Communication device and communication system

Abstract

A communication device according to the present invention comprises: a baseband signal processing unit; a common-mode signal processing unit and an quadrature signal processing unit that modulate or demodulate an input signal; a balanced antenna that includes a first port and a second port; and a phase compensation unit that outputs a signal obtained by compensating the phase of the input signal, said communication device being provided with a first route that connects the baseband signal processing unit and the first port via the common-mode signal processing unit, and a second route that connects the baseband signal processing unit and the second port via the quadrature signal processing unit, wherein the first port and the second port have opposite polarities to each other, and the phase compensation unit is provided to the baseband signal processing unit, the first route, or the second route.

Description

Communication device and communication system

[0001] The present disclosure relates to a communication device and a communication system.

[0002] In recent years, the 3GPP (registered trademark) (3rd Generation Partnership Project) has been formulating specifications for next-generation standards (beyond 5G and 6G). The terahertz wave band has been raised as a candidate for a radio frequency resource in 6G. Terahertz waves are electromagnetic waves having a frequency range of 10 GHz to 100 THz. Patent Document 1 discloses a method for oscillating electromagnetic waves in the terahertz wave band.

[0003] Japanese Patent Application Laid-Open No. 2017-201779

[0004] Patent Document 1 describes the generation of terahertz waves, but does not describe a configuration for use in communication.

[0005] An object of the present disclosure is to provide a technology that is advantageous for communication using high-frequency electromagnetic waves such as terahertz waves.

[0006] In view of the above problems, a communication device according to an embodiment of the present disclosure is a communication device including a baseband signal processing unit, an in-phase signal processing unit and a quadrature signal processing unit that modulate or demodulate an input signal, a balanced antenna having a first port and a second port, and a phase compensation unit that outputs a signal obtained by compensating the phase of the input signal, wherein the communication device comprises a first path that connects the baseband signal processing unit and the first port via the in-phase signal processing unit, and a second path that connects the baseband signal processing unit and the second port via the quadrature signal processing unit, wherein the first port and the second port have opposite polarities, and the phase compensation unit is disposed in the baseband signal processing unit, the first path, or the second path.

[0007] According to the present disclosure, it is possible to provide a technology that is advantageous for communication using high-frequency electromagnetic waves such as terahertz waves.

[0008] Other features and advantages of the present disclosure will become apparent from the following description taken in conjunction with the accompanying drawings, in which the same or similar components are designated by the same reference numerals.

[0009] The accompanying drawings are incorporated into and constitute a part of the specification, illustrate embodiments of the present disclosure, and are used, together with the description, to explain the principles of the present disclosure.

[0023] FIG. 1 shows an example of the configuration of a communication device according to an embodiment.

[0024] FIG. 1 shows an example of the configuration of a wireless communication unit of the communication device of FIG. 1.

[0025] FIG. 1 shows an example of the configuration of a wireless communication unit of the communication device of FIG. 1.

[0026] FIG. 1 shows an example of the configuration of a wireless communication unit of the communication device of FIG. 1.

[0027] FIG. 1 shows an example of the configuration of a transmission waveform of the communication device of FIG. 1.

[0028] FIG. 1 shows an example of the transmission waveform of the communication device of FIG. 1.

[0029] FIG. 1 shows an example of the configuration of a modulation / demodulation unit of the communication device of FIG. 1.

[0029] FIG. 1 shows an example of the configuration of a modulation / demodulation unit of the communication device of FIG. 1.

[0029] FIG. 1 shows an example of the configuration of a reception waveform of the communication device of FIG. 1.

[0029] FIG. 1 shows an example of the reception waveform of the communication device of FIG. 1.

[0029] FIG. 1 shows an example of the reception waveform of the communication device of FIG. 1.

[0029] FIG. 1 shows an example of the configuration of a modulation / demodulation unit of the communication device of FIG. 1.

[0029] FIG. 2 is a diagram showing an example of the configuration of a wireless communication unit of the communication device of FIG. 1. FIG. 3 is a diagram showing an example of a transmission waveform of the communication device of FIG. 1. FIG. 4 is a diagram showing an example of a transmission waveform of the communication device of FIG. 1. FIG. 5 is a diagram showing an example of a transmission waveform of the communication device of FIG. 1. FIG. 6 is a diagram showing an example of a reception waveform of the communication device of FIG. 1. FIG. 7 is a diagram showing an example of a reception waveform of the communication device of FIG. 1. FIG. 8 is a diagram showing an example of a reception waveform of the communication device of FIG. 1. FIG. 9 is a diagram showing an example of a configuration of a wireless communication unit of the communication device of FIG. 1. FIG. 10 is a diagram showing an example of a transmission waveform of the communication device of FIG. 1. FIG. 11 is a diagram showing an example of a transmission waveform of the communication device of FIG. 1. FIG. 12 is a diagram showing an example of a transmission waveform of the communication device of FIG. 1. FIG. 13 is a diagram showing an example of a transmission waveform of the communication device of FIG. 1. FIG. 14 is a diagram showing an example of a reception waveform of the communication device of FIG. 1. FIG. 15 is a diagram showing an example of a reception waveform of the communication device of FIG. 1. Fig. 2 is a diagram showing an example of the configuration of a wireless communication unit of the communication device of Fig. 1. Fig. 3 is a diagram showing an example of the configuration of a communication system using the communication device of Fig. 1.

[0010] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the scope of the claims. Although multiple features are described in the embodiments, not all of these multiple features are required, and multiple features may be combined arbitrarily. Furthermore, in the accompanying drawings, the same reference numerals are used to designate the same or similar components, and redundant explanations will be omitted.

[0011] A communication device according to an embodiment of the present disclosure will be described with reference to FIGS. 1 to 13C. The configuration of functional blocks of the communication device described below is merely an example. Some (or in some cases all) of the described functional blocks may be replaced with other functional blocks that perform similar functions, some functional blocks may be omitted, or additional functional blocks may be added. Furthermore, one functional block described below may be divided into multiple functional blocks, or multiple functional blocks may be integrated into one functional block.

[0012] FIG. 1 is a functional block diagram showing an example configuration of a communication device 101 according to this embodiment. The communication device 101 may include a control unit 102, a storage unit 103, an application unit 104, and a wireless communication unit 105. The control unit 102 controls each component of the communication device 101. The storage unit 103 stores data used in the communication device 101. The application unit 104 executes application software using the data stored in the storage unit 103. The application software may be, for example, software for watching videos or game software. The wireless communication unit 105 wirelessly communicates data from the storage unit 103 and data used by the application unit 104 with an external device. The wireless communication unit 105 performs modulation processing to superimpose digital data onto an analog signal and transmits the modulated analog signal as electromagnetic waves into space. The wireless communication unit 105 also receives electromagnetic waves in space and performs demodulation processing to extract digital data from the analog electromagnetic wave signal. For example, the wireless communication may be public wireless communication such as 4G, 5G, or 6G, or a standard wireless communication such as WLAN, Bluetooth, Zigbee, etc. Alternatively, the wireless communication may be a proprietary wireless communication based on a non-standard wireless protocol.

[0013] Next, the configuration of the above-mentioned wireless communication unit 105 will be described using Figures 2A to 2C. Figure 2A is a block diagram showing an example configuration of the wireless communication unit 105. The wireless communication unit 105 may include a baseband signal processing unit 201, an in-phase signal processing unit 202, a quadrature signal processing unit 203, a balanced antenna 204, and a phase compensation unit 205. The in-phase signal processing unit 202 and the quadrature signal processing unit 203 configure a modulation / demodulation unit 210.

[0014] The balanced antenna 204 has a positive port 206 and a negative port 207 with opposite polarities. As an example of the balanced antenna 204, a patch antenna is shown in FIG. 2B , and the voltage distribution in the vertical direction of the patch antenna shown in FIG. 2B is shown in FIG. 2C . The patch antenna, which is the balanced antenna 204, has a positive voltage region 212 in the upper half and a negative voltage region 213 in the lower half, with a center line 211 as the boundary. The balanced antenna 204 has a positive power supply port (positive port 206) in the positive voltage region 212 and a negative power supply port (negative port 207) in the negative voltage region 213. Because the positive and negative polarities of these voltages fluctuate over time, the positive and negative polarities of the above voltages and ports indicate the voltage relationship at a certain point in time for convenience. In other words, at a certain time, a negative voltage may be applied to the positive port 206 and a positive voltage may be applied to the negative port 207.

[0015] In practical terms and design, it is easier to use if the positive port 206 and the negative port 207 are out of phase. However, this is not limiting. Here, "the positive port 206 and the negative port 207 are out of phase" does not only mean that the phase difference between the positive port 206 and the negative port 207 is exactly 180 degrees, but also includes cases ranging from 175 degrees to 185 degrees, such as 178 degrees or 183 degrees. Even in such cases, the effects of this embodiment can be obtained. Furthermore, "the positive port 206 and the negative port 207 are out of phase" means that the phase of the signal at the positive port 206 and the phase of the signal at the negative port 207 are in an inverse relationship, with respect to the baseband signal. Details will be described later.

[0016] The in-phase signal processing unit 202 and the quadrature signal processing unit 203 arranged in the modem unit 210 modulate or demodulate the input signal. The in-phase signal processing unit 202 is connected to the baseband signal processing unit 201 and the positive port 206 of the balanced antenna 204. The quadrature signal processing unit 203 is connected to the phase compensation unit 205 and the negative port 207 of the balanced antenna 204. Here, the path connecting the baseband signal processing unit 201 and the positive port 206 of the balanced antenna 204 via the in-phase signal processing unit 202 is called path 208. Similarly, the path connecting the baseband signal processing unit 201 and the negative port 207 of the balanced antenna 204 via the quadrature signal processing unit 203 is called path 209.

[0017] 2A, the phase compensation unit 205 is arranged on the path 209. More specifically, the phase compensation unit 205 is arranged between the baseband signal processing unit 201 and the orthogonal signal processing unit 203. As will be described later, the phase compensation unit 205 outputs a signal obtained by compensating the phase of an input signal.

[0018] Next, the signal processing of the wireless communication unit 105 will be described using signal waveforms generated in the baseband signal processing unit 201, in-phase signal processing unit 202, quadrature signal processing unit 203, and phase compensation unit 205. First, the processing of the wireless communication unit 105 when transmitting a signal will be described. Waveforms of the transmission signal at positions (i), (ii), and (iii) shown in Figure 2A are shown in Figures 3B, 3C, and 3D, respectively.

[0019] Digital data in the storage unit 103 and digital data calculated by the application unit 104 are wirelessly transmitted from the wireless communication unit 105 to an external device of the communication device 101. This digital data is called a baseband signal and has, for example, a waveform like the baseband signal 301 shown in FIG. 3A. The baseband signal 301 may be a signal string of positive logic and double current type in which negative amplitude -A is 0 and positive amplitude A is 1, and in the example shown in FIG. 3A, it is [10010011]. Hereinafter, an example of positive logic and double current type will be described, but other types such as negative logic and single current type may also be used. Furthermore, in the following description, Quadrature Phase Shift Keying (QPSK) will be used as an example of modulation and demodulation for digital communication. However, this is not limited to this, and other types may also be used.

[0020] In QPSK modulation and demodulation, baseband signal processing unit 201 performs serial-to-parallel conversion on input baseband signal 301, two bits at a time. That is, baseband signal 301 [10010011] is converted to

[1001] and

[0101] . Furthermore, in this example, the NRZ format is used, with

[1001] assigned to the in-phase (I) component (in-phase signal) and

[0101] assigned to the quadrature (Q) component (quadrature signal). Figure 3B shows the signal waveforms of in-phase signal 302 and quadrature signal 303 at position (i) in Figure 2A.

[0021] At position (ii) shown in Fig. 2A, in-phase signal 304 remains unchanged from in-phase signal 302 in Fig. 3B and is

[1001] , as shown in Fig. 3C. On the other hand, the phase of quadrature signal 305 is inverted in phase compensation section 205, and changes from

[0101] to

[1010] , as shown in Fig. 3C.

[0022] The in-phase signal 304 is sent to the in-phase signal processing unit 202 and modulated. If the digital signal is 1 and the phase of the carrier wave is 0 degrees, and if the digital signal is 0 and the phase of the carrier wave is 180 degrees, the rectangular signal of

[1001] of the in-phase signal 304 is mixed with the carrier wave to become the in-phase signal 306, an analog signal, as shown in FIG. 3D . Similarly, the quadrature signal 305 is modulated by the quadrature signal processing unit 203 to become the quadrature signal 307, an analog signal, as shown in FIG. 3D . Here, the carrier waves mixed with the in-phase signal 306 and the quadrature signal 307, respectively, are cosine waves cos(2πft) and sine waves sin(2πft), which are orthogonal to each other, as will be described later.

[0023] The modulated in-phase signal 306 and quadrature signal 307 are sent to the positive port 206 and negative port 207 of the balanced antenna 204, respectively, which have opposite polarities, and are combined and radiated from the balanced antenna 204. The quadrature signal 307 fed to the negative port 207 is input to the negative voltage region 213 in the balanced antenna 204, and therefore its phase is inverted in the positive voltage region 212. Therefore, the in-phase signal 306 and the quadrature signal 307 with the inverted phase are combined in the balanced antenna 204. The waveform of the combined signal 308 is as shown in FIG. 3E.

[0024] In this way, when transmitting a signal, the phase of in-phase signal 306 input to positive port 206 via path 208, based on the phase of baseband signal 301 input to baseband signal processing unit 201, and the phase of quadrature signal 307 input to negative port 207 via path 208, based on the phase of baseband signal 301, are in an opposite phase relationship. When quadrature signal 307 is combined with in-phase signal 306 by balanced antenna 204, the phase is inverted again. As a result, combined signal 308, in which the in-phase signal 306 and quadrature signal 307 are in phase, is combined and radiated from balanced antenna 204.

[0025] The combined signal 308 transmitted from the balanced antenna 204 is obtained by mixing the in-phase signal 302 and the quadrature signal 303 with the in-phase carrier and the quadrature carrier, respectively, and has the same waveform as the combined in-phase signal and the quadrature signal. Generally, a cosine wave cos(2πft) and a sine wave sin(2πft) are used as the in-phase carrier and the quadrature carrier, respectively, mixed into the in-phase signal and the quadrature signal. f is the carrier frequency, and t is a time variable. Here, orthogonal means that the integral of the product of the function f(t) and the function g(t) over the entire interval is zero, i.e., the following equation 1 is satisfied:

[0026]

[0027] The cosine wave and sine wave described above satisfy equation (1). By mixing a signal with such quadrature waves and transmitting the signal, it is possible to extract the mixed signal upon reception. For example, if the in-phase signal is +1 and the quadrature signal is -1, the combined signal is cos(2πft) - sin(2πft). To extract the in-phase signal during demodulation on the receiving side, the combined signal is multiplied by the cosine wave cos(2πft) and integrated over the entire interval, as shown in equation (2). The carrier wave is a wave that repeats with a period T, and the integral over the entire interval is equal to the period T. As a result of calculating equation (2), +½, i.e., half of the in-phase signal component, can be extracted as the in-phase signal.

[0028]

[0029] Similarly, the negative phase signal can be extracted by multiplying the combined signal by a sine wave sin(2πft) as in equation (3) and integrating over the entire interval, thereby extracting −½, which is half of the negative phase signal component.

[0030]

[0031] FIG. 4 shows an example of a configuration for transmission, i.e., modulation, in the modem unit 210. As shown in FIG. 4, the modem unit 210 includes a carrier wave generation unit 400 for generating a carrier wave. The carrier wave generation unit 400 includes a carrier wave generation unit 401 and a phase shift unit 403. The in-phase signal processing unit 202 processes the in-phase signal 304 input via path 208 in accordance with the carrier wave generated by the carrier wave generation unit 401. That is, in the in-phase signal processing unit 202, the in-phase signal 304 is mixed with the carrier wave input from the carrier wave generation unit 401 and modulated. As described above, a cosine wave cos(2πft) is generally used as the carrier wave. As described above, the waveform of the modulated in-phase signal 306 becomes the waveform shown in FIG. 3D.

[0032] The quadrature signal processing unit 203 processes the quadrature signal 305 input via path 209 in accordance with the carrier wave generated by the carrier wave generation unit 401 and phase-shifted by the phase shift unit 403. That is, in the in-phase signal processing unit 202, the in-phase signal 304 is mixed with the carrier wave input from the carrier wave generation unit 401 via the phase shift unit 403 and modulated. The phase shift in the phase shift unit 403 is typically ±90 degrees, and the carrier wave input to the quadrature signal processing unit 203 is a sine wave sin(2πft). As described above, the waveform of the modulated quadrature signal 307 becomes the waveform shown in FIG. 3D .

[0033] The carrier wave generating unit 401 arranged in the carrier wave generating unit 400 may generate a terahertz wave as a carrier wave. The carrier wave generating unit 401 may include an oscillation element such as a resonant tunneling diode (RTD) or a complementary metal oxide semiconductor (CMOS) inverter. The carrier wave is not limited to the terahertz wave band, and bands such as millimeter waves and microwaves may also be used. Furthermore, the in-phase signal processing unit 202 and the quadrature signal processing unit 203 are also called mixers, and may be composed of diodes, field effect transistors (FETs), or the like. The phase shifting unit 403 may be composed of, for example, a line having a length of a quarter wavelength.

[0034] FIG. 5 is a diagram showing a modified example of the modem unit 210 shown in FIG. 4 . In the configuration shown in FIG. 5 , the carrier generation unit 500 includes an in-phase carrier generation unit 501 and a quadrature carrier generation unit 503. As a result, the carrier generation unit 500 is configured to independently generate carriers for the in-phase signal and the quadrature signal. In the in-phase signal processing unit 202, the carrier generated by the in-phase carrier generation unit 501 of the carrier generation unit 500 is mixed with the in-phase signal 304 input via path 208 to generate the in-phase signal 306 shown in FIG. 3D . Similarly, in the quadrature signal processing unit 203, the carrier generated by the quadrature carrier generation unit 503 of the carrier generation unit 500 is mixed with the quadrature signal 305 input via path 209 to generate the quadrature signal 307 shown in FIG. 3D . The carrier wave generated by the in-phase carrier wave generating section 501 and the carrier wave generated by the quadrature carrier wave generating section 503 must be orthogonal to each other.

[0035] The in-phase carrier generating unit 501 and the quadrature carrier generating unit 503 arranged in the carrier generating unit 500 may generate terahertz waves as carrier waves, similar to the carrier generating unit 401 arranged in the above-described carrier generating unit 400. The in-phase carrier generating unit 501 and the quadrature carrier generating unit 503 may include an oscillation element such as a resonant tunneling diode (RTD) or a CMOS inverter. The carrier wave is not limited to the terahertz wave band, and bands such as millimeter waves and microwaves may also be used.

[0036] The modem units 210 shown in Figures 4 and 5 may be connected in multiple stages. For example, a superheterodyne system in which two stages of the modem units 210 are connected may be used. For example, the carrier frequency of the first stage, called an intermediate frequency, may be on the order of kHz or MHz, and the carrier frequency of the second stage may be on the order of GHz. Furthermore, by arranging an amplifier in each stage to amplify the signal, communication can be stabilized.

[0037] Next, the processing of the wireless communication unit 105 when receiving a signal will be described. Electromagnetic waves in space are received by the balanced antenna 204. The waveform of this received signal 601 is, for example, the waveform shown in FIG. 6A and is similar to the combined signal 308 shown in FIG. 3E. The waveform of the in-phase signal 602 output to the positive port 206 (position (iii) in FIG. 2A) is the waveform shown in FIG. 6B and is the same as the waveform of the received signal 601 shown in FIG. 6A. On the other hand, the waveform of the quadrature signal 603 output to the negative port 207 (position (iii) in FIG. 2A) is the waveform shown in FIG. 6B and is a waveform that is positively and negatively inverted with respect to the waveform of the received signal 601 shown in FIG. 6A. These in-phase signal 602 and quadrature signal 603 are input to the in-phase signal processing unit 202 and quadrature signal processing unit 203, respectively.

[0038] An example of the configuration for reception, i.e., demodulation, of the modem unit 210 is shown in Figure 7. Compared to the configuration for modulation shown in Figure 4, the configuration for demodulation adds low-pass filters 703 and 706 to the in-phase signal processing unit 202 and the quadrature signal processing unit 203, respectively. After the in-phase signal 602 and the quadrature signal 603 are mixed with a carrier wave in the in-phase signal processing unit 202 and the quadrature signal processing unit 203, the signals pass through the low-pass filters 703 and 706. The low-pass filters 703 and 706 remove harmonic components from the signal obtained after mixing the carrier wave and the received signal, and extract the DC component. In other words, they function similarly to the integration in equations (2) and (3).

[0039] The in-phase signal processing unit 202 processes the in-phase signal 602 input via path 208 in accordance with the carrier wave generated by the carrier wave generation unit 401. That is, in the in-phase signal processing unit 202, the in-phase signal 602 is mixed with the carrier wave input from the carrier wave generation unit 401. By mixing a signal of the same frequency as the in-phase signal with the in-phase signal, the in-phase signal 602 comes to contain a DC component and a double harmonic component. The mixed signal is demodulated by the low-pass filter 703, through which only the DC component passes, and the waveform of the in-phase signal 602 becomes a waveform similar to the in-phase signal 604 shown in FIG. 6C . Similarly, the quadrature signal processing unit 203 processes the quadrature signal 603 input via path 209 in accordance with the carrier wave generated by the carrier wave generation unit 401 and phase-shifted by the phase shifter 403. That is, in orthogonal signal processing section 203, orthogonal signal 603 is mixed with the carrier wave input from carrier wave generating section 401 via phase shift section 403. The mixed signal is demodulated by low-pass filter 706, with only the DC component passing through, and the waveform of orthogonal signal 603 becomes a waveform like orthogonal signal 605 shown in Fig. 6C. As described above, the phase shift in phase shift section 403 is generally ±90 degrees.

[0040] FIG. 8 is a diagram showing a modified example of the modem unit 210 shown in FIG. 7 . In the configuration shown in FIG. 8 , similar to the configuration shown in FIG. 5 for modulation, the carrier generation unit 500 includes an in-phase carrier generation unit 501 and a quadrature carrier generation unit 503. This allows the carrier generation unit 500 to independently generate carriers for the in-phase signal and the quadrature signal. Also, similar to the configuration shown in FIG. 7 , low-pass filters 803 and 806 are added to the in-phase signal processing unit 202 and the quadrature signal processing unit 203, respectively. After the carriers are mixed with the in-phase signal 602 and the quadrature signal 603 in the in-phase signal processing unit 202 and the quadrature signal processing unit 203, the signals pass through the low-pass filters 803 and 806.

[0041] 8, in-phase signal 602 is mixed with the carrier generated by in-phase carrier generation unit 501 in in-phase signal processing unit 202, and passes through low-pass filter 803 to become in-phase signal 604 as shown in Fig. 6C. Similarly, quadrature signal 603 is mixed with the carrier generated by quadrature carrier generation unit 503 in quadrature signal processing unit 203, and passes through low-pass filter 806 to become quadrature signal 605 as shown in Fig. 6C. As with the modulation configuration shown in Fig. 5, the carrier generated by in-phase carrier generation unit 501 and the carrier generated by quadrature carrier generation unit 503 must be orthogonal.

[0042] The quadrature signal 605 demodulated by the modem unit 210 as shown in Figures 7 and 8 is further phase-inverted by the phase compensation unit 205. Therefore, at position (i) in Figure 2A, the waveform of the quadrature signal 607 becomes the waveform shown in Figure 6D. The in-phase signal 606 at position (i) in Figure 2A has the same shape as the in-phase signal 604 at position (ii) in Figure 2A. Next, the in-phase signal 606 and the quadrature signal 607 are parallel-to-serial converted in the baseband signal processing unit 201, and a baseband signal 608 is obtained. The baseband signal 608 is the same signal sequence as the baseband signal 301 described above, and indicates that communication is successful between the transmitting device and the receiving device.

[0043] In this way, when receiving a signal, the in-phase signal 602 input from the positive port 206 to the path 208 and the quadrature signal 603 input from the negative port 207 to the path 209 are in an anti-phase relationship with respect to the phase of the baseband signal 608 output from the baseband signal processing unit 201 after demodulation. However, by compensating (inverting) the phase by the phase compensation unit 205, the wireless communication unit 105 can demodulate the received signal 601 to the baseband signal 608.

[0044] Although it has been described above that a patch antenna is used as the balanced antenna 204, the balanced antenna 204 is not limited to a patch antenna. A dipole antenna, a slot antenna, a bowtie antenna, or the like may also be used as the balanced antenna 204. Furthermore, the phase compensation unit 205 is not limited to being disposed on the path 209.

[0045] In this embodiment, the phase compensation unit 205 is arranged on the path 209. However, this is not limiting, and the phase compensation unit 205 may be arranged on the path 208, more specifically, between the baseband signal processing unit 201 and the in-phase signal processing unit 202. The phase compensation unit 205 only needs to be able to compensate (invert) the phase of either the signal passing through the path 208 or the signal passing through the path 209.

[0046] Although the modulation / demodulation method has been described using QPSK as an example, the effects of this embodiment can also be obtained with other PSK methods, such as 8PSK and QAM. When QAM is used, an amplitude compensation unit may be provided to compensate (adjust) the amplitude of the signal. The amplitude compensation unit may be provided on both path 208 and path 209.

[0047] Each component included in the communication device 101 may be realized by a CMOS integrated circuit (IC) using silicon or the like. Furthermore, for example, each component included in the communication device 101 may be realized by an IC using a compound semiconductor such as gallium arsenide. The communication device 101 may be configured by a combination of an IC using a semiconductor such as silicon and an IC using a compound semiconductor.

[0048] Furthermore, a backflow prevention unit may be arranged between the in-phase signal processing unit 202 and the positive port 206 of the balanced antenna 204 to prevent a signal passing through path 209 from being input to the in-phase signal processing unit 202. Similarly, a backflow prevention unit may be arranged between the quadrature signal processing unit 203 and the negative port 207 of the balanced antenna 204 to prevent a signal passing through path 208 from being input to the quadrature signal processing unit 203. The backflow prevention unit can be realized by a circulator, a rat race, or the like.

[0049] As described above, the phase compensation unit 205 that compensates for the phase of the signal is disposed on one of the paths 208 and 209 from the baseband signal processing unit 201 to the positive port 206 and negative port 207 of the balanced antenna 204. This enables communication using the positive port 206 and negative port 207 of the balanced antenna 204.

[0050] In the above-described embodiment, the phase compensation unit 205 is disposed between the baseband signal processing unit 201 and the quadrature signal processing unit 203 (or the in-phase signal processing unit 202). However, this is not limitative, and the phase compensation unit 205 may be provided inside the baseband signal processing unit 201, as shown in Fig. 9A. The following description will focus on differences from the above description, and descriptions of configurations that may be similar will be omitted as appropriate.

[0051] Consider the case where the configuration shown in FIG. 9A transmits baseband signal 901 [10010011] shown in FIG. 9B, which is a string of "0"s and "1"s, the same as baseband signal 301 described above. Phase compensation section 205 arranged in baseband signal processing section 201 inverts the even-numbered bits of data in baseband signal 901. The inverted inverted signal 902 is [11000110], as shown in FIG. 9B. This inverted signal 902 [11000110] is serial-to-parallel converted in baseband signal processing section 201, assigned to an in-phase (I) component (in-phase signal) and a quadrature (Q) component (quadrature signal), and sent to paths 208 and 209, respectively. The waveforms of in-phase signal 903 and quadrature signal 904 at position (i) in FIG. 9A are the waveforms shown in FIG. 9C, which are the same as the waveforms of in-phase signal 304 and quadrature signal 305 described above. Next, the in-phase signal 903 and the quadrature signal 904 are modulated in the in-phase signal processing unit 202 and the quadrature signal processing unit 203. The processing in the in-phase signal processing unit 202 and the quadrature signal processing unit 203 may be the same as that described above, and therefore a description thereof will be omitted. The waveforms of the modulated in-phase signal 905 and the quadrature signal 906 at position (ii) in Figure 9A are the waveforms shown in Figure 9D, respectively, and are the same as the waveforms of the in-phase signal 306 and the quadrature signal 307 described above. The waveform of the combined signal 907 transmitted from the balanced antenna 204 is the waveform shown in Figure 9E, and the same signal as the combined signal 308 described above is transmitted. Furthermore, the configuration of the modulation / demodulation unit 210 may be the same as that shown in Figures 4 and 5 described above, and therefore a description thereof will be omitted.

[0052] Next, the processing of the wireless communication unit 105 when receiving a signal in the configuration shown in Fig. 9A will be described. The configuration of the modem unit 210 may be the same as that shown in Figs. 7 and 8 above, and therefore description thereof will be omitted.

[0053] Electromagnetic waves in space are received by balanced antenna 204 of communication device 101. The waveform of received signal 1001 is the waveform shown in Fig. 10A, which is the same waveform as combined signal 907. The waveforms of in-phase signal 1002 and quadrature signal 1003 at position (ii) in Fig. 9A are respectively the waveforms shown in Fig. 10B, which are the same as the waveforms of in-phase signal 602 and quadrature signal 603 described above. In-phase signal 1002 is a signal that passes through path 208, and quadrature signal 1003 is a signal that passes through path 209.

[0054] The in-phase signal 1002 and the quadrature signal 1003 are mixed with a carrier wave in the in-phase signal processing section 202 and the quadrature signal processing section 203, and are demodulated by passing through the low-pass filters 703, 706, 803, and 806. The processing in the in-phase signal processing section 202 and the quadrature signal processing section 203 is the same as that described above. As a result, the in-phase signal 1004 and the quadrature signal 1005 are obtained at position (i) in Figure 9A.

[0055] Next, phase compensation section 205 arranged in baseband signal processing section 201 inverts the phase of quadrature signal 1005, thereby obtaining quadrature signal 1007 shown in FIG. 10D. In-phase signal 1006 shown in FIG. 10D is the same as in-phase signal 1004. Baseband signal processing section 201 performs parallel-to-serial conversion on in-phase signal 1006 and quadrature signal 1007. This results in baseband signal 1008 [10010011]. Baseband signal 1008 is the same signal sequence as baseband signal 901 described above, and indicates that communication is successful between the transmitting device and the receiving device.

[0056] In the present embodiment, it has been described that the phase compensation unit 205 compensates (inverts) the phase of a quadrature signal. That is, it has been described that the phase compensation unit 205 inverts the phase of the signal output from the baseband signal processing unit 201 to the path 209 and the signal input from the path 209 to the baseband signal processing unit 201. However, this is not limited thereto, and the phase compensation unit 205 may also compensate (invert) the phase of an in-phase signal. That is, the phase compensation unit 205 may invert the phase of the signal output from the baseband signal processing unit 201 to the path 208 and the signal input from the path 208 to the baseband signal processing unit 201. It is sufficient that the phase compensation unit 205 is capable of compensating (inverting) the phase of either the signal passing through the path 208 or the signal passing through the path 209.

[0057] In each of the above-described embodiments, the phase compensation unit 205 compensates for the phase of the in-phase signal or the quadrature signal before modulation or after demodulation. However, the timing of phase compensation is not limited thereto. The phase compensation unit 205 may compensate for the phase of the in-phase signal or the quadrature signal after modulation or before demodulation of the in-phase signal or the quadrature signal. In the configuration shown in FIG. 11A , the phase compensation unit 205 is disposed on the path 209 between the quadrature signal processing unit 203 and the negative port 207 of the balanced antenna 204. The following description will focus on differences from the above description, and descriptions of configurations that may be similar will be omitted as appropriate.

[0058] 11A, consider the case where baseband signal 1101 shown in FIG. 11B, [10010011], is transmitted, which is a string of "0"s and "1"s similar to the above-described baseband signal 301. Waveforms of the transmission signal at positions (i), (ii), and (iii) shown in FIG. 11A are shown in FIGS. 11C, 11D, and 11E, respectively.

[0059] Baseband signal 1101 is serial-to-parallel converted in baseband signal processing section 201, assigned to an in-phase (I) component (in-phase signal) and a quadrature (Q) component (quadrature signal), and sent to paths 208 and 209, respectively. The waveforms of in-phase signal 1102 and quadrature signal 1103 at position (i) in FIG. 11A are the waveforms shown in FIG. 9C. In-phase signal 1102 and quadrature signal 1103 are modulated by modem section 210 to become in-phase signal 1104 and quadrature signal 1105 as shown in FIG. 11D. The configurations and processing of in-phase signal processing section 202 and quadrature signal processing section 203 (modem section 210) may be the same as those described above, and therefore description thereof will be omitted.

[0060] The quadrature signal 1105 is further phase compensated by the phase compensation unit 205. Here, we will explain the case where the positive port 206 and the negative port 207 of the balanced antenna 204 have a phase difference of 180 degrees, as shown in FIGS. 2B and 2C. In this case, the phase compensation is 180 degrees, i.e., inverted, and the quadrature signal 1107 shown in FIG. 11E is obtained from the quadrature signal 1105. The waveform of the in-phase signal 1106 at position (iii) in FIG. 11A is the same as the waveform of the in-phase signal 1104 at position (ii). The in-phase signal 1106 and the quadrature signal 1107 are combined in the balanced antenna 204 and transmitted from the balanced antenna 204 as the combined signal 1108 shown in FIG. 11F. The waveform of the combined signal 1108 is the same as the waveform of the combined signals 308 and 907 described above.

[0061] Next, the processing of the wireless communication unit 105 when receiving a signal in the configuration shown in Fig. 11A will be described. The received signal waveform is shown in Fig. 12. The waveforms of the received signals at (i), (ii), and (iii) shown in Fig. 11A are shown in Figs. 12D, 12C, and 12B, respectively.

[0062] Electromagnetic waves in space are received by balanced antenna 204 of communication device 101. The waveform of received signal 1201 is the waveform shown in Fig. 12A, which is the same as the waveform of combined signal 1108. The waveforms of in-phase signal 1202 and quadrature signal 1203 at position (iii) in Fig. 11A are the waveforms shown in Fig. 12B, respectively, which are the same as the waveforms of in-phase signals 602 and 100 and quadrature signals 603 and 1003 described above. In-phase signal 1202 is a signal that passes through path 208, and quadrature signal 1203 is a signal that passes through path 209.

[0063] Next, the quadrature signal 1203 passing through path 209 is phase compensated, in this case 180 degrees, i.e., inverted, by phase compensation unit 205. As a result, quadrature signal 1205 shown in FIG. 12C is obtained. The waveform of in-phase signal 1204 passing through path 208, even at position (ii), is the same as the waveform of in-phase signal 1202 at position (iii). In-phase signal 1204 and quadrature signal 1205 are demodulated in in-phase signal processing unit 202 and quadrature signal processing unit 203 (modulation / demodulation unit 210), resulting in in-phase signal 1206 and quadrature signal 1207, respectively. The configurations and processing of in-phase signal processing unit 202 and quadrature signal processing unit 203 (modulation / demodulation unit 210) may be the same as those described above, and therefore will not be described here.

[0064] In-phase signal 1206 and quadrature signal 1207 are converted from parallel to serial in baseband signal processing section 201 to obtain [10010011], which is baseband signal 1208. Baseband signal 1208 is the same signal sequence as baseband signal 1101 described above, and indicates that communication is possible between the transmitting device and the receiving device.

[0065] Phase compensation in the phase compensation unit 205 can be achieved, for example, by a high-frequency signal transmission line. When inverting the signal phase as described above, the phase compensation unit 205 can be achieved by using a line whose length is an odd multiple of approximately half the wavelength of the carrier wave generated by the carrier wave generation units 400 and 500. In practice, using the shortest line length, approximately half the wavelength, reduces the wiring area. For example, for a carrier wave with a frequency of 300 GHz, one wavelength is approximately 1 mm. When mounting such a line on a dielectric substrate, the wavelength can be determined taking into account the dielectric constant of the dielectric and the line structure. Furthermore, for example, if the phase difference between the positive port 206 and the negative port 207 of the balanced antenna 204 is not 180 degrees (not out of phase), e.g., if the phase difference between the positive port 206 and the negative port 207 is 150 degrees, the line length should be set according to the phase difference to be compensated. This allows for signal phase compensation.

[0066] 11A , the phase compensation unit 205 is arranged between the quadrature signal processing unit 203 on the path 209 and the negative port 207 of the balanced antenna 204. However, this is not limited thereto, and the phase compensation unit 205 may be arranged between the in-phase signal processing unit 202 on the path 208 and the positive port 206 of the balanced antenna 204. The phase compensation unit 205 only needs to be able to compensate (invert) the phase of either the signal passing through the path 208 or the signal passing through the path 209.

[0067] As described above, the modulation / demodulation units 210 may be connected in multiple stages. For example, in the case of a superheterodyne system in which the modulation / demodulation units 210 are connected in two stages, the phase compensation unit 205 may be disposed between the two modulation / demodulation units 210 to compensate the phase of the signal in the intermediate frequency band.

[0068] In each of the above-described embodiments, the carrier wave is generated within the modem unit 210. In this case, as shown in Figures 13A to 13C, resonant tunneling diodes (RTDs) 214, 215 serving as carrier wave signal sources may be disposed near at least one of the positive port 206 and the negative port 207. Below, an embodiment in which a carrier wave signal source is disposed near the positive port 206 and the negative port 207 will be described, focusing on differences from the above, and a description of configurations that may be similar will be omitted as appropriate.

[0069] 2, 9, and 11, in a configuration in which a carrier wave is generated within the modem unit 210, a modulated signal is transmitted between the positive port 206 and the modem unit 210, and between the negative port 207 and the modem unit 210. During transmission, the modulated signal is attenuated. This signal attenuation becomes greater as the frequency increases, and is particularly noticeable in the millimeter wave band and the terahertz wave band.

[0070] Therefore, in this embodiment, RTDs 214 and 215 are arranged near the positive port 206 and the negative port 207 as carrier signal sources. This suppresses signal attenuation due to transmission between the positive port 206 and the modem unit 210 and between the negative port 207 and the modem unit 210. For example, if the positive port 206 and the negative port 207 are formed by vias, the RTDs 214 and 215 may be arranged directly below the vias, or the RTDs 214 and 215 may be connected to signal lines immediately adjacent to the vias. It can also be said that the RTD 214 is connected to a path 208 between the in-phase signal processing unit 202 and the positive port 206, and the RTD 215 is connected to a path 209 between the quadrature signal processing unit 203 and the negative port 207. 13A , the RTD 214 may be connected to a position of the path 208 between the in-phase signal processing unit 202 and the positive port 206, closer to the positive port 206 than the in-phase signal processing unit 202. For example, the ratio of the length of the path 208 from the in-phase signal processing unit 202 to the connection part of the RTD 214 to the length of the path 208 from the connection part of the RTD 214 to the positive port 206 may be 1:2 or more, 1:5 or more, or 1:10 or more. Similarly, the RTD 215 may be connected to a position of the path 209 between the quadrature signal processing unit 203 and the negative port 207, closer to the negative port 207 than the quadrature signal processing unit 203. For example, the ratio of the length of the path 209 from the quadrature signal processing unit 203 to the connection part of the RTD 215 to the length of the path 209 from the connection part of the RTD 215 to the negative port 207 may be 1:2 or more, 1:5 or more, or 1:10 or more.

[0071] Next, the principles of a signal source using a resonant tunneling diode are explained. Resonant tunneling diodes are composed of multiple different semiconductor materials, such as indium, gallium, phosphorus, and arsenic. Resonant tunneling diodes used as signal sources have a double-barrier resonant tunneling structure, which creates a negative resistance region in which current decreases with increasing applied voltage within a specific applied voltage range due to the tunneling structure. By connecting a resonator to a resonant tunneling diode having a negative resistance region and applying a voltage in the negative resistance region, the resistance component of the resonator is canceled by the negative resistance of the resonant tunneling diode, resulting in oscillation at the resonant frequency of the resonator. The resonator connected to the resonant diode may be a resonator consisting of an inductor and a capacitor, an antenna, or a stub. Resonant tunneling diodes are often used as signal sources in the terahertz wave band due to their good response, but they may also be used in other frequency bands, such as millimeter waves and microwave bands.

[0072] As described above, in this embodiment, RTDs 214 and 215 are arranged as signal sources near the positive port 206 and the negative port 207, but the resonant frequency of the resonator (not shown) is set to be approximately equal to the resonant frequency of the carrier wave generated by the modulation / demodulation unit 210. The RTDs 214 and 215 are also connected to the modulation / demodulation unit 210, and the carrier wave generated by the modulation / demodulation unit 210 is injected into the RTDs 214 and 215, causing the signal generated from the signal source using the RTDs 214 and 215 to synchronize with the carrier wave. By synchronizing with the carrier wave, in the case of transmission, the attenuated signal transmitted from the modulation / demodulation unit 210 is amplified, and in the case of reception, the small signal received by the antenna is amplified and transmitted to the modulation / demodulation unit 210. As a result, signal attenuation due to transmission between the positive port 206 and the modulation / demodulation unit 210 and between the negative port 207 and the modulation / demodulation unit 210 can be suppressed in both transmission and reception. Here, the RTD may be arranged at either the positive port 206 or the negative port 207, or may be arranged at the positive port 206 and the negative port 207, respectively, as shown in Figures 13A and 13B. When the RTDs 214 and 215 are arranged at the positive port 206 and the negative port 207, respectively, the locations of the RTDs may be different between the ports. Furthermore, when the RTDs 214 and 215 are arranged at the positive port 206 and the negative port 207, respectively, the RTDs 214 and 215 may have the same structure or different structures. Furthermore, the voltages applied to the RTDs 214 and 215 and the resonators connected thereto may have the same structure or different structures.

[0073] Next, with reference to FIG. 14 , a case where the above-described communication device 101 is applied to a communication system will be described. The communication system may be configured using a superheterodyne system or a direct conversion system, using a simple ASK modulation method or the like. A superheterodyne communication system includes, for example, an antenna 1400, an amplifier 1401, a mixer 1402, a filter 1403, a mixer 1404, a converter 1405, a digital baseband modulator / demodulator 1406, and local oscillators 1407 and 1408. In the case of a receiving device, a terahertz wave TW received via the antenna 1400 is converted into an intermediate frequency signal by the mixer 1402, and then converted into a baseband signal by the mixer 1404. The analog waveform is converted into a digital waveform by the converter 1405. The digital waveform is then demodulated at the baseband to obtain a communication signal. In the case of a transmitting device, a communication signal is modulated and then converted from a digital waveform to an analog waveform by converter 1405, and then frequency-converted via mixer 1404 and mixer 1402, and output as a terahertz wave from antenna 1400. A direct conversion communication system includes antenna 1400, amplifier 1411, mixer 1412, modulator / demodulator 1413, and local oscillator 1414. In the direct conversion system, during reception, mixer 1412 directly converts the received terahertz wave into a baseband signal, and during transmission, mixer 1412 converts the baseband signal to be transmitted into a terahertz band signal. The other configurations are the same as those of the superheterodyne system. The above-described components of communication device 101 can function as a receiving device and a transmitting device of a communication system such as that shown in FIG. 14.

[0074] The technical ideas derived from this disclosure are not limited to the disclosed exemplary embodiments, but are intended to encompass various modifications to the exemplary embodiments, or the replacement of equivalent structures or functions, etc. The scope of the following claims should be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

[0075] This application claims priority based on Japanese Patent Application No. 2024-150227 filed on August 30, 2024, and Japanese Patent Application No. 2025-053751 filed on March 27, 2025, the entire contents of which are incorporated herein by reference.

Claims

1. A communications device comprising a baseband signal processing unit, an in-phase signal processing unit and a quadrature signal processing unit that modulate or demodulate an input signal, a balanced antenna having a first port and a second port, and a phase compensation unit that outputs a signal obtained by compensating the phase of the input signal, wherein the communications device comprises a first path that connects the baseband signal processing unit and the first port via the in-phase signal processing unit, and a second path that connects the baseband signal processing unit and the second port via the quadrature signal processing unit, wherein the first port and the second port have opposite polarities, and the phase compensation unit is disposed in the baseband signal processing unit, the first path, or the second path.

2. The communication device according to claim 1, wherein the phase compensation unit compensates for the phase of either the signal passing through the first path or the signal passing through the second path.

3. A communication device according to claim 1 or 2, characterized in that the phase compensation unit is arranged in the first path or the second path and inverts the phase of an input signal.

4. The communication device according to claim 3, wherein the phase compensation unit is disposed between the baseband signal processing unit and the in-phase signal processing unit, or between the baseband signal processing unit and the quadrature signal processing unit.

5. A communication device according to claim 3, characterized in that the phase compensation unit is arranged between the in-phase signal processing unit and the first port, or between the quadrature signal processing unit and the second port.

6. The communication device according to claim 5, further comprising a carrier wave generating unit that generates a carrier wave, wherein the in-phase signal processing unit and the quadrature signal processing unit process the signals input thereto in accordance with the carrier wave, and the phase compensation unit is a line having a length that is an odd multiple of half the wavelength of the carrier wave.

7. A communication device according to claim 1 or 2, characterized in that the phase compensation unit is arranged in the baseband signal processing unit and inverts the phase of a signal output from the baseband signal processing unit to the first path and a signal input from the first path to the baseband signal processing unit, or inverts the phase of a signal output from the baseband signal processing unit to the second path and a signal input from the second path to the baseband signal processing unit.

8. The communication device according to claim 7, further comprising a carrier wave generating unit that generates a carrier wave, wherein the in-phase signal processing unit and the quadrature signal processing unit process signals input thereto in accordance with the carrier wave.

9. The communication device according to claim 6 or 8, wherein the carrier wave generating section generates a terahertz wave.

10. The communication device according to any one of claims 6, 8 and 9, wherein the carrier wave generating section includes a resonant tunneling diode or a CMOS inverter.

11. A communications device according to any one of claims 1 to 10, characterized in that, when transmitting a signal, the phase of the signal input to the first port via the first path, based on the phase of the first baseband signal input to the baseband signal processing unit, and the phase of the signal input to the second port via the second path, based on the phase of the first baseband signal, are in an anti-phase relationship; and, when receiving a signal, the phase of the signal input from the first port to the first path, based on the phase of the second baseband signal output from the baseband signal processing unit, and the phase of the signal input from the second port to the second path, based on the phase of the second baseband signal, are in an anti-phase relationship.

12. The communication device according to any one of claims 1 to 11, wherein the balanced antenna includes a patch antenna, a dipole antenna, a slot antenna, or a bowtie antenna.

13. A communication device as described in any one of claims 1 to 12, further comprising at least one of a first backflow prevention unit arranged between the in-phase signal processing unit and the first port, for preventing a signal passing through the second path from being input to the in-phase signal processing unit, and a second backflow prevention unit arranged between the quadrature signal processing unit and the second port, for preventing a signal passing through the first path from being input to the quadrature signal processing unit.

14. The communication device according to any one of claims 1 to 13, further comprising an amplitude compensation unit for compensating for the amplitude of a signal in each of the first path and the second path.

15. A communication device according to any one of claims 1 to 14, characterized in that a resonant tunneling diode is connected to at least one of the first path between the in-phase signal processing unit and the first port and the second path between the quadrature signal processing unit and the second port.

16. The communication device according to claim 15, wherein when the resonant tunneling diode is connected to the first path between the in-phase signal processing unit and the first port, the resonant tunneling diode synchronizes with the in-phase signal processed by the in-phase signal processing unit, and when the resonant tunneling diode is connected to the second path between the quadrature signal processing unit and the second port, the resonant tunneling diode synchronizes with the quadrature signal processed by the in-phase signal processing unit.

17. A communication system comprising a transmitting device and a receiving device, wherein at least one of the transmitting device and the receiving device includes a communication device according to any one of claims 1 to 16.

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