Radio frequency orthogonal switched capacitor transmitter

Abstract

A radio frequency orthogonal switched capacitor transmitter disclosed by the present invention comprises an up-conversion circuit, a Doherty-level switched capacitor array and an output matching circuit, the Doherty-level switched capacitor array comprises an amplification unit, the up-conversion circuit is used for carrying out up-conversion on a first baseband phase signal and a second baseband phase signal to obtain a radio frequency phase signal, and the output matching circuit is used for outputting the radio frequency phase signal to the Doherty-level switched capacitor array. The Doherty-level switched capacitor array is used for controlling the starting number of the amplification units according to the baseband amplitude signal and the radio frequency phase signal to obtain a radio frequency amplification signal and realize power amplification, and the output matching circuit is used for performing digital-to-analog conversion and impedance matching on the radio frequency amplification signal. Amplitude modulation is directly performed on the carrier waves by controlling the number of the opened amplification units, so that the functions of digital-to-analog conversion and power amplification are realized, the system efficiency can be improved, the circuit power consumption is reduced, and the circuit can be widely applied to the technical field of wireless communication.

Description

Technical Field

[0001] The present invention relates to the field of wireless communication technologies, and more particularly to a radio frequency quadrature switched capacitor transmitter. Background Art

[0002] A wireless transmitter system is an important part of a wireless communication device. Traditional transmitters are analog circuits composed of a local oscillator, a mixer, an analog filter, a linear power amplifier, etc. Such a transmitter has a complex structure and a single function, and cannot meet the requirements of multiple function integrations. Based on this, in the prior art, it is proposed to implement the local oscillator, mixer, etc. using digital circuits, and to realize signal transmission through a radio frequency digital-to-analog converter (DAC) and a switched power amplifier, that is, to integrate the digital intermediate frequency and digital radio frequency units, and then complete transmission and reception through a small number of analog devices. However, such a wireless transmitter architecture requires an independent DAC module, which will bring additional power consumption and system efficiency limitations. Summary of the Invention

[0003] To solve the above technical problems, an object of the present invention is to provide a radio frequency quadrature switched capacitor transmitter, which can improve system efficiency and reduce power consumption.

[0004] To achieve the above object, one aspect of the embodiments of the present application provides a radio frequency quadrature switched capacitor transmitter, including an up-conversion circuit, a Doherty-stage switched capacitor array, and an output matching circuit. The input end of the up-conversion circuit is used to input a baseband phase signal, and the input end of the Doherty-stage switched capacitor array is used to input a baseband amplitude signal. The Doherty-stage switched capacitor array includes an amplification unit. The output end of the up-conversion circuit is connected to the input end of the amplification unit, the output end of the amplification unit is connected to the input end of the output matching circuit, and the output end of the output matching circuit is used to connect to an external antenna. The up-conversion circuit is used to perform up-conversion on the baseband phase signal to obtain a radio frequency phase signal. The Doherty-stage switched capacitor array is used to control the number of turned-on amplification units according to the baseband amplitude signal and the radio frequency phase signal to obtain a radio frequency amplified signal and realize power amplification. The output matching circuit is used to perform digital-to-analog conversion and impedance matching on the radio frequency amplified signal, and then transmit the impedance-matched radio frequency amplified signal through the external antenna. Wherein, the baseband phase signal includes an orthogonal first baseband phase signal and a second baseband phase signal.

[0005] In some embodiments, the radio frequency phase signals include a first positive radio frequency phase signal, a first negative radio frequency phase signal, a second positive radio frequency phase signal, and a second negative radio frequency phase signal. The phase difference between the first positive radio frequency phase signal and the first negative radio frequency phase signal is 180°. The phase difference between the second positive radio frequency phase signal and the second negative radio frequency phase signal is 180°. The phase difference between the first positive radio frequency phase signal and the second positive radio frequency phase signal is 90°. The phase difference between the first negative radio frequency phase signal and the second negative radio frequency phase signal is 90°.

[0006] In some embodiments, the up-conversion circuit includes a first up-conversion circuit. The input end of the first up-conversion circuit is used to input the first baseband phase signal, the first positive local oscillator phase signal, and the first negative local oscillator phase signal. The output end of the first up-conversion circuit is connected to the input end of the amplification unit. The first up-conversion circuit is used to modulate the first baseband phase signal according to the first positive local oscillator phase signal and the first negative local oscillator phase signal to obtain the first positive radio frequency phase signal and the first negative radio frequency phase signal.

[0007] In some embodiments, the up-conversion circuit includes a second up-conversion circuit. The input end of the second up-conversion circuit is used to input the second baseband phase signal, the second positive local oscillator phase signal, and the second negative local oscillator phase signal. The output end of the second up-conversion circuit is connected to the input end of the amplification unit. The second up-conversion circuit is used to modulate the second baseband phase signal according to the second positive local oscillator phase signal and the second negative local oscillator phase signal to obtain the second positive radio frequency phase signal and the second negative radio frequency phase signal.

[0008] In some embodiments, the Doherty stage switched capacitor array further includes a non-overlapping clock signal generation unit. The output end of the up-conversion circuit is connected to the input end of the non-overlapping clock signal generation unit. The output end of the non-overlapping clock signal generation unit is connected to the clock input end of the amplification unit. The non-overlapping clock signal generation unit is used to convert the radio frequency phase signals to obtain a non-overlapping first positive radio frequency phase signal, a non-overlapping first negative radio frequency phase signal, a non-overlapping second positive radio frequency phase signal, and a non-overlapping second negative radio frequency phase signal.

[0009] In some embodiments, the amplification unit includes a main power amplifier circuit and a sub-power amplifier circuit. The clock input ends of the main power amplifier circuit and the sub-power amplifier circuit are both connected to the output end of the non-overlapping clock signal generation unit. The output ends of the main power amplifier circuit and the sub-power amplifier circuit are both connected to the input end of the output matching circuit.

[0010] In some embodiments, the Doherty-class switched-capacitor array further includes a logic control unit. The input end of the logic control unit is used to input the baseband amplitude signal. The amplitude input ends of the main power amplifier circuit and the auxiliary power amplifier circuit are respectively connected to the output end of the logic control unit. The logic control unit is used to control the main power amplifier circuit and the auxiliary power amplifier circuit to be turned on or off according to the baseband amplitude signal, so as to realize amplitude modulation and power amplification.

[0011] In some embodiments, the main power amplifier circuit includes a first switched-capacitor array and a second switched-capacitor array. The output ends of the non-overlapping clock signal generating unit and the logic control unit are both connected to the input end of the first switched-capacitor array. The output ends of the non-overlapping clock signal generating unit and the logic control unit are both connected to the input end of the second switched-capacitor array. The output ends of the first switched-capacitor array and the second switched-capacitor array are both connected to the input end of the output matching circuit. The first switched-capacitor array uses the non-overlapping first positive radio frequency phase signal as the clock signal input, and the second switched-capacitor array uses the non-overlapping second positive radio frequency phase signal as the clock signal input. The first switched-capacitor array and the second switched-capacitor array include a plurality of switched-capacitor units, and the number of switched-capacitor units that are turned on is determined by the baseband amplitude signal.

[0012] In some embodiments, the auxiliary power amplifier circuit includes a third switched-capacitor array and a fourth switched-capacitor array. The output ends of the non-overlapping clock signal generating unit and the logic control unit are both connected to the input end of the third switched-capacitor array. The output ends of the non-overlapping clock signal generating unit and the logic control unit are both connected to the input end of the fourth switched-capacitor array. The output ends of the third switched-capacitor array and the fourth switched-capacitor array are both connected to the input end of the output matching circuit. The third switched-capacitor array uses the non-overlapping first negative radio frequency phase signal as the clock signal input, and the fourth switched-capacitor array uses the non-overlapping second negative radio frequency phase signal as the clock signal input. The third switched-capacitor array and the fourth switched-capacitor array include a plurality of switched-capacitor units, and the number of switched-capacitor units that are turned on is determined by the baseband amplitude signal.

[0013] In some embodiments, the output matching circuit includes a first inductor, a second inductor, and a transformer. One end of the first inductor is connected to the output end of the main power amplifier circuit, one end of the second inductor is connected to the output end of the auxiliary power amplifier circuit, the other ends of the first inductor and the second inductor are connected to one end of the transformer, and the other end of the transformer is connected to the external antenna. The first inductor, the second inductor, and the transformer are used for impedance matching with the external antenna.

[0014] The beneficial effects of the present invention are as follows: A radio frequency quadrature switched-capacitor transmitter of the present invention includes an up-conversion circuit, a Doherty-stage switched-capacitor array, and an output matching circuit. The Doherty-stage switched-capacitor array includes amplification units. Frequency modulation is achieved through the up-conversion circuit, and the orthogonal first baseband phase signal and second baseband phase signal are up-converted to obtain a radio frequency phase signal. Then, the baseband amplitude signal and the radio frequency phase signal modulated by the up-conversion circuit are input into the Doherty-stage switched-capacitor array together. The number of amplification units turned on is directly controlled by the Doherty-stage switched-capacitor array to perform amplitude modulation on the carrier, thereby realizing the function of power amplification, improving system efficiency, simplifying the circuit structure, and reducing circuit power consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following introduces the drawings required to be used in the embodiments of the present invention. It should be understood that the drawings introduced below are only for conveniently and clearly expressing some embodiments of the technical solutions in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative efforts.

[0016] Figure 1 It is a structural block diagram of a radio frequency quadrature switched-capacitor transmitter provided by an embodiment of the present invention;

[0017] Figure 2 It is a schematic diagram of the top-level circuit structure of a radio frequency quadrature switched-capacitor transmitter provided by an embodiment of the present invention;

[0018] Figure 3 It is a circuit structure diagram of an up-conversion circuit provided by an embodiment of the present invention.

[0019] Reference numerals: L1, first inductor; L2, second inductor; U1, transformer. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] In order to make the objectives, technical solutions and advantages of the present application more clear and understandable, the present application will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application. When the following description refers to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the embodiments of the present application. They are only examples of devices and methods consistent with some aspects of the embodiments of the present application as detailed in the appended claims.

[0021] It can be understood that the terms "first", "second", etc. used in the present application may be used in this document to describe various concepts, but unless otherwise specified, these concepts are not limited by these terms. These terms are only used to distinguish one concept from another. For example, without departing from the scope of the embodiments of the present application, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Depending on the context, the words "if", "when" as used herein may be interpreted as "when...", "while...", or "in response to determining".

[0022] The terms "at least one", "multiple", "each", "any one", etc. used in the present application, at least one includes one, two or more, multiple includes two or more, each refers to each of the corresponding multiple, and any one refers to any one of the multiple.

[0023] Before elaborating on the embodiments of the present application in detail, some nouns and terms involved in the embodiments of the present application will be described first. The nouns and terms involved in the embodiments of the present application are applicable to the following explanations.

[0024] SCPA (Switched Capacitor Power Amplifiers): Switched Capacitor Power Amplifiers.

[0025] Cascode: Cascode.

[0026] AM (Amplitude Modulation): Amplitude Modulation.

[0027] PM (Phase Modulation): Phase Modulation.

[0028] DAC (Digital-to-Analog Converter): Digital-to-Analog Converter.

[0029] I: In-Phase; Q: Quadrature (90-degree phase shift): That is, it represents two signals with a 90-degree phase difference.

[0030] LO (Local Oscillator): The local oscillator signal is an intermediate frequency signal used to generate a modulated signal.

[0031] RF (Radio Frequency): The electromagnetic frequency that can be radiated into space.

[0032] The wireless transmitter system is an important part of wireless communication devices. Traditional transmitters are analog circuits, consisting of a local oscillator, a mixer, an analog filter, and a linear power amplifier, etc. Such transmitters have a complex structure and a single function, and cannot meet the requirements of integrating multiple functions. Based on this, in the prior art, it was proposed to implement the local oscillator, mixer, etc. using digital circuits, and to realize signal transmission through a radio frequency digital-to-analog converter (DAC) and a switched-mode power amplifier, that is, to integrate the digital intermediate frequency and digital radio frequency units, and then complete transmission and reception through a small number of analog devices. However, such a wireless transmitter architecture requires an independent DAC module, which will bring additional power consumption and system efficiency limitations.

[0033] Therefore, the embodiment of the present invention proposes a radio frequency quadrature switched-capacitor transmitter, which includes an up-conversion circuit, a Doherty-stage switched-capacitor array, and an output matching circuit. The Doherty-stage switched-capacitor array includes an amplification unit. Frequency modulation is realized through the up-conversion circuit, and the orthogonal first baseband phase signal and second baseband phase signal are up-converted to obtain a radio frequency phase signal. Furthermore, the baseband amplitude signal and the radio frequency phase signal modulated by the up-conversion circuit are input into the Doherty-stage switched-capacitor array together. The number of amplification units turned on is directly controlled by the Doherty-stage switched-capacitor array to perform amplitude modulation on the carrier, thereby realizing the function of power amplification, which can improve system efficiency, simplify the circuit structure, and reduce circuit power consumption.

[0034] Refer to Figure 1 , Figure 1A structural block diagram of a radio frequency quadrature switched capacitor transmitter provided by an embodiment of the present invention. An embodiment of the present invention proposes a radio frequency quadrature switched capacitor transmitter, which includes an up-conversion circuit, a Doherty stage switched capacitor array, and an output matching circuit. The input end of the up-conversion circuit is used to input a baseband phase signal, and the input end of the Doherty stage switched capacitor array is used to input a baseband amplitude signal. The Doherty stage switched capacitor array includes an amplification unit. The output end of the up-conversion circuit is connected to the input end of the amplification unit, and the output end of the amplification unit is connected to the input end of the output matching circuit. The output end of the output matching circuit is used to connect to an external antenna. The up-conversion circuit is used to up-convert the baseband phase signal to obtain a radio frequency phase signal. The Doherty stage switched capacitor array is used to control the number of turned-on amplification units according to the baseband amplitude signal and the radio frequency phase signal to obtain a radio frequency amplified signal and achieve power amplification. The output matching circuit is used to perform digital-to-analog conversion and impedance matching on the radio frequency amplified signal, and then transmit the impedance-matched radio frequency amplified signal through the external antenna. Among them, the baseband phase signal includes orthogonal first baseband phase signal and second baseband phase signal.

[0035] Specifically, the up-conversion circuit is used to modulate the first baseband phase signal and the second baseband phase signal (i.e., PM-I signal and PM-Q signal) by using a local oscillator signal, also raise the signal frequency to the sum of the baseband signal frequency and the local oscillator signal frequency to obtain a radio frequency phase signal, and finally input the baseband amplitude signal (AM signal) and the modulated baseband phase signal (PM signal) into the Doherty stage switched capacitor array;

[0036] The Doherty stage switched capacitor array is used to selectively switch or not switch a group of integrated capacitors at the FR carrier frequency by using the baseband amplitude signal (AM signal) to provide a linear output characteristic. The number of turned-on amplification units determines the amplitude of the output signal. Therefore, by controlling the number of turned-on amplification units, it means directly performing amplitude modulation on the carrier wave, thereby achieving power amplification.

[0037] Further as an optional implementation manner, the radio frequency phase signal includes a first positive radio frequency phase signal, a first negative radio frequency phase signal, a second positive radio frequency phase signal, and a second negative radio frequency phase signal. The phase difference between the first positive radio frequency phase signal and the first negative radio frequency phase signal is 180°, the phase difference between the second positive radio frequency phase signal and the second negative radio frequency phase signal is 180°, the phase difference between the first positive radio frequency phase signal and the second positive radio frequency phase signal is 90°, and the phase difference between the first negative radio frequency phase signal and the second negative radio frequency phase signal is 90°.

[0038] Refer to Figure 2 and Figure 3 , Figure 2Schematic diagram of the top-level circuit structure of the RF quadrature switched-capacitor transmitter provided by the embodiment of the present invention Figure 3 Circuit structure diagram of the up-conversion circuit provided by the embodiment of the present invention. Further as an optional implementation manner, the up-conversion circuit includes a first up-conversion circuit. The input end of the first up-conversion circuit is used to input a first baseband phase signal, a first local oscillator phase signal, and a first negative local oscillator phase signal. The output end of the first up-conversion circuit is connected to the input end of the amplification unit. The first up-conversion circuit is used to modulate the first baseband phase signal according to the first local oscillator phase signal and the first negative local oscillator phase signal to obtain a first positive RF phase signal and a first negative RF phase signal.

[0039] Referring to Figure 2 and Figure 3 Further as an optional implementation manner, the up-conversion circuit includes a second up-conversion circuit. The input end of the second up-conversion circuit is used to input a second baseband phase signal, a second local oscillator phase signal, and a second negative local oscillator phase signal. The output end of the second up-conversion circuit is connected to the input end of the amplification unit. The second up-conversion circuit is used to modulate the second baseband phase signal according to the second local oscillator phase signal and the second negative local oscillator phase signal to obtain a second positive RF phase signal and a second negative RF phase signal.

[0040] Specifically, first, the input I and Q baseband signals are respectively decomposed into AM-I, PM-I, AM-Q, and PM-Q signals, corresponding to the amplitude and phase signals of I and Q. The orthogonal first baseband phase signal (PM-I signal) and the second baseband phase signal (PM-Q signal) are respectively input to the EN ports of two up-conversion circuits. At the same time, the differential first local oscillator phase signal (LO_I+) and the first negative local oscillator phase signal (LO_I-) corresponding to the first baseband phase signal (PM-I signal) are input to an up-conversion circuit through the LO_N and LO_P ports, and the differential second local oscillator phase signal (LO_Q+) and the second negative local oscillator phase signal (LO_Q-) corresponding to the second baseband phase signal (PM-Q signal) are input to another up-conversion circuit through the LO_N and LO_P ports. Finally, the signals output from the OUT_N and OUT_P ports of the circuit respectively correspond to the modulated first positive RF phase signal (I+ phase signal), the second positive RF phase signal (Q+ phase signal), the first negative RF phase signal (I- phase signal), and the second negative RF phase signal (Q- phase signal).

[0041] It should be noted that the up-conversion circuit mainly realizes the modulation of the baseband phase signal (PM signal). After passing through the up-conversion circuit, the output signal becomes differential while its frequency is also raised to the sum of the frequencies of the baseband signal and the local oscillator signal. While realizing the function of signal modulation, the circuit has a relatively simple structure. At the same time, the symmetric input structure also improves the output efficiency and power, facilitating the layout drawing.

[0042] Referring to Figure 1 and Figure 2 , as a further optional implementation manner, the Doherty-stage switched capacitor array further includes a non-overlapping clock signal generation unit. The output end of the up-conversion circuit is connected to the input end of the non-overlapping clock signal generation unit, and the output end of the non-overlapping clock signal generation unit is connected to the clock input end of the amplification unit. The non-overlapping clock signal generation unit is used to convert the radio frequency phase signal to obtain a non-overlapping first positive radio frequency phase signal, a non-overlapping first negative radio frequency phase signal, a non-overlapping second positive radio frequency phase signal, and a non-overlapping second negative radio frequency phase signal.

[0043] Specifically, the four PM components (the first positive radio frequency phase signal I+, the second positive radio frequency phase signal Q+, the first negative radio frequency phase signal I-, and the second negative radio frequency phase signal Q-) after up-conversion to the RF carrier frequency are converted into non-overlapping clock signals through a plurality of non-overlapping clock signal generation circuits to reduce the crowbar current generated during the switching process of the cascode output stage. The obtained non-overlapping clock signals are used as the clock signals of the Doherty-stage switched capacitor array (which can also be referred to as the Doherty-stage SCPA module). Among them, the baseband amplitude signal (AM signal) input to the Doherty-stage SCPA module is the sampled value of the envelope amplitude.

[0044] Referring to Figure 2 , as a further optional implementation manner, the amplification unit includes a main power amplifier circuit and a secondary power amplifier circuit. The clock input ends of the main power amplifier circuit and the secondary power amplifier circuit are both connected to the output end of the non-overlapping clock signal generation unit, and the output ends of the main power amplifier circuit and the secondary power amplifier circuit are both connected to the input end of the output matching circuit.

[0045] Specifically, the embodiment of the present invention adopts the Doherty technology to implement the SCPA, that is, the power back-off is realized by combining the main power amplifier and the secondary power amplifier. The turning on and off of the main and secondary power amplifier circuits are controlled by the logic control unit.

[0046] Referring to Figure 1 and Figure 2, Further as an optional implementation, the Doherty-class switched capacitor array further includes a logic control unit. The input end of the logic control unit is used to input a baseband amplitude signal. The amplitude input ends of the main power amplifier amplification circuit and the auxiliary power amplifier amplification circuit are respectively connected to the output end of the logic control unit. The logic control unit is used to control the main power amplifier amplification circuit and the auxiliary power amplifier amplification circuit to turn on or off according to the baseband amplitude signal, so as to achieve amplitude modulation and power amplification.

[0047] In some optional embodiments, the baseband amplitude signal (AM signal), non-overlapping first positive RF phase signal, first negative RF phase signal, second positive RF phase signal, and second negative RF phase signal are used as inputs to control the turning on and off of the main power amplifier amplification circuit and the auxiliary power amplifier amplification circuit. When the output power is low, the auxiliary power amplifier amplification circuit is turned off and the main power amplifier amplification circuit is turned on; when the output power is high, the main power amplifier amplification circuit is saturated and the auxiliary power amplifier amplification circuit is turned on, so that a high efficiency can also be exhibited at a low output power, realizing power back-off.

[0048] Specifically, the logic control unit is divided into a main power amplifier logic control circuit and an auxiliary power amplifier logic control circuit. The baseband amplitude signal (AM signal) is used as an input. When the normalized output voltage is less than 50%, that is, when the most significant bit of the baseband amplitude signal (AM signal) is 0, the auxiliary power amplifier amplification circuit is in the off state, the main power amplifier amplification circuit is turned on, and the number of switched capacitor units turned on is determined by the lower 6 bits of the baseband amplitude signal (AM signal); when the normalized output voltage is greater than 50%, that is, when the most significant bit of the baseband amplitude signal (AM signal) is 1, the main power amplifier amplification circuit is in the saturated state, all switched capacitor units are in the on state, the auxiliary power amplifier amplification circuit is turned on, and the number of switched capacitor units turned on is determined by the lower 6 bits of the baseband amplitude signal (AM signal). The logic control unit is composed of a level shift circuit, a driving unit, several logic gates, and a cascode output stage, which controls the switching of the cascode output stage voltage between the 2VDD and GND modes, according to the capacitive voltage division:

[0049]

[0050] Refer to Figure 2, Further as an optional embodiment, the main power amplifier amplification circuit includes a first switched-capacitor array and a second switched-capacitor array. The output terminals of the non-overlapping clock signal generation unit and the logic control unit are both connected to the input terminal of the first switched-capacitor array, and the output terminals of the non-overlapping clock signal generation unit and the logic control unit are both connected to the input terminal of the second switched-capacitor array. The output terminals of the first switched-capacitor array and the second switched-capacitor array are both connected to the input terminal of the output matching circuit. The first switched-capacitor array uses a non-overlapping first positive radio frequency phase signal as the clock signal input, and the second switched-capacitor array uses a non-overlapping second positive radio frequency phase signal as the clock signal input. The first switched-capacitor array and the second switched-capacitor array include a plurality of switched-capacitor units, and the number of turned-on switched-capacitor units is determined by the baseband amplitude signal.

[0051] Referring to Figure 2 , Further as an optional embodiment, the auxiliary power amplifier amplification circuit includes a third switched-capacitor array and a fourth switched-capacitor array. The output terminals of the non-overlapping clock signal generation unit and the logic control unit are both connected to the input terminal of the third switched-capacitor array, and the output terminals of the non-overlapping clock signal generation unit and the logic control unit are both connected to the input terminal of the fourth switched-capacitor array. The output terminals of the third switched-capacitor array and the fourth switched-capacitor array are both connected to the input terminal of the output matching circuit. The third switched-capacitor array uses a non-overlapping first negative radio frequency phase signal as the clock signal input, and the fourth switched-capacitor array uses a non-overlapping second negative radio frequency phase signal as the clock signal input. The third switched-capacitor array and the fourth switched-capacitor array include a plurality of switched-capacitor units, and the number of turned-on switched-capacitor units is determined by the baseband amplitude signal.

[0052] Specifically, both the main power amplifier amplification circuit and the auxiliary power amplifier amplification circuit are composed of two identical switched-capacitor arrays. The two switched-capacitor arrays (i.e., the first switched-capacitor array and the second switched-capacitor array) in the main power amplifier amplification circuit use orthogonal radio frequency PM components (the first positive radio frequency phase signal I+ and the second positive radio frequency phase signal Q+) as the clock signal input, and the clock signal inputs of the two switched-capacitor arrays (i.e., the third switched-capacitor array and the fourth switched-capacitor array) in the auxiliary power amplifier amplification circuit respectively form differential signals (the first negative radio frequency phase signal I- and the second negative radio frequency phase signal Q-) with the clock signal inputs in the main power amplifier amplification circuit. To comprehensively consider the output power and efficiency, each switched-capacitor array is composed of 64 switched-capacitor units, and 1 switched-capacitor unit is used to improve the resolution.

[0053] It should be noted that an embodiment of the present invention provides a switched-capacitor digital power amplifier (SCPA). As a voltage-type digital power amplifier, it provides linear output characteristics by selectively switching or not switching a set of integrated capacitors at the RF carrier frequency using a baseband amplitude signal (AM signal); for the SCPA, the number of enabled amplification units determines the amplitude of the output signal. Therefore, controlling the number of enabled amplification units means directly performing amplitude modulation on the carrier, thereby realizing the conversion from a digital signal to an analog signal. At the same time, the SCPA can also play a role in power amplification, making the architecture of the transmitter more concise.

[0054] Referring to Figure 2 , further as an optional implementation, the output matching circuit includes a first inductor L1, a second inductor L2, and a transformer U1. One end of the first inductor L1 is connected to the output end of the main power amplifier circuit, one end of the second inductor L2 is connected to the output end of the auxiliary power amplifier circuit, the other ends of the first inductor L1 and the second inductor L2 are connected to one end of the transformer U1, and the other end of the transformer U1 is connected to an external antenna. The first inductor L1, the second inductor L2, and the transformer U1 are used for impedance matching with the external antenna.

[0055] Specifically, the output ports of the two switched-capacitor arrays in the main power amplifier circuit are commonly connected to the first inductor L1 of the output matching circuit, and the output ports of the two switched-capacitor arrays in the auxiliary power amplifier circuit are also commonly connected to the second inductor L2 of the output matching circuit. The output matching circuit consists of a first inductor L1, a second inductor L2, and a transformer U1, and the load is an antenna with a resistance of 50Ω. The two inductors resonate with the total capacitance of the main power amplifier circuit and the auxiliary power amplifier circuit respectively at the carrier frequency, which can reduce energy loss and improve the efficiency of the transmitter. By using the resonance of the inductor and the capacitor, the transmitter operates at a specific frequency, and the stability is improved. At the same time, the load RL = 50Ω is converted into the optimal terminal resistance Ropt required for the output through the transformer U1, and the output reaches the maximum power at this time.

[0056] The structure and working principle of a radio frequency quadrature switched-capacitor transmitter according to an embodiment of the present invention are described above. It can be recognized that compared with traditional transmitters, traditional analog transmitters have complex structures, single functions, poor flexibility, and low integration. The structure of a digital-analog combined transmitter requires multiple modules such as an independent DAC module, filters, and upconverters, which brings additional power consumption and system efficiency limitations. The present invention includes an upconversion circuit, a Doherty-stage switched-capacitor array, and an output matching circuit. The baseband I and Q quadrature signals are respectively decomposed into a baseband amplitude signal (AM signal) and a baseband phase signal (PM signal). The upconversion circuit is used in the circuit architecture to achieve phase modulation. The AM signal and the PM signal modulated by the upconversion circuit are input to the Doherty-stage SCPA module together. At the same time, the function of power amplification is achieved through the Doherty-stage SCPA module. The structure is optimized to a structure formed only by connecting the upconversion circuit, the Doherty-stage SCPA module, and the output matching circuit, replacing the DAC, mixer, filter, and power amplifier structures of the original transmitter structure, which can simplify the circuit structure, save redundant circuit power consumption, and improve system efficiency.

[0057] In the above description of this specification, the descriptions referring to terms such as "one embodiment", "another embodiment", or "certain embodiments" mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0058] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the claims and their equivalents.

[0059] The above is a specific description of the preferred embodiment of the present invention, but the present invention is not limited to the embodiment. Those skilled in the art can also make various equivalent deformations or substitutions without departing from the spirit of the present invention, and these equivalent deformations or substitutions are all included in the scope defined by the claims of this application.

Claims

1. A radio frequency orthogonal switched capacitor transmitter, characterized in that: The invention comprises an up-conversion circuit, a Doherty-level switched capacitor array and an output matching circuit, wherein the input end of the up-conversion circuit is used to input a baseband phase signal, the input end of the Doherty-level switched capacitor array is used to input a baseband amplitude signal, the Doherty-level switched capacitor array comprises an amplifying unit, the output end of the up-conversion circuit is connected to the input end of the amplifying unit, the output end of the amplifying unit is connected to the input end of the output matching circuit, the output end of the output matching circuit is used to connect an external antenna, the up-conversion circuit is used to up-convert the baseband phase signal to obtain a radio frequency phase signal, the Doherty-level switched capacitor array is used to control the number of openings of the amplifying units according to the baseband amplitude signal and the radio frequency phase signal, obtain a radio frequency amplified signal, and realize power amplification, the output matching circuit is used to perform digital-to-analog conversion and impedance matching on the radio frequency amplified signal, and then transmit the radio frequency amplified signal after impedance matching through the external antenna, wherein the baseband phase signal comprises an orthogonal first baseband phase signal and a second baseband phase signal.

2. The radio frequency orthogonal switched capacitor transmitter according to claim 1, characterized in that: The RF phase signal includes a first positive RF phase signal, a first negative RF phase signal, a second positive RF phase signal and a second negative RF phase signal. The phase difference between the first positive RF phase signal and the first negative RF phase signal is 180°, the phase difference between the second positive RF phase signal and the second negative RF phase signal is 180°, the phase difference between the first positive RF phase signal and the second positive RF phase signal is 90°, and the phase difference between the first negative RF phase signal and the second negative RF phase signal is 90°.

3. The radio frequency orthogonal switched capacitor transmitter according to claim 2, characterized in that: The up-conversion circuit includes a first up-conversion circuit, an input end of the first up-conversion circuit is used to input the first baseband phase signal, the first positive local oscillator phase signal and the first negative local oscillator phase signal, the output end of the first up-conversion circuit is connected to the input end of the amplification unit, and the first up-conversion circuit is used to modulate the first baseband phase signal according to the first positive local oscillator phase signal and the first negative local oscillator phase signal to obtain the first positive radio frequency phase signal and the first negative radio frequency phase signal.

4. The radio frequency orthogonal switched capacitor transmitter according to claim 2, characterized in that: The up-conversion circuit includes a second up-conversion circuit, the input end of the second up-conversion circuit is used to input the second baseband phase signal, the second positive local oscillator phase signal and the second negative local oscillator phase signal, the output end of the second up-conversion circuit is connected to the input end of the amplification unit, and the second up-conversion circuit is used to modulate the second baseband phase signal according to the second positive local oscillator phase signal and the second negative local oscillator phase signal to obtain the second positive radio frequency phase signal and the second negative radio frequency phase signal.

5. The radio frequency orthogonal switched capacitor transmitter according to claim 1, characterized in that: The Doherty-level switched capacitor array also includes a non-overlapping clock signal generating unit, the output end of the up-conversion circuit is connected to the input end of the non-overlapping clock signal generating unit, the output end of the non-overlapping clock signal generating unit is connected to the clock input end of the amplification unit, and the non-overlapping clock signal generating unit is used to convert the RF phase signal to obtain a non-overlapping first positive RF phase signal, a non-overlapping first negative RF phase signal, a non-overlapping second positive RF phase signal, and a non-overlapping second negative RF phase signal.

6. The radio frequency orthogonal switched capacitor transmitter according to claim 5, characterized in that: The amplification unit includes a main power amplifier circuit and an auxiliary power amplifier circuit, the clock input ends of the main power amplifier circuit and the auxiliary power amplifier circuit are both connected to the output end of the non-overlapping clock signal generating unit, and the output ends of the main power amplifier circuit and the auxiliary power amplifier circuit are both connected to the input end of the output matching circuit.

7. The radio frequency orthogonal switched capacitor transmitter according to claim 6, characterized in that: The Doherty-level switched capacitor array also includes a logic control unit, an input end of the logic control unit is used to input the baseband amplitude signal, the amplitude input ends of the main power amplifier circuit and the auxiliary power amplifier circuit are respectively connected to the output end of the logic control unit, and the logic control unit is used to control the main power amplifier circuit and the auxiliary power amplifier circuit to be turned on or off according to the baseband amplitude signal to achieve amplitude modulation and power amplification.

8. The radio frequency orthogonal switched capacitor transmitter according to claim 7, characterized in that: The main power amplifier circuit includes a first switch capacitor array and a second switch capacitor array, the output ends of the non-overlapping clock signal generating unit and the logic control unit are both connected to the input end of the first switch capacitor array, the output ends of the non-overlapping clock signal generating unit and the logic control unit are both connected to the input end of the second switch capacitor array, the output ends of the first switch capacitor array and the second switch capacitor array are both connected to the input end of the output matching circuit, the first switch capacitor array uses the non-overlapping first positive RF phase signal as the clock signal input, the second switch capacitor array uses the non-overlapping second positive RF phase signal as the clock signal input, the first switch capacitor array and the second switch capacitor array include multiple switch capacitor units, and the number of switch capacitor units turned on is determined by the baseband amplitude signal.

9. The radio frequency orthogonal switched capacitor transmitter according to claim 7, characterized in that: The auxiliary power amplifier circuit includes a third switch capacitor array and a fourth switch capacitor array. The output ends of the non-overlapping clock signal generating unit and the logic control unit are both connected to the input end of the third switch capacitor array. The output ends of the non-overlapping clock signal generating unit and the logic control unit are both connected to the input end of the fourth switch capacitor array. The output ends of the third switch capacitor array and the fourth switch capacitor array are both connected to the input end of the output matching circuit. The third switch capacitor array uses the non-overlapping first negative RF phase signal as the clock signal input, and the fourth switch capacitor array uses the non-overlapping second negative RF phase signal as the clock signal input. The third switch capacitor array and the fourth switch capacitor array include multiple switch capacitor units, and the number of switch capacitor units turned on is determined by the baseband amplitude signal.

10. The radio frequency orthogonal switched capacitor transmitter according to claim 6, characterized in that: The output matching circuit includes a first inductor, a second inductor and a transformer, one end of the first inductor is connected to the output end of the main power amplifier circuit, one end of the second inductor is connected to the output end of the auxiliary power amplifier circuit, the other ends of the first inductor and the second inductor are connected to one end of the transformer, the other end of the transformer is connected to the external antenna, and the first inductor, the second inductor and the transformer are used for impedance matching with the external antenna.

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