Patent Application
20250211477
This application claims the benefit under 35 USC § 119 (a) of Korean Patent Application No. 10-2023-0190217, filed on Dec. 22, 2023, in the Korean Intellectual Property Office, the entire disclosure of which is incorporated herein by reference for all purposes.
Embodiments of the present disclosure relate to a quadrature amplitude modulation (QAM) transmitter and a wireless communication device equipped with the same.
Quadrature amplitude modulation (QAM) is one of the high-speed modulation schemes widely used in digital communication, and is a modulation scheme that uses amplitude and phase simultaneously. QAM is implemented by using two orthogonal carrier waves (sine and cosine waves) that have the same frequency and are 90 degrees out of phase with each other, modulating each carrier wave component using an amplitude shift keying (ASK) scheme, and synthesizing the carrier waves. Bits representing digital data are modulated with various amplitudes and phases by these carrier waves, and a plurality of bits can be transmitted simultaneously through this modulation. Meanwhile, conventional high-order QAM transmitters have a problem in that the power amplifier thereof operates in a linear region, which reduces the efficiency of the transmitter.
Examples of the related art include Korean Patent Registered Publication No. 10-1050928 (2011 Jul. 20).
Embodiments of the present disclosure are intended to provide a QAM transmitter with improved power efficiency and a wireless communication device equipped with the same.
A QAM transmitter according to an embodiment of the preset disclosure includes a first quadrature phase shift keying (QPSK) generator configured to generate a first QPSK signal, a second QPSK generator configured to generate a second QPSK signal, a first amplifier configured to receive the first QPSK signal, amplify power thereof, and output the power amplified first QPSK signal, a second amplifier configured to receive the second QPSK signal, amplify power thereof, and outputs the power amplified second QPSK signal, and a power combining unit configured to synthesize a QAM signal by combining the first QPSK signal output from the first amplifier and the second QPSK signal output from the second amplifier at a terminating end.
The first QPSK generator may include a first real component generator configured to generate a real component of the first QPSK signal and a first imaginary component generator configured to generate an imaginary component of the first QPSK signal, and the second QPSK generator may include a second real component generator configured to generate a real component of the second QPSK signal and a second imaginary component generator configured to generate an imaginary component of the second QPSK signal.
The first QPSK signal and the second QPSK signal may be independent signals and may be generated to respectively have a preset reference magnitude.
Each of the first amplifier and the second amplifier may be configured to operate in a saturation region to amplify output power of each QPSK signal of which information is transmitted only through a phase of a carrier wave.
Each of the first QPSK signal and the second QPSK signal may be generated to have a reference magnitude in which each of coefficients of the real component and the imaginary component is 1.
The first amplifier may be configured to output a first QPSK signal having a first saturation power, and the second amplifier may be configured to output a second QPSK signal having a second saturation power, and the magnitude of the second saturation power may be four times the magnitude of the first saturation power.
The first amplifier may include one power amplification unit, and the power amplification unit may have a gain preset so that the first amplifier outputs the first saturation power.
The second amplifier may include a divider configured to split the second QPSK signal, four power amplification units each of which is configured to receive the second QPSK signal from the divider, and a combiner configured to synthesize the second QPSK signals of first saturation power each of which is output from each of the four power amplification units, and output the second QPSK signal having four times the first saturation power.
The power combining unit may synthesize a 16-QAM signal by combining the power of a first QPSK signal of the first saturation power and a second QPSK signal of the second saturation power which is four times the magnitude of the first saturation power.
The power combining unit may include a first antenna connected to an output end of the first amplifier and transmitting the first QPSK signal of the first saturation power and a second antenna connected to an output end of the second amplifier and transmitting the second QPSK signal of the second saturation power, and the power combining unit may synthesize a 16-QAM signal by combining the transmitted first QPSK signal and second QPSK signal in space.
A QAM transmitter according to another embodiment of the preset disclosure includes a first QPSK generator configured to generate a first quadrature phase shift keying (QPSK) signal having a preset reference magnitude, a second QPSK generator configured to generate a second QPSK signal having the reference magnitude, a first amplifier configured to receive the first QPSK signal, amplify power thereof, and output the power amplified signal, but operate in a saturation region, a second amplifier configured to receive the second QPSK signal, amplify power thereof, and output the power amplified signal, but operate in a saturation region, and a power combining unit configured to synthesize a quadrature amplitude modulation (QAM) signal by combining the first QPSK signal output from the first amplifier and the second QPSK signal output from the second amplifier at a terminating end.
The first amplifier may be configured to output a first QPSK signal having a first saturation power, and the second amplifier may be configured to output a second QPSK signal having a second saturation power, and the magnitude of the second saturation power may be four times the magnitude of the first saturation power.
The power combining unit may synthesize a 16-QAM signal by combining power of the first QPSK signal of the first saturation power and the second QPSK signal of the second saturation power which is four times the magnitude of the first saturation power.
The power combining unit may include a first antenna connected to an output end of the first amplifier and transmitting the first QPSK signal having the first saturation power, and a second antenna connected to the output end of the second amplifier and transmitting the second QPSK signal of the second saturation power, and the power combining unit may synthesize a 16-QAM signal by combining the transmitted first QPSK signal and second QPSK signal in space.
A high-order QAM transmitter according to another embodiment of the present disclosure include M quadrature phase shift keying (QPSK) generators each of which is configured to generate an independent QPSK signal, M amplifiers each of which is configured to receive an independent QPSK signal, amplify the power thereof, and output a preset saturation power, and a power combining unit configured to synthesize a quadrature amplitude modulation (QAM) signal by combining M QPSK signals that respectively from the M amplifiers at a terminating end, and each of the M amplifiers may be set to output a saturation power of 4k (k=0, 1, . . . , M−1).
Hereinafter, specific embodiments of the present disclosure will be described with reference to the drawings. The following detailed description is provided to help a comprehensive understanding of the methods, devices, and/or systems described in this specification. However, this is merely an exemplary, and the present disclosure is not limited thereto.
In describing embodiments of the present disclosure, when it is determined that a detailed description of a known technology related to the present disclosure may unnecessarily obscure the gist of the present disclosure, the detailed description will be omitted. The terms described below are terms defined in consideration of the functions in the present disclosure, and may vary depending on the intention or custom of the user or operator. Therefore, the definition should be made based on the contents throughout this specification. The terms used in the detailed description are only for describing embodiments of the present disclosure and should never be limited. Unless clearly used otherwise, the singular form includes the plural form. In this description, expressions such as “including” or “having” are intended to indicate certain characteristics, numbers, steps, operations, elements, parts or combinations thereof, and should not be construed to exclude the existence or possibility of one or more other characteristics, numbers, steps, operations, elements, parts or combinations thereof other than those described.
Meanwhile, directional terms such as upper side, lower side, one side, the other side, etc. are used in relation to the orientation of the disclosed drawings. Since the components of the embodiments of the present disclosure can be positioned in various orientations, the directional terms are used for illustrative purposes and are not intended to be limiting.
In addition, terms such as first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms may be used to distinguish one component from another. For example, without departing from the scope of the present disclosure, a first component may be named a second component, and similarly, a second component may also be named a first component.
Referring to
The first QPSK generator 102 may generate a first QPSK signal. In an embodiment, the first QPSK generator 102 may include a first real component generator 102-1 and a first imaginary component generator 102-2. The first real component generator 102-1 may generate a real component (i.e., an I component) of the first QPSK signal. The first real component generator 102-1 may generate the first real component by mixing a first bit B0 generated from a first pseudo random binary sequence (PRBS) 102-1a and a first local oscillator (LO) signal through a first mixer 102-1b.
The first imaginary component generator 102-2 may generate an imaginary component (i.e., Q component) of the first QPSK signal. The first imaginary component generator 102-2 may generate the first imaginary component by mixing a second bit B1 generated from a second PRBS 102-2a and a first LOQ signal through a second mixer 102-2b.
The first QPSK generator 102 may generate a first QPSK signal by synthesizing the first real component and the first imaginary component, and input the generated first QPSK signal to the first amplifier 106. The first QPSK signal may have a preset reference magnitude. For example, the first QPSK signal may have a reference magnitude in which each of coefficients of a first real component I1 and a first imaginary component Q1 is 1. That is, the first QPSK signal may be expressed as QPSK1=I1+jQ1. In this case, the first QPSK signal may be understood as having only a phase component.
The second QPSK generator 104 may generate a second QPSK signal. The second QPSK signal may be a signal independent of the first QPSK signal and having the same magnitude as the first QPSK signal. In an embodiment, the second QPSK generator 104 may include a second real component generator 104-1 and a second imaginary component generator 104-2.
The second real component generator 104-1 may generate a real component (i.e., an I component) of the second QPSK signal. The second real component generator 104-1 may generate the second real component by mixing a third bit B2 generated from a third PRBS 104-1a and a second LOI signal through a third mixer 104-1b.
The second imaginary component generator 104-2 may generate an imaginary component (i.e., a Q component) of the second QPSK signal. The second imaginary component generator 104-2 may generate the second imaginary component by mixing a fourth bit B3 generated from a fourth PRBS 104-2a and a second LOQ signal through a fourth mixer 104-2b.
The second QPSK generator 104 may generate the second QPSK signal by synthesizing the second real component and the second imaginary component, and input the generated second QPSK signal to the second amplifier 108. The second QPSK signal may have a preset reference magnitude. For example, the second QPSK signal may have a reference magnitude in which each of coefficients of a second real component I2 and a second imaginary component Q2 is 1. That is, the second QPSK signal may be expressed as QPSK2=I2+jQ2. In this case, the second QPSK signal may be understood as having only a phase component.
That is, in the disclosed embodiment, in order to implement a 16-QAM high-efficiency transmitter, the first QPSK signal and the second QPSK signal that are independent and have the same reference magnitude are input to the first amplifier 106 and the second amplifier 108, respectively.
The first amplifier 106 and the second amplifier 108 are provided to operate in a saturation region, respectively. Here, since the first QPSK signal and the second QPSK signal are independent signals and have only a phase component as a reference magnitude, the first amplifier 106 and the second amplifier 108 may be operated in a saturation region. That is, the first amplifier 106 and the second amplifier 108 may be provided to operate in the saturation region, respectively, in order to amplify output power of each QPSK signal of which information is transmitted only through the phase of the carrier wave.
In an embodiment, the first amplifier 106 may be provided to have first saturation power Psat1. In this case, when the first QPSK signal is input to the first amplifier 106, the first amplifier 106 may operate in a saturation region, and thus the first QPSK signal having the first saturation power Psat1 is output.
The second amplifier 108 may be provided to have second saturation power Psat2. The second saturation power Psat2 may be 4M-1 times (M is a natural number greater than or equal to 2) the magnitude of the first saturation power Psat1. For example, the second saturation power Psat2 may be 4 times (M=2) the magnitude of the first saturation power Psat1. In this case, when the second QPSK signal is input to the second amplifier 108, the second amplifier 108 may operate in the saturation region, and thus the second QPSK signal having four times the first saturation power Psat1 is output. In this case, the difference in output saturation power between the second amplifier 108 and the first amplifier 106 is 6 dB.
First, referring to
Referring to
The divider 108a may split the input second QPSK signal and respectively input the split second QPSK signals into four PA units 108b. Each of the four power amplification units 108b may be provided to have a preset gain so that the first saturation power Psat1 is output. That is, each of the four PA units 108b of the second amplifier 108 may be provided in the same manner as the PA unit of the first amplifier 106. In this case, each of the four PA units 108b outputs a second QPSK signal having the first saturation power Psat1.
The combiner 108c may synthesize the second QPSK signals of the first saturation power Psat1 each of which is output from each of the four PA units 108b. Then, the combiner 108c outputs the second QPSK signal having four times the magnitude of the first saturation power Psat1.
The power combining unit 110 may transmit a 16-QAM signal by combining the power of the first QPSK signal output from the first amplifier 106 and second QPSK signal output from the second amplifier 108. In an embodiment, the power combining unit 110 may be a power combiner.
For example, when the first amplifier 106 outputs the first QPSK signal of the first saturation power Psat1 and the second multiplier 108 outputs the second QPSK signal having four times the first saturation power Psat1, the power combining unit 110 may synthesize a 16-QAM signal by combining the first QPSK signal and the second QPSK signal.
Here, the power combining unit 110 is described as a power combiner as an example, but is not limited thereto. As illustrated in
In this case, the first antenna 110-1 and the second antenna 110-2 may synthesize the 16-QAM signal by combining the first QPSK signal output from the first amplifier 106 and the second QPSK signal output from the second amplifier 108 in space.
Meanwhile, this structure may be extended in the same way to implement higher-order QAM than 16-QAM. For example, when there are M independent QPSK signals, the order of N-order QAM implemented becomes N=4M. In this time, in order to configure higher-order QAM, the magnitude of the power of each QPSK may be set to have a magnitude of 2k, (k=0, 1, . . . , M−1) when the magnitude of the minimum QPSK signal is 1. For example, when M=3, the magnitudes of three independent QPSK signals may be set to 1, 2, and 4, respectively, to implement 64-QAM. From the above, when power amplifiers drive antennas or ports of the power combining units having the same resistance as the load R, the magnitudes of the saturation power of the required power amplifiers may be respectively set to 4k, (where k=0, 1, . . . , M−1).
According to the disclosed embodiment, since the first amplifier and the second amplifier may operate in the saturation region by inputting the first QPSK signal and the second QPSK signal that are mutually independent and have the same reference to the first amplifier 106 and the second amplifier 108, respectively, and output the first QPSK signal having first saturation power Psat1 and the second QPSK signal having second saturation power Psat2, the power efficiency of the 16-QAM transmitter can be increased.
According to the disclosed embodiment, since a method in which power of respective QPSK signals is combined through an antenna or a power combining unit after the first amplifier and the second amplifier operate in the saturation region by inputting the first QPSK signal and the second QPSK signal that are mutually independent and have the same reference size to the first amplifier and the second amplifier, respectively, and outputting the first QPSK signal having first saturation power Psat1 and the second QPSK signal having second saturation power Psat2, the power efficiency of the high-order QAM transmitter can be greatly increased compared to a conventional high-order QAM transmitter in which a linear power amplifier is used by considering both magnitude and phase information.
Although representative embodiments of the present invention have been described in detail above, those skilled in the art will understand that various modifications may be made to the above-described embodiments without departing from the scope of the present invention. Therefore, the scope of the rights of the present disclosure should not be limited to the described embodiments, but should be determined by the claims described below as well as equivalents of the claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2023-0190217 | Dec 2023 | KR | national |
