JP7652020B2 - COMMUNICATION DEVICE, COMMUNICATION METHOD, AND PROGRAM - Google Patents

Description

The present invention relates to a communication device, a communication method, and a program.

In recent years, 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 the transmission signal output from each of multiple 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.

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. At this time, if the phase of the LO (Local Oscillator) differs for each transmission port, there is a possibility that beamforming will not be performed with high precision.

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

Therefore, a compensation circuit and compensation method have been proposed that compensate for phase fluctuations by storing in memory the relationship between the temperature and the LO phase obtained in advance, obtaining 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 obtained from the memory (see, for example, Patent Document 1).

JP 2019-212947 A

However, there are two areas that need improvement in the technology for storing the relationship between temperature and LO phase in memory.

The first problem is that a time lag occurs between when the ambient temperature change is detected and when the phase shift is compensated for, meaning that the compensation for the phase shift cannot keep up with sudden temperature changes.

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.

Therefore, it is desirable to provide technology that can improve the accuracy of beamforming.

In order to solve the above problem, according to one aspect of the present invention, a communication device is provided that includes a signal output unit that outputs a baseband signal to each of a plurality of local oscillators based on a reference oscillation signal, and 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.

The communication device may include an AD converter at a position where the 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 unit.

The communication device may include a buffer , and the output from the phase comparator may be input to the AD converter via the buffer and sampled by the AD converter.

The signal output unit may calculate the phase delay of the feedback signal relative to the phase of the reference oscillation signal as the phase correction value.

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

The communication device may be applied to a transmission circuit.

The communication device may be applied to a receiving circuit.

In addition, 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, each of the plurality of local oscillators including 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.

In accordance with another aspect of the present invention, a program is provided that causes a computer to function as a communications device that includes 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 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.

As described above, the present invention provides technology that makes it possible to improve the accuracy of beamforming.

FIG. 1 is a diagram illustrating an example of the configuration of a general beamforming transmission circuit. FIG. 2 is a diagram illustrating an example of a functional configuration of a beamforming transmission circuit. FIG. 2 is a diagram illustrating an example of the configuration of a beamforming transmission circuit in which the internal configuration of an LO is detailed. FIG. 2 is a diagram illustrating an example of the configuration of a phase frequency reference oscillation source. FIG. 1 is a diagram showing an example of the configuration of a PFD formed by a D-type flip-flop circuit. 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. 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. 10 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 embodiment; 11 is a diagram showing an example of timing when the phase frequency reference oscillation signal and each LO are locked in the same embodiment. FIG. FIG. 1 is a diagram showing an example of the configuration of a PFD formed by a JK type flip-flop circuit. 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. 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. 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. 11 is a diagram showing an example of timing when the phase frequency reference oscillation signal and each LO are locked in the same embodiment. FIG.

The preferred embodiment of the present invention will be described in detail below with reference to the attached drawings. Note that in this specification and the drawings, components having substantially the same functional configuration are designated by the same reference numerals to avoid redundant description.

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 will be used. In addition, similar components in different embodiments may be distinguished by adding different letters 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 will be used.

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

Figure 1 is a diagram showing an example of the configuration of a typical beamforming transmission circuit. As shown in Figure 1, a typical beamforming transmission circuit 9 includes a phase frequency reference oscillator 11 and a BB MPU 90. The BB MPU 90 has mixers 12-0 to 12-n that correspond to transmission ports from 0 to n (n is a natural number).

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 the transmission ports 0 to n.

The phase frequency reference oscillation source 11 outputs a phase frequency reference oscillation signal to the BB MPU 90. The BB MPU 90 controls the phase of the IQ signal generated by the mixer 12 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 0 to n, and outputs the controlled signal to the DAC 13 as a baseband signal. Next, the following operations are performed for each of the transmission ports 0 to n.

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 oscillator 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.

In this case, the phase of LO14 may differ for each transmit port, which may result in beamforming not being performed with high accuracy.

The main reasons why the phase of LO14 differs for each transmitting port include the timing at which the PLL control of LO14 locks differing for each transmitting port, and the phase of LO14 differing for each transmitting port due to temperature changes during operation. For example, the temperature change of LO14 is not necessarily the same for all transmitting ports, so the phase fluctuation of LO14 due to temperature change may differ for any two or more transmitting ports.

Therefore, in the embodiment of the present invention, we mainly propose a technology that makes it possible to improve the accuracy of beamforming.

The above describes an overview of an embodiment of the present invention.

1. First embodiment
Next, a first embodiment of the present invention will be described.

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

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

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, which correspond to the transmission ports 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, which correspond to the transmission ports 0 to n.

The ADC 18 samples the output obtained by branching the output from the 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.

Figure 3 is a diagram showing an example of the configuration of a beamforming transmission circuit with the internal configuration of the LO in detail. As shown in Figure 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. This causes the phase references of the entire beamforming transmission circuit to be aligned with the phase of the phase frequency reference oscillation source 11.

Since the configurations of LO#1 to LO#N are 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.

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

CP23 increases the pulse voltage (output voltage) from PFD21. Filter 24 obtains a DC voltage proportional to the pulse width by performing time integration on the signal output from CP23. Filter 24 outputs the DC voltage proportional to the pulse width to VCO25.

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.

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.

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

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.

The BB MPU 10 realizes its functions by having the processor read and execute a program recorded in the memory. 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.

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 signal output from the ADC 18. The BB MPU 10 corrects the phase of the baseband signal output to LO#N based on the calculated phase correction value.

More specifically, the BB MPU 10 calculates the phase delay of the VCO 25 based on the phase of the phase frequency reference oscillator 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, controls so that the updated phase difference is added to the IQ signal, and outputs the controlled signal to the DAC 13 as a baseband signal.

The same control as that for LO#N described above is also performed for LO#1 to #N-1. This adjusts the phases of the baseband signals output from BB MPU10 corresponding to each of the multiple transmit ports so that they match. This is expected to improve the accuracy of beamforming.

(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 MPU 10 via a distributor.

(Configuration example of PFD 21)
The PFD in the LO is generally configured with a D-type or JK-type flip-flop circuit.

Figure 5 is a diagram showing an example of the configuration of a 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.

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

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

The above describes an example of the configuration of a beamforming transmission circuit according to the first embodiment of the present invention.

(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.

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

The BB MPU 10 sets the division ratio in the divider 26 in each of the LO#1 to LO#N to set the frequency of the feedback signal input to the PFD 21 in each of the LO#1 to LO#N to the desired frequency. The PFD 21 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 divider 26.

(Initial Phase Detection)
6 is a timing chart showing the input/output relationship of the PFD 21 when the phase of the feedback signal is delayed compared to the phase of the phase frequency reference oscillation signal. Referring to FIG. 6, the phase of the feedback signal IN_B is delayed by a phase difference ΔΦ compared to the phase of the phase frequency reference oscillation signal IN_A (i.e., the phase delay ΔΦ>0 is established). 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.

Figure 7 is a timing chart showing the input/output relationship of PFD 21 when the phase of the feedback signal leads compared to the phase of the phase frequency reference oscillation signal. Referring to Figure 7, the phase of feedback signal IN_B leads compared to the phase of phase frequency reference oscillation signal IN_A by a phase difference ΔΦ (i.e., 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 Figure 7, output signal OUT_A from D-type flip-flop 211 and output signal OUT_B from D-type flip-flop 212 are shown.

Figure 8 is a timing chart showing the input/output relationship of PFD21 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 (Figures 6 and 7), when the comparison of the phases in PFD21 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 negative feedback control in LO, as shown in Figure 8.

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 locked. 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 locked.

Figure 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 Figure 9, for all of LO#1 to LO#N, the phase of the phase frequency reference oscillation signal IN_A is controlled to be synchronized with the phase of the feedback signal IN_B, and the rising edge of the phase frequency reference oscillation signal IN_A at which the LO is locked is recorded in memory.

The BB MPU 10 calculates at what cycle the other LOs locked, using the first locked LO as a reference. In the example shown in FIG. 9, LO#2 locked first, and using LO#2 as a reference, LO#1 locked in the first cycle, and LO#N locked in the fifth cycle. Since the number of cycles is the value after division by the divider 26 (FIG. 3), the BB MPU 10 multiplies the calculated number of cycles by the division number to obtain the initial phase.

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

(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.

In more detail, 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 greater 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 the value obtained by multiplying the phase difference ΔΦ by the division number as the phase correction value of the baseband signal.

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 the phase obtained by subtracting the phase correction value from the phase difference w added to the IQ signal is added to the phase of the IQ signal, and outputs the controlled signal to the DAC 13 as a baseband signal. The above-described operations are repeatedly executed until the negative feedback control in the LO is completed.

The above describes an example of the operation of the beamforming transmission circuit 1 according to the first embodiment of the present invention.

(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.

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. This is expected to improve the accuracy of beamforming.

The above describes the effects of the beamforming transmission circuit according to the first embodiment of the present invention.

2. Second embodiment
Next, a second embodiment of the present invention will be described, however, the configurations of the beamforming transmission circuit according to the second embodiment of the present invention that are 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 same configurations as those of the beamforming transmission circuit according to the first embodiment of the present invention will be omitted.

(2-1. Configuration of Beamforming Transmission Circuit)
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.

(Configuration example of PFD 21)
As described above, the PFD in the LO is generally configured by 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 by a JK-type flip-flop circuit is mainly assumed.

Figure 10 is a diagram showing an example of the configuration of a PFD 21 composed of 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.

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 (Figure 3), via the buffer 221, which is an example of the buffer 22 (Figure 3). The signal sampled by the ADC181 is output to the BB MPU10.

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 CP23, forming a negative feedback loop. The other output from the JK flip-flop 214 is input to the ADC182, which is an example of the ADC18 (Figure 3), via the buffer 222, which is an example of the buffer 22 (Figure 3). The signal sampled by the ADC182 is output to the BB MPU10.

The above describes an example of the configuration of a beamforming transmission circuit according to the second embodiment of the present invention.

(2-2. Operation of Beamforming Transmission Circuit)
Next, an example of the operation 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 outputting the phase frequency reference oscillation signal to setting the output division ratio is performed in the same manner as in the first embodiment of the present invention. The PFD 21 provided 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.

(Initial Phase Detection)
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 flip-flop 213 and the output signal OUT_B from the JI flip-flop 214 are shown.

Figure 12 is a timing chart showing the input/output relationship of PFD 21 when the phase of the feedback signal leads compared to the phase of the phase frequency reference oscillation signal. Referring to Figure 12, the phase of the feedback signal IN_B leads compared to 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 Figure 12, the output signal OUT_A from JK flip-flop 213 and the output signal OUT_B from JK flip-flop 214 are shown.

Figure 13 is a timing chart showing the input/output relationship of PFD21 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 (Figures 11 and 12), when the comparison of the phases in PFD21 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 negative feedback control in LO, as shown in Figure 13.

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

Figure 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 Figure 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 memory. Subsequent operations can be performed in the same manner as in the first embodiment of the present invention.

(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.

The above describes the effects of the beamforming transmission circuit according to the second embodiment of the present invention.

(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.

For example, the above description mainly describes the case where the initial phase detection method and phase variation tracking method, which are features of the embodiment of the present invention, are 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 phase variation tracking method, which are features of the embodiment of the present invention, may be applied to a beamforming reception circuit. This may also improve the estimation accuracy of a radio wave arrival direction estimation circuit, which requires real-time and accurate phase detection.

1 Beamforming transmission circuit 10 BB MPU
11 Phase frequency reference oscillation source 12 Mixer 13 DAC
14 L.O.
15 mixer 16 variable gain amplifier 17 antenna 18 ADC
21 P.F.D.
22 Buffer 23 CP
24 Filter 25 VCO
26 Divider 27 GPS receiver

Claims (9)

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

Images