KR102611737B1 - Optical beamforming device using phased array antenna and operating method thereof - Google Patents

Abstract

The present disclosure relates to an optical beamforming device using a phased array antenna and a method of operating the same. An optical beamforming device according to an embodiment of the present disclosure includes an RF front end for transmitting and receiving RF signals, and an optical beamformer for compensating or forming time delay for each of a plurality of channels based on the RF signal, wherein the optical beam The former includes E/O converters configured to convert RF signals into optical signals, a linear modulator that generates an optical modulation signal based on the RF input signal, and an optical combined signal that compensates for the time delay of the input optical signals. A TTD array that outputs or distributes an optical modulation signal to output optical signals with a time delay for each channel, an optical detector that generates an RF output signal to the RF backend based on the optical combined signal, and optical signals It includes E/O converters configured to convert to RF signals. According to the present disclosure, an optical beamforming device capable of beamforming regardless of bandwidth is provided.

Description

Optical beamforming device using phased array antenna and operating method thereof {OPTICAL BEAMFORMING DEVICE USING PHASED ARRAY ANTENNA AND OPERATING METHOD THEREOF}

The present disclosure relates to an optical beamforming device and an operating method thereof, and more specifically, to an optical beamforming device using a phased array antenna that forms or compensates for time delay for each channel in a TTD method and an operating method thereof. will be.

In the recently developing 5G+ wireless communication technology, research on phased array antennas is being actively conducted to expand ultra-bandwidth, ultra-low latency, and ultra-connectivity. A phased array antenna is an antenna that can scan a beam in various directions by electrically controlling the phase difference between a plurality of antennas. Beamforming or beamshaping refers to the function of electrically controlling the phase difference by forming or shaping the wavefront of the beam. A beamformer or beam shaper that performs a beamforming function can quickly and stably scan the direction of the beam, and has been used in communications and military radars, and has recently been used in smart antennas.

Methods for implementing the beamforming function can be divided into phase shifting (PS) and true time delay (TTD) methods. The PS method has a problem in that it is difficult to apply to fields that require wideband operation and rapid frequency changes because beam squint occurs due to dispersion characteristics that vary depending on frequency.

The TTD method is a method of forming a phase difference by varying the starting point of the phase using the time delay difference of the signal. The configuration of the beamforming device using the general TTD method can be divided into a ring resonator-based configuration and a distributed configuration using a multi-wavelength light source and WDM method. Ring resonator-based configurations have the problem of limited bandwidth to several GHz and relatively short delay time of several ns. Distributed configurations using multi-wavelength light sources and WDM methods have complex structures, make integration difficult, and have high production costs.

The purpose of the present disclosure is to provide an optical beamforming device using a phased array antenna that enables beamforming regardless of bandwidth and has a simple configuration and operation, and a method of operating the same.

An optical beamforming device according to an embodiment of the present disclosure includes an RF front end that receives a plurality of RF antenna input signals or transmits a plurality of RF antenna output signals using a phased array antenna having a plurality of channels, and the plurality of An optical beamformer for compensating or forming a time delay for each of the plurality of channels based on RF antenna input signals or an RF input signal from an RF backend, wherein the optical beamformer is configured to compensate for the plurality of RF antenna input signals a plurality of E/O converters configured to convert the input optical signals into a plurality of input optical signals, a linear modulator for generating an optical modulation signal based on the RF input signal from the RF backend, and compensating for a degree of time delay of the input optical signals. A TTD array that outputs an optical combined signal or distributes the optical modulation signal to output optical signals with a time delay for each channel, and generates an RF output signal to the RF backend based on the optical combined signal. an optical detector configured to convert the output optical signals into the plurality of RF antenna output signals.

A method of operating an optical beamforming device according to an embodiment of the present disclosure includes linearly modulating the RF antenna input signal into an optical signal based on the RF antenna input signal received from the RF backend by a linear modulator, and a TTD array using a power splitter. generating a plurality of optical distribution signals by distributing the optical signal to a plurality of TTD elements for each channel, wherein the TTD array distributes the plurality of optical distribution signals to each of the plurality of optical distribution signals based on an electrical control signal. Generating output optical signals delayed in real time by the delay time required in the channel, converting the output optical signals into RF antenna output signals by a plurality of O/E converters, and converting the output optical signals into RF antenna output signals by a plurality of O/E converters, and converting the output optical signals into RF antenna output signals by a plurality of O/E converters. and radiating the antenna output signals to the outside.

A method of operating an optical beamforming device according to an embodiment of the present disclosure includes the steps of individual antennas receiving RF antenna input signals for each channel from the outside, and a plurality of E/O converters receiving the RF antenna input signals respectively as input optical signals. converting the input optical signals into signals, the TTD array generating optical compensation signals that compensate for the delay time of the input optical signals based on an electrical control signal, the TTD array using a power combiner to generate an optical compensation signal generating an optical combined signal by combining the optical combined signals, and generating, by a balance detector, an RF output signal to an RF backend based on the optical combined signal.

According to the present disclosure, beamforming without bandwidth limitations can be performed because the optical path and time delay are determined regardless of the wavelength or frequency of the beam.

According to an embodiment of the present disclosure, operation and control are easy with the same time delay for each unit cell constituting the TTD device, and it is implemented in a chip form to enable integration with peripheral devices.

1 is a conceptual diagram of beamforming according to an embodiment of the present disclosure.
Figure 2 is a configuration diagram schematically showing an optical beamforming device according to an embodiment of the present disclosure.
FIG. 3 is a configuration diagram showing the configuration of the TTD array 1240 shown in FIG. 2 in more detail.
FIG. 4 is a configuration diagram showing the configuration of the TTD array 1240 shown in FIG. 3 according to an embodiment.
Figure 5 is a configuration diagram showing a unit cell constituting the TTD device shown in Figures 2 and 3.
FIG. 6 is a configuration diagram showing the configuration of the TTD device shown in FIGS. 2 and 3 in more detail.
Figure 7 is an example flowchart when a phased array antenna transmits a signal in the optical beamforming method according to an embodiment of the present disclosure.
Figure 8 is an example flowchart when a phased array antenna receives a signal in the optical beamforming method according to an embodiment of the present disclosure.

Below, embodiments of the present disclosure will be described clearly and in detail so that a person skilled in the art can easily practice the present disclosure.

1 is a conceptual diagram of beamforming according to an embodiment of the present disclosure. The optical beamforming device 1000 according to an embodiment of the present disclosure may use a linear phased array antenna (PAA). The optical beamforming device 1000 transmits an output signal based on an input signal from an RF back-end (radio frequency back-end; RF_BE), or sends an output signal to the RF back-end (RF_BE) based on an input signal received from the outside. It can be delivered. For convenience of explanation, the description below assumes that an output signal is transmitted based on an input signal from an RF back-end (radio frequency back-end; RF_BE).

For example, a linear phased array antenna may include n antenna elements. Here, n is a natural number of 2 or more. n antenna elements can form each channel. For example, if a linear phased array antenna includes 10 antenna elements, 10 channels can be formed. The optical beamforming device 1000 can radiate an output signal in the form of an electromagnetic wave in a desired direction through each channel, based on an input signal in the form of an electric signal received from the RF backend (RF_BE). For example, the optical beamforming device 1000 may set delay times for each channel differently using a true time delay (TTD) method. The optical beamforming device 1000 can change the radiation direction of the linear phased array antenna by using the difference in phase start point according to the delay time of each channel.

The output signal of the optical beamforming device 1000 may have a specific phase front. For example, a state with a specific phase plane may correspond to State 0, State 1, ..., State k depending on the radiation angle of the linear phased array antenna, and is not limited to the radiation angle shown in FIG. 1. Here, k is 0 or any natural number. For example, when the output signal of the optical beamforming device 1000 is State 0, the phase front of the output signal (Phase front at State 0) may be a plane perpendicular to the D2 direction, and the radiation direction of the signal is in the phase plane. It may be in the vertical D2 direction. Here, the D1 direction is the direction of an arbitrary vector on an arbitrary plane. When the output signal of the optical beamforming device 1000 is State 1, the phase front of the output signal (Phase front at State 1) is parallel to the direction having an angular difference of α ₁ in the clockwise or counterclockwise direction from the D1 direction. It can be done, and the radiation direction of the signal can be perpendicular to the phase plane. In the same principle, when the output signal of the optical beamforming device 1000 is State k, the phase front of the output signal (Phase front at State k) has an angle difference of α _k in the D1 direction and in the clockwise or counterclockwise direction. It may be parallel to the direction of the signal, and the radiating direction of the signal may be perpendicular to the phase plane.

In order to specify the phase plane of the signal, delay times of channels of the optical beamforming device 1000 may be set differently. For example, when the unit delay time is defined as Δτ, the real-time delay (TTD_CHn) of channel n may follow the relationship in Equation 1.

Referring to Equation 1, n is defined as the sequential order of each channel, and t _n is defined as the delay time of channel n, which is the nth channel. k is defined as a specific state (eg, State 0, State 1, ..., State k) of the output signal of the optical beamforming device 1000. Δτ is defined as the unit delay time. For example, the real-time delay (TTD_CHn) of channel n can be determined as k*(n-1)*Δτ according to Equation 1. For example, the real-time delay (TTD_CH2) of channel 2 may be determined as k*1*Δτ. As a result, the optical beamforming device 1000 can radiate an output signal with a specific phase plane based on the continuous real-time delay of each channel.

The optical beamforming device 1000 may linearly rotate the phase plane to have a discrete time delay as shown in FIG. 1 . According to an exemplary embodiment of the present disclosure, the optical beamforming device 1000 may non-linearly control the time delay of each channel for fine adjustment of the output signal. For example, although not shown, the optical beamforming device 1000 may further include a phase tuner (PT) for non-linear control of time delay.

Figure 2 is a configuration diagram schematically showing an optical beamforming device according to an embodiment of the present disclosure. The optical beamforming device 1000 may include an RF front-end (radio frequency front-end) 1100 and an optical beamformer 1200. The optical beamforming device 1000 according to an embodiment of the present disclosure may transmit and/or receive signals. Accordingly, the optical beamforming device 1000 may be configured to perform both transmission and reception functions in each antenna element, as shown in FIG. 2. However, although not shown, the optical beamforming device 1000 may be configured so that each antenna element performs at least one of a transmission function and a reception function.

The RF front end 1100 may include antenna elements 1110_1 to 1110_n, first circulators 1120_1 to 1120_n, LNAs 1130_1 to 1130_n, and PAs 1140_1 to 1140_n. The RF front end 1100 may transmit an output signal to the outside or receive an input signal from the outside using a phased array antenna having a plurality of channels. Furthermore, the RF front end 1100 may amplify power before transmitting an output signal to the outside, or may amplify the signal after receiving an external input signal while minimizing noise.

Each antenna element (1110_1 to 1110_n) radiates electromagnetic waves to the outside based on each RF antenna output signal (RF _{out_1} to RF _{out_n} ) in the form of an electric signal, or RF antenna input signal in the form of an electric signal based on an external electromagnetic wave. (RF _{in_1} to RF _{in_n} ) can be received. The first circulators (1120_1 to 1120_n) are 3-port non-reciprocal electronic devices, and each antenna element (1110_1 to 1110_n) converts each RF antenna input signal (RF _{in_1} to RF _{in_n} ) received from the outside into LNAs (low noise amplifiers (1130_1 to 1130_n), or transmit each RF antenna output signal (RF _{out_1} to RF _{out_n} ) from power amplifiers (PAs) (1140_1 to 1140_n) to each antenna element (1110_1 to 1110_n). You can. The LNAs 1130_1 to 1130_n can amplify while minimizing noise of each RF antenna input signal (RF _{in_1} to RF _{in_n} ). The PAs 1140_1 to 1140_n may generate respective RF antenna output signals (RF _{out_1} to RF _{out_n} ) obtained by amplifying the RF signal for external transmission.

The optical beamformer 1200 includes E/O converters 1210_1 to 1210_n, O/E converters 1220_1 to 1220_n, second circulators 1230_1 to 1230_n, a TTD array 1240, and a third circulator 1260. ), an optical detector 1270, and a linear modulator 1280. The optical beamformer 1200 converts an RF signal into an optical signal and delays the optical signal in real time using a TTD method to form or compensate for a difference in the phase starting point of the signal for each channel.

The E/O converters (1210_1 to 1210_n) output optical signals (OF) based on each of the RF antenna input signals (RF _{in_1} to RF _{in_n} ) amplified by the LNAs and the first optical reference signal (OF _LD1 ). _{in_1} to OF _{in_n} ) can be generated. Here, the first optical reference signal OF _LD1 may be generated by the first laser diode LD1 (not shown). For example, the first laser diode LD1 may be located externally. In this case, the first laser diode LD1 may be connected to the LD1 node N _LD1 and transmit the first optical reference signal OF _LD1 to the E/O converters 1210_1 to 1210_n. However, unlike shown, the first laser diode LD1 may be included in the optical beamforming device 1000 and transmit the first optical reference signal OF _LD1 to the E/O converters 1210_1 to 1210_n.

For example, the E/O converters 1210_1 to 1210_n optically modulate each RF antenna input signal (RF _{in_1} to RF _{in_n} ) using the first optical reference signal (OF _LD1 ), thereby generating electrical- Electro-optic transformation can be performed. According to an exemplary embodiment of the present disclosure, the E/O converters 1210_1 to 1210_n may include Mach-Zehnder modulators (MZM) for optical modulation of electrical signals. As a result, the E/O converters 1210_1 to 1210_n may generate respective input optical signals OF _{in_1} to OF _{in_n} .

The O/E converters 1220_1 to 1220_n may generate RF antenna output signals RF _{out_1} to RF _{out_n} based on the output optical signals OF _{out_1} to OF _{out_n} . According to an exemplary embodiment of the present disclosure, the O/E converters 1220_1 to 1220_n may include a photo detector (PD) for electrical modulation of an optical signal. Here, the photo detector is a separate configuration from the photo detector 1270 shown in FIG. 2.

The second circulators (1230_1 to 1230_n) transfer each of the input optical signals (OF _{in_1} to OF _{in_n} ) from the E/O converters (1210_1 to 1210_n) to the TTD array 1240, or each output optical signal (OF) _{out_1} to OF _{out_n} ) may be transmitted from the TTD array 1240 to the O/E converters 1220_1 to 1220_n.

The TTD array 1240 generates an optical combined signal (OF out_TTD) based on at least some of the plurality of input optical signals (OF _{in_1} to OF _{in_n} ) or generates each output optical signal (OF _{out_TTD} ) based on the optical modulation signal (OF _{in_TTD} ). Signals (OF _{out_1} to OF _{out_n} ) can be generated. For example, the TTD array 1240 is controlled by an electrical control signal (ECS) and can compensate or create time delay based on the transmitted and received signals of each channel. Accordingly, the TTD array 1240 can compensate for or create a phase start point difference by varying the degree of real-time delay for each channel. The specific configuration and operation of the TTD array 1240 will be explained through FIGS. 3 and 4.

The electrical controller 1250 may control the operation of the TTD array 1240. For example, the electrical controller 1250 may control an optical switch (OSW) included in the TTD array 1240 by transmitting an electrical control signal (ECS) to the TTD array 1240. The electrical controller 1250 can control the degree of real-time delay formed by the TTD array 1240 by controlling the OSW. The specific operation of the electric controller 1250 will be explained through FIGS. 5 and 6.

The third circulator 1260 transfers the optical combined signal (OF _{out_TTD} ) from the TTD array 1240 to the optical detector 1270, or transmits the optical modulation signal (OF _{in_TTD} ) from the linear modulator 1280 to the TTD array 1240. It can be passed on. According to an exemplary embodiment of the present disclosure, the optical beamformer 1200 may further include a single side band filter (SSBF). The SSBF may be located between TTD array 1240 and photo detector 1270 and/or between TTD array 1240 and linear modulator 1280. SSBF can suppress signal distortion by filtering the optical combined signal (OF _{out_TTD} ) and/or the optical modulation signal (OF _{in_TTD} ).

The optical detector 1270 may generate an RF output signal (RF _{out_B} ) to the backend based on the optical combined signal (OF _{out_TTD} ) and the first optical reference signal (OF _LD1 ). The photo detector 1270 may transmit the RF output signal (RF _{out_B} ) to the backend to the backend input node (N _B1 ) connected to the RF backend. For example, the photo detector 1270 may be comprised of a photo diode (PD). According to an exemplary embodiment of the present disclosure, the photo detector 1270 detects correlated noise through differential amplification from the optical combined signal (OF _{out_TTD} ) and the first optical reference signal (OF _LD1 ). By removing it, balanced detection that improves the signal-to-noise ratio (SNR) can be performed.

The linear modulator 1280 may generate an optical modulation signal (OF _{in_TTD} ) based on the RF input signal (RF _{in_B} ) from the backend and the second optical reference signal (OF _LD2 ). The linear modulator 1280 is connected to the backend output node (N _B2 ) connected to the RF backend and can receive the RF input signal (RF _{in_B} ) from the backend, which is the output signal of the RF backend. Additionally, the linear modulator 1280 is connected to the LD2 node (N _LD2 ) connected to the second laser diode (LD2) and can receive the second optical reference signal (LD2). According to an exemplary embodiment of the present disclosure, the second laser diode LD2 may be located externally or, unlike shown, may be included in the optical beamforming device 1000. According to an exemplary embodiment of the present disclosure, the linear modulator 1280 may perform single-side band operation.

FIG. 3 is a configuration diagram showing the configuration of the TTD array 1240 shown in FIG. 2 in more detail. The TTD array 1240 may include a power splitter/combiner 1241 and TTD elements 1242_1 to 1242_n.

The power splitter/combiner 1241 can operate as a power splitter when receiving an optical modulation signal (OF _{in_TTD} ). In this case, the power splitter/combiner 1241 is based on the optical modulation signal (OF _{in_TTD} ), each TTD connected to each channel (e.g., channel 1 (FIG. 1, CH1)) ports (PA1 to PAn) Each optical distribution signal (OF _{in_TTD_1} to OF _{in_TTD_n} ) may be transmitted to the elements 1242_1 to 1242_n. Furthermore, the power splitter/combiner 1241 may operate as a power combiner when receiving a plurality of optical compensation signals (OF _{out_TTD_1} to OF _{out_TTD_n} ). In this case, _the power splitter/combiner 1241 sends an _optical combined signal ( OF _{out_TTD} ) can be passed.

For example, the power splitter/combiner 1241 may be implemented in the form of an optical fiber or optical waveguide. For example, when the power splitter/combiner 1241 is in the form of an optical waveguide, the power splitter/combiner 1241 is made of silica (SiO ₂ ), silicon (Si), or amorphous silicon ( It can be implemented with materials such as amorphous silicon, silicon nitride (SiNx), and silicon oxynitride (SiON).

The TTD elements (1242_1 to 1242_n) generate optical compensation signals (OF _{out_TTD_1} to OF _{out_TTD_n} ) based on the input optical signals (OF _{in_1} to OF _{in_n} ) from each channel port (PA1 to PAn). , Output optical signals (OF _{out_1} to OF _{out_n} ) may be generated based on each optical distribution signal (OF _{in_TTD_1} to OF _{in_TTD_n} ) and transmitted to each channel port (PA1 to PAn). For example, each TTD element (1242_1 to 1242_n) may vary the degree of real-time delay for the input signals to compensate for or form a phase start point difference and output the signal. The electrical controller 1250 can adjust the degree of real-time delay of signals input to each TTD element (1242_1 to 1242_n) through each electrical control signal (ECS ₁ to ECS _n ). According to an exemplary embodiment of the present disclosure, an electrical control signal (ECS) (eg, ECS ₁ ) may include a plurality of control signals. The specific configuration and operation of each TTD elements 1242_1 to 1242_n will be explained with reference to FIGS. 5 and 6.

FIG. 4 is a configuration diagram showing the configuration of the TTD array 1240 shown in FIG. 3 according to an embodiment. FIG. 4 shows some components added to the TTD array 1240 shown in FIG. 3, and for simplification of the illustration, signal notations are omitted in FIG. The TTD array 1240 according to an embodiment of the present disclosure may further include amplifiers 1243_1 to 1243_n and attenuators 1244_1 to 1244_n. Amplifiers 1243_1 to 1243_n and attenuators 1244_1 to 1244_n may amplify or attenuate the strength of signals input/output to the TTD. The amplifiers 1243_1 to 1243_n and the attenuators 1244_1 to 1244_n are not limited to the connection relationship shown in FIG. 4, and as long as they amplify or attenuate the strength of signals input or output to the TTD array 1240, the TTD It may be positioned arbitrarily within array 1240. Although not shown, the TTD array 1240 may further include a phase tuner (PT) for non-linear fine phase adjustment.

Figure 5 is a configuration diagram showing a unit cell constituting the TTD device shown in Figures 2 and 3. Each TTD element (FIG. 3, 1242_1 to 1242_n) may be composed of a plurality of unit cells 1242_u. The unit cell 1242_u of the TTD device may include a 1x2 optical switch (OSW) and a 2x1 optical combiner (OC). For example, OSWs are implemented with compound semiconductor materials such as indium phosphide (InP) or gallium arsenide (GaAs), or in the form of polymer total internal reflection (TIR) switches. It can be implemented.

The unit cell 1242_u compares the signal input to the input port (P _{in_u} ) of the unit cell to the signal output to the output port (P _{out_u} ) of the unit cell based on the electrical control signal (ECS) from the electrical controller 1250. It may or may not be delayed by the unit delay time (Δτ). Here, the electrical control signal (ECS) constitutes one of a plurality of electrical control signals (ECS 1 to ECS n in FIG. 3) input to one of a plurality of TTD elements (1242_1 to _{1242_n} in FIG. ₃ ). This refers to each electrical control signal input to each unit cell. For example, the electrical control signal input to the TTD device (1242_2 in Figure 3) of channel 2 is ECS ₂ , and ECS ₂ is composed of each electrical control signal input to each unit cell (1242_u) in the TTD device. Since the unit cell 1242_u is configured to be non-reciprocal with respect to the input port (P _{in_u} ) of the unit cell and the output port (P _{out_u} ) of the unit cell, the signal is transmitted from the input port (P _{in_u} ) of the unit cell. It must be entered as a unit cell (1242_u).

When the signal input from the input port (P _{in_u} ) of the unit cell is input to the x node ( _N (N _y1 ) or y2 node (N _y2 ) can be connected with x node (N _x ). Here, the on/off state of the electrical control signal (ECS) determines whether the signal is delayed by a unit delay time (Δτ). For example, if the electrical control signal (ECS) is in the off state, the electrical control signal (ECS) does not indicate a time delay, and in this case, the x node (N _x ) of the OSW is the y1 node connected to the first path ( It is connected to N _y1 ). On the other hand, if the electric control signal (ECS) is in the on state, the electric control signal (ECS) indicates a time delay, and OSW is y2 connected to the second path longer than the first path to be delayed by the unit delay time (Δτ). It can be switched to node (N _y2 ). However, the connection relationship of OSW according to the on/off state of the electrical control signal (ECS) is not limited to what has been described, and has an opposite relationship (e.g., when the electrical control signal (ECS) is off, it is connected to the y2 node, When the electrical control signal (ECS) is on, it can follow (connected to node y1). OC may be configured to connect the first path and the second path.

FIG. 6 is a configuration diagram showing the configuration of the TTD device shown in FIGS. 2 and 3 in more detail. Referring to FIG. 6 along with FIG. 5 , the TTD element 1242 may be composed of a plurality of unit cells 1242_u. Since the unit cell 1242_u of FIG. 5 and the unit cell of FIG. 6 are substantially the same, reference numbers and signal notation of the unit cell of FIG. 6 are omitted for simplification of the illustration. Each unit cell constituting the TTD element 1242 may be controlled by a plurality of electrical control signals (ECS) from the electrical controller 1250. When the electrical control signal (ECS) is in the on state, the description below assumes that the unit cell delays the signal by the unit delay time (Δτ). If the number of OSWs that have received an electrical control signal (ECS) in the on state is defined as M, the total delay time of the signal by the TTD element 1242 can be calculated as M*Δτ. Here, the OSW inside the TTD element 1242 If the number of is m and the number of channels is defined as n, m is greater than or equal to n-1, and M may correspond to any integer between 0 and m.

Since the unit cell is non-reciprocal with respect to the unit cell's input port (P _{in_u} ) and the unit cell's output port (P _{out_u} ), it is composed of a plurality of unit cells. The TTD element 1242 is also configured to be irreversible with respect to the input port (P _in ) and the output port (P _out ). Therefore, although not shown, the optical beamforming device 1000 according to an exemplary embodiment of the present disclosure configures the TTD elements for transmission and reception differently. For example, the transmission TTD element receives each optical distribution signal (OF _{in_TTD_1} to OF _{in_TTD_n} ) from the input port (P _in ), and transmits each output optical signal (OF _{out_1} to OF _{out_n} ) to the output port (P _out ). ) can be output. For example, the receiving TTD element receives each of the input optical signals (OF _{in_1} to OF _{in_n} ) from the input port (P _in ), and transmits each optical compensation signal (OF _{out_TTD_1} to OF _{out_TTD_n} ) to the output port (P _out ). ) can be output.

Figure 7 is an example flowchart when a phased array antenna transmits a signal in the optical beamforming method according to an embodiment of the present disclosure. For convenience of explanation, FIG. 7 will be described with reference to the reference numerals of FIGS. 1 to 3 .

In step S110, the linear modulator 1280 receives the RF input signal from the backend (RF _{in_B} ) and the RF input signal (RF _{in_B} ) from the backend based on the second optical reference signal (OF _LD2 ). It can be linearly modulated with an optical signal.

In step S120, the TTD array 1240 uses a power splitter to distribute the TTD input optical signal (OF _{in_TTD} ), which is a linearly modulated optical signal, to the TTD elements 1242_1 to 1242_n for each channel to produce each optical distribution signal. (OF _{in_TTD_1} to OF _{in_TTD_n} ) can be created.

In step S130, the TTD array 1240 configures each optical distribution signal (OF _{in_TTD_1} to OF _{in_TTD_n} ) as required in each channel (CH1 to CHn) based on the electrical control signal (ECS) from the electrical controller 1250. It can be delayed in real time by the delay time. Here, the delay time required for each channel (CH1 to CHn) follows the relationship of Equation 1 described above.

In step S140, the O/E converters 1220_1 to 1220_n may convert each output optical signal (OF _{out_1} to OF _{out_n} ) output by the TTD array 1240 for each channel into an RF signal.

In step S150, the antenna elements (1110_1 to 1110_n) place each RF antenna output signal (RF _{out_1} to RF _{out_n} ), which is a converted RF signal, in a specific state (e.g., State 0, State 1, ..., State k). A signal in the form of an electromagnetic wave with a phase plane of can be radiated to the outside.

Figure 8 is an example flowchart when a phased array antenna receives a signal in the optical beamforming method according to an embodiment of the present disclosure. For convenience of explanation, FIG. 8 will be described with reference to the reference numerals of FIGS. 1 to 3 .

In step S210, the antenna elements 1110_1 to 1110_n constituting the phased array antenna transmit a signal in the form of an external electromagnetic wave having a phase plane of a specific state (e.g., State 0, State 1, ..., State k) into RF. It can be received as a signal in the form

In step S220, the E/O converters (1210_1 to 1210_n) convert each RF antenna input signal (RF _{in_1} to RF _{in_n} ) received by the antenna elements (1110_1 to 1110_n) into each input optical signal (OF), which is an optical signal. can be converted to _{in_1} to OF _{in_n} ).

In step S230, the TTD array 1240 may compensate for the delay time of each input optical signal (OF _{in_1} to OF _{in_n} ) based on the electrical control signal (ECS) from the electrical controller 1250. Here, the delayed time follows the relationship of Equation 1 described above.

In step S240, the TTD array 1240 combines the optical compensation signals (OF _{out_TTD_1} to OF _{out_TTD_n} ), which are output signals of the TTD elements 1242_1 to 1242_n for each channel, using a power combiner to perform optical combine. A signal (OF _{out_TTD} ) can be generated.

In step S250, the balance detector 1270 may detect the RF signal based on the optical combined signal (OF _{out_TTD} ) and the first optical reference signal (OF _LD1 ). The RF output signal (RF _{out_B} ) to the backend, which is the detected RF signal, may be output to the RF backend.

The above contents are specific examples for carrying out the present disclosure. The present disclosure will include not only the embodiments described above, but also embodiments that can be simply changed or easily changed in design. In addition, the present disclosure will also include technologies that can be easily modified and implemented in the future using the above-described embodiments. Accordingly, the scope of the present disclosure should not be limited to the embodiments described above and should be determined by the claims and equivalents of the present disclosure as well as the claims described later.

1000: Optical beamforming device 1100: RF front end
1110_1 to 1110_n: antenna elements
1120_1 to 1120_n: first circulators
1130_1 to 1130_n: LNAs
1140_1 to 1140_n: PAs 1200: Optical beamformer
1210_1 to 1210_n: E/O converters
1220_1 to 1220_n: O/E converters
1230_1 to 1230_n: second circulators
1240: TTD Array 1241: Power Splitter/Combiner
1242: TTD element
1242_1 to 1242_n: TTD elements 1242_u: unit cell
1250: Electrical controller 1260: Third circulator
1270: Photodetector 1280: Linear modulator

Claims (17)

An RF front end that transmits a plurality of RF antenna output signals using a phased array antenna having a plurality of channels; and
An optical beamformer that forms a time delay for each of the plurality of channels based on an RF input signal from an RF backend,
The optical beamformer is,
a linear modulator that generates an optical modulation signal based on the RF input signal;
a TTD array that distributes the optical modulation signal to output optical signals with time delays for each of the plurality of channels; and
A plurality of O/E converters configured to respectively convert the output optical signals into the plurality of RF antenna output signals,
An optical beamforming device in which the TTD array discretely determines the degree of time delay for the plurality of channels according to Equation 1 below.
Equation 1:
(However, n: consecutive sequence of individual channels, tn: delay time of channel n, k: status value according to the phase plane rotation angle of the signal, integer greater than or equal to 0, delay time in Δτ unit) According to claim 1,
The RF front end is,
a plurality of antennas each transmitting the plurality of RF antenna output signals; and
An optical beamforming device comprising a plurality of amplifiers that respectively amplify the plurality of RF antenna output signals. delete According to claim 1,
The TTD array is,
a plurality of TTD elements each generating the plurality of output optical signals by forming a time delay for each of the plurality of channels based on a plurality of optical distribution signals; and
An optical beamforming device comprising a power splitter that generates the plurality of optical distribution signals when the optical modulation signal is input. According to claim 4,
Each of the plurality of TTD elements includes a plurality of unit cells,
Each of the plurality of unit cells,
If the electrical control signal does not indicate a time delay, switching to a first node connected to the first path, and if the electrical control signal indicates a time delay, switching to a second node connected to a second path that is longer than the first path. an optical switch that switches with; and
An optical beamforming device comprising an optical combiner connecting the first path and the second path. According to claim 4,
The TTD array is,
Further comprising a plurality of attenuators and a plurality of amplifiers respectively corresponding to the plurality of channels,
The plurality of attenuators and the plurality of amplifiers are configured to respectively adjust the intensity of the plurality of output optical signals. According to claim 4,
The TTD array is,
An optical beamforming device further comprising a phase tuner that non-linearly adjusts the phase of one of the plurality of output optical signals. According to claim 4,
The power splitter is an optical beamforming device implemented with an optical fiber or an optical waveguide. According to claim 8,
When the power splitter is implemented with the optical waveguide, the power splitter is implemented with a silica, silicon, amorphous silicon, silicon nitride, or silicon oxynitride material. According to claim 5,
The optical combiner is an optical beamforming device implemented in the form of an optical waveguide. According to claim 5,
The optical switch is an optical beamforming device implemented with a compound semiconductor material containing indium phosphide (InP) or gallium arsenide (GaAs). According to claim 5,
The optical switch is an optical beamforming device implemented in the form of a polymer total reflection switch. delete delete According to claim 1,
An optical beamforming device further comprising a single-side band filter (SSBF) connected between the TTD array and the linear modulator. In a method of operating an optical beamforming device that outputs an RF signal,
A linear modulator linearly modulating the RF antenna input signal into an optical signal based on the RF antenna input signal received from the RF backend;
generating, by a TTD array, a plurality of optical distribution signals by distributing the optical signal to a plurality of TTD elements for each of a plurality of channels using a power splitter;
generating, by the TTD array, output optical signals generated by delaying the plurality of optical distribution signals in real time by a delay time requested for each channel, based on an electrical control signal;
A plurality of O/E converters converting the output optical signals into RF antenna output signals, respectively; and
A plurality of antenna elements radiating the RF antenna output signals out of the optical beamforming device,
A method for the TTD array to discretely determine the degree of time delay for the plurality of channels according to Equation 1 below.
Equation 1:
(However, n: consecutive sequence of individual channels, tn: delay time of channel n, k: status value according to the phase plane rotation angle of the signal, integer greater than or equal to 0, delay time in Δτ unit) delete