Antenna device, communication device, and imaging system

Abstract

To improve the performance of an antenna device by reducing the phase noise of an oscillator.SOLUTION: An antenna device includes: an active antenna which generates or detects electromagnetic waves and includes an antenna, a semiconductor structure operating as an oscillator, and at least two power lines for providing a potential difference to the semiconductor structure; and a control line which is electrically connected to one of the at least two power lines and into which a signal for controlling a phase of the oscillator in the active antenna is injected.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an antenna device for outputting or detecting electromagnetic waves. [Background technology]

[0002] As a current-injection type light source that generates electromagnetic waves such as terahertz waves, an oscillator that integrates an element with terahertz wave electromagnetic wave gain and a resonator is known. Among these, an oscillator that integrates a resonant tunneling diode (RTD) and an antenna is expected to be an element that operates at room temperature in the frequency range near 1 THz. Patent Document 1 discloses a terahertz wave antenna array in which multiple active antennas, each integrating an RTD oscillator and an antenna, are arranged on the same substrate. In the antenna array of Patent Document 1, a coupling line is used to connect the multiple active antennas to each other, and the multiple active antennas are synchronized with each other in phase to cause them to oscillate. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2014-200065 [Non-patent literature]

[0004] [Non-Patent Document 1] Jpn.J.Appl.Phys.,Vol.47,No.6(2008), pp.4375-4384 [Non-Patent Document 2] J.Appl.Phys.,Vol.103,124514(2008) [Overview of the project] [Problems that the invention aims to solve]

[0005] This invention provides a technology to improve the performance of an antenna device by reducing the phase noise of the oscillator. [Means for solving the problem]

[0006] An antenna device according to one aspect of the present invention includes an antenna, a semiconductor structure that operates as an oscillator, and at least two power lines that provide a potential difference to the semiconductor structure, and an active antenna that generates or detects electromagnetic waves, and a power supply that is electrically connected to one of the at least two power lines and controls the phase of the oscillator in the active antenna. , master from another transmitter It has a control line into which a signal is injected. [Effects of the Invention]

[0007] According to the present invention, the performance of an antenna device can be improved by reducing the phase noise of the oscillator. [Brief explanation of the drawing]

[0008] [Figure 1] (a) A block diagram showing the antenna device 10, (b) A schematic top view showing an example of the configuration of the antenna device 10, and (c) A schematic diagram showing the behavior of the injection synchronization phenomenon. [Figure 2] (a) A diagram showing an example of a 3x3 antenna array, (b) A diagram showing an example of a 4x4 antenna array, (c) A diagram explaining power distribution, and (d) A diagram showing an example of a 3x3 antenna array. [Figure 3] (a) A block diagram showing the antenna device 20, (b) A schematic top view showing a first configuration example of the antenna device 20, and (c) A schematic top view showing a first configuration example of the antenna device 20. [Figure 4] This is a circuit diagram explaining the master oscillator. [Figure 5A] This is a plan view of the first example of an antenna array. [Figure 5B] This is a cross-sectional view of a first example of an antenna array. [Figure 6A] This is a plan view of a second example of an antenna array. [Figure 6B] This is a cross-sectional view of a second example of an antenna array. [Figure 7A] This is a plan view of a third example of an antenna array. [Figure 7B] This is a cross-sectional view of a third example of an antenna array. [Figure 8A] This is a plan view of the fourth example of an antenna array. [Figure 8B] This is a cross-sectional view of a fourth example of an antenna array. [Figure 9] (a) This figure shows an example configuration of a camera system using an antenna device, and (b) an example configuration of a communication system using an antenna device. [Modes for carrying out the invention]

[0009] The embodiments will be described in detail below with reference to the attached drawings. Note that the following embodiments do not limit the invention as defined in the claims. While the embodiments describe multiple features, not all of these features are essential to the invention, and the features may be combined in any way. Furthermore, in the attached drawings, identical or similar configurations are given the same reference numerals, and redundant descriptions are omitted.

[0010] [Embodiment 1] The configuration of the antenna device 10 applicable to terahertz waves according to this embodiment will be described with reference to Figures 1, 2, 4, and 5. In the following description, the case where the antenna device 10 is used as a transmitter will be explained in particular, but it is also possible to use the antenna device 10 as a receiver. Here, terahertz waves refer to electromagnetic waves in the frequency range of 10 GHz to 100 THz, and in one example, electromagnetic waves in the frequency range of 30 GHz to 30 THz.

[0011] Figure 1(a) shows a block diagram illustrating an example of the system configuration of the antenna device 10, and Figure 1(b) shows a schematic top view of the antenna device 10 in one example. The antenna device 10 consists of n active antennas AA1~AA arranged in an array.n The active antenna AA1 is composed of an antenna array 11, a bias control unit 12, and a master wave source (hereinafter sometimes referred to as "master oscillator 13"). The bias control unit 12 and master oscillator 13 may be provided outside the antenna array 11. The active antenna AA1 integrates at least one antenna AN1 and a semiconductor RTD1 which is an oscillation source, and has an oscillation frequency f THz It is configured to emit terahertz waves TW. Note that among the active antenna AA1, the components other than the semiconductor RTD1 which is the oscillation component may be considered as antenna AN1, or for example, the antenna conductor alone or a combination of the antenna conductor and a ground (GND) conductor may be considered as antenna AN1. Other active antennas AA2~AA n The same applies to the following. As shown in Figure 1(b), a rectangular patch antenna can be used as an example of antenna AN. However, this is just one example, and antennas of shapes other than rectangular patch antennas may be used, as long as they can output electromagnetic waves in a predetermined frequency band, such as the terahertz band. Figure 1(b) shows an example of a configuration in which nine patch antennas are arranged in a 3x3 matrix. Semiconductor RTD1~RTD of each active antenna n This includes a semiconductor structure for generating or detecting terahertz waves. In this embodiment, an example using a resonant tunneling diode (RTD) as this semiconductor structure will be described. Note that the semiconductor structure here is not limited to RTDs and only requires a semiconductor having electromagnetic wave gain or carrier nonlinearity (nonlinearity of current due to voltage change in current-voltage characteristics) for terahertz waves. Therefore, in the following description, semiconductor RTDs 1 to RTDs will be used. n This is sometimes described as the semiconductor layer 100. The bias control unit 12 controls the semiconductor RTD1~RTD n This is a power supply for controlling the bias signal applied to the semiconductor RTD1~RTD n It is electrically connected to the semiconductor RTD1~RTD. nis configured to apply a bias signal. That is, the semiconductor RTDs 1 to RTD n There are at least two power supply lines for supplying power to n . One of the at least two power supply lines is a line for supplying power to the semiconductor at a frequency up to about 10 GHz, and is realized by a microstrip line or a coplanar line. Another one of the power supply lines is a line into which a master signal emitted by the master oscillator 13 from 10 GHz to terahertz waves is injected. Also, the semiconductor RTD is connected to a ground conductor or the like, and this ground conductor can also be said to be a power supply line that gives a potential difference to the semiconductor RTD. Also, wiring other than these may be used as a power supply line that gives a potential difference to the semiconductor RTD. For example, the semiconductor RTD may be connected to a ground conductor and further connected to two or more power supply lines that give different potential differences, and any one of the two or more power supply lines may be turned on and the other power supply lines may be turned off. That is, regarding the power supply lines connected to the semiconductor RTD, the number and manner thereof are not limited.

[0012] FIG. 4(a) is a circuit diagram for explaining the master oscillator 13 that is connected to the active antennas AA1 and AA2 and injects a master signal. Note that the other active antennas AA3 to AA9 also have the same configuration. The active antenna AA1 is an oscillator in which the negative resistance -r of the semiconductor RTD1 and the impedance Z of the antenna AN1 are connected in parallel. The impedance Z includes a resistance component and an LC component resulting from the structure of the antenna AN1. Also, a bias control unit 12 for supplying a bias signal to the semiconductor RTD1 is connected in parallel with the semiconductor RTD1 via a power supply line. Note that the active antenna AA2 also has the same configuration. The bias control unit 12 supplies the current necessary for driving the semiconductor RTDs 1 and RTD2 and adjusts the bias signals applied to the semiconductor RTDs 1 and RTD2. When an RTD is used as the oscillator, the bias signal is selected from the voltage in the differential negative resistance region of the RTD.

[0013] The master oscillator 13 is a wave source for synchronizing the timing of terahertz waves, and its oscillation frequency f of the terahertz waves THz It outputs an electrical signal with a subharmonic frequency that is 1 / 2N (where N is a natural number) times the original frequency. In other words, the master oscillator 13 outputs a signal with a frequency that is an even fraction of the oscillation frequency of the oscillator in the active antenna, according to the bias given by the bias control unit 12.

[0014] The relationship between the master oscillator 13 and the active antenna oscillators (semiconductor RTDs) is such that the master oscillator 13 is the master and the active antennas are the slaves. In other words, the active antennas operate in accordance with the signal waveform output by the master oscillator 13. The master oscillator 13 outputs a signal with greater power than the output of the active antennas acting as slaves. In one example, the power injected from the master oscillator 13 to each RTD is P, which is the power of the output signal of a single RTD. RTD It can be set to be greater than or equal to ((3 / 16)cos(ωτ)·ΔIΔV). In one example, the power injected from the master oscillator 13 to each RTD can be set to be 10 times or more the power of the output signal of a single RTD. Here, P RTD ω is the output of one RTD, where ω is the angular frequency of the electrical signal output by the RTD, and τ is the carrier travel time within the semiconductor layer (RTD). ΔI and ΔV represent the current difference and voltage difference between the current peak and current valley in the negative resistance region of the RTD, respectively. For example, in Figure 4(a), when the master oscillator 13 injects the master signal into two active antennas AA1 and AA2, P is applied to RTD1 and RTD2 respectively. RTD A power of ((3 / 16)cos(ωτ)·ΔIΔV) or more may be input. Therefore, when the master oscillator 13 injects power to the two RTDs, 2·P RTDIn addition to ((3 / 16)cos(ωτ)·ΔIΔV), the output power can also include the power lost from the master oscillator 13 to each RTD. In one example, the length of the path from the master signal output from the master oscillator 13 to each RTD can be configured to be within 20 wavelengths of the wavelength of the master oscillator 13. By imposing such constraints, it is possible to ensure that the master signal reaches the RTD with sufficient power.

[0015] The master oscillator 13 connects to the semiconductor RTD1 of the active antenna AA1 via control lines IL1 and RL1 and capacitance C1, and injects the master signal. A stub S1 is connected to port 1 between control lines IL1 and RL1, and the stub S1 is connected to capacitance C 1S It is grounded to the earth (GND) via this, and becomes a short stub. Capacitance C 1S An active antenna can be designed to have low impedance in the frequency band of the electrical signal output from the active antenna (e.g., the terahertz band). In the following, it is assumed that the oscillation frequency of the oscillator in the active antenna is in the terahertz band, and that the electrical signal output by the active antenna is a terahertz wave. That is, the terms "terahertz band" and "terahertz wave" used below refer to the oscillation frequency of the oscillator in the active antenna and the electromagnetic wave of that frequency. Note that terahertz waves are just one example of electromagnetic waves, and the following discussion can be applied to antenna devices in frequency bands other than the terahertz band. Capacitance C 1S For example, at 0.5 THz, it is designed to be around 0.01 to 0.1 pF. Furthermore, the stub S1 is set to frequency f THzThe length of the control line IL1 can be set to one-quarter of the wavelength of the terahertz wave. In this case, the terahertz wave becomes open at port 1. Therefore, the master signal can be injected into the semiconductor RTD1 without the control line IL1 affecting the terahertz wave. Also, the control line RL1 can be set to one-quarter of the wavelength of the terahertz wave, in which case the terahertz wave becomes open at port 1. Therefore, the control line RL1 functions as a resonator for the semiconductor RTD1 together with the antenna AN. Note that the stub S1 may be omitted.

[0016] The semiconductor RTD1 of active antenna AA1 synchronizes with the timing according to the injected master signal. For example, as shown in Figure 1(c), the semiconductor RTD1 outputs a terahertz wave, and the timing at which the amplitude of the terahertz wave becomes zero coincides with the master signal. The same applies to active antenna AA2. When synchronizing active antennas AA1 and AA2, capacitors C1 and C2 are made to have the same structure, and the difference in the electrical length of control lines IL1 and IL2 is made to an integer multiple of the wavelength of the master oscillator 13. As a result, for example, the timing at which the amplitude of the master signal becomes zero is the same for each active antenna, thus establishing synchronization between these active antennas. Note that in one example, the values ​​of capacitors C1 and C2 are around 1 fF to several tens of pF, and can be about 1 / 10 to 10 times the negative resistance of the semiconductor RTD.

[0017] Figures 1 and 4(a) show an example where the antenna device 10 has only one master oscillator 13, but the master oscillator 13 is not limited to one. For example, as shown in Figures 2(a) and (b), the antenna device 10 may have multiple master oscillators 13 that are synchronized with each other. The subharmonic frequency f is the frequency of the master oscillator 13. sub The frequency f of terahertz waves THzThe frequency is lower. Furthermore, oscillators with frequencies lower than terahertz waves can achieve higher phase accuracy. Therefore, by using a relatively low-frequency oscillator capable of high phase accuracy as the master oscillator 13, terahertz waves can be synchronized with high precision. As the master oscillator 13, for example, an oscillator obtained by stabilizing a transistor oscillator in the millimeter-wave band with high precision using a phase-locked loop (PLL) circuit can be used. In one example, the master oscillator 13 is constructed using a semiconductor heterostructure, a semiconductor multilayer structure, a resonant tunnel diode, and a negative resistance diode.

[0018] As shown in Figure 2(a), synchronization can be established between multiple master oscillators 13 by electrically connecting them with control lines. In Figure 2(a), three master oscillators 13 are provided. Each of these master oscillators 13 distributes the master signal to three active antennas located in different columns of a matrix of active antennas. The subscript attached to the reference number "13" that refers to a master oscillator is a code that specifies the active antenna to which that master oscillator 13 supplies the master signal. For example, master oscillator 13 123 The master signal is supplied to the active antennas AA1-AA3. Similarly, the master oscillator 13 456 This supplies the master signal to the active antennas AA4~AA6 and the master oscillator 13 789This supplies the master signal to active antennas AA7 to AA9. The same applies to the other drawings. The distributed master signal is injected into the semiconductor RTD contained in each of the multiple active antennas AA, and the electrical length of each control line IL is set so that they are in phase at each point. Note that Figure 2(a) shows an example in which one master oscillator 13 supplies the master signal to active antennas arranged in vertical columns in a matrix of active antennas, but it is not limited to this. For example, a configuration in which one master oscillator 13 supplies the master signal to active antennas arranged in horizontal columns may be used.

[0019] Figure 2(b) shows an example where the active antennas are arranged in a 4x4 matrix. In the example in Figure 2(b), four master oscillators 13 1256 , 13 3478 , 13 9101314 , and 13 11121516 However, each of these master oscillators supplies a master signal to the four corresponding active antennas. These four master oscillators are electrically connected to, for example, a master oscillator 13 that supplies a reference master signal via control lines, and are configured to synchronize with each other. Note that the central master oscillator 13 in Figure 2(b) may be omitted, and a configuration in which the four master oscillators are electrically connected to each other via control lines to establish synchronization may be used. In one example, each master oscillator may be positioned so that it is at an equal distance from each of the four active antennas to which the master signal is supplied. That is, each master oscillator may be configured so that the master signal distributed to each active antenna is injected into the semiconductor RTD with equal power and in phase.

[0020] Here, using Figure 2(c), we will explain an example in which a master signal is injected with power P into the semiconductor RTD of each active antenna AA. Note that Figure 2(c) is a diagram showing the configuration from Figure 2(b) with the bias control unit 12 removed for illustrative purposes. As shown in Figure 2(c), for example, the master oscillator 13 1256This supplies the master signal to the active antennas AA1, AA2, and AA5, AA6. At this time, the master oscillator 13 1256 For example, a master signal is output to active antennas AA1 and AA5 via a common first control line, and then the master signal is equally distributed to active antennas AA1 and AA5 via a branch line. Also, the master oscillator 13 1256 For example, the master signal can be output to active antennas AA2 and AA6 via a second control line different from the first control line. Subsequently, the master signal is equally distributed to active antennas AA1 and AA5 via a branch line. At this time, the master oscillator 13 1256 This system outputs a master signal with power 2·P to the first and second control lines, respectively, thereby supplying a master signal with power P to each of the active antennas AA1, AA2, AA5, and AA6. Here, the electrical length of each injection line IL is set to be in phase at the position of the semiconductor RTD of each active antenna into which the master signal is injected. Although this description explains a design in which equal-power master signals are supplied at the position of the semiconductor RTD of each active antenna, it is possible to synchronize each active antenna even if the powers are not equal.

[0021] The above example describes a case where multiple master oscillators are used, each supplying a master signal to an active antenna, but it is not limited to this. For example, as shown in Figure 2(d), even if multiple master oscillators 13 are provided, only a portion of them (one in the example of Figure 2(d)) may supply a master signal to the active antenna. For example, in the example of Figure 2(d), there are two master oscillators 13. L and 13 H This shows an example configuration in which a master oscillator 13 is provided. L The frequency of the master oscillator 13 that supplies the master signal to the active antenna H It is lower than the frequency of the master oscillator 13. LTherefore, a high-precision signal source using a phase-locked loop (PLL) in the millimeter-wave or microwave region can be used. For this reason, a master oscillator 13 that outputs a relatively high-frequency master signal can be used. H This improves the phase accuracy and makes it possible to realize oscillators with low phase noise in the terahertz band.

[0022] (Implementation example) Next, the structure and configuration of the antenna device 10 described above will be explained using Figures 5A and 5B. Figure 5A is a schematic top view of the antenna array 11 in which nine active antennas AA1 to AA9 are arranged in a 3x3 matrix, and Figure 5B is a cross-sectional view of the antenna array 11 at A-A', B-B', C-C', and D-D' shown in Figure 5A. The antenna array 11 operates at frequency f THz This is an element that emits or detects terahertz waves and is constructed using semiconductor materials. In this embodiment, an antenna array 11 is described using as an example an antenna array in which nine active antennas AA1 to AA9 are arranged in a 3x3 matrix, but it is not limited to this. For example, the active antennas may be arranged in a straight line or in other forms. Also, the number of active antennas is not limited to nine, and even when arranged in a matrix, they may be arranged in a form other than 3x3. The active antennas AA1 to AA9 serve as both a resonator that resonates with terahertz waves and a radiator that transmits or receives terahertz waves. In the antenna array 11, each active antenna may be arranged at a pitch (spacing) that is less than or equal to the wavelength of the detected or generated terahertz wave, or an integer multiple of that wavelength. In the following description, in order to more generalize the semiconductor RTD, which is a semiconductor structure for generating or detecting terahertz waves, it will be referred to as a semiconductor layer 100. In addition to the semiconductor structure described above, the semiconductor layer 100 may also include electrodes for ohmic bonding to the semiconductor structure and electrode layers for connecting to the upper and lower wiring layers.

[0023] Each of the active antennas AA1 to AA9 has a similar configuration. Therefore, in the following, when it is not necessary to distinguish between the active antennas AA1 to AA9, the term "active antenna AA" will be used as a general term. In other words, the configuration of "active antenna AA" described below applies to each of the active antennas AA1 to AA9 that constitute the antenna array 11.

[0024] (Regarding active antennas) As shown in Figure 5B, the active antenna AA is composed of a substrate 110, a conductor layer 109, a conductor layer 101, and dielectric layers 104-106. As shown in Figure 5B, the substrate 110, conductor layer 109, and conductor layer 101 are stacked in that order, and the dielectric layers 104-106 are located between the two conductor layers (wiring layers) of conductor layer 109 and conductor layer 101. The dielectric layers 104-106 are arranged in the order of dielectric layer 106, dielectric layer 105, and dielectric layer 104 from the conductor layer 109 side. The antenna configuration shown in Figure 5B is called a microstrip type antenna, which uses a microstrip line of finite length. Here, we will explain an example using a patch antenna, which is a microstrip type resonator. Conductor layer 101 is the patch conductor (upper conductor of the patch antenna) of the active antenna AA, which is arranged to face conductor layer 109 via dielectric layers 104-106. The conductor layer 109 is an electrically grounded ground conductor (ground conductor, GND conductor) and also a reflector layer. In the active antenna AA, the width of the conductor layer 101 in the A-A' direction (resonance direction) is λ THz It is configured to operate as a resonator of magnitude 2. THz λ0 is the effective wavelength of the terahertz wave resonating in the dielectric layers 104-106 of the active antenna AA. λ0 is the wavelength of the terahertz wave in a vacuum, and ε is the effective relative permittivity of the dielectric layer 104. r Therefore, λ THz =λ0×ε r -1 / 2 It is expressed as follows.

[0025] The active antenna AA has a semiconductor structure which is a semiconductor layer 100. The semiconductor layer 100 corresponds to RTD1 to RTD9 in Figure 1, and as described above, in this embodiment it is a resonant tunneling diode (RTD). An RTD is a typical semiconductor structure that has electromagnetic wave gain in the terahertz frequency band and is also called an active layer. For this reason, the semiconductor layer 100 may be referred to as "RTD" below. The RTD has a resonant tunnel structure layer composed of multiple tunnel barrier layers, with quantum well layers provided between the multiple tunnel barriers, and has a multiple quantum well structure that generates terahertz waves by inter-subband transitions of carriers. In the differential negative resistance region of the current-voltage characteristics, the RTD has electromagnetic wave gain in the terahertz frequency region based on the photon-assisted tunneling phenomenon, and self-oscillates in the differential negative resistance region.

[0026] The semiconductor layer 100 is electrically connected to the conductor layer 101. The semiconductor structure is, for example, a mesa-type structure, and the semiconductor layer 100 includes electrodes (ohmic or Schottky) that contact this semiconductor structure and electrode layers for connecting to the upper and lower wiring layers. The semiconductor layer 100 is located inside the active antenna AA and is configured for oscillating or detecting terahertz waves. The semiconductor layer 100 is composed of a semiconductor layer having electromagnetic wave gain or nonlinearity with respect to terahertz waves.

[0027] The active antenna AA is an active antenna that integrates a semiconductor layer 100 and a patch antenna (antenna AN). The frequency f of the terahertz wave emitted from the active antenna AA alone is THz This is determined by the resonant frequency of the fully parallel resonant circuit, which combines the reactance of the patch antenna and the semiconductor layer 100. Specifically, from the equivalent circuit of the oscillator described in Non-Patent Literature 1, for a resonant circuit combining the RTD and the admittance of the antenna (YRTD and Yaa), the frequency that satisfies the amplitude condition of equation (1) and the phase condition of equation (2) is the oscillation frequency f. THz It will be decided as such. Re[YRTD]+Re[Y11]≦0 (1) Im[YRTD]+Im[Y11]=0 (2) Here, YRTD is the admittance of semiconductor layer 100, where Re is the real part and Im is the imaginary part. Since semiconductor layer 100 contains an RTD, which is a negative resistive element, Re[YRTD] has a negative value. Also, Y11 represents the admittance of the entire structure of the active antenna AA1 as seen from semiconductor layer 100.

[0028] Furthermore, a quantum cascade laser (QCL) structure with a multilayer semiconductor structure of several hundred to several thousand layers may be used as the semiconductor layer 100. In this case, the semiconductor layer 100 is a semiconductor layer containing the QCL structure. Alternatively, negative resistance elements such as Gunn diodes and INPAT diodes, which are commonly used in the millimeter-wave band, may be used as the semiconductor layer 100. Alternatively, high-frequency elements such as transistors terminated at one terminal may be used as the semiconductor layer 100, and examples of transistors that can be used include heterojunction bipolar transistors (HBTs), compound semiconductor layer FETs, and high electron mobility transistors (HEMTs). Alternatively, the differential negative resistance of a Josephson element using a superconductor layer may be used as the semiconductor layer 100. In other words, the semiconductor layer 100 does not have to be an RTD; any semiconductor structure with similar characteristics may be used as long as it is a semiconductor structure for generating or detecting electromagnetic waves in a predetermined frequency band. Furthermore, while an RTD is used here as a configuration suitable for terahertz waves, an antenna array corresponding to electromagnetic waves of any frequency band may be realized by a configuration as described in this embodiment. In other words, the semiconductor layer 100 in this embodiment is not limited to an RTD that outputs terahertz waves, but can be formed using a semiconductor capable of outputting electromagnetic waves of any frequency band.

[0029] Microstrip-type resonators, such as patch antennas, benefit from thicker dielectric layers, which reduce conductor losses and improve radiation efficiency. Dielectric layers 104-106 are required to be thick (typically 3 μm or thicker), have low loss and low dielectric constant in the terahertz band, and be easily microfabricated (planarization and etching). While increased dielectric thickness improves radiation efficiency, excessive thickness can lead to multimode resonance. Therefore, the dielectric layer thickness can be designed to be limited to 1 / 10 or less of the oscillation wavelength. Furthermore, increasing the frequency and power output of oscillators requires miniaturization and high current density of the diodes; therefore, the dielectric layer, as an insulating structure for the diodes, must also suppress leakage current and migrating. To satisfy these two requirements, dielectric layers 104-106 may be made of different materials.

[0030] The dielectric layer 104 is made of BCB (benzocyclobutene, manufactured by Dow Chemical, ε) as its material. r1 Organic dielectric materials such as polytetrafluoroethylene and polyimide can be used. Here, ε r1 is the relative permittivity of the first dielectric layer 104. Furthermore, inorganic dielectric materials such as TEOS oxide film or spin-on-glass, which can form relatively thick films and have low dielectric constants, may be used for the first dielectric layer 104. In addition, dielectric layers 105-106 are required to have insulating properties (the property of behaving as an insulator or high resistive material that does not conduct electricity to a DC voltage), barrier properties (the property of preventing diffusion of metal materials used in electrodes), and processability (the property of being processable with submicron precision). As a material that satisfies these requirements, for example, silicon oxide (ε r2 =4), silicon nitride (ε r2 =7), inorganic insulating materials such as aluminum oxide and aluminum nitride are used. ε r2 This is the relative permittivity of dielectric layers 105 and 106.

[0031] Here, as in this embodiment, when the dielectric layers 104 to 106 are in a multilayer configuration, the relative permittivity ε of the dielectric layers 104 to 106 r The thickness of the dielectric layer 104 and the relative permittivity εr1 and the thickness of the dielectric layer 105-106 and the relative permittivity ε r2 This is the effective relative permittivity determined from the above. Also, from the perspective of impedance matching between the antenna and space, in order to reduce the difference in dielectric constant between the antenna and air, dielectric layer 104 is made of a different material from dielectric layers 105-106 and has a low relative permittivity (ε r1 <ε r2 Materials such as the above may be used. In addition, the dielectric layer in the antenna device 10 does not need to be a multilayer structure, and may be composed of only one layer of the above-mentioned materials.

[0032] The semiconductor layer 100 is placed on top of a conductor layer 109 formed on a substrate 110. The semiconductor layer 100 and the conductor layer 109 are electrically connected. To reduce ohmic losses, the semiconductor layer 100 and the conductor layer 109 can be connected with low resistance. A via 103 is placed on the side of the semiconductor layer 100 opposite to the side where the conductor layer 109 is located, and the via 103 is electrically connected to the semiconductor layer 100. The semiconductor layer 100 is embedded in a dielectric layer 106 and is surrounded by the dielectric layer 106.

[0033] The semiconductor layer 100 includes an ohmic electrode, which is a conductor that makes an ohmic connection with the semiconductor, in order to reduce ohmic losses and RC delay caused by series resistance. The material of the ohmic electrode can be, for example, Ti / Au, Ti / Pd / Au, Ti / Pt / Au, AuGe / Ni / Au, TiW, Mo, ErAs, etc. Note that these material names are based on elemental symbols, and the substances represented by each symbol will not be explained in detail here. The same applies to the following explanation. Furthermore, by using a semiconductor doped with a high concentration of impurities in the region where the semiconductor and the ohmic electrode are in contact, the contact resistance can be lowered, thereby achieving higher power output and higher frequencies. As the semiconductor layer 100, the absolute value of the negative resistance, which indicates the magnitude of the gain of an RTD used in the terahertz wave band, is generally on the order of 1 to 100 Ω; therefore, the electromagnetic wave loss can be configured to be kept below 1% of that value. Accordingly, the contact resistance of the ohmic electrode can be suppressed to 1 Ω or less as a guideline. Furthermore, in order to operate in the terahertz wave band, the semiconductor layer 100 is formed to have a width of approximately 0.1 to 5 μm as a typical value. Therefore, the contact resistance has a resistivity of 10 Ω·μm 2 The following configuration is used to suppress the impedance to a range of 0.001 to several ohms.

[0034] Furthermore, the semiconductor layer 100 may also include a metal (Schottky electrode) that is not ohmic but rather Schottky-connected. In this case, the contact interface between the Schottky electrode and the semiconductor exhibits rectification, and the active antenna AA can be used as a terahertz wave detector. The configuration using an ohmic electrode will be described below.

[0035] As shown in Figure 5B(1), the interior of the active antenna AA is constructed by stacking layers in the following order: substrate 110, conductor layer 109, semiconductor layer 100, via 103, and conductor layer 101. Via 103 is formed inside dielectric layers 104-106, and the conductor layer 101 and semiconductor layer 100 are electrically connected via via 103. If the width of conductor 103 is too large, it will degrade the resonant characteristics of the patch antenna and reduce radiation efficiency due to increased parasitic capacitance. Therefore, the width of conductor 103 should be such that it does not interfere with the resonant field, typically at the constant oscillation frequency f of the active antenna AA. THz The conductor can be configured to have an effective wavelength λ of terahertz waves that is less than 1 / 10 of the effective wavelength λ. Furthermore, the width of the conductor 103 can be small enough not to increase the series resistance, and as a guideline, it can be reduced to about twice the skin depth. Considering the need to reduce the series resistance to no more than 1Ω, the width of the conductor 103 is typically in the range of 0.1μm to 20μm.

[0036] In Figure 5B (2), the conductor layer 101 is electrically connected to the wiring 108 via vias, and the wiring 108 is electrically connected to the bias control unit 12 via a bias wiring layer 102, which is a common wiring formed within the chip. The bias control unit 12 may also be called a power supply circuit. The wiring layer 102 is located between the dielectric layer 104 and the dielectric layer 105. The wiring 108 is drawn out from each of the antennas. The bias control unit 12 is a power supply for supplying bias signals to the semiconductor layer 100 of the active antenna AA. Therefore, bias signals are supplied to the semiconductor layer 100 of each antenna by connecting the wiring layer 102 and the wiring 108 drawn out from each of the adjacent antennas. Because the bias wiring layer 102 is common, a sufficient wiring width can be secured, which reduces variations in operating voltage between antennas caused by variations in wiring resistance, thus stabilizing synchronization even when the number of arrays increases. In addition, it becomes possible to make the structure around the antennas symmetrical, and the radiation pattern does not become distorted.

[0037] The via 107 connecting the conductor layer 101 and the wiring 108 is a connection point for electrically and mechanically connecting the wiring 108 to the conductor layer 101. This structure, which electrically connects upper and lower layers, is called a via. In addition to their role as components of the patch antenna, the conductor layers 109 and 101 also serve as electrodes for injecting current into the semiconductor layer 100, which is the RTD, by being connected to these vias. In this embodiment, a material with a resistivity of 1 × 10⁻⁶ Ω·m or less may be used as the via. Specifically, metals and metal compounds such as Ag, Au, Cu, W, Ni, Cr, Ti, Al, AuIn alloy, and TiN can be used as materials.

[0038] The width of the via 107 connecting the conductor layer 101 and the wiring 108 is smaller than the width of the conductor layer 101. Here, the width of the conductor layer 101 refers to its width in the electromagnetic wave resonance direction (i.e., the A-A' direction) within the active antenna AA. Also, the width of the portion of the wiring 108 connected to via 107 (the connection point) is smaller (thinner) than the width of the conductor layer 101 (active antenna AA). Furthermore, these widths are relative to the oscillation frequency f present in the active antenna AA. THz The effective wavelength λ of the terahertz wave can be set to 1 / 10 or less (λ / 10 or less). This is because the radiation efficiency can be improved by positioning via 107 and wiring 108 to a size and position that does not interfere with the resonant electric field in the active antenna AA.

[0039] Furthermore, the position of via 107 is fixed at the oscillation frequency f of the active antenna AA. THz It can be placed at the nodes of the electric field of the terahertz wave. In this case, via 107 and wiring 108 are at the oscillation frequency f THz In the vicinity of the frequency band, the impedance is configured to be sufficiently higher than the absolute value of the differential negative resistance of the semiconductor layer 100, which is the RTD. In other words, via 107 and wiring 108 are configured to have an impedance that is sufficiently higher than the absolute value of the differential negative resistance of the semiconductor layer 100. THz In this configuration, the active antenna AA is connected to the RTD in such a way that it has a high impedance. In this case, the active antenna AA has a frequency of f THzIn this configuration, the path via the bias wiring layer 102 is isolated. As a result, the oscillation frequency f induced in each active antenna is transmitted via the wiring layer 102 and the bias control unit 12. THz The current does not affect adjacent antennas. Also, the oscillation frequency f remains constant within the active antenna AA. THz Interference between the electric field and these power supply components is suppressed.

[0040] The bias wiring layer 102 is a common bias wiring for multiple active antennas AA. The bias control unit 12 is located outside the chip to supply bias signals to the semiconductor layer 100 of each antenna. The bias control unit 12 includes a stabilization circuit for suppressing low-frequency parasitic oscillations. The stabilization circuit is set to have an impedance lower than the absolute value of the negative resistance corresponding to the gain of the semiconductor layer 100 in the frequency band from DC to 10 GHz. For stabilization at relatively high frequencies of 0.1 to 10 GHz, an AC short is provided for each active antenna, as shown in (3) of Figure 5B, by connecting a TiW resistive layer 127 and a MIM (Metal-insulator-Metal) capacitor 126 in series. In this case, the MIM capacitor 126 has a large capacitance within the aforementioned frequency range, and in one example, it has a capacitance of several pF. The MIM capacitor 126 in this embodiment uses a structure in which a part of the dielectric layer 106 is sandwiched between a conductor layer 113 and a conductor layer 109 which is GND.

[0041] In this embodiment, focusing on the active antenna AA1, for example, as shown in Figure 5A, a master signal is injected from the bias control unit 13 to port 1 via the control line IL. In the example in Figure 5A, the stub 125 is configured to extend from port 1 to the opposite side of the semiconductor layer 100. Here, the stub 125 is set to a length of one-quarter of the wavelength of the terahertz wave and is grounded via the MIM capacitor 126. The master signal injected into port 1 is then injected into the semiconductor RTD 100 via the control line RL, which extends to the opposite side of the stub 125. The length of the control line RL is designed to be one-quarter of the wavelength of the terahertz wave so that it acts as a resonator for the semiconductor RTD. As shown in Figure 5B(2), the control line IL is installed between the dielectric layer 105 and the dielectric layer 106 so that the master signal can be injected into each active antenna. Furthermore, as shown in (4) of Figure 5B, the stub 125 and control line RL are also positioned between the dielectric layer 105 and the dielectric layer 106, and branch off from the control line IL to the stub 125 and control line RL. Note that in (4) of Figure 5B, the control line IL, control line RL, and stub 125 are shown separately for explanatory purposes, but these are a series of conductors and are not necessarily separated as shown in the figure. The stub 125 is connected to the conductor layer 113 and grounded to the conductor layer 109, which is GND, via the MIM capacitance 126. Also, as shown in (1) and (4) of Figure 5B, the control line RL is connected to the via 103 and configured to inject the master signal into the semiconductor layer 100.

[0042] (Regarding antenna arrays) The antenna array 11 in Figure 5A has a configuration in which nine active antennas AA1 to AA9 are arranged in a 3x3 matrix, and each of these active antennas operates at a frequency f THzThe terahertz waves are emitted individually. Note that the number of active antennas is not limited to nine; for example, 16 active antennas may be arranged in a 4x4 matrix, or 15 active antennas may be arranged in a 3x5 matrix. In this case, as described above, each active antenna AA contains an oscillator such as a semiconductor layer 100 including an RTD, and when these oscillators operate independently, multiple active antennas may output electromagnetic waves with different phases. In this case, the electromagnetic waves may weaken each other, and it is conceivable that the antenna characteristics cannot be fully obtained. In contrast, in this embodiment, the phase of the oscillators in each active antenna can be synchronized with high precision by injecting a master signal, making it possible to improve the gain of the antenna array.

[0043] (Specific materials and structural dimensions) A specific example of the antenna array 11 will be described. The antenna array 11 is a semiconductor device capable of single-mode oscillation in a frequency band of 0.45 to 0.50 THz. The substrate 110 is a semi-insulating InP substrate. The semiconductor layer 100 is composed of a lattice-matched InGaAs / AlAs multiple quantum well structure on the substrate 110, and in this embodiment, a double-barrier RTD is used. This is also called a semiconductor heterostructure of the RTD. The current-voltage characteristics of the RTD used in this embodiment are measured, with a peak current density of 9 mA / μm 2 The differential negative conductance per unit area is 10 mS / μm 2 The semiconductor layer 100 is formed in a mesa structure and consists of a semiconductor structure containing RTDs and ohmic electrodes for electrical connection with the semiconductor structure. The mesa structure is circular with a diameter of 2 μm, and the magnitude of the differential negative resistance of the RTDs in this case is approximately -30 Ω per diode. In this case, the differential negative conductance of the semiconductor layer 100 containing the RTDs is estimated to be approximately 30 mS, and the diode capacitance is estimated to be approximately 10 fF.

[0044] The active antenna AA is a patch antenna with a structure in which dielectric layers 104-106 are sandwiched between a conductor layer 101, which is a patch conductor, and a conductor layer 109, which is a ground conductor. The conductor layer 101 is a square patch antenna with sides of 150 μm, and the antenna's resonator length (L) is 150 μm. A semiconductor layer 100 containing an RTD is integrated inside the antenna.

[0045] The conductor layer 101, which is a patch conductor, is composed of a metal layer (Ti / Au) mainly consisting of a low resistivity Au thin film. The conductor layer 109, which is a ground conductor, is composed of a Ti / Au layer and a semiconductor layer consisting of an n+-InGaAs layer, and the metal and semiconductor layers are connected by low-resistance ohmic contact. The dielectric layer 104 is made of BCB (benzocyclobutene, manufactured by Dow Chemical). In addition, dielectric layers 105 and 106 are each made of SiO2 with a thickness of 1 μm.

[0046] As shown in Figure 5B(1), around the semiconductor layer 100, the following layers are stacked in order from the substrate 110 side: conductor layer 109, semiconductor layer 100, via 103 made of a conductor containing Cu, and conductor layer 101, and are electrically connected. The RTD, which is semiconductor layer 100, is positioned at a location shifted by 40% (60 μm) of one side of the conductor layer 101 in the resonance direction (i.e., A-A' direction) from the centroid of the conductor layer 101. Here, the position of the RTD in the antenna determines the input impedance when feeding high frequency from the RTD to the patch antenna. As shown in Figure 5B(2), the conductor layer 101 is connected to a wiring layer 108, which is on the same layer as the bias wiring layer 102 placed on the dielectric layer 105, via a via 107 made of Cu. Wiring layers 102 and 108 are formed of metal layers containing Ti / Au stacked on the dielectric layer 105. The wiring layer 108 is connected to the bias control unit 12 via the bias wiring layer 102, which is a common wiring formed within the chip. The active antenna AA is biased to the negative resistance region of the RTD contained in the semiconductor layer 100, thereby setting the frequency f THz It is designed to produce oscillation with a power of 0.2mW at 0.5THz.

[0047] Vias such as vias 103 and 107 are cylindrical structures with a diameter of 10 μm. The wiring layer 108 is composed of a pattern formed of a Ti / Au-containing metal layer with a width of 10 μm and a length of 75 μm in the resonant direction (i.e., the A-A' direction). Via 107 is the center in the resonant direction (i.e., the A-A' direction) and is connected to the conductor layer 101 at its end in the C-C' direction. This connection point is at the frequency f of the active antenna AA1. THz This corresponds to a node in the electric field of a terahertz wave.

[0048] Antenna array 11 is an antenna array in which active antennas are arranged in a matrix. In this embodiment, as an example, an antenna array in which nine active antennas AA1 to AA9 are arranged in a 3x3 matrix is ​​described. Each active antenna operates at a frequency f THz It is designed to emit terahertz waves and is arranged at a 340 μm pitch (spacing) in both the A-A' and C-C' directions.

[0049] (Regarding the manufacturing method) Next, the manufacturing method (fabrication method) for the antenna array 11 will be described.

[0050] (1) First, an InGaAs / AlAs-based semiconductor multilayer structure constituting a semiconductor layer 100 containing an RTD is formed on a substrate 110 made of InP by epitaxial growth. This is formed by methods such as molecular beam epitaxy (MBE) or metal-organic vapor phase epitaxy (MOVPE).

[0051] (2) The ohmic electrode Ti / Au layer constituting the semiconductor layer 100 is formed by sputtering.

[0052] (3) The semiconductor layer 100 is formed into a circular mesa structure with a diameter of 2 μm. Photolithography and dry etching are used to form the mesa shape.

[0053] (4) After a conductor layer 109 is formed on the substrate 110 by the lift-off method on the etched surface, silicon oxide is deposited to form a dielectric layer 106. A Ti / Au layer is formed as a conductor constituting the wiring layer 125 on the dielectric 106. Control lines IL are also formed on the dielectric layer 106. The control lines IL can be implemented in the form of, for example, slot lines, but other types of lines may be used.

[0054] (5) A silicon oxide film is formed to become the dielectric layer 105. Ti / Au layers are formed as conductors that make up the wiring layers 102 and 108 on the dielectric layer 105.

[0055] (6) The dielectric layer 104 is filled and planarized with BCB using the spin coating method and the dry etching method.

[0056] (7) BCB and silicon oxide in the areas where vias 103 and 107 are to be formed are removed by photolithography and dry etching, thereby forming via holes (contact holes).

[0057] (8) Vias 103 and 107 are formed in the via holes by a conductor containing Cu. Formation is carried out by filling the via holes with Cu and planarizing using sputtering, electroplating, or chemical mechanical polishing.

[0058] (9) The electrode Ti / Au layer that will become the conductor layer 101 of each antenna is deposited by sputtering. The conductor layer 101 is patterned by photolithography and dry etching.

[0059] (10) A silicon nitride film is formed to become the dielectric layer 112.

[0060] (11) Finally, the resistive layer 127 and MIM capacitor 126 are formed and connected to the wiring layer 102 and bias control unit 12 by wire bonding or the like, thereby completing the antenna array 11.

[0061] Power to the antenna device 10 is supplied from the bias control unit 12. When a bias voltage, which is normally in the differential negative resistance region, is applied and a bias current is supplied, the antenna device 10 operates as an oscillator.

[0062] [Embodiment 2] In this embodiment, a method for injecting a master signal by a master oscillator 13 in an antenna device 20 in which active antennas are coupled with coupling lines to cause a mutual injection synchronization phenomenon is described. Figure 3 shows the configuration of the antenna device 20. Figure 3(a) is a block diagram illustrating the system configuration of the antenna device 20, and Figures 3(b) and (c) are schematic top views of the antenna device 20 as seen from above.

[0063] As shown in Figure 3(a), the antenna device 20 of this embodiment has coupling lines CL1 to CL between each active antenna, compared to the antenna device 10 of Embodiment 1. n-1 It has a configuration with the addition of the coupling line CL, which has a frequency f osc These are transmission lines for mutual injection synchronization, and active antennas are electrically connected by these coupling lines CL. For example, in an example where active antennas are arranged in a 3x3 matrix as shown in Figures 3(b) and (c), adjacent active antennas are coupled by coupling lines. In one example, two coupling lines CL are used to synchronize active antennas AA1-AA4 in the horizontal direction. 141 and CL 142 These are connected between the active antennas. The same applies to the other active antennas. Here, the coupling line is implemented, for example, as a microstrip line. However, it is not limited to this, and the coupling line may be implemented as a slotted line. By connecting each active antenna with a coupling line, the accuracy of frequency and phase can be improved.

[0064] Fig. 4(b) shows a circuit diagram for explaining the master oscillator 13 that is connected between the active antennas AA1 - AA4 and injects a master signal. As shown in Fig. 4(b), the adjacent active antennas AA1 and AA4 are electrically connected via the coupling line CL 14 Thereby, in the terahertz band, the active antennas AA1 and AA4 are mutually coupled, and it becomes possible to control the frequency and phase. Note that between the active antennas AA1 - AA2 and AA4 - AA5, they are also mutually coupled via other coupling lines in the same manner.

[0065] The coupling line CL 14 includes two lines CL 14a and CL 14b connected in series, and is connected to the active antennas AA1 and AA4 via the capacitors C 14 and C 41 The capacitors C 14 and C 41 function as high - pass filters and are set to capacitors that are short - circuited for electromagnetic waves in the terahertz band and open for electromagnetic waves in the low - frequency band. The connection between the active antennas AA2 and AA5 and the coupling line is the same. Ports 14 and 25 are ports for injecting the master signal from the master oscillator 13 into the coupling lines CL 14 and CL 25 In this embodiment, they are arranged between the lines CL 14a -CL 14b and between the lines CL 25a -CL 25b By making the difference in the electrical lengths of the control lines IL 14 and IL 25 an integer multiple of the master signal wavelength, the phase of the master signal can be aligned in each semiconductor RTD of each active antenna AA. In one example, when the positions of ports 14 and 25 are at the center of the coupling line CL 14 as shown in Fig. 3(b), the master signals injected into each semiconductor RTD are synchronized. Also, as shown in Fig. 3(c), for the coupling line CL 14A configuration may be used in which a master signal is injected at the node positions of the terahertz wave electric field. With this configuration, the phase of the master signal injected into each semiconductor RTD can be made different, and the antenna device 20 can function as a directional antenna.

[0066] (Implementation example) Next, the structure and configuration of the antenna device 10 described above will be explained using Figures 6A and 6B. Figure 6A is a schematic top view of the antenna array 21 in which nine active antennas AA1 to AA9 are arranged in a 3x3 matrix, and Figure 6B is a cross-sectional view of the antenna array 21 at A-A', B-B', and C-C' shown in Figure 6A. Note that a detailed explanation of the configuration similar to that of the antenna device 10 in Embodiment 1 will be omitted below.

[0067] In a configuration like that shown in Figure 6A, adjacent antennas are coupled to each other by a coupling line CL, and the terahertz wave oscillation frequency f THz They are synchronized with each other by the mutual injection synchronization phenomenon. The mutual injection synchronization phenomenon is a phenomenon in which multiple self-excited oscillators interact with each other and synchronize their oscillations. For example, active antenna AA1 and active antenna AA4 are connected by a coupling line CL 14They are mutually connected by [description missing in original], and further, as shown in (1) of FIG. 6B, they are mutually connected via the conductor layer 109. Note that the conductor layer 111 is composed of, for example, Ti / Au. The same applies to other adjacent active antennas. Note that "mutually connected" means a relationship in which the current induced in one active antenna acts on other adjacent active antennas due to this connection, changing their transmission and reception characteristics. By synchronizing the mutually connected active antennas in the same phase or the opposite phase, the mutual injection synchronization phenomenon causes the electromagnetic fields between the active antennas to reinforce or weaken each other. As a result, the increase or decrease of the antenna gain can be adjusted. In this embodiment, when representing the entire coupling line that couples the active antennas, it is denoted as the coupling line CL. Also, for the coupling lines that couple between the antennas constituting the coupling line CL, they are denoted using the numbers and alphabets corresponding to each active antenna. For example, the coupling line that couples the active antenna AA1 and the active antenna AA4 is the coupling line CL 14 is denoted as

[0068] The oscillation conditions of the antenna array 11 are determined by the conditions of mutual injection synchronization in the configuration in which two or more individual RTD oscillators described in Non-Patent Document 2 are coupled. Specifically, consider the oscillation conditions of the antenna array in which the active antenna AA1 and the active antenna AA2 are coupled by the coupling line CL 12 At this time, two oscillation modes occur: mutual injection synchronization in the positive phase and mutual injection synchronization in the negative phase. The oscillation conditions of the oscillation mode of mutual injection synchronization in the positive phase (even mode) are expressed by equations (4) and (5), and the oscillation conditions of the oscillation mode of mutual injection synchronization in the negative phase (odd mode) are expressed by equations (6) and (7). Positive phase (even mode): Frequency f = feven Yeven = Y11 + Y12 + YRTD Re(Yeven) ≦ 0 (4) Im(Yeven) = 0 (5) Negative phase (odd mode): Frequency f = fodd Yodd = Y11 + Y12 - YRTD Re(Yodd)≦0 (6) Im(Yodd)=0 (7) Here, Y12 is the mutual admittance between active antenna AA1 and active antenna AA2. Y12 is proportional to the coupling constant, which represents the strength of the coupling between the antennas, and ideally, the real part of -Y12 is large and the imaginary part is zero. The antenna array 11 in this embodiment is coupled under the condition of mutual injection synchronization in positive phase, and the oscillation frequency f THz It is approximately five. Similarly, for the other antennas, they are coupled at the coupling line CL such that the above-mentioned positive-phase mutual injection synchronization condition is satisfied.

[0069] The bonding line CL is a microstrip line in which dielectric layers 104-106 are sandwiched between conductor layer 111 and conductor layer 109 or conductor layer 102. For example, as shown in (1) of Figure 5B, the bonding line CL 45 This is the conductor layer 111 (CL 45 The dielectric layers 104-106 are sandwiched between the conductive layer 109 or conductive layer 102. Similarly, the bonding line CL 56 This is the conductor layer 111 (CL 56 The dielectric layers 104-106 are sandwiched between a conductive layer 109 or a conductive layer 102.

[0070] The antenna array 11 is an antenna array configured in which each antenna is coupled by AC coupling (AC coupling, capacitive coupling). For example, coupling line CL 45 The conductor layer 111, which is the upper conductor layer, overlaps the conductor layer 101 and dielectric layer 112, which are the patch conductors of the active antennas AA4 and AA5 respectively, in a plan view, and is connected by capacitive coupling. More specifically, the coupling line CL 45 In a plan view, the conductor layer 111 overlaps with the conductor layer 101 by 5 μm, with the dielectric layer 112 in between, near the radiating ends of the active antennas AA4 and AA5, forming capacitive structures C1 and C2. Capacitive structures C1 and C2 are the capacitance C in the circuit diagram of Figure 4(b). 14 and C 41This corresponds to the above. Capacitors C1 and C2 in this configuration function as a high-pass filter, contributing to the suppression of multimode oscillation by short-circuiting the terahertz band and leaving the low-frequency band open. However, this configuration is not a mandatory requirement, and the coupling line CL 45 A DC coupling configuration may be used in which the conductor layer 111 of the antenna and the conductor layer 101 of the active antennas AA4 and AA5 are directly coupled (directly connected). An antenna array synchronized by DC coupling can synchronize adjacent antennas with strong coupling, making it easier to perform synchronization operations by pull-in and robust against variations in the frequency and phase of each antenna. Although the coupling between active antennas AA4 and AA5 has been explained as an example here, the same applies to the coupling between the other active antennas AA1 to AA9.

[0071] In the antenna array 11, the conductor layer 101 of the active antenna AA, the conductor layer 111 of the coupling line CL, and the wiring layer 102 for biasing are arranged on different layers. In this way, high frequencies (f THz The conductor layer 101 of the active antenna AA that transmits the signal and the conductor layer 111 of the coupling line CL are placed on different layers from the bias wiring layer that transmits low frequencies (DC to tens of GHz). This allows for flexible configuration of the width, length, routing, and other layout elements of the transmission lines within each layer. Furthermore, as shown in Figure 5A, when viewed from above (in a plan view), the coupling line CL and the bias wiring layer 102 intersect with each other, resulting in a more space-saving configuration. This allows for an increase in the number of antennas that can be placed, even in antenna arrays where the antennas are arranged in an m × n (m≧2, n≧2) matrix. Additionally, the impedance control of the coupling line CL and the bias control of the semiconductor layer 100 can be performed independently.

[0072] Furthermore, in the terahertz band, resistance due to the skin effect increases, so conductor loss associated with high-frequency transmission between antennas cannot be ignored. Conductor loss per unit length (dB / mm) increases with increasing current density between conductor layers. In the case of microstrip lines, conductor loss per unit length (dB / mm) is inversely proportional to the square of the dielectric thickness. Therefore, in order to increase the radiation efficiency of the antenna array, conductor loss can be reduced not only by increasing the thickness of the antennas but also by increasing the thickness of the dielectric that constitutes the coupling line CL. In contrast, the antenna array 11 of this embodiment has a bias wiring layer 102 arranged in the dielectric layer 105, and the frequency f THz This configuration involves arranging the conductor layer 101 of the antenna, which transmits high frequencies, and the conductor layer 111 of the coupling line CL on top of the dielectric layer 104. This configuration suppresses the decrease in the radiation efficiency of the antenna array due to conductor loss in the terahertz band. From the viewpoint of conductor loss, the thickness of the dielectric constituting the coupling line CL should be 1 μm or more, and in one example, by setting the dielectric thickness to 2 μm or more, the loss due to conductor loss in the terahertz band can be suppressed to about 20%. Similarly, from the viewpoint of conductor loss, a wide gap can be secured in the thickness direction between the conductor layer 111 constituting the coupling line CL and the conductor layers 102 and 109. For the bias wiring layer 102, by setting the dielectric to 2 μm or less, and in one example to 1 μm or less, it can function as a low-impedance line up to the vicinity of the gigahertz band. Furthermore, even when the dielectric is set to a thickness of 2 μm or more, as in this embodiment, by connecting a shunt component consisting of a resistive layer 127 and an MIM capacitor 126 to the bias wiring layer 102, it can function as a low-impedance line and suppress low-frequency oscillation.

[0073] The length of the conductor layer 111 (coupling line CL) is designed to satisfy the phase matching condition in either the lateral direction (magnetic field direction, H direction) or the vertical direction (electric field direction, E direction), or both, when adjacent antennas are connected by a coupling line. The coupling line CL may be designed, for example, to be such that the electrical length between adjacent RTDs is an integer multiple of 2π. That is, the length of the coupling line CL is set such that the length of the path through the coupling line CL when RTDs are connected by the coupling line CL is an integer multiple of the wavelength of the propagating electromagnetic wave. For example, in Figure 6A, the coupling line CL extends in the horizontal direction. 14 The coupling line CL extending in the vertical direction can be designed to have an electrical length of 4π between the semiconductor layers 100 of the active antennas AA1 and AA4. 12 The electrical length between the semiconductor layers 100 of active antennas AA1 and AA2 can be designed to be 2π. Here, the electrical length refers to the wiring length considering the propagation speed of high-frequency electromagnetic waves propagating within the coupling line CL. An electrical length of 2π corresponds to the length of one wavelength of electromagnetic waves propagating within the coupling line CL. With this design, the semiconductor layers 100 of each active antenna AA1 to AA9 are mutually injection-synchronized in positive phase. The error range of the electrical length at which mutual injection-synchronization occurs is ±1 / 4π.

[0074] The conductive layer 111 is formed, for example, in (10) above, by depositing the electrode Ti / Au layer, which will become the conductive layer 111, by sputtering after the silicon nitride film, which will become the dielectric layer 112, has been deposited. Then, the conductive layer 111 is patterned by photolithography and dry etching.

[0075] The active antennas AA1 to AA9 constituting the antenna array 11 are fed by a common bias wiring layer 102 placed between the antennas. By making the bias wiring layer 102, which is a wiring within the chip, common among each antenna, it becomes possible to drive on the same channel, simplifying the driving method. Furthermore, this configuration reduces the number of wires and allows for thicker individual wires, thereby suppressing the increase in wiring resistance that comes with an increase in the number of arrays and the resulting shift in the operating point between antennas. This suppresses the frequency and phase shifts between each antenna caused by an increase in the number of arrays, making it easier to obtain the synchronization effect of the array. Note that the commonality of the bias wiring layer 102 is not an essential configuration. For example, by stacking or miniaturizing multilayer wiring, multiple bias wiring layers 102 may be provided for each antenna, and the system may be configured to provide individual power. In this case, the isolation between each antenna via the bias wiring layer 102 is strengthened, reducing the risk of low-frequency parasitic oscillation. In addition, signal modulation control for each antenna becomes possible through individual control of the bias signal. The bias wiring layer 102 is for the oscillation frequency f THz In the lower frequency range, the configuration can be such that the impedance is lower than the negative resistance of the semiconductor layer 100. Furthermore, it is preferable that the impedance is equal to or slightly less than the absolute value of the combined differential negative resistance of all semiconductor layers 100 connected in parallel within the antenna array 11. This can suppress parasitic oscillations at low frequencies.

[0076] The control line IL is connected to the coupling line CL. For example, as shown in Figure 6A, the coupling line CL is between active antennas AA1 and AA4. 14 A port 14 is provided at the center to which the control line IL is coupled. The control line IL may be formed between the dielectric layer 112 and the dielectric layer 104, as shown in (2) of Figure 6B, and configured to capacitively couple with the conductor layer 111 of the coupling line CL. Note that this is just one example, and the coupling line CL and the control line IL may be configured to be directly coupled. The master signal output from the master oscillator 13 passes through the control line IL, for example, to the port14 In this case, the connecting line CL 14 The signal is injected into the master signal, and active antennas AA1 and AA4 can establish high-precision synchronization based on this master signal. While active antennas AA1 and AA4 have been described here, other active antennas operate similarly with a similar configuration.

[0077] [Embodiment 3] Next, another embodiment of the antenna device will be described using Figures 7A and 7B. Figure 7A is a schematic top view of the antenna array 31 according to this embodiment, and Figure 7B is a cross-sectional view of the antenna array 31 at A-A', B-B', and C-C' shown in Figure 7A.

[0078] In this embodiment, as shown in Figure 7B, a first substrate 151 integrating an antenna array for transmitting and receiving terahertz waves and a semiconductor layer 100 made of a compound semiconductor, and a second substrate 152 including an integrated circuit for controlling the antenna array are joined at a junction surface BS. This configuration is realized by stacking a compound semiconductor antenna substrate including the antenna array and a Si integrated circuit substrate using semiconductor stacking technology. In the antenna array 31, wiring from the second substrate 152 is electrically connected individually to the active antennas AA1 to AA9. The active antenna AA is composed of an antenna conductor layer 101, two semiconductor layers 100a and 100b, a conductor layer 109 (reflector), and dielectric layers 104 and 105. The active antenna AA also includes vias 103a and 103b connecting the antenna 101 and the semiconductor layer 100. In one example, RTDs are used as semiconductor layers 100a and 100b. The two RTDs are positioned opposite each other, centered on the node of the resonant electric field in the active antenna AA. In this configuration, the two RTDs oscillate in a push-pull mode, mutually injecting and synchronously synchronized with each other in a phase-inverted state (out of phase). This configuration, in which the RTDs are arranged symmetrically within the antenna (left-right, up-down, and down-right), makes it easy to obtain improvements in directivity and frontal intensity as the number of arrays increases.

[0079] As shown in (1) of Figure 7B, the semiconductor layer 100 is stacked in the order of lower electrode layer 164, semiconductor structure 162, and upper electrode layer 163 from the conductor layer 109 side, and these are electrically connected. The semiconductor structure 162 is a semiconductor structure that has electromagnetic wave gain or nonlinearity for terahertz waves, and in this embodiment, an RTD is used. The upper electrode layer 163 and lower electrode layer 164 are structures that also serve as electrode layers for connecting the upper and lower contact electrodes (ohmic or Schottky) of the semiconductor structure 162 and the upper and lower wiring layers in order to apply a potential difference or current to the semiconductor structure 162. The upper electrode layer 163 and lower electrode layer 164 can be composed of metallic materials (Ti, Pd, Au, Cr, Pt, AuGe, Ni, TiW, Mo, ErAs, etc.) known as ohmic electrodes or Schottky electrodes, or semiconductors doped with impurities. The upper electrode layer 163 is connected to via 103, and the lower electrode layer 164 is connected to conductor layer 109, thereby applying a potential difference or current to the semiconductor structure 162. Therefore, it can be said that the upper electrode layer 163 and via 103 and the lower electrode layer 164 and conductor layer 109 are connected to two power lines, respectively.

[0080] To apply a bias control signal to the semiconductor layer 100, a bias wiring layer 102 common to all active antennas AA1 to AA9 is provided. As shown in (3) of Figure 7B, vias 107a and 107b arranged for each antenna connect the active antennas AA1 to AA9 to the frequency f THz It is connected at the node position of the resonant electric field. The wiring layer 102 is connected to the MIM capacitance 126 and resistance layer 127, which are arranged for each antenna, and the frequency f THzOther high frequencies are AC shorted to reduce impedance. These configurations suppress multimode oscillation in the array antenna. As shown in (3) of Figure 7B, the bias wiring layer 102 connected to the semiconductor layer 100 of the first substrate 151 is electrically connected to the bias control wiring layer 143 provided in the integrated circuit region 154 of the second substrate 152. The bias wiring layer 102 of the first substrate 151 is electrically connected in the order of via 117, wiring layer 135b, through via 137b, and electrode layer 138b to reach the junction surface BS. The via 117 is formed to penetrate the dielectric layer 105 and is connected to the wiring layer 135b provided in the opening 136b of the conductor layer 109, which is a reflector. The wiring layer 135b is then connected to the junction electrode layer 138b provided in the insulating layer 148 through the through via 137b provided in the compound semiconductor substrate 131. Similarly, on the second substrate 152, the bias control wiring layer 143 is connected in the order of via 141b and bonding electrode layer 139b, reaching the bonding surface BS. When the first substrate 151 and the second substrate 152 are bonded, the electrode layer 138b and electrode layer 139b are connected, thereby creating conductivity between the bias wiring layer 102 of the antenna array and the wiring layer 143 of the integrated circuit region 154. This makes it possible to apply bias control signals to all antennas. The bias signal can be supplied externally to the bias control wiring layer 143 via an application terminal separately provided on the second substrate 152.

[0081] Active antennas AA1 to AA9 have vias 130 for coupling the injection synchronization signal from the master oscillator 13. Via 130 is capacitively coupled to the conductor layer 101 of the active antenna via capacitance C, and the connection between the master oscillator 13 and the active antennas AA is short for the terahertz band and open for the RF band. Via 130 also has a frequency f within the active antennas AA1 to AA9. THz It is connected at the node position of the resonant electric field. As a result, via 130 has a frequency f within the antenna. THzThis results in high impedance for terahertz frequencies and low impedance for subharmonic frequencies, allowing for high efficiency in both terahertz radiation and master signal injection.

[0082] The active antenna AA is electrically connected to the gate of the transistor TRa (MOS-FET) of the master oscillator 13, which is located in the integrated circuit region 154 of the second substrate 152, via a via 130 for master oscillation. The master synchronization via 130, formed in the dielectric layers 104 and 105 of the first substrate 151, is electrically connected in the order of wiring layer 135a, through via 137a, and electrode layer 138a, reaching the junction surface BS. The wiring layer 135a is located in the opening 136a of the conductor layer 109, which is a reflector, and the through via 137a is located in the insulating layer 131. Similarly, the transistor TRa, formed in the integrated circuit region 154 of the second substrate 152, is connected in the order of via 141a formed in the integrated circuit region 154 and the junction electrode layer 139a, reaching the junction surface BS. The first substrate 151 and the second substrate 152 are joined at the junction surface BS, thereby electrically connecting the electrode layer 138a of the first substrate 151 and the electrode layer 139a of the second substrate 152 at the junction surface BS. This allows the active antenna array AA1~AA9 and the transistor TRa for individually controlling each active antenna to conduct, making it possible to apply control signals to each active antenna individually. As described above, each active antenna has a bias structure in which the upper electrode layer 163 and via 103 and the lower electrode layer 164 and conductor layer 109 apply a potential difference from above and below the semiconductor structure 162. The subharmonic signal from the master oscillator 13 is injected into the semiconductor layers 100a and 100b via this path. Therefore, the subharmonic frequency (e.g., f) from the master oscillator 13 is injected into the semiconductor layers 100a and 100b, which consist of RTDs that act as oscillation sources in the active antennas. THz A power signal of ( / 2) is injected, forcing the phase of each active antenna to be controlled.

[0083] Thus, according to the configuration of this embodiment, the harmonics of the terahertz wave (f THzUsing / 2N (where N is a natural number) as the master signal, with frequency f THz This is injected into an active antenna operating at a frequency f. The injection synchronization caused by this master signal injection results in the active antenna's frequency f THz Timing control can be performed in this context, and phase noise can be reduced.

[0084] [Embodiment 4] In the configurations of the embodiments described above, the control line IL to which the master oscillator 13 is connected is electrically connected to the high-potential power line that is biased by the bias control unit 12, among the two power lines that provide a potential difference. In contrast, in this embodiment, the control line IL is electrically connected to the low-potential power line (for example, the ground conductor) among the two power lines that provide a potential difference. A circuit diagram illustrating this configuration is shown in Figure 4(c). Figure 8A is a schematic top view of the antenna array 41 configured in this way, and Figure 8B is a cross-sectional view of the antenna array 41 at the line A-A' shown in Figure 8A. The antenna array 41, as an example, has a configuration similar to the antenna array 31 of Embodiment 3, in which a first substrate 151 integrating semiconductor layers 100 and a second substrate 152 including an integrated circuit for antenna array control are joined at a junction surface BS. The configuration similar to that of the antenna array 31 will not be explained here.

[0085] In this embodiment, as shown in Figure 8B(1), a through-via 137 extending from the master oscillator 13 is connected to the conductor layer 109, which is the reflector layer of the antenna. In this case, by providing a slit 167, the conductor layer 109, which corresponds to the terahertz GND, and the substrate GND layer 165 are electrically isolated. This allows the signal from the master oscillator 13 to be injected into the active antenna with lower noise. Also, as shown in Figure 8B(2), the through-via 137 extending from the master oscillator 13 can be connected to the conductor layer 166 placed on the insulating layer 131. In this case, the master oscillator 13 and the conductor layer 109, which is the reflector layer of the antenna, can be connected by capacitive coupling using a capacitive structure formed by the conductor layer 109 and the conductor layer 166, thereby limiting the bandwidth.

[0086] With this configuration, complex wiring from the master oscillator 13 is unnecessary, and an antenna device with a simple structure that suppresses phase noise can be realized.

[0087] [Embodiment 5] This embodiment describes the case in which any of the antenna devices of the above embodiments is applied to a terahertz camera system (imaging system). The following description will be made with reference to Figure 9(a). The terahertz camera system 1100 has a transmitter 1101 that emits terahertz waves and a receiver 1102 that detects terahertz waves. Furthermore, the terahertz camera system 1100 has a control unit 1103 that controls the operation of the transmitter 1101 and the receiver 1102 based on an external signal, processes an image based on the detected terahertz waves, or outputs it to the outside. The antenna device of each embodiment may be the transmitter 1101 or the receiver 1102.

[0088] Terahertz waves emitted from the transmitter 1101 are reflected by the subject 1105 and detected by the receiver 1102. A camera system having such a transmitter 1101 and receiver 1102 can also be called an active camera system. In a passive camera system without a transmitter 1101, the antenna device of each embodiment described above can be used as the receiver 1102.

[0089] By using the antenna devices of each embodiment that are capable of beamforming, it becomes possible to improve the detection sensitivity of the camera system and obtain high-quality images.

[0090] [Embodiment 6] This embodiment describes the case where any of the antenna devices of the above embodiments are applied to a terahertz communication system (communication device). The following description will be made with reference to Figure 9(b). The antenna device can be used as the antenna 1200 of the communication system. As a communication system, various methods can be envisioned, from a simple ASK method to superheterodyne and direct conversion. A superheterodyne communication system, for example, includes an antenna 1200, an amplifier 1201, a mixer 1202, a filter 1203, a mixer 1204, a converter 1205, a digital baseband modulator / demodulator 1206, and local oscillators 1207 and 1208. In the case of a receiver, the terahertz wave received via the antenna 1200 is converted to an intermediate frequency signal by the mixer 1202, then converted to a baseband signal by the mixer 1204, and the analog waveform is converted to a digital waveform by the converter 1205. The digital waveform is then demodulated in the baseband to obtain a communication signal. In the case of a transmitter, after the communication signal is modulated, it is converted from a digital waveform to an analog waveform by the converter 1205, then frequency-converted via mixers 1204 and 1202, and output as a terahertz wave from the antenna 1200. The direct conversion communication system includes the antenna 1200, an amplifier 1211, a mixer 1212, a modulator / demodulator 1213, and a local oscillator 1214. In the direct conversion method, during reception, the received terahertz wave is directly converted into a baseband signal by the mixer 1212, and during transmission, the baseband signal to be transmitted is converted into a terahertz signal by the mixer 1212. The other configurations are the same as those of the superheterodyne method. The antenna devices according to each of the above embodiments can perform terahertz wave beamforming by electrical control of the chip alone. Therefore, radio wave alignment between the transceiver and receiver is possible. Therefore, by using the antenna devices of each embodiment that are capable of beamforming, it becomes possible to improve wireless quality such as the signal-to-noise ratio in a communication system, and to transmit large amounts of information over a wide coverage area at low cost.

[0091] [Other embodiments] Although embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications and changes are possible within the scope of its gist.

[0092] For example, the above embodiment is described assuming that the carrier is an electron, but it is not limited to this, and holes may also be used. Furthermore, the substrate and dielectric materials can be selected according to the application, and semiconductor layers such as silicon, gallium arsenide, indium arsenide, and gallium phosphide, or resins such as glass, ceramic, polytetrafluoroethylene, and polyethylene terephthalate can be used.

[0093] Furthermore, although a square patch antenna is used as the terahertz wave resonator in the above-described embodiment, the shape of the resonator is not limited to this. For example, a resonator with a structure using patch conductors of polygonal shapes such as rectangles and triangles, or circular or elliptical shapes may be used.

[0094] Furthermore, the number of differential negative resistive elements integrated into the element is not limited to one, and a resonator containing multiple differential negative resistive elements may be used. The number of transmission lines is also not limited to one, and a configuration with multiple transmission lines may be used. By using the antenna device described in the above embodiment, it is possible to generate and detect terahertz waves.

[0095] Furthermore, in each of the embodiments described above, a double-barrier RTD made of InGaAs / AlAs grown on an InP substrate was described as the RTD. However, the present invention is not limited to these structures or material systems, and other structures and material combinations can also be used to provide the device. For example, an RTD having a triple-barrier quantum well structure or an RTD having four or more multi-barrier quantum wells may be used.

[0096] Furthermore, while some embodiments described above show examples where antennas AN included in two active antennas located adjacent to each other in an array arrangement are coupled, the examples are not limited to this. If wiring is possible, two antennas AN included in two non-adjacent active antennas may also be coupled.

[0097] Furthermore, although the above embodiment described a method for forming an antenna device using a laminated structure, it is not limited to this. That is, the above discussion can also be applied to antenna devices that do not use a laminated structure. In this case, for example, the semiconductor layer 100 described above can be read as a semiconductor structure or any oscillator. For other structures as well, it is possible to obtain an antenna device with similar performance to the antenna device discussed in this embodiment by designing it according to a circuit diagram such as that shown in Figure 4.

[0098] Furthermore, any of the following combinations may be used as materials for the RTD. • GaAs / AlGaAs and GaAs / AlAs, InGaAs / GaAs / AlAs formed on a GaAs substrate InGaAs / InAlAs, InGaAs / AlAs, InGaAs / AlGaAsSb formed on an InP substrate InAs / AlAsSb and InAs / AlSb formed on an InAs substrate • SiGe / SiGe formed on a Si substrate The above-mentioned structure and materials can be appropriately selected depending on the desired frequency and other factors.

[0099] [Summary of Embodiments] At least some of the embodiments described above can be summarized as follows:

[0100] (Item 1) An active antenna that generates or detects electromagnetic waves, comprising an antenna, a semiconductor structure that operates as an oscillator, and at least two power lines that provide a potential difference to the semiconductor structure, A control line electrically connected to one of the at least two power lines, into which a signal controlling the phase of the oscillator in the active antenna is injected, An antenna device characterized by having the following features.

[0101] (Item 2) The antenna device according to item 1, characterized in that the signal is an electrical signal with a frequency of one even fraction of the oscillation frequency of the oscillator.

[0102] (Item 3) The antenna device according to item 1 or 2, characterized in that the signal is an electrical signal that reaches the oscillator with a power greater than or equal to the power of the output signal from the oscillator.

[0103] (Item 4) The antenna device according to item 3, characterized in that the signal is an electrical signal that reaches the oscillator with a power of 10 times or more the power of the output signal from the oscillator.

[0104] (Item 5) The antenna device according to any one of items 1 to 4, characterized in that the length of the path from a predetermined oscillator that outputs the signal to the oscillator included in the active antenna via the control line is within 20 wavelengths of the wavelength of the signal.

[0105] (Item 6) The at least two power lines include a first power line that provides a first potential and a second power line that provides a second potential, wherein the second potential is higher than the first potential. The antenna device according to any one of items 1 to 5, characterized in that the control line is electrically connected to the second power line.

[0106] (Item 7) The at least two power lines include a first power line that provides a first potential and a second power line that provides a second potential, wherein the second potential is higher than the first potential. The antenna device according to any one of items 1 to 5, characterized in that the control line is electrically connected to the first power line.

[0107] (Item 8) The antenna device according to any one of items 1 to 7, characterized in that it includes an antenna array in which a plurality of the active antennas are arranged in an array.

[0108] (Item 9) The antenna device according to item 8, further comprising coupling lines that connect at least two of the active antennas, each of the plurality of active antennas, to each other.

[0109] (Item 10) In the array arrangement of the multiple active antennas, the coupling line connecting the antennas included in at least two adjacent active antennas is set such that the length of the path through which the semiconductor structures included in the at least two active antennas are connected via the coupling line is determined based on the electrical length of the electromagnetic wave in the coupling line. The antenna device according to item 9, characterized by the features described herein.

[0110] (Item 11) The antenna device according to item 10, characterized in that the coupling line is set such that the length of the path is an integer multiple of 2π for the electrical length of the electromagnetic wave.

[0111] (Item 12) The antenna device according to any one of items 9 to 11, characterized in that the control line is coupled to the coupling line and electrically connected to one of the at least two power lines via the antenna.

[0112] (Item 13) The antenna device according to any one of items 9 to 12, characterized in that the length of the path from a predetermined oscillator that outputs the signal to the oscillator included in the active antenna via the control line and the coupling line is an integer multiple of the wavelength of the signal.

[0113] (Item 14) The antenna device according to any one of items 9 to 13, characterized in that the antenna, the semiconductor structure, the control line, and the coupling line are laminated on a semiconductor substrate, the control line and the coupling line are arranged on different layers, and the control line and the coupling line are electrically connected at the frequency of the signal.

[0114] (Item 15) The antenna device according to any one of items 1 to 13, characterized in that the antenna, the semiconductor structure, and the control line are stacked on a semiconductor substrate.

[0115] (Item 16) The antenna device according to any one of items 8 to 14, characterized in that the control line is configured such that the difference between the electrical length of the control line connected to the first active antenna among the plurality of active antennas and the electrical length of the control line connected to the second active antenna among the plurality of active antennas is an integer multiple of the wavelength of the signal.

[0116] (Item 17) The antenna device according to any one of items 1 to 16, characterized in that the predetermined oscillator that outputs the aforementioned signal is composed of a semiconductor heterostructure, a semiconductor multilayer structure, a resonant tunneling diode, or a negative resistance diode.

[0117] (Item 18) The antenna device according to any one of items 1 to 17, characterized in that the electromagnetic waves are electromagnetic waves in the terahertz band.

[0118] (Item 19) A first active antenna that generates or detects electromagnetic waves and acts as a slave, each including a first antenna, a first semiconductor structure that operates as a first oscillator, and at least two power lines that provide a potential difference to the first semiconductor structure, and which generates or detects electromagnetic waves. A second active antenna that generates or detects electromagnetic waves and acts as a slave, each including a second antenna, a second semiconductor structure that operates as a second oscillator, and at least two power lines that provide a potential difference to the second semiconductor structure, and which generates or detects electromagnetic waves. A master third oscillator that outputs a signal to control the phases of the first oscillator and the second oscillator, A first control line electrically connects one of the at least two power lines of the first active antenna to the third oscillator, A second control line electrically connects one of the at least two power lines of the second active antenna to the third oscillator, An antenna device characterized by having the following features.

[0119] (Item 20) The antenna device according to item 19, characterized in that the third oscillator is constructed using a semiconductor heterostructure, a semiconductor multilayer structure, a resonant tunneling diode, and a negative resistance diode.

[0120] (Item 21) The antenna device according to item 19 or 20, characterized in that the electromagnetic waves are electromagnetic waves in the terahertz band.

[0121] (Item 22) An antenna device as described in any one of items 1 to 21, The transmitting unit that emits the aforementioned electromagnetic waves, The receiving unit for detecting the electromagnetic waves, A communication device characterized by having the following features.

[0122] (Item 23) An antenna device as described in any one of items 1 to 21, A transmitting unit that emits the aforementioned electromagnetic waves toward the subject, A detection unit for detecting the electromagnetic waves reflected by the subject, An imaging system characterized by having the following features.

[0123] The invention is not limited to the embodiments described above, and various modifications and variations are possible without departing from the spirit and scope of the invention. Accordingly, claims are attached to disclose the scope of the invention. [Explanation of Symbols]

[0124] AA: Active antenna, 10: Antenna device, 11, 21, 31, 41: Antenna array, 12: Bias control unit, 13: Master oscillator, IL, RL: Control line, CL: Coupling line, RTD: Semiconductor layer, AN: Antenna

Claims

1. An active antenna that generates or detects electromagnetic waves, comprising an antenna, a semiconductor structure that acts as an oscillator, and at least two power lines that provide a potential difference to the semiconductor structure, A control line electrically connected to one of the at least two power lines, into which a master signal from another oscillator is injected to control the phase of the oscillator in the active antenna, An antenna device characterized by having the following features.

2. The antenna device according to claim 1, characterized in that the master signal is an electrical signal with a frequency of one even fraction of the oscillation frequency of the oscillator.

3. The antenna device according to claim 1, characterized in that the master signal is an electrical signal that reaches the oscillator with a power greater than or equal to the power of the output signal from the oscillator.

4. The antenna device according to claim 3, characterized in that the master signal is an electrical signal that reaches the oscillator with a power of 10 times or more the power of the output signal from the oscillator.

5. The antenna device according to claim 1, characterized in that the length of the path from the other oscillator that outputs the master signal to the oscillator included in the active antenna via the control line is within 20 wavelengths of the wavelength of the master signal.

6. The at least two power lines include a first power line that provides a first potential and a second power line that provides a second potential, wherein the second potential is higher than the first potential. The antenna device according to claim 1, characterized in that the control line is electrically connected to the second power line.

7. The at least two power lines include a first power line that provides a first potential and a second power line that provides a second potential, wherein the second potential is higher than the first potential. The antenna device according to claim 1, characterized in that the control line is electrically connected to the first power line.

8. The antenna device according to claim 1, characterized in that it includes an antenna array in which a plurality of the active antennas are arranged in an array.

9. The antenna device according to claim 8, further comprising coupling lines that connect at least two of the active antennas, each of the plurality of active antennas, to each other.

10. In the array arrangement of the multiple active antennas, the coupling line connecting the antennas included in at least two adjacent active antennas is such that the length of the path through which the semiconductor structures included in the at least two active antennas are connected via the coupling line is set based on the electrical length of the electromagnetic wave in the coupling line. The antenna device according to feature 9.

11. The antenna device according to claim 10, characterized in that the coupling line is set such that the length of the path is an integer multiple of 2π for the electrical length of the electromagnetic wave.

12. The antenna device according to claim 9, characterized in that the control line is coupled to the coupling line and electrically connected to one of the at least two power lines via the antenna.

13. The antenna device according to claim 9, characterized in that the length of the path from the other oscillator that outputs the master signal to the oscillator included in the active antenna via the control line and the coupling line is an integer multiple of the wavelength of the master signal.

14. The antenna device according to claim 9, characterized in that the antenna, the semiconductor structure, the control line, and the coupling line are laminated on a semiconductor substrate, the control line and the coupling line are arranged on different layers, and the control line and the coupling line are electrically connected at the frequency of the master signal.

15. The antenna device according to claim 1, characterized in that the antenna, the semiconductor structure, and the control line are stacked on a semiconductor substrate.

16. The antenna device according to claim 8, characterized in that the control line is configured such that the difference between the electrical length of the control line connected to the first active antenna among the plurality of active antennas and the electrical length of the control line connected to the second active antenna among the plurality of active antennas is an integer multiple of the wavelength of the master signal.

17. The antenna device according to claim 1, characterized in that the predetermined oscillator that outputs the master signal is configured using a semiconductor heterostructure, a semiconductor multilayer structure, a resonant tunneling diode, and a negative resistance diode.

18. The antenna device according to claim 1, characterized in that the electromagnetic waves are electromagnetic waves in the terahertz band.

19. A first active antenna that generates or detects electromagnetic waves and acts as a slave, each including a first antenna, a first semiconductor structure that operates as a first oscillator, and at least two power lines that provide a potential difference to the first semiconductor structure, and which generates or detects electromagnetic waves. A second active antenna that generates or detects electromagnetic waves and acts as a slave, each including a second antenna, a second semiconductor structure that operates as a second oscillator, and at least two power lines that provide a potential difference to the second semiconductor structure, and which generates or detects electromagnetic waves. A master third oscillator that outputs a signal to control the phases of the first oscillator and the second oscillator, A first control line electrically connects one of the at least two power lines of the first active antenna to the third oscillator, A second control line electrically connects one of the at least two power lines of the second active antenna to the third oscillator, An antenna device characterized by having the following features.

20. The antenna device according to claim 19, characterized in that the third oscillator is composed of a semiconductor heterostructure, a semiconductor multilayer structure, a resonant tunneling diode, and a negative resistance diode.

21. The antenna device according to claim 19, characterized in that the electromagnetic waves are electromagnetic waves in the terahertz band.

22. An antenna device according to any one of claims 1 to 21, The transmitting unit that emits the aforementioned electromagnetic waves, The receiving unit for detecting the electromagnetic waves, A communication device characterized by having the following features.

23. An antenna device according to any one of claims 1 to 21, A transmitting unit that emits the aforementioned electromagnetic waves toward the subject, A detection unit for detecting the electromagnetic waves reflected by the subject, An imaging system characterized by having the following features.

Images