COMMUNICATION DEVICE, COMMUNICATION METHOD, AND PROGRAM

Abstract

To provide a technology for improving accuracy of beamforming.SOLUTION: A communication apparatus comprises a signal output unit configured to output baseband signals to each of multiple local oscillators on the basis of a reference oscillation signal. Each of the local oscillators includes a phase comparator which outputs pulse signals in accordance with a difference between a phase of a feedback signal from a voltage-controlled oscillator and a phase of the reference oscillation signal, to the signal output unit. The signal output unit calculates phase correction values of the baseband signals output to each of the local oscillators, on the basis of the pulse signals output from each of the local oscillators, and corrects the phases of the baseband signals output to each of the local oscillators, on the basis of the phase correction values.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a communication device, a communication method, and a program. [Background technology]

[0002] In recent years, a technology for transmitting radio waves in a specific direction or receiving radio waves from a specific direction (so-called beamforming technology) has become known. For example, a circuit that transmits radio waves using beamforming technology (hereinafter also referred to as a "beamforming transmission circuit") controls the phase or amplitude of a transmission signal output from each of a plurality of transmission ports to form a transmission beam and control the transmission power to be maximized in the desired direction. This improves the spatial efficiency of radio wave utilization.

[0003] In a digital beamforming transmission circuit, the BB MPU (BaseBand Micro-Processing Unit) controls the beam by adding a phase difference to the IQ signal to be transmitted. In this case, if the phase of the LO (Local Oscillator) differs for each transmission port, it is possible that beamforming will not be performed with high precision.

[0004] The main reasons why the LO phase differs for each transmitting port include the locking timing of the LO PLL (Phase Locked Loop) control differing for each transmitting port, the LO phase differing for each transmitting port due to temperature changes during operation, etc. For example, since the temperature change of the LO is not necessarily the same for all transmitting ports, the LO phase fluctuation due to temperature change may differ for two or more transmitting ports.

[0005] Therefore, a compensation circuit and a compensation method have been proposed that compensate for phase fluctuations by storing in memory the relationship between the temperature acquired in advance and the LO phase, acquiring from the memory the LO phase corresponding to the temperature obtained from the temperature sensor, and adjusting the LO phase based on the LO phase acquired from the memory (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2019-212947 A Summary of the Invention [Problem to be solved by the invention]

[0007] However, there are two points that need to be improved in the technology for storing the relationship between temperature and LO phase in memory.

[0008] The first problem is that a time lag occurs between the timing at which a change in the surrounding temperature is detected and the timing at which the phase fluctuation is compensated for, so that the compensation for the phase fluctuation cannot keep up with sudden temperature changes.

[0009] The second problem is that the accuracy of phase fluctuation compensation is limited because it is difficult to accurately measure the temperature of the LO. In order to accurately measure the temperature of the VCO (Voltage Controlled Oscillator) that constitutes the LO, it is necessary to accurately measure the temperature inside the oscillation transistor. However, because it is difficult to accurately measure the temperature inside the oscillation transistor, it is difficult to accurately measure the temperature of the VCO, i.e., the temperature of the LO.

[0010] Therefore, it is desirable to provide a technique that enables the accuracy of beamforming to be improved. [Means for solving the problem]

[0011] In order to solve the above problems, according to one aspect of the present invention, there is provided a communication device including a signal output unit that outputs a baseband signal to each of a plurality of local oscillators based on a reference oscillation signal, wherein each of the plurality of local oscillators includes a phase comparator that outputs a pulse signal to the signal output unit according to a phase difference between the phase of a feedback signal from a voltage controlled oscillator and the phase of the reference oscillation signal, and the signal output unit calculates a phase correction value of the baseband signal to be output to each of the plurality of local oscillators based on the pulse signal output from each of the plurality of local oscillators, and corrects the phase of the baseband signal to be output to each of the plurality of local oscillators based on the phase correction value.

[0012] The communication device may include an AD converter at a position where an output from the phase comparator in the local oscillator is branched, and the AD converter may sample the output from the phase comparator and output it to the signal output section.

[0013] The communication device , B The output from the phase comparator may be input to the AD converter via the buffer and sampled by the AD converter.

[0014] The signal output section may calculate, as the phase correction value, a delay in the phase of the feedback signal relative to a phase of the reference oscillation signal.

[0015] The signal output unit may update the phase difference obtained by subtracting the phase correction value from the phase difference to be added to the IQ signal as the phase difference to be added to the IQ signal, and perform control so that the updated phase difference is added to the IQ signal.

[0016] The communication device may be applied to a transmission circuit.

[0017] The communication device may be applied to a receiving circuit.

[0018] According to another aspect of the present invention, there is provided a communication method using a communication device including a signal output unit that outputs a baseband signal to each of a plurality of local oscillators based on a reference oscillation signal, wherein each of the plurality of local oscillators includes a phase comparator that outputs a pulse signal to the signal output unit according to a phase difference between the phase of a feedback signal from a voltage controlled oscillator and the phase of the reference oscillation signal, and the signal output unit calculates a phase correction value of the baseband signal to be output to each of the plurality of local oscillators based on the pulse signal output from each of the plurality of local oscillators, and corrects the phase of the baseband signal to be output to each of the plurality of local oscillators based on the phase correction value.

[0019] According to another aspect of the present invention, there is provided a program for causing a computer to function as a communications device comprising a signal output unit that outputs a baseband signal to each of a plurality of local oscillators based on a reference oscillation signal, each of the plurality of local oscillators comprising a phase comparator that outputs a pulse signal to the signal output unit according to a phase difference between the phase of a feedback signal from a voltage controlled oscillator and the phase of the reference oscillation signal, the signal output unit calculating a phase correction value of the baseband signal to be output to each of the plurality of local oscillators based on the pulse signal output from each of the plurality of local oscillators, and correcting the phase of the baseband signal to be output to each of the plurality of local oscillators based on the phase correction value. Effect of the Invention

[0020] As described above, according to the present invention, a technique is provided that makes it possible to improve the accuracy of beamforming. [Brief description of the drawings]

[0021] [Figure 1] FIG. 1 is a diagram illustrating an example of the configuration of a general beamforming transmission circuit. [Diagram 2] FIG. 2 is a diagram illustrating an example of a functional configuration of a beamforming transmission circuit. [Diagram 3]FIG. 1 is a diagram illustrating a configuration example of a beamforming transmission circuit in which the internal configuration of an LO is detailed. [Figure 4] FIG. 2 is a diagram illustrating an example of the configuration of a phase frequency reference oscillation source. [Diagram 5] This figure shows an example of a PFD configuration made up of D-type flip-flop circuits. [Figure 6] 5 is a timing chart showing the input / output relationship of the PFD when the phase of a feedback signal lags behind the phase of a phase frequency reference oscillation signal in the first embodiment of the present invention. [Figure 7] 10 is a timing chart showing the input / output relationship of the PFD in the embodiment when the phase of a feedback signal leads the phase of a phase frequency reference oscillation signal. [Figure 8] 11 is a timing chart showing the input / output relationship of the PFD when the phase of a phase frequency reference oscillation signal IN_A and the phase of a feedback signal IN_B are synchronized in the same embodiment. [Figure 9] 11 is a diagram showing an example of timing at which the phase frequency reference oscillation signal and each LO are locked in the same embodiment. FIG. [Figure 10] This figure shows an example of a PFD configuration made up of JK flip-flop circuits. [Figure 11] 10 is a timing chart showing the input / output relationship of the PFD when the phase of a feedback signal lags behind the phase of a phase frequency reference oscillation signal in the second embodiment of the present invention. [Figure 12] 10 is a timing chart showing the input / output relationship of the PFD in the embodiment when the phase of a feedback signal leads the phase of a phase frequency reference oscillation signal. [Figure 13] 10 is a timing chart showing the input / output relationship of the PFD when the phase of the phase frequency reference oscillation signal and the phase of the feedback signal are synchronized in the embodiment. [Figure 14] 11 is a diagram showing an example of timing at which the phase frequency reference oscillation signal and each LO are locked in the same embodiment. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In this specification and the drawings, components having substantially the same functional configurations are designated by the same reference numerals, and duplicated explanations will be omitted.

[0023] In addition, in this specification and drawings, multiple components having substantially the same functional configuration may be distinguished by adding different numbers after the same reference symbol. However, if there is no particular need to distinguish between multiple components having substantially the same functional configuration, only the same reference symbol is used. Furthermore, similar components in different embodiments may be distinguished by adding different alphabets after the same reference symbol. However, if there is no particular need to distinguish between similar components in different embodiments, only the same reference symbol is used.

[0024] (0. Overview) First, an overview of the embodiment of the present invention will be described.

[0025] Fig. 1 is a diagram showing an example of the configuration of a general beamforming transmission circuit. As shown in Fig. 1, a general beamforming transmission circuit 9 includes a phase frequency reference oscillation source 11 and a BB MPU 90. The BB MPU 90 has mixers 12-0 to 12-n corresponding to transmission ports from 0 to n (n is a natural number).

[0026] The beamforming transmission circuit 9 also includes DACs (Digital-Analog Converters) 13-0 to 13-n, LOs 14-0 to 14-n, mixers 15-0 to 15-n, variable gain amplifiers 16-0 to 16-n, and antennas 17-0 to 17-n, which correspond to transmission ports 0 to n.

[0027] The phase frequency reference oscillation source 11 outputs a phase frequency reference oscillation signal to the BB MPU 90. The BB MPU 90 performs control so that a phase difference w based on the phase of the phase frequency reference oscillation signal is added to the phase of the IQ signal generated by the mixer 12 for each of the transmission ports from 0 to n, and outputs the controlled signal as a baseband signal to the DAC 13. Next, the following operation is performed for each of the transmission ports from 0 to n.

[0028] DAC 13 converts the signal output from BB MPU 90 from digital to analog format, and outputs the converted signal to mixer 15. Mixer 15 mixes the signal output from DAC 13 with the local oscillation signal output from LO 14, and outputs the result to variable gain amplifier 16. Variable gain amplifier 16 amplifies the signal output from mixer 15, and antenna 17 radiates radio waves into space based on the signal output from variable gain amplifier 16.

[0029] In this case, the phase of the LO 14 may differ for each transmitting port, which may result in beam forming not being performed with high accuracy.

[0030] The main reasons why the phase of LO 14 differs for each transmitting port include the timing of locking the PLL control of LO 14 differing for each transmitting port, the phase of LO 14 differing for each transmitting port due to temperature changes during operation, etc. For example, since the temperature change of LO 14 is not necessarily the same for all transmitting ports, the phase fluctuation of LO 14 due to temperature change may differ for any two or more transmitting ports.

[0031] Therefore, in the embodiment of the present invention, a technique that enables improvement in the accuracy of beamforming is mainly proposed.

[0032] The outline of the embodiment of the present invention has been described above.

[0033] 1. First Embodiment Next, a first embodiment of the present invention will be described.

[0034] (1-1. Beamforming transmission circuit configuration) First, a configuration example of a beamforming transmission circuit according to a first embodiment of the present invention will be described.

[0035] (Example of a transmitter circuit configuration) Fig. 2 is a diagram showing an example of a functional configuration of a beamforming transmission circuit according to a first embodiment of the present invention. As shown in Fig. 2, the beamforming transmission circuit 1 includes a phase frequency reference oscillation source 11 and a BB MPU 10. The BB MPU 10 has mixers 12-0 to 12-n corresponding to transmission ports 0 to n.

[0036] The beamforming transmission circuit 1 also includes DACs 13-0 to 13-n, LOs 14-0 to 14-n, mixers 15-0 to 15-n, variable gain amplifiers 16-0 to 16-n, and antennas 17-0 to 17-n corresponding to the transmission ports from 0 to n. Furthermore, in the first embodiment of the present invention, the beamforming transmission circuit 1 also includes ADCs (Analog-Digital Converters) 18-0 to 18-n corresponding to the transmission ports from 0 to n.

[0037] The ADC 18 samples the output obtained by branching the output from a phase comparator (PFD: Phase Frequency Detector) included in the LO 14. More specifically, the ADC 18 converts the output signal from the phase comparator (hereinafter also referred to as "PFD") included in the LO 14 from analog format to a digital signal, and outputs the converted signal to the BB MPU 10.

[0038] Fig. 3 is a diagram showing a configuration example of a beamforming transmission circuit with the internal configuration of the LO in detail. As shown in Fig. 3, the phase frequency reference oscillation source 11 outputs phase frequency reference oscillation signals to LO#1 to LO#N (N corresponds to n+1) and the BB MPU 10 via a distributor. As a result, the phase references of the entire beamforming transmission circuit are all aligned with the phase of the phase frequency reference oscillation source 11.

[0039] Since the configuration of each of LO#1 to LO#N is similar, in the example shown in Fig. 3, the configuration of LO#N is marked with a reference symbol, and the reference symbols of the configurations of the other LOs are omitted. Each of LO#1 to LO#N includes a PFD 21, a CP (Charge Pump) 23, a filter 24, a VCO 25, a divider 26, a mixer 15, and a DAC 13.

[0040] Moreover, in the first embodiment of the present invention, each of LO#1 to LO#N includes a buffer 22 and an ADC 18 at a position where the output from the PFD 21 is branched.

[0041] The CP 23 increases the pulse voltage (output voltage) from the PFD 21. The filter 24 obtains a DC voltage proportional to the pulse width by performing time integration on the signal output from the CP 23. The filter 24 outputs the DC voltage proportional to the pulse width to the VCO 25.

[0042] The VCO 25 changes the frequency of the output signal according to the value of the DC voltage output from the filter 24. This controls the phase to be synchronized between the input signal to the LO and the output signal from the LO. The frequency divider 26 divides the frequency of the output signal from the VCO 25 by a set division ratio, and outputs the divided signal to the PFD 21 as a feedback signal.

[0043] The PFD 21 obtains a phase difference by comparing the phase of the input signal (i.e., the phase frequency reference oscillation signal) from the phase frequency reference oscillation source 11 with the phase of the feedback signal output from the frequency divider 26. The PFD 21 outputs a pulse signal having a duty ratio according to the phase difference to the CP 23. At the same time, the PFD 21 outputs the pulse signal to the buffer 22 located at the position where the output to the CP 23 is branched.

[0044] The buffer 22 has a high input impedance over a wide band so as not to affect the negative feedback control in the LO.

[0045] The ADC 18 samples the pulse signal input from the PFD 21 via the buffer 22. More specifically, the ADC 18 divides the analog pulse signal into fixed time units and performs sampling to extract the signal level for each time unit as a digital pulse signal. The ADC 18 outputs the digital pulse signal obtained by sampling to the BB MPU 10.

[0046] The BB MPU 10 realizes its functions by reading and executing a program recorded in the memory by the processor. As described above, the BB MPU 10 functions as a signal output unit that controls the phase of the IQ signal so that a phase difference w based on the phase of the phase frequency reference oscillation signal is added to the phase of the IQ signal, and outputs the controlled signal to the DAC 13 as a baseband signal.

[0047] At this time, the BB MPU 10 calculates the phase difference between the phase of the phase frequency reference oscillation source 11 and the phase of the VCO 25 as a phase correction value of the baseband signal based on the pulse signal output from the ADC 18. The BB MPU 10 corrects the phase of the baseband signal output to the LO#N based on the calculated phase correction value.

[0048] More specifically, the BB MPU 10 calculates the phase delay of VCO 25 based on the phase of the phase frequency reference oscillation source 11 as a phase correction value, updates the phase difference obtained by subtracting the phase correction value from the phase difference w to be added to the IQ signal as the phase difference to be added to the IQ signal, performs control so that the updated phase difference is added to the IQ signal, and outputs the controlled signal to DAC 13 as a baseband signal.

[0049] The same control as that in LO#N described above is also executed for LO#1 to #N-1. This adjusts the phases of the baseband signals output from the BB MPU10 and corresponding to each of the multiple transmission ports to match. This is expected to improve the accuracy of beamforming.

[0050] (Example of configuration of phase frequency reference oscillation source 11) Fig. 4 is a diagram showing a configuration example of the phase frequency reference oscillation source 11. As shown in Fig. 4, the phase frequency reference oscillation source 11 is connected to a GPS (Global Positioning System) receiver 27, and outputs a phase frequency reference oscillation signal synchronized with a GPS time pulse output by the GPS receiver 27. The phase frequency reference oscillation signal output by the phase frequency reference oscillation source 11 is input to each of LO#1 to LO#N and BB MPU10 via a distributor.

[0051] (Example of PFD21 configuration) The PFD in the LO is generally constructed using a D-type or JK-type flip-flop circuit.

[0052] 5 is a diagram showing an example of the configuration of the PFD 21 composed of a D-type flip-flop circuit. A distributor is connected to IN_A of the D-type flip-flop 211, and the phase frequency reference oscillation signal output from the phase frequency reference oscillation source 11 is input to IN_A via the distributor. On the other hand, a frequency divider is connected to IN_B of the D-type flip-flop 211, and the feedback signal output from the frequency divider is input to IN_B.

[0053] The output from the D-type flip-flop 211 is branched, and one of the outputs from the D-type flip-flop 211 is input to the CP23, forming a negative feedback loop. The other output from the D-type flip-flop 211 is input to the ADC181 as an example of the ADC18 (FIG. 3) via the buffer 221 as an example of the buffer 22 (FIG. 3). The signal sampled by the ADC181 is output to the BB MPU10.

[0054] Similarly, the output from the D-type flip-flop 212 is branched, and one of the outputs from the D-type flip-flop 212 is input to the CP23, forming a negative feedback loop. The other output from the D-type flip-flop 212 is input to the ADC182, which is an example of the ADC18 (FIG. 3), via the buffer 222, which is an example of the buffer 22 (FIG. 3). The signal sampled by the ADC182 is output to the BB MPU10.

[0055] An example of the configuration of the beamforming transmission circuit according to the first embodiment of the present invention has been described above.

[0056] (1-2. Operation of beamforming transmission circuit) Next, an example of the operation of the beamforming transmission circuit 1 according to the first embodiment of the present invention will be described.

[0057] An example of the operation of the beamforming transmission circuit 1 will be described with reference to Fig. 2 to Fig. 5. The phase frequency reference oscillation source 11 outputs a phase frequency reference oscillation signal synchronized with a GPS time pulse output by the GPS receiver 27 (Fig. 4). The phase frequency reference oscillation signal output by the phase frequency reference oscillation source 11 is input to each of LO #1 to LO #N and BB MPU 10 via a distributor.

[0058] The BB MPU 10 sets the division ratio in the frequency divider 26 provided in each of the LO#1 to LO#N to set the frequency of the feedback signal input to the PFD 21 provided in each of the LO#1 to LO#N to the desired frequency. The PFD 21 provided in each of the LO#1 to LO#N starts comparing the phase of the phase frequency reference oscillation signal output from the phase frequency reference oscillation source 11 with the phase of the feedback signal output from the frequency divider 26.

[0059] (Initial phase detection) 6 is a timing chart showing the input / output relationship of the PFD 21 when the phase of the feedback signal lags behind the phase of the phase frequency reference oscillation signal. Referring to FIG. 6, the phase of the feedback signal IN_B lags behind the phase of the phase frequency reference oscillation signal IN_A by a phase difference ΔΦ (i.e., the phase lag ΔΦ>0 holds). In the first embodiment, the width between the rising edges of IN_A and IN_B corresponds to the phase difference. Also referring to FIG. 6, the output signal OUT_A from the D-type flip-flop 211 and the output signal OUT_B from the D-type flip-flop 212 are shown.

[0060] 7 is a timing chart showing the input / output relationship of the PFD 21 when the phase of the feedback signal leads the phase of the phase frequency reference oscillation signal. Referring to FIG. 7, the phase of the feedback signal IN_B leads the phase of the phase frequency reference oscillation signal IN_A by a phase difference ΔΦ (i.e., the phase delay ΔΦ<0 holds). In the first embodiment, the width between the rising edges of IN_A and IN_B corresponds to the phase difference. Also referring to FIG. 7, the output signal OUT_A from the D-type flip-flop 211 and the output signal OUT_B from the D-type flip-flop 212 are shown.

[0061] Fig. 8 is a timing chart showing the input / output relationship of the PFD 21 when the phase of the phase frequency reference oscillation signal IN_A and the phase of the feedback signal IN_B are synchronized. Even if there is a phase difference between the phase of the phase frequency reference oscillation signal IN_A and the phase of the feedback signal IN_B (Figs. 6 and 7), when the comparison of the phases in the PFD 21 starts, the phase of the phase frequency reference oscillation signal IN_A and the phase of the feedback signal IN_B are controlled to be synchronized by the negative feedback control in LO as shown in Fig. 8.

[0062] When the phase of the phase frequency reference oscillation signal IN_A and the phase of the feedback signal IN_B are synchronized (i.e., when the pulse width of OUT_A and the pulse width of OUT_B are aligned), the LO state becomes a locked state. While observing OUT_A and OUT_B, the BB MPU 10 records in memory at which rising edge of the phase frequency reference oscillation signal IN_A the LO is locked.

[0063] Fig. 9 is a diagram showing an example of the timing when the phase frequency reference oscillation signal IN_A and each LO are locked. As shown in Fig. 9, for all of LO#1 to LO#N, the phase of the phase frequency reference oscillation signal IN_A and the phase of the feedback signal IN_B are controlled to be synchronized, and the rising edge of the phase frequency reference oscillation signal IN_A at which the LO is locked is recorded in memory.

[0064] The BB MPU 10 calculates the number of cycles at which the other LOs are locked, based on the first locked LO. In the example shown in Fig. 9, LO#2 is locked first, and based on LO#2, LO#1 is locked in the first cycle, and LO#N is locked in the fifth cycle. Since the number of cycles is a value after division by the divider 26 (Fig. 3), the BB MPU 10 obtains the initial phase by multiplying the calculated number of cycles by the division number.

[0065] The BB MPU 10 adds a phase difference equivalent to the initial phase to the baseband signal corresponding to each transmission port and outputs the signal to the DAC 13 .

[0066] (Random variation of phase value) The phase of each LO may vary randomly from the initial phase. At this time, the BB MPU 10 calculates the phase difference between the phase of the phase frequency reference oscillator 11 and the phase of the VCO 25 as a phase correction value of the baseband signal based on the pulse signals OUT_A and OUT_B input from the PFD 21 via the buffer 22 and the ADC 18.

[0067] More specifically, when the pulse widths of OUT_A and OUT_B are the same, the BB MPU 10 calculates the phase difference ΔΦ as 0, and the phase difference ΔΦ increases as the pulse width of OUT_A is larger than that of OUT_B, and the phase difference ΔΦ decreases as the pulse width of OUT_A is smaller than that of OUT_B. The BB MPU 10 calculates a value obtained by multiplying the phase difference ΔΦ by the frequency division number as the phase correction value of the baseband signal.

[0068] The BB MPU 10 corrects the phase of the baseband signal output to the LO based on the calculated phase correction value. More specifically, the BB MPU 10 performs control so that a phase obtained by subtracting the phase correction value from the phase difference w to be added to the IQ signal is added to the phase of the IQ signal, and outputs the controlled signal as a baseband signal to the DAC 13. The above-described operation is repeatedly executed until the negative feedback control in the LO is completed.

[0069] An example of the operation of the beamforming transmission circuit 1 according to the first embodiment of the present invention has been described above.

[0070] (1-3. Effects) As described above, in the beamforming transmission circuit 1 according to the first embodiment of the present invention, the BB MPU 10 calculates the phase difference between the phase of the phase frequency reference oscillation source 11 and the phase of the VCO 25 as a phase correction value of the baseband signal, based on the pulse signals OUT_A and OUT_B input from the PFD 21 via the buffer 22 and the ADC 18. Then, the BB MPU 10 corrects the phase of the baseband signal output to each LO based on the calculated phase correction value.

[0071] With this configuration, even if random phase fluctuations occur for each LO, the phase of each LO can be adjusted in almost real time to accommodate the phase fluctuations, which is expected to improve the accuracy of beamforming.

[0072] The effects achieved by the beamforming transmission circuit according to the first embodiment of the present invention have been described above.

[0073] 2. Second Embodiment Next, a second embodiment of the present invention will be described. However, among the configurations of the beamforming transmission circuit according to the second embodiment of the present invention, the configurations different from the configuration of the beamforming transmission circuit according to the first embodiment of the present invention will be mainly described, and a detailed description of the configurations that are the same as the configuration of the beamforming transmission circuit according to the first embodiment of the present invention will be omitted.

[0074] (2-1. Beamforming transmission circuit configuration) First, a configuration example of a beamforming transmission circuit according to a second embodiment of the present invention will be described. The beamforming transmission circuit according to the second embodiment of the present invention and the beamforming transmission circuit according to the first embodiment of the present invention mainly differ in the configuration of the PFD. Therefore, in the following description, the configuration of the PFD will be mainly described.

[0075] (Example of PFD21 configuration) As described above, the PFD in the LO is generally configured with a D-type or JK-type flip-flop circuit. In the second embodiment of the present invention, the case where the PFD in the LO is configured with a JK-type flip-flop circuit is mainly assumed.

[0076] 10 is a diagram showing an example of the configuration of a PFD 21 configured with a JK flip-flop circuit. A distributor is connected to IN_A of the JK flip-flop 213, and the phase frequency reference oscillation signal output from the phase frequency reference oscillation source 11 is input to IN_A via the distributor. On the other hand, a frequency divider is connected to IN_B of the JK flip-flop 214, and the feedback signal output from the frequency divider is input to IN_B.

[0077] The output from the JK flip-flop 213 is branched, and one of the outputs from the JK flip-flop 213 is input to the CP23, forming a negative feedback loop. The other output from the JK flip-flop 213 is input to the ADC181, which is an example of the ADC18 (FIG. 3), via a buffer 221, which is an example of the buffer 22 (FIG. 3). The signal sampled by the ADC181 is output to the BB MPU10.

[0078] Similarly, the output from the JK flip-flop 214 is branched, and one of the outputs from the JK flip-flop 214 is input to the CP 23, forming a negative feedback loop. The other output from the JK flip-flop 214 is input to the ADC 182, which is an example of the ADC 18 (FIG. 3), via a buffer 222, which is an example of the buffer 22 (FIG. 3). The signal sampled by the ADC 182 is output to the BB MPU 10.

[0079] An example of the configuration of the beamforming transmission circuit according to the second embodiment of the present invention has been described above.

[0080] (2-2. Operation of beamforming transmission circuit) Next, an operation example of the beamforming transmission circuit 1 according to the second embodiment of the present invention will be described. In the second embodiment of the present invention, the process from output of the phase frequency reference oscillation signal to setting of the output division ratio is executed in the same manner as in the first embodiment of the present invention. The PFD 21 included in LO#1 to LO#N starts comparing the phase of the phase frequency reference oscillation signal output from the phase frequency reference oscillation source 11 with the phase of the feedback signal output from the frequency divider 26.

[0081] (Initial phase detection) Fig. 11 is a timing chart showing the input / output relationship of the PFD 21 when the phase of the feedback signal lags behind the phase of the phase frequency reference oscillation signal. Referring to Fig. 11, the phase of the feedback signal IN_B lags behind the phase of the phase frequency reference oscillation signal IN_A by a phase difference ΔΦ (i.e., the phase lag ΔΦ>0 holds). In the second embodiment, the width between the falling edges of IN_A and IN_B corresponds to the phase difference. Also referring to Fig. 11, the output signal OUT_A from the JK-type flip-flop 213 and the output signal OUT_B from the JI-type flip-flop 214 are shown.

[0082] Fig. 12 is a timing chart showing the input / output relationship of the PFD 21 when the phase of the feedback signal leads the phase of the phase frequency reference oscillation signal. Referring to Fig. 12, the phase of the feedback signal IN_B leads the phase of the phase frequency reference oscillation signal IN_A by a phase difference ΔΦ (i.e., the phase delay ΔΦ<0 holds). In the second embodiment, the width between the falling edges of IN_A and IN_B corresponds to the phase difference. Also referring to Fig. 12, the output signal OUT_A from the JK-type flip-flop 213 and the output signal OUT_B from the JK-type flip-flop 214 are shown.

[0083] Fig. 13 is a timing chart showing the input / output relationship of the PFD 21 when the phase of the phase frequency reference oscillation signal IN_A and the phase of the feedback signal IN_B are synchronized. Even if there is a phase difference between the phase of the phase frequency reference oscillation signal IN_A and the phase of the feedback signal IN_B (Figs. 11 and 12), when the comparison of the phases in the PFD 21 starts, the phase of the phase frequency reference oscillation signal IN_A and the phase of the feedback signal IN_B are controlled to be synchronized by the negative feedback control in LO as shown in Fig. 13.

[0084] In the second embodiment of the present invention, the BB MPU 10 records in memory at which falling edge of the phase frequency reference oscillation signal IN_A the LO is locked while observing OUT_A and OUT_B.

[0085] Fig. 14 is a diagram showing an example of the timing when the phase frequency reference oscillation signal IN_A and each LO are locked. As shown in Fig. 14, for all of LO#1 to LO#N, the phase of the phase frequency reference oscillation signal IN_A and the phase of the feedback signal IN_B are controlled to be synchronized, and the falling edge of the phase frequency reference oscillation signal IN_A at which the LO is locked is recorded in the memory. The subsequent operations can be performed in the same manner as in the first embodiment of the present invention.

[0086] (2-3. Effects) As described above, the beamforming transmission circuit according to the second embodiment of the present invention is different from the beamforming transmission circuit according to the first embodiment of the present invention in the configuration of the PFD 21. However, the beamforming transmission circuit according to the second embodiment of the present invention can also achieve the same effects as those achieved by the beamforming transmission circuit according to the first embodiment of the present invention.

[0087] The effects achieved by the beamforming transmission circuit according to the second embodiment of the present invention have been described above.

[0088] (3. Summary) Although the preferred embodiment of the present invention has been described in detail above with reference to the accompanying drawings, the present invention is not limited to such an example. It is clear that a person having ordinary knowledge in the technical field to which the present invention pertains can conceive of various modified or altered examples within the scope of the technical ideas described in the claims, and it is understood that these also naturally belong to the technical scope of the present invention.

[0089] For example, in the above, the initial phase detection method and the phase variation tracking method, which are features of the embodiment of the present invention, are mainly described as being applied to a beamforming transmission circuit. However, other communication devices having these features may also be realized. For example, the initial phase detection method and the phase variation tracking method, which are features of the embodiment of the present invention, may be applied to a beamforming reception circuit. This may improve the estimation accuracy of a radio wave arrival direction estimation circuit that requires real-time and accurate phase detection. [Explanation of symbols]

[0090] 1 Beamforming transmitter circuit 10BB MPU 11 Phase Frequency Reference Oscillator 12 Mixer 13 DAC 14 LO 15 Mixer 16 Variable Gain Amplifier 17 Antenna 18 ADC 21 PFD 22 Buffer 23 CP 24 Filters 25 VCO 26 frequency divider 27 GPS receiver

Claims

1. A communication device comprising a signal output unit that outputs a baseband signal to each of a plurality of local oscillators based on a reference oscillation signal, Each of the plurality of local oscillators includes a phase comparator that outputs a pulse signal corresponding to a phase difference between a phase of a feedback signal from a voltage controlled oscillator and a phase of the reference oscillation signal to the signal output section, the signal output unit calculates a phase correction value of a baseband signal to be output to each of the plurality of local oscillators based on the pulse signal output from each of the plurality of local oscillators, and corrects the phase of the baseband signal to be output to each of the plurality of local oscillators based on the phase correction value. Communications equipment.

2. The communication device includes: an AD converter is provided at a position where an output from the phase comparator in the local oscillator is branched; The AD converter samples the output from the phase comparator and outputs the sampled output to the signal output unit. The communication device according to claim 1 .

3. The communication device includes a buffer; The output from the phase comparator is input to the AD converter via the buffer and sampled by the AD converter. The communication device according to claim 2 .

4. The signal output unit calculates a phase delay of the feedback signal based on a phase of the reference oscillation signal as the phase correction value. A communication device according to any one of claims 1 to 3.

5. the signal output unit updates the phase difference to be added to the IQ signal with a phase difference obtained by subtracting the phase correction value from the phase difference to be added to the IQ signal, and performs control so that the updated phase difference is added to the IQ signal. A communication device according to any one of claims 1 to 4.

6. The communication device is applied to a transmission circuit. A communication device according to any one of claims 1 to 5.

7. The communication device is applied to a receiving circuit, A communication device according to any one of claims 1 to 5.

8. A communication method using a communication device including a signal output unit that outputs a baseband signal to each of a plurality of local oscillators based on a reference oscillation signal, Each of the plurality of local oscillators includes a phase comparator that outputs a pulse signal corresponding to a phase difference between a phase of a feedback signal from a voltage controlled oscillator and a phase of the reference oscillation signal to the signal output section, the signal output unit calculates a phase correction value of a baseband signal to be output to each of the plurality of local oscillators based on the pulse signal output from each of the plurality of local oscillators, and corrects the phase of the baseband signal to be output to each of the plurality of local oscillators based on the phase correction value. Communication methods.

9. Computer, A communication device comprising a signal output unit that outputs a baseband signal to each of a plurality of local oscillators based on a reference oscillation signal, Each of the plurality of local oscillators includes a phase comparator that outputs a pulse signal corresponding to a phase difference between a phase of a feedback signal from a voltage controlled oscillator and a phase of the reference oscillation signal to the signal output section, the signal output unit calculates a phase correction value of a baseband signal to be output to each of the plurality of local oscillators based on the pulse signal output from each of the plurality of local oscillators, and corrects the phase of the baseband signal to be output to each of the plurality of local oscillators based on the phase correction value. A program that functions as a communication device.

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