JP2011071909A - Noise reduction circuit and noise reduction method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a noise reduction circuit, a noise reduction apparatus, a noise reduction method and a noise reduction program in which noise of a clock signal can be attenuated even when a plurality of radio circuits are connected with a function circuit and a common terminal. <P>SOLUTION: A noise reduction circuit includes switching circuits 302 and 303 and a plurality of noise cancellation circuits 311 and 312. Each of the switching circuits 302 and 303 switches a passing route of a clock signal in accordance with a radio circuit, which receives a radio signal, among a plurality of radio circuits for receiving radio signals of different frequency bands. Each of the noise cancellation circuits 311 and 312 is disposed in the passing route switched by the switching circuits 302 and 303 for canceling from the clock signal noise of a different frequency band for each passing route. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a noise reduction circuit and a noise reduction method for reducing noise of a clock signal.

  A portable communication terminal is equipped with functional circuits such as a wireless circuit, an LCD (Liquid Crystal Display), and a camera. In order to attenuate noise in the reception band of the radio circuit, a noise removal circuit such as an EMI (Electro Magnetic Interference) filter or a coil or a capacitor is arranged in the path of the clock signal of the functional circuit. Under such circumstances, a noise reduction circuit for reducing the noise of the clock signal has been proposed (see, for example, Patent Documents 1-5).

  The noise reduction circuit of Patent Document 1 includes a switching circuit and operates as follows. The switching circuit switches the passage route of the clock signal to be used according to the clock signal. By selecting the passage route, the delay time is compensated for by the clock bus wiring length, and the setup time is kept at a predetermined time.

  The noise reduction circuit of Patent Document 2 includes a control circuit and operates as follows. The control circuit performs noise suppression according to the noise level in the received signal.

  The noise reduction circuit of Patent Document 3 includes a changeover switch and operates as follows. The changeover switch switches the transmission path of the imaging clock signal according to the imaging clock switching control signal input from the CPU. Thus, the imaging clock signal is directly input to the timing generator.

  The noise reduction circuit of Patent Document 4 includes a two-stage noise removal circuit, an error detection circuit, and a switching circuit, and operates as follows. The two-stage noise removal circuits are connected in cascade and reduce noise in the image outline. The error detection circuit calculates the absolute value of the difference between the input signal and the output signal of the first-stage noise removal circuit. According to the output level from the error detection circuit, the switching circuit outputs an output signal of the second stage noise elimination circuit, an output signal of the first stage noise elimination circuit, and an input signal of the first stage noise elimination circuit. , Switch. As a result, blurring of the image due to a mistake in detecting the contour of the image is reduced.

  The noise reduction circuit of Patent Document 5 includes a plurality of noise removal circuits and operates as follows. An optimum noise removal circuit is selectively used from a plurality of noise removal circuits according to the operation mode. This prevents the control circuit from malfunctioning during the data read operation due to noise.

JP 2003-316470 A JP 2004-048317 A JP 2008-109485 A JP 09-233369 A Japanese Patent Laid-Open No. 11-110968

  When the noise removal circuit is not disposed in the clock signal passing path, the entire band passes as shown in FIG. On the other hand, when a noise removing circuit as shown in FIG. 1B is used, noise in a desired frequency band can be attenuated. At this time, if FIG. 2A is the original waveform, the waveform is distorted as shown in FIG.

  A plurality of wireless circuits are mounted on a portable communication terminal. In this case, if the noise removal circuit as shown in FIG. 1B is used, it is difficult to reduce the noise in the reception band of all the radio circuits.

  In the noise reduction circuit described in Patent Documents 1-5 described above, the path is switched in order to remove noise generated in the clock signal passing path or to optimize the operation. For this reason, in a portable communication terminal having a plurality of radio circuits, it is difficult to reduce the noise in the reception band of all radio circuits.

  Further, it is assumed that a noise removal circuit that attenuates broadband noise is used as shown in FIG. In this case, since the waveform of the clock signal is greatly distorted as shown in FIG. 2C, there is a problem that the functional circuit does not operate normally. Alternatively, it is necessary to reduce the frequency of the clock signal so that the waveform is not distorted.

  In order to solve the above-described problems, the present invention provides a noise reduction circuit, a noise reduction device, and a noise reduction method capable of attenuating the noise of a clock signal even when a plurality of radio circuits are mounted on a terminal shared with a functional circuit. And to provide a noise reduction program.

  The noise reduction circuit of the present invention includes a switching circuit that switches a clock signal passage path according to a wireless circuit that receives a wireless signal among a plurality of wireless circuits that receive wireless signals of different frequency bands, and the switching circuit includes: A plurality of noise removal circuits arranged on the switched passage paths and for removing noise in a different frequency band for each passage path from the clock signal.

  The noise reduction device of the present invention includes a CPU that outputs a clock signal of a functional circuit, a noise reduction circuit of the present invention that reduces noise of the clock signal from the CPU, and a clock signal output from the noise reduction circuit. And a functional circuit that operates using the same.

  The noise reduction method of the present invention includes a switching procedure for switching a clock signal passage path according to a wireless circuit that receives a wireless signal among a plurality of wireless circuits that receive wireless signals of different frequency bands, and the switching procedure. A noise removal procedure for removing noise in a different frequency band from the clock signal for each switched passage path.

  The noise reduction program of the present invention includes a switching step of switching a clock signal passage path according to a wireless circuit receiving a wireless signal among a plurality of wireless circuits receiving wireless signals of different frequency bands, and the switching step. A noise removal step of removing noise in a different frequency band for each switched passage path from the clock signal is sequentially executed by the computer.

  According to the present invention, it is possible to provide a noise reduction circuit, a noise reduction device, a noise reduction method, and a noise reduction program capable of attenuating the noise of a clock signal even when a plurality of radio circuits are mounted on a terminal shared with a functional circuit. Can do.

It is an example of the change of the passage loss when using a noise removal circuit, (a) shows the case where a noise removal circuit is not used, (b) shows the case where a narrow band noise removal circuit is used, and (c) shows The case where a wide band noise elimination circuit is used is shown. It is an example of the change of the waveform of the clock signal when using the noise elimination circuit, (a) shows the case where the noise elimination circuit is not used, (b) shows the case where the noise elimination circuit with a narrow band is used, (c ) Shows a case where a wide band noise elimination circuit is used. 2 shows an example of a noise reduction circuit according to the first embodiment. An example of the noise reduction method which concerns on Embodiment 1 is shown. An example of the noise reduction program which concerns on Embodiment 1 is shown. An example of the noise reduction apparatus which concerns on Embodiment 2 is shown. An example of the noise reduction method which concerns on Embodiment 2 is shown. An example of the noise reduction program which concerns on Embodiment 2 is shown. An example of the noise reduction apparatus which concerns on Embodiment 3 is shown. It is an example of the passage loss which concerns on Embodiment 3, (a) shows the case where the noise removal circuit 311 is used, (b) shows the case where the noise removal circuit 312 is used. The 1st example of operation | movement of a radio | wireless machine is shown. The 2nd example of operation | movement of a radio | wireless machine is shown. An example of the noise reduction apparatus which concerns on Embodiment 4 is shown. An example of the noise reduction apparatus which concerns on Embodiment 5 is shown.

  Embodiments of the present invention will be described with reference to the accompanying drawings. The embodiments described below are examples of the present invention, and the present invention is not limited to the following embodiments. In the present specification and drawings, the same reference numerals denote the same components.

(Embodiment 1)
FIG. 3 shows an example of a noise reduction circuit according to this embodiment. The noise reduction circuit according to the present embodiment includes switching circuits 302 and 303 and a plurality of noise removal circuits 311 and 312, and executes the noise reduction method according to the present embodiment.

  The switching circuits 302 and 303 switch a clock signal passing path according to a radio circuit that receives a radio signal among a plurality of radio circuits (not shown) that receive radio signals in different frequency bands. As a result, the noise removal circuits 311 and 312 that pass through can be switched according to the radio circuit to be used. The noise removal circuits 311 and 312 are arranged on the passage paths switched by the switching circuits 302 and 303, and remove noises having different frequency bands for the passage paths from the clock signal. Thereby, the kind of noise countermeasure components to pass can be changed, and the frequency which attenuates noise can be changed.

  FIG. 4 shows an example of a noise reduction method according to this embodiment. The noise reduction method according to the present embodiment includes a switching procedure S112 and a noise removal procedure S113 in order. In the switching procedure S112, the switching circuits 302 and 303 switch the clock signal passage path in accordance with a radio circuit that receives a radio signal among a plurality of radio circuits (not shown) that receive radio signals in different frequency bands. . As a result, the noise removal circuits 311 and 312 that pass through can be switched according to the radio circuit to be used. In the noise removal procedure S113, noise in a different frequency band is removed from the clock signal for each passage route switched in the switching procedure S112. Thereby, the kind of noise countermeasure components to pass can be changed, and the frequency which attenuates noise can be changed.

  Note that the noise reduction circuit according to the present embodiment may be realized by causing a computer to execute the noise reduction program according to the present embodiment. FIG. 5 shows an example of a noise reduction program according to this embodiment. The noise reduction program according to the present embodiment causes the computer to sequentially execute the switching step S212 and the noise removal step S213.

  In the switching step S212, the clock signal passing path is switched according to a radio circuit that receives a radio signal among a plurality of radio circuits (not shown) that receive radio signals in different frequency bands. In the noise removal step S213, noise in a different frequency band is removed from the clock signal for each passing path switched in the switching step S212. Thereby, the noise reduction circuit according to the present embodiment can be realized.

  By using the noise reduction circuit according to the present embodiment, it is possible to switch the path of a clock signal sent from the CPU to a functional circuit such as an LCD or a camera. Thereby, the kind of noise countermeasure components to pass can be changed, and the frequency which attenuates noise can be changed. Accordingly, it is possible to provide a noise reduction circuit, a noise reduction method, and a noise reduction program that can attenuate noise of a clock signal even when a plurality of wireless circuits are mounted on a terminal that is shared with a functional circuit. Further, since no noise countermeasure component that attenuates broadband noise is used, waveform distortion can be reduced even with a high-frequency clock signal.

  Furthermore, the following effects can be obtained by using the noise reduction circuit according to the present embodiment. First, the communication quality in a low electric field can be improved by removing the noise of the clock signal. Second, the distortion of the clock signal waveform can be reduced by using a narrow band noise elimination circuit. Third, since the distortion of the clock signal waveform can be reduced, the frequency of the clock signal can be increased. Fourth, since distortion of the clock signal waveform can be reduced, it can be applied to a clock signal having a small amplitude. Fifth, it is possible to cope with simultaneous use of a plurality of wireless circuits by selecting an appropriate noise removal circuit with a low electric field.

(Embodiment 2)
FIG. 6 shows an example of a noise reduction apparatus according to this embodiment. The noise reduction apparatus 100 according to the present embodiment further includes a CPU 301 and a functional circuit 304 in addition to the noise reduction circuit described in the first embodiment, and executes the noise reduction method according to the present embodiment.

  The CPU 301 outputs a clock signal for the functional circuit 304. The switching circuits 302 and 303 switch the passage route of the clock signal from the CPU 301 in accordance with a radio circuit that receives a radio signal among a plurality of radio circuits (not shown) that receive radio signals in different frequency bands. The noise removal circuits 311 and 312 are arranged on the passing path switched by the switching circuit 302 and remove noise from a frequency band that is different for each passing path from the clock signal.

  The functional circuit 304 operates using the clock signal output from the noise reduction circuit shown in FIG. That is, the operation is performed using the clock signal output from the noise removal circuit 311 or the noise removal circuit 312. Since the noise of the frequency corresponding to the reception band of the radio circuit can be reduced from the clock signal, the functional circuit 304 operates normally without greatly distorting the waveform of the clock signal or reducing the frequency of the clock signal. Can be made.

  FIG. 7 shows an example of a noise reduction method according to this embodiment. The noise reduction method according to the present embodiment further includes a functional circuit operation procedure S114 after the noise reduction method illustrated in FIG. In the functional circuit operation procedure S114, the functional circuit 304 is operated using the clock signal from which noise has been removed in the noise removal procedure S113. Noise with a frequency corresponding to the reception band of the wireless circuit can be reduced. For this reason, the functional circuit 304 can be normally operated without greatly distorting the waveform of the clock signal or reducing the frequency of the clock signal.

  FIG. 8 shows an example of a noise reduction program according to this embodiment. The noise reduction program according to the present embodiment further includes a functional circuit operation step S214 after the noise reduction program shown in FIG. In functional circuit operation step S214, the functional circuit 304 is operated using the clock signal from which noise has been removed in noise removal step S213. Thereby, the noise reduction apparatus 100 which concerns on this embodiment is realizable.

  By switching the path of the clock signal used by the functional circuit 304, it is possible to change the type of noise countermeasure component passing therethrough and change the frequency at which noise is attenuated. Therefore, even when a plurality of wireless circuits are mounted on a terminal common to the functional circuit 304, it is possible to provide a noise reduction device, a noise reduction method, and a noise reduction program that can attenuate noise of a clock signal. Further, since no noise countermeasure component that attenuates broadband noise is used, waveform distortion can be reduced even with a high-frequency clock signal.

(Embodiment 3)
FIG. 9 shows an example of a noise reduction apparatus according to this embodiment. The noise reduction device according to the present embodiment will be described for the case where the noise reduction device 100 described in the second embodiment is a wireless device 101. The wireless device 101 is, for example, a mobile phone or a PDA (Personal Digital Assistant).

  The wireless device 101 includes a plurality of wireless circuits 201 and 202, and also includes a plurality of noise removal circuits 311 and 312. The CPU 301 is connected to the wireless circuit 201 and the wireless circuit 202 and controls each circuit. The wireless circuit 201 and the antenna # 1 are circuits that operate when the wireless system A is used. The radio circuit 202 and the antenna # 2 are circuits that operate when the radio system B is used, and are different from the radio system A in use frequency band. The wireless system A and the wireless system B are wireless systems that use different frequency bands and communicate with one another. Alternatively, both may communicate simultaneously.

  The wireless system A and the wireless system B are, for example, W-CDMA (Wideband Code Division Multiple Access), GSM (Global System for Mobile Communications), WLAN (Wireless LAN), DTV (Digital TGPS, Digital TGPS, Digital TGPS). is there.

The functional circuit 304 is a circuit having a function other than the communication function, and is a functional circuit that operates with a clock signal having a frequency f _A sent from the CPU 301. Functions other than the communication function are, for example, an LCD (Liquid Crystal Display) and a camera.

  The noise removal circuit 311 has characteristics as shown in FIG. 10B and attenuates noise in the reception band of the wireless circuit 201. The noise removal circuit 312 has a characteristic as shown in FIG. 10C and attenuates noise in the reception band of the wireless circuit 202 different from the reception band of the wireless circuit 201.

  The switching circuit 302 and the switching circuit 303 are circuits that switch the path of the clock signal, and select a path that passes through the noise removal circuit 311 during communication by the wireless circuit 201. Further, a route that passes through the noise removal circuit 312 is selected during communication by the wireless circuit 202.

FIG. 11 shows a first example of the operation of the wireless device. In the first example of the operation of the wireless device, a case where the wireless circuit 201 and the wireless circuit 202 communicate with each other will be described.
In step S11, it is assumed that the wireless circuit 201 is performing communication. At this time, the switching circuit 302 and the switching circuit 303 have selected a path that passes through the noise removal circuit 311.

  In step S12, it is determined which of the wireless circuit 201 and the wireless circuit 202 performs communication. For example, it is assumed that there is a request from the CPU 301 to stop communication with the wireless circuit 201 and perform communication with the wireless circuit 202. In this case, it is determined that communication is performed by the wireless circuit 202, and the process proceeds to step S13. If there is no request from the CPU 301 to stop communication with the wireless circuit 201 and communicate with the wireless circuit 202, the process proceeds to step S11.

  In step S <b> 13, communication is performed using the wireless circuit 202, and the wireless communication circuit 202 is switched to a communication state. At this time, the switching procedure S112 shown in FIG. 7 is executed, and the switching circuit 302 and the switching circuit 303 select a path that passes through the noise removal circuit 312.

  And the noise removal procedure S113 shown in FIG. 7 is performed. At this time, the noise removal circuit 312 attenuates the noise in the reception band of the wireless circuit 202 in the clock signal from the CPU 301. Then, the functional circuit operation procedure S114 shown in FIG. 7 is executed. At this time, the functional circuit 304 operates using the clock signal that has passed through the noise removal circuit 312.

  In step S14, it is determined which of the wireless circuit 201 and the wireless circuit 202 performs communication. For example, it is assumed that there is a request from the CPU 301 to communicate with the wireless circuit 201. In this case, it is determined that communication is performed by the wireless circuit 201, and the process proceeds to step S11.

  In step S11, the radio circuit 201 switches to a state where communication is performed. Then, the switching procedure S112 shown in FIG. 7 is executed, and the switching circuit 302 and the switching circuit 303 select a path that passes through the noise removal circuit 311. Then, the noise removal procedure S113 shown in FIG. 7 is executed, and the noise removal circuit 312 attenuates the noise in the reception band of the wireless circuit 201 among the clock signals from the CPU 301. Then, the functional circuit operation procedure S114 shown in FIG. 7 is executed. At this time, the functional circuit 304 operates using the clock signal that has passed through the noise removal circuit 311.

  Here, in the switching procedure S <b> 112 illustrated in FIG. 7, the switching circuit 302 and the switching circuit 303 may switch the clock signal passing path according to the reception bands of the wireless circuit 201 and the wireless circuit 202. For example, the frequency band removed by the noise removal circuit 311 corresponds to the frequency band received by the wireless circuit 201, and the frequency band removed by the noise removal circuit 312 corresponds to the frequency band received by the wireless circuit 202.

  In this case, if the frequency band of the received radio signal corresponds to the frequency band received by the radio circuit 201, the switching circuit 302 and the switching circuit 303 are arranged in the noise removal circuit 311 in the switching procedure S112 shown in FIG. The clock signal passing path is switched to the passing path. If the frequency band of the received radio signal corresponds to the frequency band received by the radio circuit 202, the switching circuit 302 and the switching circuit 303 are arranged in the noise removal circuit 312 in the switching procedure S112 shown in FIG. The clock signal passing path is switched to the passing path. As a result, noise having a frequency suitable for each of the wireless circuit 201 and the wireless circuit 202 can be removed, so that noise of the clock signal can be efficiently removed.

  The noise reduction apparatus according to the present embodiment may cause a computer to execute a noise reduction program shown in FIG. In this case, in the switching step S212 shown in FIG. 8, the computer is executed as follows. If the frequency band of the received radio signal corresponds to the frequency band received by the radio circuit 201, the switching circuit 302 and the switching circuit 303 are arranged in the noise removal circuit 311 in the switching step S212 shown in FIG. The clock signal passing path is switched to the passing path. If the frequency band of the received radio signal corresponds to the frequency band received by the radio circuit 202, the switching circuit 302 and the switching circuit 303 are arranged in the noise removal circuit 312 in the switching step S212 shown in FIG. The clock signal passing path is switched to the passing path.

FIG. 12 shows a second example of the operation of the wireless device. In the second example of the operation of the wireless device, a case where both the wireless circuit 201 and the wireless circuit 202 communicate simultaneously will be described.
In step S21, the CPU 301 monitors whether the reception level of the wireless circuit 201 or the wireless circuit 202 is below a certain value. At this time, the switching circuit 302 and the switching circuit 303 have selected a path that passes through the previously selected noise removal circuit. If the reception level is sufficiently high, the noise removal circuit does not affect the communication quality regardless of which is selected.

  In step S22, it is determined whether or not the reception levels of both the wireless circuit 201 and the wireless circuit 202 are equal to or lower than a predetermined value. When the reception levels of the wireless circuit 201 and the wireless circuit 202 are both equal to or less than a certain value at the same time, the process proceeds to step S25. If the reception levels of both the radio circuit 201 and the radio circuit 202 exceed a certain value at the same time, the process proceeds to step S23. In step S25, the switching circuit 302 and the switching circuit 303 select a path that passes through a noise removal circuit that attenuates noise of a radio circuit having a high priority. In this case, a radio circuit having a high priority is determined in advance.

  As described above, the switching circuit 302 and the switching circuit 303 may switch the passage route of the clock signal according to the priority order of the wireless circuit 201 and the wireless circuit 202. For example, it is assumed that the priority of the wireless circuit 201 is higher than that of the wireless circuit 202. In this case, in the switching procedure S112 illustrated in FIG. 7, the switching circuit 302 and the switching circuit 303 are noise elimination circuits corresponding to the wireless circuit 201 having the highest priority among the wireless circuit 201 and the wireless circuit 202 that receive the wireless signal. The passage route of the clock signal is switched to the passage route in which is arranged. Thereby, when the degree of influence on the clock signal is different for each of the wireless circuit 201 and the wireless circuit 202, the noise of the clock signal can be efficiently removed by setting the priority order.

  You may implement | achieve the noise reduction apparatus which concerns on this embodiment by making a computer run the noise reduction program shown in FIG. In this case, in the switching step S212 shown in FIG. 8, the switching circuit 302 and the switching circuit 303 remove noise corresponding to the wireless circuit 201 having the highest priority among the wireless circuit 201 and the wireless circuit 202 that receive the wireless signal. The clock signal passing path is switched to the passing path where the circuit is arranged.

  In the switching procedure S112 illustrated in FIG. 7, the switching circuit 302 and the switching circuit 303 may switch the clock signal passage path according to the reception levels of the wireless circuit 201 and the wireless circuit 202. For example, it is assumed that the reception level of the wireless circuit 201 is lower than that of the wireless circuit 202. In this case, the switching circuit 302 and the switching circuit 303 are arranged on a passage route in which the noise removal circuit 311 corresponding to the wireless circuit 201 having the lowest reception level is arranged among the wireless circuit 201 and the wireless circuit 202 that receive the wireless signal. , Switching the clock signal passage path. Thereby, the noise of a clock signal can be removed efficiently.

  You may implement | achieve the noise reduction apparatus which concerns on this embodiment by making a computer run the noise reduction program shown in FIG. In this case, in the switching step S212 shown in FIG. 8, the switching circuit 302 and the switching circuit 303 remove noise corresponding to the wireless circuit 201 having the lowest reception level among the wireless circuit 201 and the wireless circuit 202 that receive the wireless signal. The passage route of the clock signal is switched to the passage route where the circuit 311 is arranged.

  In step S23, it is determined whether or not the reception level of the wireless circuit 201 has become a certain value or less. When the reception level of the wireless circuit 201 becomes a predetermined value or less, the process proceeds to step S26. If the reception level of the wireless circuit 201 does not become a certain value or less, the process proceeds to step S24. In step S <b> 26, the switching circuit 302 and the switching circuit 303 select a path that passes through the noise removal circuit 311.

  In step S24, it is determined whether or not the reception level of the wireless circuit 202 has become a certain value or less. When the reception level of the radio circuit 202 becomes equal to or lower than the predetermined value, the process proceeds to step S27. In step S27, the switching circuit 302 and the switching circuit 303 select a path that passes through the noise removal circuit 312.

(Embodiment 4)
FIG. 13 shows an example of a noise reduction apparatus according to this embodiment. The noise reduction apparatus according to the present embodiment will be described for the case where the noise reduction apparatus described in the third embodiment is the wireless device 102.

  The wireless device 102 includes three wireless circuits 201, 202, 203 and three noise removal circuits 311, 312, 313. Noise removal circuits 311, 312, and 313 attenuate the noise in the reception bands of the radio circuits 201, 202, and 203, respectively. At that time, the switching circuit 302 and the switching circuit 303 select a path that passes through the noise removal circuit corresponding to each wireless circuit in accordance with the wireless circuit that is communicating. When three radio circuits 201, 202, and 203 are communicating at the same time, the reception level is monitored as in the case of two radio circuits, and the reception levels of the switching circuit 302 and the switching circuit 303 are below a certain value. A passage path of a noise removal circuit that attenuates noise in the reception band of the wireless circuit is selected.

(Embodiment 5)
FIG. 14 shows an example of a noise reduction apparatus according to this embodiment. The noise reduction apparatus according to the present embodiment will be described for the case where the noise reduction apparatus described in the third embodiment is the wireless device 103.

  The wireless device 103 includes three wireless circuits 201, 202, and 203 and two noise removal circuits 311 and 312. When any two reception bands of the radio circuits 201, 202, and 203 are close, the noise removal circuit is shared by the corresponding radio circuits. Furthermore, the noise reduction circuit, the noise reduction device, the noise reduction method, and the noise reduction program according to the present embodiment can be extended to N radio circuits and M noise removal circuits. At this time, N ≧ M.

  Since the present invention can be applied to a mobile phone, a smartphone, a PDA, a notebook PC, and the like, it can be used in the information communication industry.

100: Noise reduction apparatus 101, 102, 103: Radio 201, 202, 203: Radio circuit 301: CPU
302, 303: switching circuit 304: functional circuits 311, 312, 313: noise removal circuit

Claims (15)

A switching circuit that switches a clock signal passing path according to a radio circuit that receives a radio signal among a plurality of radio circuits that receive radio signals of different frequency bands;
A plurality of noise removing circuits that are arranged in the passing path switched by the switching circuit and remove noise of a different frequency band for each passing path from the clock signal;
A noise reduction circuit comprising: The frequency bands of noise to be removed by the plurality of noise removal circuits respectively correspond to the frequency bands received by the wireless circuit,
The noise reduction circuit according to claim 1, wherein the switching circuit switches a passage route of a clock signal in accordance with a frequency band of a wireless signal received by the wireless circuit.   The switching circuit switches a clock signal passing path to a passing path in which a noise removing circuit corresponding to a radio circuit having the lowest reception level among the radio circuits receiving a radio signal is arranged. The noise reduction circuit described in 1. Priorities are set in advance for the plurality of radio circuits,
The switching circuit switches a clock signal passing path to a passing path in which a noise removing circuit corresponding to a radio circuit having the highest priority among the radio circuits receiving a radio signal is arranged. The noise reduction circuit according to any one of the above. A CPU that outputs a clock signal of a functional circuit;
The noise reduction circuit according to any one of claims 1 to 4, which reduces noise of a clock signal from the CPU;
A functional circuit that operates using a clock signal output from the noise reduction circuit;
A noise reduction device comprising: A switching procedure for switching a clock signal passing path according to a radio circuit receiving a radio signal among a plurality of radio circuits receiving radio signals of different frequency bands,
A noise removal procedure for removing noise in a different frequency band from the clock signal for each passing path switched in the switching procedure;
A noise reduction method comprising: The frequency band of the noise of each passing path to be removed by the noise removal procedure corresponds to the frequency band received by the plurality of radio circuits,
The noise reduction method according to claim 6, wherein in the switching procedure, a clock signal passing path is switched according to a frequency band of a radio signal received by the radio circuit.   The noise reduction method according to claim 6 or 7, wherein, in the switching procedure, the clock signal passing path is switched to a passing path corresponding to a radio circuit having the lowest reception level among the radio circuits receiving the radio signal. Priorities are set in advance for the plurality of radio circuits,
9. The noise reduction according to claim 6, wherein, in the switching procedure, the clock signal passing path is switched to the passing path corresponding to the radio circuit having the highest priority among the radio circuits receiving the radio signal. Method.   The noise reduction method according to claim 6, further comprising a functional circuit operation procedure for operating a circuit using a clock signal from which noise has been removed by the noise removal procedure, after the noise removal procedure. A switching step of switching a clock signal passing path according to a radio circuit that receives a radio signal among a plurality of radio circuits that receive radio signals of different frequency bands;
A noise removing step of removing noise in a different frequency band for each passing path switched in the switching step from the clock signal;
A noise reduction program that causes a computer to execute in order. The frequency band of the noise of each passing path to be removed in the noise removing step corresponds to the frequency band received by the plurality of radio circuits,
The noise reduction program according to claim 11, wherein, in the switching step, the clock signal passing path is switched in accordance with a frequency band of a radio signal received by the radio circuit.   The noise reduction program according to claim 11 or 12, wherein, in the switching step, the clock signal passing path is switched to the passing path corresponding to the radio circuit having the lowest reception level among the radio circuits receiving the radio signal. Priorities are set in advance for the plurality of radio circuits,
14. The noise reduction according to claim 11, wherein, in the switching step, the clock signal passing path is switched to the passing path corresponding to the radio circuit having the highest priority among the radio circuits receiving the radio signal. program.   15. The noise reduction program according to claim 11, further causing a computer to execute a functional circuit operation step for operating a circuit using a clock signal from which noise has been removed in the noise removal step, after the noise removal step.

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