Patent Publication Number: US-2021181300-A1

Title: Phase shifter generating pulse signals and continuous frequency signals, radar including the same, and transmitter of radar

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority under 35 U.S.C. § 119 to Korean Patent Application No. 10-2019-0166957 filed on Dec. 13, 2019, and 10-2020-0118159, filed on Sep. 15, 2020, in the Korean Intellectual Property Office, the disclosures of which are incorporated by reference herein in their entireties. 
     BACKGROUND 
     Embodiments of the inventive concept described herein relate to a phase shifter required for beamforming of a radar, and more particularly, relate to a radar including a phase shifter having an injection locked oscillator. 
     Recently developed radars are being developed in a form that may use various types of radar signals depending on user settings in various operating environments. 
     However, in the case of generating a signal of which phase is shifted using an injection locked oscillator in a conventional radar, there is a problem in that it is difficult to process an input signal, and there is a technical problem in generating various signals. 
     SUMMARY 
     Embodiments of the inventive concept provide a phase shifter that generates a phase-shifted signal using an injection locked oscillator, and a radar including the same. 
     In addition, embodiments of the inventive concept provide a phase shifter that generates various signals in a pulse mode or a continuous frequency mode (CW mode) depending on a user&#39;s setting, and a radar including the same. 
     According to an embodiment of the inventive concept, a radar includes a phase shifter including a first oscillator that receives an external signal that is a basis for generating an oscillation signal and generates a first signal, and a second oscillator that generates a second signal, and that crosses and adds a gain of the first signal and a gain of the second signal and generates an oscillation signal of which phase is shifted, and the oscillation signal is operated in one of a first mode as a pulse signal or a second mode as a frequency continuous wave, a signal amplifier that amplifies a phase-shifted oscillation signal to generate an output signal, a transmitter including the phase shifter and the signal amplifier, and that radiates the output signal to an outside, a receiver that receives a signal from the outside, and a controller that receives a control mode signal corresponding to one of the first mode and the second mode, controls power supplied to the transmitter, based on the received signal, and transmits a frequency tuning signal to the phase shifter, based on the received signal. 
     According to an embodiment, when the control mode signal corresponds to the first operation mode, the controller may control a power supply of the phase shifter and the signal amplifier, based on a preset reference, may transmit a frequency lock code to the phase shifter during a duty cycle, and the transmitter may generate the output signal having the same waveform as the oscillation signal. 
     According to an embodiment, when the control mode signal corresponds to the first operation mode, the controller may control a power supply of the phase shifter and the signal amplifier, based on a preset reference, and may transmit a frequency free running code to the phase shifter in a section other than a duty cycle, and the transmitter may stop the output signal from being output. 
     According to an embodiment, when the control mode signal corresponds to the second operation mode, the controller always may supply the power to the transmitter and may control a capacitance value of the phase shifter. 
     According to an embodiment, the controller may transmit a frequency lock code to the phase shifter in all sections, and the transmitter continuously may generate the output signal. 
     According to an embodiment, the radar may further include an input device that receives a command corresponding to the first operation mode or the second operation mode, and the controller may determine the operation modes, based on the command. 
     According to an embodiment, the receiver may include a low pass filter that filters the received signal. 
     According to an embodiment, the controller may transmit a BW (band width) control signal to the receiver, and the low pass filter may determine a cutoff frequency, based on the BW control signal. 
     According to another embodiment of the inventive concept, a transmitter of a radar includes a phase shifter including a first oscillator that receives an external signal that is a basis for generating an oscillation signal and generates a first signal, and a second oscillator that generates a second signal, and that crosses and adds a gain of the first signal and a gain of the second signal and generates an oscillation signal of which phase is shifted, and the oscillation signal is operated in one of a first mode as a pulse signal or a second mode as a frequency continuous wave and a signal amplifier that amplifies the phase-shifted oscillation signal to generate an output signal. 
     According to an embodiment, the phase shifter may receive a control mode signal from a controller, and when the input control mode signal corresponds to a first mode, the phase shifter may generate a signal having the same frequency as the external signal during a duty cycle of the control mode signal. 
     According to an embodiment, the phase shifter may receive a control mode signal from a controller, and when the control mode signal corresponds to a first mode, the phase shifter may generate a signal corresponding to a frequency free running code in a section other than a duty cycle. 
     According to an embodiment, the phase shifter may receive a control mode signal from a controller, and when the control mode signal corresponds to a second mode, the phase shifter may always keep power in an ON mode and may change a capacitance value to generate a signal synchronized with a frequency of the input external signal. 
     According to an embodiment, the phase shifter may continuously generate the output signal in all sections. 
     According to an embodiment, the phase shifter may generate a signal corresponding to a first mode or a second mode, based on a command of a user. 
     According to another embodiment of the inventive concept, a phase shifter includes a 90 degree phase shifter that receives an external signal that is a basis for generating an oscillation signal, quadrature injection locked oscillators including a first oscillator that receives the external signal and generates a first signal and a second oscillator that generates a second signal, and that cross and add a gain of the first signal and a gain of the second signal and generates an oscillation signal of which phase is shifted, and the oscillation signal is operated in one of a first mode as a pulse signal or a second mode as a frequency continuous wave, and a quadrant phase selector that selects one of outputs of the quadrature injection locked oscillators. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       The above and other objects and features of the inventive concept will become apparent by describing in detail exemplary embodiments thereof with reference to the accompanying drawings. 
         FIG. 1  is a diagram illustrating a configuration of a radar according to an embodiment of the inventive concept. 
         FIG. 2  is a diagram illustrating a configuration of a transmitter according to an embodiment of the inventive concept. 
         FIG. 3  is a diagram illustrating a phase shifter according to an embodiment of the inventive concept. 
         FIG. 4  is a diagram illustrating a circuit of an oscillator according to an embodiment of the inventive concept. 
         FIG. 5  is a diagram illustrating a configuration of a receiver according to an embodiment of the inventive concept. 
         FIG. 6  is a diagram illustrating a configuration of a controller according to an embodiment of the inventive concept. 
         FIG. 7  is a diagram illustrating a waveform of an output signal according to a pulse mode of the inventive concept. 
         FIG. 8  is a diagram illustrating a frequency domain of a received signal of the inventive concept. 
         FIG. 9  is a diagram illustrating a capacitor circuit included in a phase shifter according to an embodiment of the inventive concept. 
         FIG. 10  is a flowchart illustrating a process of controlling a radar in a pulse mode by a controller according to an embodiment of the inventive concept. 
         FIG. 11  is a flowchart illustrating a process of controlling a radar in a continuous frequency mode (CW mode) by a controller according to an embodiment of the inventive concept. 
     
    
    
     DETAILED DESCRIPTION 
     Throughout the specification, the same reference numerals refer to the same components. This specification does not describe all elements of the embodiments, and overlaps between general contents or embodiments in the technical field to which the inventive concept pertains are omitted. The term “unit, module, member, or block” used in the specification may be implemented by software or hardware, and according to embodiments, it is also possible that a plurality of “unit, module, member, or block” may be implemented as one component, or that one “part, module, member, or block” includes a plurality of components. 
     Throughout the specification, when a part is “connected” to another part, this includes a case of being directly connected as well as being connected indirectly, and indirect connection includes connecting through a wireless communication network. 
     Also, when a part is said to “comprise” a certain component, this means that other components may be further included instead of excluding other components unless specifically stated otherwise. 
     Throughout the specification, when one member is positioned “on” another member, this includes not only the case where one member abuts another member, but also another member presents between the two members. 
     Terms such as first and second are used to distinguish one component from other components, and the component is not limited by the above-described terms. 
     A singular expression includes a plural expression unless the context clearly has an exception. 
     In each of steps, an identification code is used for convenience of description, and the identification code does not describe the order of each of the steps, and each of the steps may be performed differently from the specified order, unless a specific order is explicitly stated in the context. 
     Hereinafter, the principle and embodiments of the inventive concept will be described with reference to accompanying drawings. 
       FIG. 1  illustrates a configuration of a radar  100  according to an embodiment of the inventive concept,  FIG. 2  illustrates a configuration of a transmitter  130  according to an embodiment of the inventive concept, and  FIG. 3  illustrates a phase shifter according to an embodiment of the inventive concept. 
     Referring to  FIG. 1 , the radar  100  according to an embodiment of the inventive concept includes a controller  120 , the transmitter  130 , and a receiver  140 , and may include an input device  110 . 
     The input device  110  receives a command and a frequency tune code corresponding to a control mode of the radar  100  from a user, and transmits the input command and the frequency tune code to the controller  120 . 
     The controller  120  receives the command and the frequency tune code corresponding to the control mode of the radar  100  from the input device  110 , and controls the transmitter  130  and the receiver  140 , based on the command and the frequency tune code corresponding to the control mode of the radar  100 . In more detail, the control mode may be classified into a first mode or a second mode. The first mode refers to a pulse mode in which an oscillation signal is a pulse waveform signal and the radar  100  radiates the pulse waveform signal. The second mode refers to a continuous wave (CW) mode in which the oscillation signal is a frequency continuous wave and the radar  100  radiates the frequency continuous wave. In addition, the controller  120  may receive a signal corresponding to the first mode or the second mode, may control power supplied to the transmitter  130  based on the input signal, and may transmit a frequency tuning signal to a phase shifter  131 , based on the input signal. A control process of the controller  120  will be described in detail below while describing operations of the transmitter  130  and the receiver  140 . 
     Referring to  FIGS. 1, 2, and 3 , the transmitter  130  includes the phase shifter  131  and a signal amplifier  132 . In addition, the phase shifter  131  includes a 90 degree phase shifter  131 - 1 , quadrature injection locked oscillators  131 - 2 , and a quadrant phase selector  131 - 3 . 
     The 90 degree phase shifter  131 - 1  receives a signal Sin, which is a basis for generating an oscillation signal, from an outside, branches the input external signal into I/Q signals to input the input external signal to each I/Q path of the quadrature injection locked oscillators  131 - 2 . When the branched I/Q signals (Sij, Sqj) are input to the quadrature injection locked oscillators  131 - 2  and a frequency and a magnitude of the input oscillation signal satisfy a frequency locking condition, the quadrature injection locked oscillators  131 - 2  synchronize an output signal with the frequency of the input oscillation signal, and maintains the frequency of the output signal in a locked state. In this case, the frequency locked state means a state in which a frequency is maintained in a uniform waveform. 
     The quadrature injection locked oscillators  131 - 2  include a first oscillator generating a first signal and a second oscillator generating a second signal, and allow the oscillators to generate an oscillation frequency. In this case, each of the oscillators is configured to generate an injection locking based frequency with each other. In addition, the quadrature injection locked oscillators  131 - 2  may cross and add gains of a first signal Cqj and a second signal Cij, and may generate phase-shifted oscillation signals in which phases of the quadrature injection locked oscillators  131 - 2  are adjusted. In this case, a stable variable phase change range of each output of the quadrature injection locked oscillators  131 - 2  has a value of approximately 90 degrees, but the inventive concept is not limited thereto. 
     The quadrant phase selector  131 - 3  selects one of the outputs of the quadrature injection locked oscillators  131 - 2  with differential structure, outputs the oscillation signal of which phase is shifted, and transmits the output signal to the signal amplifier  132 . In this case, there may be four output signals of the quadrature injection locked oscillators  131 - 2 . 
     The signal amplifier  132  amplifies the oscillation signal of which phase is shifted to generate an output signal. 
     The transmitter  130  radiates the output signal generated while the oscillation signal passes through the phase shifter  131  and the signal amplifier  132  to the outside. 
     The receiver  140  receives a signal from the outside and filters the received signal. The receiver  140  may include a low pass filter  141 , a mixer  142 , and a low noise amplifier  143 , and may determine a cutoff frequency of the received signal. A detailed configuration of the receiver  140  will be described later in  FIG. 5 . 
       FIG. 4  illustrates a circuit of the quadrature injection locked oscillators  131 - 2  according to an embodiment of the inventive concept. 
     Referring to  FIG. 4 , the quadrature injection locked oscillators  131 - 2  according to the inventive concept include an input signal injector, a quadrature OSC injector, and an oscillator. 
     In this case, the gain of the first signal Cqj may be implemented by varying a current Icj of a current source of the Quadrature OSC injector. In this case, Sj+ and Sj− of the input signal injector may be provided from the 90 degree phase shifter  131 - 1 . In addition. Cj+ and Cj− of the quadrature OSC injector may be output signals of a Q-path side ILO of the quadrature injection locked oscillators  131 - 2 . In addition, to change an output phase of the quadrature injection locked oscillators  131 - 2 , a current source Ioj of the oscillator, a current source Icj of the quadrature OSC injector, and a current source Isj of the input signal injector may be adjusted. 
       FIG. 5  illustrates a configuration of the receiver  140  according to an embodiment of the inventive concept. 
     As described above, the receiver  140  receives the signal from the outside and filters the received signal. The receiver  140  may include the low pass filter  141 , the mixer  142 , and the low noise amplifier  143 , and may determine the cutoff frequency of the received signal. 
     In more detail, the signal received from the outside is amplified by passing through the low noise amplifier  143 , is passed through the mixer  142 , and is input to the low pass filter  141 . In this case, the receiver  140  cancels components other than the cutoff frequency from a reception signal RX_in and outputs an intermediate signal if_out. In this case, the cutoff frequency is determined based on a band width (BW) control signal received from the controller  120 . Specifically, since a signal band width to be output from the receiver  140  is different depending on a radar control mode, it is necessary to set the cutoff frequency of the low pass filter  141  differently. The BW control signal is a signal that sets an appropriate bandwidth of signals for each mode and determines the cutoff frequency of the low pass filter  141 . 
       FIG. 6  illustrates a configuration of the controller  120  according to an embodiment of the inventive concept. 
     The controller  120  according to the inventive concept may include a mode controller  121 , a power controller  122 , a pulse generator  123 , a memory  124 , and a frequency tuning controller  125 . 
     The mode controller  121  receives an input signal corresponding to the pulse mode or the continuous frequency mode and controls the power controller  122 , the pulse generator  123 , or the memory  124 . 
     In more detail, when the radar  100  is controlled in the pulse mode, the mode controller  121  transmits a power control signal to the power controller  122  during a section in which a pulse signal is generated, and cuts off power of the transmitter  130  while the pulse signal is not generated. In addition, when the radar  100  is controlled in the pulse mode, since a setting time is required for the signal amplifier  132  to operate normally, the mode controller  121  transmits a control signal to supply power to the signal amplifier  132  in advance such that the signal amplifier  132  operates stably. However, when the radar  100  is controlled in the continuous frequency mode, the mode controller  121  always transmits the power control signal to the power controller  122 , and always keeps the power of the transmitter  130  in ON state. 
     When the power is supplied to the power controller  122 , the pulse generator  123  generates a pulse and causes the transmitter  130  to generate a pulse signal. 
     The memory  124  stores a lock code and a free running code during the initialization process of the transmitter  130 . In this case, the lock code refers to a code corresponding to a lock frequency of the signal generated from the transmitter  130 , and the free running code refers to a code corresponding to a frequency generated while no pulse signal is generated. 
     The frequency tuning controller  125  receives information about the lock code and the free running code from the memory  124 , and allows the transmitter  130  to generate the signal, based on the input information. As a result, the transmitter  130  may generate the output signal by adjusting a capacitance of the quadrature injection locked oscillators  131 - 2  while the pulse is generated in the pulse mode. Also, the transmitter  130  may generate the output signal by always adjusting the capacitance of the quadrature injection locked oscillators  131 - 2  in the continuous frequency mode. 
       FIG. 7  illustrates a waveform of an output signal according to a pulse mode of the inventive concept. 
     Referring to  FIG. 7 , an external signal (Lo RF Signal) input while the radar  100  is operating is always input. As described above, the controller  120  controls a power supply of the transmitter  130  and allows the transmitter  130  to generate the signal, based on the frequency tune code. 
     In more detail, when the radar  100  is controlled in the pulse mode, the power control is performed by the controller  120  supplying power to the transmitter  130  (Tpc) and the signal amplifier  132  entering a normal operation section (Tlock) through a setting time (Tsettle_On). In addition, when the signal amplifier  132  enters the normal operation section (Tlock), the frequency tuning controller  125  transmits the free running code and then transmits the lock code to the transmitter  130 . As a result, when the power control starts, an output signal (TX_OUT Signal) gradually changes from a waveform corresponding to the free running code to a waveform corresponding to the lock code, and when the signal amplifier  132  enters the normal operating section (Tock), the transmitter  130  generates the output signal having a frequency corresponding to the lock code. In addition, when the output signal is reflected to the target and is input to the receiver  140 , the receiver  140  may generate a signal having a waveform corresponding to a reception signal Tres while generating the intermediate signal (IF_out signal). When the normal operation section (Tlock) of the signal amplifier  132  ends, the transmitter  130  generates a signal corresponding to the free running code again through a delay section Tdelay. 
       FIG. 8  illustrates a frequency domain of a received signal of the inventive concept. 
     Referring to  FIG. 8 , the reception signal RX_in input to the receiver  140  is a signal reflected by the target and is composed of spectral components having a free frequency Ffree and a reflection frequency Flo. In this case, the free frequency Ffree means a reception frequency component related to a signal generated by the free running code of the transmitter  130 , and the reflection frequency Flo means a reception frequency related to a signal generated by the lock code of the transmitter  130 . The free frequency Ffree and the reflection frequency Flo are mixed in the mixer  142 , and the reflection frequency Flo is shifted to a frequency (a DC frequency) having the same magnitude due to a mixing effect. In this case, the low pass filter  141  cancels a component of the free frequency from the reflection frequency based on the free running frequency, and restores the pulse signal Fbw of which band width is adjusted. 
       FIG. 9  illustrates a capacitor circuit included in the phase shifter  131  according to an embodiment of the inventive concept. 
     Referring to  FIG. 9 , the phase shifter  131  according to the inventive concept includes a plurality of capacitors Cu and switching circuits S 0  to Sn- 1 . When the power control signal and the frequency tuning signal are input from the controller  120 , the phase shifter  131  controls on/off of switches connected to a plurality of capacitors, and consequently controls the capacitance of the phase shifter  131  to generate the phase-shifted oscillation signal. 
       FIG. 10  illustrates a process of controlling the radar  100  in a pulse mode by the controller  120  according to an embodiment of the inventive concept. 
     Referring to  FIG. 10 , when the user inputs a pulse mode command to the input device  110 , the radar  100  is controlled in the pulse mode (S 1001 ). 
     When the radar  100  starts to be controlled in the pulse mode, the controller  120  controls power supplied to the phase shifter  131  and the signal amplifier  132  (S 1002 ). As described above, when power control is started, the controller  120  supplies power to the transmitter  130  (Tpc), and the signal amplifier  132  passes through the setting time (Tsettle_On) and then enters the normal operation section (Tlock). 
     When power supplied to the phase shifter  131  and the signal amplifier  132  is controlled, the controller  120  determines whether the pulse section is a duty cycle section (S 1003 ). 
     When it is determined that the pulse section is the duty cycle section, the controller  120  outputs the frequency lock code (S 1004 ), and controls the transmitter  130  to generate the output signal. When it is determined that the pulse section is not the duty cycle section, the controller  120  outputs the free running code (S 1005 ), and the transmitter  130  does not generate the output signal. 
       FIG. 11  illustrates a process of controlling the radar  100  in a continuous frequency mode (CW mode) by the controller  120  according to an embodiment of the inventive concept. 
     Referring to  FIG. 11 , when the user inputs a continuous frequency mode command to the input device  110 , the radar  100  is controlled in the continuous frequency mode (S 2001 ). 
     When the radar  100  is controlled in the continuous frequency mode, the controller  120  supplies power to the transmitter  130  such that the power of the transmitter  130  is always in ON mode (S 2002 ). 
     When power is always supplied to the transmitter  130 , the controller  120  controls the transmitter  130  to output the output signal in an entire section (S 2003 ). 
     An embodiment of the inventive concept may provide a phase shifter that generates a phase-shifted signal using a quadrature injection locked oscillator, and a radar including the same. 
     In addition, an embodiment of the inventive concept may provide a phase shifter that generates various signals in a pulse mode or a continuous frequency mode (CW mode) depending on a user&#39;s setting, and a radar including the same. 
     The contents described above are specific embodiments for implementing the inventive concept. The inventive concept may include not only the embodiments described above but also embodiments in which a design is simply or easily capable of being changed. In addition, the inventive concept may also include technologies easily changed to be implemented using embodiments.