable capacitor, one end of which is electrically connected to the first output end of the differential amplifier module and the other end is grounded; a second adjustable capacitor, one end of which is electrically connected to the second output end of the differential amplifier module and the other end is grounded; a tuning module, which is electrically connected to the output end of the differential amplifier module and is used to tune the amplified signal and perform signal conversion to output a target signal. The present invention can effectively reduce the second harmonic in the output signal and increase the bandwidth, thereby improving the efficiency of the transmitter power amplifier.

Description

Technical Field

[0001] The present invention relates to the technical field of integrated circuits, and in particular to a harmonic suppression circuit and a transmitter. Background Art

[0002] At present, the transmitter generally uses a power amplifier set at the end of the transmitter to amplify the transmission signal. The power amplifier mainly has indicators such as saturation power, efficiency, and linearity. The transmitter is usually a complementary metal oxide semiconductor process (CMOS), and the power amplifier usually uses a GaAs compound process. According to the manufacturing process, it is generally difficult to integrate the power amplifier and the transmitter on the same chip. Therefore, traditional transmitters are to separate the power amplifier and the transmitter on two chips. On the other hand, since the output spectrum of the power amplifier often has second or higher harmonics, and the harmonics must be low enough to meet the protocol requirements. In the differential power amplifier, the asymmetry of the P and N paths will also produce larger second harmonics. If the second harmonic is too high, it will place high requirements on the off-chip filter, which is often difficult to achieve, or it is necessary to sacrifice insertion loss, so that the power amplifier efficiency will be reduced.

[0003] Therefore, it is necessary to provide a novel harmonic suppression circuit and transmitter to solve the above problems existing in the prior art. Summary of the invention

[0004] The object of the present invention is to provide a harmonic suppression circuit and a transmitter, which can effectively reduce the second harmonic in the output signal and increase the bandwidth, thereby improving the power amplifier efficiency of the transmitter.

[0005] To achieve the above object, the harmonic suppression circuit of the present invention comprises:

[0006] A differential amplifier module, used for amplifying an input differential signal to output an amplified signal;

[0007] A first adjustable capacitor, one end of which is electrically connected to the first output end of the differential amplifier module, and the other end of which is grounded;

[0008] A second adjustable capacitor, one end of which is electrically connected to the second output end of the differential amplifier module, and the other end of which is grounded; the first adjustable capacitor and the second adjustable capacitor are used to compensate for the signal difference caused by the asymmetry of the P and N paths;

[0009] The tuning module is electrically connected to the output end of the differential amplifier module and is used to tune the amplified signal and perform signal conversion to output a target signal.

[0010] The beneficial effect of the harmonic suppression circuit of the present invention is that after the differential signal is input, the tuning module is used as the load, and the capacitance values ​​of the first adjustable capacitor and the second adjustable capacitor are adjusted to compensate for the asymmetry of the input signal, thereby reducing the output second harmonic and increasing the bandwidth. At the same time, the gain is improved by adjusting the capacitance value at different frequencies.

[0011] Optionally, the tuning module includes a balun device, a first capacitor and a second capacitor, the balun device includes a first input terminal, a second input terminal, a third output terminal and a fourth output terminal, the first input terminal is electrically connected to the first output terminal of the differential amplifier module, the second input terminal is electrically connected to the second output terminal of the differential amplifier module, the two ends of the first capacitor are electrically connected to the first input terminal and the second input terminal, respectively, the two ends of the second capacitor are electrically connected to the third output terminal and the fourth output terminal, and the fourth output terminal is grounded.

[0012] Optionally, the first adjustable capacitor and the second adjustable capacitor are programmable capacitors.

[0013] The present invention also provides a transmitter, comprising:

[0014] A digital module, used for outputting a digital signal to be transmitted;

[0015] A signal conversion module, electrically connected to the digital module, for converting and filtering the digital signal to obtain a filtered signal;

[0016] A first mixing module, electrically connected to the signal conversion module, to mix the filtered signal to obtain a first mixed signal;

[0017] A second mixing module, electrically connected to the signal conversion module, to mix the filtered signal to obtain a second mixed signal;

[0018] A first suppression module, electrically connected to the first mixing module, and configured to perform harmonic suppression on the first mixing signal to obtain a first target signal;

[0019] A second suppression module, electrically connected to the second mixing module, and configured to perform harmonic suppression on the second mixing signal to obtain a second target signal;

[0020] The transmitting module is electrically connected to the output ends of the first suppression module and the second suppression module respectively, and is used to transmit the first target signal or the second target signal.

[0021] Wherein, at least one of the first suppression module and the second suppression module adopts the above-mentioned harmonic suppression circuit.

[0022] The transmitter of the present invention has the beneficial effect that after the digital module outputs the digital signal to be transmitted, the input digital signal is converted and processed by the signal conversion module to obtain a filtered signal, and after mixing processing is respectively performed by the first mixing module and the second mixing module, the first mixing signal and the second mixing signal are obtained, so that the first mixing signal and the second mixing signal are input as differential signals to the first suppression module and the second suppression module, thereby reducing the second harmonic in the first mixing signal or the second mixing signal, increasing the bandwidth of the output signal, and improving the efficiency of the transmitter.

[0023] This reduces the output second harmonic and increases the bandwidth, while at the same time increasing the gain by adjusting the capacitance value at different frequencies.

[0024] Optionally, the transmitter also includes a switching module, the input end of the switching module is electrically connected to the output end of the first suppression module and the output end of the second suppression module, respectively, and the output end of the switching module is electrically connected to the input end of the transmitting module for switching the signal transmitted by the transmitting module.

[0025] Optionally, the transmitter also includes a first low-pass filter and a second low-pass filter, the output end of the first suppression module is electrically connected to the input end of the switch module through the first low-pass filter, and the output end of the second suppression module is electrically connected to the input end of the switch module through the second low-pass filter.

[0026] Optionally, both the first suppression module and the second suppression module are the harmonic suppression circuits.

[0027] Optionally, the signal conversion module includes a first digital-to-analog converter, a second digital-to-analog converter, a third low-pass filter and a fourth low-pass filter, the input end of the first digital-to-analog converter and the input end of the second digital-to-analog converter are respectively electrically connected to the two output ends of the digital module, the output end of the third low-pass filter is electrically connected to the input end of the first mixing module and the input end of the second mixing module, and the output end of the fourth low-pass filter is electrically connected to the input end of the first mixing module and the input end of the second mixing module.

[0028] Optionally, the first frequency mixing module and the second frequency mixing module each have four inputs and two outputs.

[0029] Optionally, the transmitting module is a transmitting antenna. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 A circuit diagram of a harmonic suppression circuit according to an embodiment of the present invention;

[0031] Figure 2is a structural block diagram of a transmitter according to an embodiment of the present invention;

[0032] Figure 3 A power amplifier power curve diagram of the transmitter according to an embodiment of the present invention;

[0033] Figure 4 The figure is a curve diagram of the magnitude of the second harmonic in the signal transmitted by the transmitter according to the embodiment of the present invention. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Unless otherwise defined, the technical terms or scientific terms used herein should be understood by people with general skills in the field to which the present invention belongs. "Including" and similar words used in this article mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects.

[0035] In view of the problems existing in the prior art, an embodiment of the present invention provides a harmonic suppression circuit, referring to Figure 1 ,include:

[0036] The differential amplifier module 11 is used to amplify the input differential signal to output an amplified signal;

[0037] A first adjustable capacitor 12, one end of which is electrically connected to the first output end of the differential amplifier module 11, and the other end of which is grounded;

[0038] A second adjustable capacitor 13, one end of which is electrically connected to the second output end of the differential amplifier module 11, and the other end of which is grounded; the first adjustable capacitor and the second adjustable capacitor are used to compensate for the signal difference caused by the asymmetry of the P and N paths;

[0039] The tuning module 14 is electrically connected to the output end of the differential amplification module 11 and is used to tune the amplified signal and perform signal conversion to output a target signal.

[0040] In this embodiment, the differential amplifier module 11 adopts a differential structure to amplify the input differential signals RFin_P and RFin_N and then output the amplified signals. Since the two outputs P and N of the differential amplifier module 11 are respectively connected to the first adjustable capacitor 12 and the second adjustable capacitor 13, after the amplified signals are output, the capacitance of the two outputs is changed by adjusting the capacitance values ​​of the first adjustable capacitor 12 and the second adjustable capacitor 13, so as to compensate for the asymmetry of the two outputs of the differential amplifier module 11, thereby reducing the subsequent output second harmonics. After the two outputs of the differential amplifier module 11 are compensated, the tuning module 14 is used as a load, and the two asymmetric compensated amplified signals are converted into single-ended signal outputs, thereby completing the signal tuning process, effectively reducing the second harmonic of the output signal, and increasing the bandwidth at the same time. At different frequencies, the capacitance value is adjusted to improve the overall gain value.

[0041] In some embodiments, the tuning module 14 includes a balun device 141, a first capacitor 142 and a second capacitor 143. The balun device 141 includes a first input terminal, a second input terminal, a third output terminal and a fourth output terminal. The first input terminal is electrically connected to the first output terminal of the differential amplifier module 11, the second input terminal is electrically connected to the second output terminal of the differential amplifier module 11, the two ends of the first capacitor 142 are electrically connected to the first input terminal and the second input terminal, respectively, the two ends of the second capacitor 143 are electrically connected to the third output terminal and the fourth output terminal, and the fourth output terminal is grounded.

[0042] After the two output signals are asymmetric compensated, the two output signals are tuned by the balun device 141, the first capacitor 142 and the second capacitor 143 of the tuning module 14, and the tuned signals are converted into single-ended signal outputs to complete the signal processing process.

[0043] In some embodiments, the first adjustable capacitor 12 and the second adjustable capacitor 13 are programmable capacitors. Exemplarily, the first adjustable capacitor 12 and the second adjustable capacitor 13 are both programmable capacitors, and the capacitance value is adjusted by inputting different instructions to improve the gain and efficiency at the frequency to increase the bandwidth of the power amplifier. For example, when the frequency is low, a large capacitance value is used, and when the frequency is high, a small capacitance value is used to meet the use requirements.

[0044] It should be noted that the first adjustable capacitor 12 and the second adjustable capacitor 13 may have different capacitance values ​​or the same capacitance value, which is selected according to specific requirements, and this solution does not specifically limit this.

[0045] The present invention also discloses a transmitter, referring to Figure 2 ,include:

[0046] A digital module 21, used for outputting a digital signal to be transmitted;

[0047] A signal conversion module 22, electrically connected to the digital module, for converting and filtering the digital signal to obtain a filtered signal;

[0048] A first mixing module 23, electrically connected to the signal conversion module, to mix the filtered signal to obtain a first mixed signal;

[0049] A second mixing module 24, electrically connected to the signal conversion module, to mix the filtered signal to obtain a second mixed signal;

[0050] A first suppression module 25, electrically connected to the first mixing module, and configured to perform harmonic suppression on the first mixing signal to obtain a first target signal;

[0051] A second suppression module 26, electrically connected to the second mixing module, and configured to perform harmonic suppression on the second mixing signal to obtain a second target signal;

[0052] The transmitting module 27 is electrically connected to the output ends of the first suppression module and the second suppression module respectively, and is used to transmit the first target signal or the second target signal.

[0053] Wherein, at least one of the first suppression module and the second suppression module adopts the above-mentioned harmonic suppression circuit.

[0054] In this embodiment, after the transmitter outputs the digital signal to be transmitted through the digital module 21, the digital signal is converted into an analog signal through the signal conversion module 22 to obtain an analog signal, and a filtered signal is obtained after the first filtering process, and then the first mixing module 23 and the second mixing module 24 are respectively mixed, so that after the filtered signal is mixed, the first mixing signal and the second mixing signal are respectively obtained, wherein the first mixing signal and the second mixing signal are low frequency and high frequency respectively, and the first mixing signal and the second mixing signal are harmonically suppressed by the first suppression module 25 and the second suppression module 26 respectively. Since at least one of the first suppression module 25 and the second suppression module 26 adopts the above-mentioned harmonic suppression circuit, the first mixing signal or the second mixing signal is harmonically suppressed by the harmonic suppression circuit, so as to effectively suppress the second harmonic in the mixing signal, and then obtain the first target signal and the second target signal respectively, and the first target signal or the second target signal is transmitted through the transmitting module 27 to complete the signal transmission process.

[0055] It should be noted that in this scheme, the first mixing module 23 and the first suppression module 25 are used as a group of signal processing devices, and the second mixing module 24 and the second suppression module 26 are used as a group of signal processing devices to respectively generate a first target signal and a second target signal for signal transmission by the transmitting module 27. However, the present application scheme is not limited to using only two groups of signal processing devices consisting of mixing modules and suppression modules. Three or more groups of signal processor devices can also be selected for signal processing according to the type of signal frequency. For example, if there are analog signals of three frequencies, three mixing modules and three suppression modules can be selected to form three groups of signal processing devices to obtain three mixing signals and target signals respectively. These three mixing signals can be selected as low frequency, medium frequency and high frequency respectively. This scheme does not make any special limitations on this and will not be repeated here.

[0056] In some embodiments, the signal conversion module 22 includes a first digital-to-analog converter 221, a second digital-to-analog converter 222, a third low-pass filter 223, and a fourth low-pass filter 224. The input end of the first digital-to-analog converter 221 and the input end of the second digital-to-analog converter 222 are electrically connected to the two output ends of the digital module 21, respectively. The output end of the third low-pass filter 223 is electrically connected to the input end of the first frequency mixing module 23 and the input end of the second frequency mixing module 24. The output end of the fourth low-pass filter 224 is electrically connected to the input end of the first frequency mixing module 23 and the input end of the second frequency mixing module 24. Exemplarily, the two output ends of the digital module 21 output N-bit signals to the input ends of the first digital-to-analog converter 221 and the second digital-to-analog converter 222, respectively.

[0057] In some other embodiments, the first mixing module 23 and the second mixing module 24 each have four inputs and two outputs.

[0058] Exemplarily, after the digital module 21 generates a digital signal, it outputs N bits of digital signals to the first digital-to-analog converter 221 and the second digital-to-analog converter 222, respectively, and the digital signals are converted into two analog signals by the first digital-to-analog converter 221 and the second digital-to-analog converter 222, respectively, and then the two analog signals output by the first digital-to-analog converter 221 are first filtered by the third low-pass filter 223 to output two filtered signals, and the two analog signals output by the second digital-to-analog converter 222 are first filtered by the fourth low-pass filter 224 to output two filtered signals, thereby completing the digital-to-analog conversion and filtering process of the digital signal. The two filtered signals output by the third low-pass filter 223 and the fourth low-pass filter 224 are output to the first mixing module 23 and the second mixing module 24, respectively, so that the first mixing module 23 and the second mixing module 24 input four filtered signals. After the first mixing module 23 and the second mixing module 24 respectively mix the input four-way filter signal, the first mixing module 23 and the second mixing module 24 respectively output two first mixing signals and two second mixing signals, so that the two first mixing signals are used as the signal input of the first suppression module 25, and the two second mixing signals are used as the signal input of the second mixing module 26, and the first suppression module 25 and the second suppression module 26 perform harmonic suppression on the input signal to suppress the second harmonic in the signal, thereby improving the power amplifier power of the transmitter output signal. It can also reduce the suppression requirement of the external low-pass filter in the transmitter for the second harmonic, thereby removing the external low-pass filter or using a low-pass filter with a smaller specification, optimizing performance while saving hardware costs.

[0059] In this embodiment, the first mixing module 23 outputs a low-frequency first mixing signal, the second mixing module 24 outputs a high-frequency second mixing signal, the first suppression module 25 suppresses harmonics of the low-frequency first mixing signal, and the second suppression module 26 suppresses harmonics of the high-frequency second mixing signal.

[0060] Specifically, refer to Figure 3 The saturation power of the transmitter of this scheme is significantly higher than that of the traditional transmitter under the same frequency signal, and the reference Figure 4 , the second harmonic in the signal of the transmitter of this scheme is significantly lower than the second harmonic in the traditional method. It can be seen that the transmitter in this scheme can effectively suppress the second harmonic of the transmitted signal and improve the power amplifier power.

[0061] It should be noted that, in this embodiment, the above-mentioned harmonic suppression circuit can be adopted in the first suppression module 25 or the second suppression module 26. Since the above-mentioned harmonic suppression circuit has been described in the above content, it will not be repeated here. Alternatively, both the first suppression module 25 and the second suppression module 26 can adopt the above-mentioned harmonic suppression circuit, and this scheme does not specifically limit this.

[0062] Exemplarily, the harmonic suppression circuit is used in both the first suppression module 25 and the second suppression module 26, which can reduce the second harmonic in the mixed signal by at least 15 dB and increase the bandwidth of the output signal by 125%.

[0063] In some embodiments, the transmitter also includes a switch module 28, the input end of the switch module 28 is electrically connected to the output end of the first suppression module 25 and the output end of the second suppression module 26, respectively, and the output end of the switch module 28 is electrically connected to the input end of the transmitting module 27 for switching the signal transmitted by the transmitting module 27.

[0064] Exemplarily, after the first suppression module 25 and the second suppression module 26 perform harmonic suppression on the input differential signal and obtain the first target signal and the second target signal respectively, the output signal is switched by the switch module 28, so that the first target signal and the second target signal are respectively transmitted outwardly through the transmission module 27.

[0065] In some embodiments, the transmitter also includes a first low-pass filter 29 and a second low-pass filter 30, the output end of the first suppression module 25 is electrically connected to the input end of the switch module 28 through the first low-pass filter 29, and the output end of the second suppression module 26 is electrically connected to the input end of the switch module 28 through the second low-pass filter 30.

[0066] After the first suppression module 25 and the second suppression module 26 perform harmonic suppression on the mixing signal and output the first target signal and the second target signal, the first target signal is further filtered by the first low-pass filter 29, and the second target signal is filtered by the second low-pass filter 30, so as to reduce the second harmonic of the final output signal. Moreover, since the first suppression module 25 and the second suppression module 26 have already performed second harmonic suppression, the suppression requirements of the first low-pass filter 29 and the second low-pass filter 30 on the second harmonic are reduced, thereby further reducing the in-band insertion loss of the final output signal. While achieving second harmonic suppression of the transmitted signal, the hardware cost is reduced and the bandwidth of the transmitted signal is increased.

[0067] In some other embodiments, the transmitting module 27 is a transmitting antenna.

[0068] Although the embodiments of the present invention are described in detail above, it is obvious to those skilled in the art that various modifications and variations can be made to these embodiments. However, it should be understood that such modifications and variations are within the scope and spirit of the present invention as described in the claims. Moreover, the present invention described herein may have other embodiments and may be implemented or realized in a variety of ways.

Claims

1. A harmonic suppression circuit, characterized in that: include: A differential amplifier module, used for amplifying an input differential signal to output an amplified signal; A first adjustable capacitor, one end of which is electrically connected to the first output end of the differential amplifier module, and the other end of which is grounded; A second adjustable capacitor, one end of which is electrically connected to the second output end of the differential amplifier module, and the other end of which is grounded; the first adjustable capacitor and the second adjustable capacitor are used to compensate for the signal difference caused by the asymmetry of the P and N paths; A tuning module, electrically connected to the output end of the differential amplification module, for tuning the amplified signal and performing signal conversion to output a target signal; The tuning module includes a balun device, a first capacitor and a second capacitor. The balun device includes a first input terminal, a second input terminal, a third output terminal and a fourth output terminal. The first input terminal is electrically connected to the first output terminal of the differential amplifier module, the second input terminal is electrically connected to the second output terminal of the differential amplifier module, the two ends of the first capacitor are electrically connected to the first input terminal and the second input terminal respectively, the two ends of the second capacitor are electrically connected to the third output terminal and the fourth output terminal respectively, and the fourth output terminal is grounded.

2. The harmonic suppression circuit according to claim 1, characterized in that: The first adjustable capacitor and the second adjustable capacitor are programmable capacitors.

3. A transmitter, characterized in that: include: A digital module, used for outputting a digital signal to be transmitted; A signal conversion module, electrically connected to the digital module, for converting and filtering the digital signal to obtain a filtered signal; A first mixing module, electrically connected to the signal conversion module, to mix the filtered signal to obtain a first mixed signal; A second mixing module, electrically connected to the signal conversion module, to mix the filtered signal to obtain a second mixed signal; A first suppression module, electrically connected to the first mixing module, and configured to perform harmonic suppression on the first mixing signal to obtain a first target signal; A second suppression module, electrically connected to the second mixing module, and configured to perform harmonic suppression on the second mixing signal to obtain a second target signal; a transmitting module, electrically connected to the output ends of the first suppression module and the second suppression module respectively, and configured to transmit the first target signal or the second target signal; Wherein, at least one of the first suppression module and the second suppression module adopts the harmonic suppression circuit according to any one of claims 1 to 2.

4. The transmitter according to claim 3, characterized in that The transmitter also includes a switch module, the input end of the switch module is electrically connected to the output end of the first suppression module and the output end of the second suppression module respectively, and the output end of the switch module is electrically connected to the input end of the transmission module for switching the signal transmitted by the transmission module.

5. The transmitter according to claim 4, characterized in that The transmitter also includes a first low-pass filter and a second low-pass filter, the output end of the first suppression module is electrically connected to the input end of the switch module through the first low-pass filter, and the output end of the second suppression module is electrically connected to the input end of the switch module through the second low-pass filter.

6. The transmitter according to claim 3, characterized in that The first suppression module and the second suppression module both contain the harmonic suppression circuit.

7. The transmitter according to any one of claims 3 to 6, characterized in that: The signal conversion module includes a first digital-to-analog converter, a second digital-to-analog converter, a third low-pass filter and a fourth low-pass filter. The input end of the first digital-to-analog converter and the input end of the second digital-to-analog converter are electrically connected to the two output ends of the digital module respectively, the output end of the third low-pass filter is electrically connected to the input end of the first mixing module and the input end of the second mixing module, and the output end of the fourth low-pass filter is electrically connected to the input end of the first mixing module and the input end of the second mixing module.

8. The transmitter according to claim 7, characterized in that The first frequency mixing module and the second frequency mixing module each have four inputs and two outputs.

9. The transmitter according to claim 3, characterized in that The transmitting module is a transmitting antenna.

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