JP4352768B2 - Signal processing apparatus and communication device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a signal processing device used for obtaining a signal of a specific frequency component from a signal to be processed, and a communication device including the signal processing device.
[0002]
[Prior art]
2. Description of the Related Art In recent years, small and portable communication devices that support multi-band wireless communication, such as mobile phones, have been widely used. In such a communication device, it is essential to include a signal processing device for performing signal processing on a communication signal, more specifically, a signal processing device as an RF (high frequency) processing portion of the communication signal.
[0003]
FIG. 3 is a block diagram illustrating an example of a schematic configuration of a signal processing device used in a communication device. The figure shows a so-called Super Heterodyne type signal processing apparatus. The signal processing apparatus includes a reception processing system 100 for demodulating a communication signal received from the outside (hereinafter simply referred to as “reception signal”) and a communication signal to be transmitted to the outside (hereinafter simply referred to as “transmission signal”). It is roughly divided into a transmission processing system 200 for modulation. Among these, the reception processing system 100 includes at least a band pass filter 101, an image reject filter 102, a VCO (reference oscillator) 103, a mixer 104, an IF (intermediate frequency) filter 105, and an IF mixer 106. The received signal received by the antenna 107 is subjected to bandpass filter 101 and image reject filter 102 to remove unnecessary frequency bands, and then mixed with a reference signal of an intermediate frequency generated by VCO 103 by mixer 104. After lowering the frequency and passing through the IF filter 105, the IF mixer 106 performs phase adjustment. Thereby, in the reception processing system 100, only the channel band component from which the carrier band component is removed from the received signal is extracted, and the baseband signal in the received signal (for example, a signal regarding information to be communicated such as an audio signal). Is obtained.
[0004]
By the way, recently, with the progress of miniaturization manufacturing technology on a substrate, so-called micromachines (micro electro-mechanical systems; hereinafter referred to as “MEMS”) and small devices incorporating the MEMS. Etc. are attracting attention. The MEMS is an element obtained by electrically and mechanically coupling a vibrator that is a movable structure and a semiconductor integrated circuit that controls driving of the vibrator. A vibrator is incorporated in a part of the element, and the vibrator is electrically driven by applying a Coulomb attractive force between the electrodes.
[0005]
Among such MEMS, those formed using a semiconductor process, in particular, have a small occupied area of the device, can realize a high Q value (an amount representing the sharpness of resonance of the vibration system), and other semiconductor devices. Therefore, use as a high frequency filter (for example, IF filter 105) in a signal processing apparatus for wireless communication has been proposed (see, for example, Patent Document 1). ).
[0006]
[Patent Document 1]
Japanese Patent Laid-Open No. 2002-94328
[Problems to be solved by the invention]
However, the conventional signal processing apparatus for wireless communication has the following problems. For example, in the signal processing apparatus of the superheterodyne system shown in FIG. 3, the reception processing system 100 includes a number of components such as a bandpass filter 101, a VCO 103, an IF filter 105, etc., for demodulating the received signal. Moreover, each is arranged as an independent component on the substrate. Therefore, in such a signal processing device, the number of components arranged on the board increases, or the signal is attenuated by the connection wiring between components, so that the power consumption in the amplifier increases to avoid this. For example, it is not always easy to reduce the size and cost. Further, for example, in a so-called direct conversion type signal processing apparatus using MEMS as a high frequency filter, the IF filter can be reduced, but a VCO, a mixer and the like used for demodulation are still necessary as separate components. is there. Therefore, even in such a signal processing device, it cannot always be realized that the size and cost thereof are reduced.
[0008]
Therefore, the present invention makes it possible to integrate functions required for demodulating the received signal in a very small area by utilizing the MEMS technology, thereby further reducing the size of the signal processing apparatus for one chip. It is an object of the present invention to provide a signal processing device and a communication device that can realize the conversion.
[0009]
[Means for Solving the Problems]
The present invention is a signal processing device devised to achieve the above object, and a first mechanical vibrator having a transmission frequency band as a carrier band of a communication signal in which a channel band component is superimposed on a carrier band component. A second mechanical vibrator whose transmission frequency band is a frequency band including the channel band component in addition to the carrier band component, and the first mechanical vibrator and the first by applying the communication signal Excitation means for simultaneously exciting anti-phase vibrations for two mechanical vibrators, and anti-phase vibrations transmitted through each of the first mechanical vibrator and the second mechanical vibrator are simultaneously detected. And detecting means for extracting and extracting a baseband signal from the communication signal.
[0011]
The present invention is also a communication device devised to achieve the above object. In other words, at least a carrier band components by a communication device channel band component had a reception function of the superimposed communication signal, a first mechanical oscillator to the carrier band of the communication signal and the transmission frequency band, the A second mechanical vibrator having a transmission frequency band including a frequency band including the channel band component in addition to a carrier band component; and the first mechanical vibrator and the second machine by applying the communication signal Excitation means for simultaneously exciting anti-phase vibrations with respect to the mechanical vibrator and anti-phase vibrations transmitted through each of the first mechanical vibrator and the second mechanical vibrator are simultaneously detected and synthesized. And detecting means for extracting a baseband signal in the communication signal .
[0012]
According to the signal processing device and the communication device configured as described above, with respect to a communication signal that is an electric signal in which a channel band component is superimposed on a carrier band component, the first mechanical vibrator has a carrier band of the communication signal, That is, an extremely narrow frequency band is set as a transmission frequency band. On the other hand, the second mechanical vibrator uses a channel band of a communication signal, that is, a wider frequency band than the first mechanical vibrator as a transmission frequency band, and includes a channel band component in addition to a carrier band component. Make it transparent. Thus, for example, if the signals transmitted through each are in reverse phase, the first mechanical vibrator and the second mechanical vibrator are vibrated simultaneously by applying a communication signal, and the vibrations in each are simultaneously detected and synthesized. Thus, frequency band components common to each other, for example, carrier band components cancel each other, and only other baseband signals are extracted. That is, a baseband signal that is a signal of a specific frequency component is extracted from a communication signal that is a signal to be processed by passing through the first mechanical vibrator, the second mechanical vibrator, the excitation unit, and the detection unit. Can be obtained.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a signal processing apparatus and a communication device according to the present invention will be described with reference to the drawings.
[0014]
First, a communication device equipped with a signal processing device will be briefly described. The communication device described here corresponds to multiband wireless communication, such as a mobile phone. A communication signal handled by a communication device, that is, a communication signal to be transmitted / received, is an electric signal in which a channel band component is superimposed on a carrier band component that functions as a carrier wave in communication. The electric signal consisting only of the channel band component corresponds to a baseband signal for specifying the content of information to be communicated, such as an audio signal.
[0015]
Next, a signal processing apparatus that is mounted and used in such a communication device will be described. The signal processing apparatus described here is roughly divided into a reception processing system for demodulating a reception signal and a transmission processing system for modulating a transmission signal, as in the conventional apparatus (see FIG. 3). Of these, the reception processing system is different from the conventional one. Therefore, only the reception processing system of the signal processing apparatus will be described below, and the description of the transmission processing system will be omitted.
[0016]
FIG. 1 is a block diagram showing an outline of a reception processing system of a signal processing apparatus according to the present invention. As shown in the figure, the reception processing system of the signal processing apparatus described here includes at least the first vibrator filter 1, the second vibrator filter 2, the voltage → vibration conversion unit 3, and the vibration → voltage. And a conversion unit 4.
[0017]
The first vibrator filter 1 is composed of, for example, a mechanical vibrator constituting a MEMS, and includes a carrier band of a reception signal as a reference frequency, and uses the carrier band as a transmission frequency band. That is, the first vibrator filter 1 functions as one of the mechanical vibrators in the present invention. More specifically, the first vibrator filter 1 functions as a first mechanical vibrator that uses the carrier band of the received signal as the transmission frequency band. To do.
[0018]
Similar to the first vibrator filter 1, the second vibrator filter 2 is composed of, for example, a mechanical vibrator constituting a MEMS. However, in the second vibrator filter 2, the channel band including the wavelength of the carrier of the received signal as the reference frequency is set as the transmission frequency band. That is, the second vibrator filter 2 functions as one of the mechanical vibrators in the present invention. More specifically, the second vibrator filter 2 functions as a second mechanical vibrator in which the channel band of the received signal is a transmission frequency band. To do.
[0019]
The voltage-to-vibration conversion unit 3 includes an electrode for vibrating a MEMS mechanical vibrator, for example, and is applied to the first vibrator filter 1 and the second vibrator filter 2 by application of a reception signal. At the same time, it excites vibration. That is, the voltage-to-vibration conversion unit 3 functions as an excitation unit in the present invention. However, the voltage-to-vibration conversion unit 3 excites vibrations for the first and second vibrator filters 1 and 2 so that the phases are inverted. For example, the vibration phase in the first vibrator filter 1 is “+ π / 2”, whereas the vibration phase in the second vibrator filter 2 is “−π / 2”. .
[0020]
The vibration-to-voltage converter 4 is provided with an electrode for detecting vibration in a MEMS mechanical vibrator, for example, and the vibration in each of the first vibrator filter 1 and the second vibrator filter 2 is detected. It is detected and synthesized at the same time. By this synthesis, the vibration-to-voltage converter 4 extracts a signal of a specific frequency component included in the received signal, more specifically a baseband signal in the received signal. That is, the vibration → voltage conversion unit 4 functions as detection means in the present invention.
[0021]
Subsequently, a processing operation in the reception processing system of the signal processing apparatus configured as described above will be described. When the antenna of the communication device equipped with this signal processing apparatus receives a reception signal, the reception signal is input to the voltage → vibration conversion unit 3. Then, the voltage → vibration converter 3 excites the first vibrator filter 1 and the second vibrator filter 2 in accordance with the input of the received signal.
[0022]
At this time, the first vibrator filter 1 uses the carrier band of the received signal as the transmission frequency band and transmits a carrier band component belonging to an extremely narrow frequency band to the vibration → voltage conversion unit 4 side. On the other hand, the second vibrator filter 2 uses the channel band of the received signal as a transmission frequency band, and transmits a wider channel band component than the first vibrator filter 1 including the carrier band component to the vibration → voltage converter 4 side. . Moreover, the phase of vibration is inverted between the first vibrator filter 1 and the second vibrator filter 2. Therefore, when the vibration-to-voltage converter 4 simultaneously detects and synthesizes vibrations in each of the first vibrator filter 1 and the second vibrator filter 2, the carrier band component that is a common frequency band component cancels out. Therefore, other frequency band components, that is, baseband signals are extracted.
[0023]
That is, the baseband which is a signal of a specific frequency component from the received signal by passing through the first vibrator filter 1, the second vibrator filter 2, the voltage → vibration converter 3 and the vibration → voltage converter 4. A signal can be extracted and obtained. Therefore, even when the baseband signal is obtained from the received signal, if the reception processing system of the signal processing apparatus is configured using the MEMS as described above, components such as a VCO and a mixer are not required. In addition, the reception processing system can be made into one chip, and it is very easy to realize downsizing and cost reduction of the signal processing device and the communication device using the signal processing device.
[0024]
Next, the reception processing system of the signal processing apparatus as described above will be described in detail with a specific example. FIG. 2 is a plan view showing a specific configuration example of the reception processing system of the signal processing apparatus according to the present invention. Similarly to the example described with reference to FIG. 1, the reception processing system of the illustrated example also includes the first vibrator filter 1, the second vibrator filter 2, the voltage → vibration conversion unit 3, and the vibration → voltage conversion. Part 4.
[0025]
The first vibrator filter 1 includes a single mechanical vibrator 13 that is installed on a base 11 via a support base 12 and that is fixed at both ends by the support base 12. is there. In other words, the first vibrator filter 1 includes a mechanical vibrator 13 that functions as a movable electrode of the MEMS. Usually, the movable electrode of MEMS has a very high Q value of about 10,000, and in the case of a single vibrator, the transmission frequency band is mainly determined by its length (distance between fixed points). In the vibrator filter 1, the length of the mechanical vibrator 13, that is, the distance between the support bases 12, is set so that the carrier band of the received signal is the transmission frequency band.
[0026]
The second vibrator filter 2 is arranged in parallel with the first vibrator filter 1 and is installed on the base 21 via the support base 22 like the first vibrator filter 1. In addition, a mechanical vibrator 23 having both ends fixed by the support base 22 is provided. However, the mechanical vibrator 23 in the second vibrator filter 2 is formed by mechanically connecting a plurality of vibrators. As a result, the second vibrator filter 2 corresponds to a wider transmission frequency band than the first vibrator filter 1. Specifically, in the second vibrator filter 2, the length of the mechanical vibrator 23 and the number of connections thereof are set such that the channel band including the wavelength of the carrier of the received signal as the reference frequency is the transmission frequency band. Is set.
[0027]
The voltage → vibration conversion unit 3 is an input electrode disposed between the mechanical vibrator 13 in the first vibrator filter 1 and the mechanical vibrator 23 in the second vibrator filter 2 that are arranged in parallel. 31. By applying a high frequency signal to the input electrode 31, the mechanical vibrators 13 and 23 are excited simultaneously. However, in the voltage-to-vibration conversion unit 3, the input electrode 31 is disposed between the mechanical vibrator 13 and the mechanical vibrator 23. Become. Therefore, exciting vibrations for each simultaneously excites vibrations in opposite phases.
[0028]
The vibration-to-voltage converter 4 generates vibrations in the first detection electrode 41 that detects vibration in the mechanical vibrator 13 of the first vibrator filter 1 and in the mechanical vibrator 23 of the second vibrator filter 2. A second detection electrode 42 for detection is provided, so that vibrations in each can be detected simultaneously. Note that the relative position between the first detection electrode 41 and the mechanical vibrator 13 and the relative position between the second detection electrode 42 and the mechanical vibrator 23 are different from the case of the input electrode 31. It is almost the same. In addition, the vibration-to-voltage converter 4 includes a mechanical vibrator 43 that functions as a movable electrode of the MEMS and a fixed electrode 44 attached thereto, and the first detection electrode 41 performs DC (direct current) boosting. Then, the second detection electrode 42 is connected to the fixed electrode 44 while being connected to the mechanical vibrator 43. With this configuration, the vibration-to-voltage converter 4 can synthesize (mix) the vibration detected by the first detection electrode 41 and the vibration detected by the second detection electrode 42, and the frequency of the combined vibration can be obtained. It can be converted.
[0029]
Next, processing operations in the reception processing system configured as described above will be described. When the received signal is input, the voltage → vibration converter 3 applies the received signal to the input electrode 31. At this time, in a state where an electrostatic field is applied to the mechanical vibrator 13 of the first vibrator filter 1 and the mechanical vibrator 23 of the second vibrator filter 2, a reception signal that is a high-frequency signal is applied to the input electrode 31. When applied, an oscillating electric field is generated, so that the mechanical vibrators 13 and 23 are driven. That is, when a reception signal is applied to the input electrode 31, the mechanical vibrators 13 and 23 are excited to vibrate.
[0030]
When the mechanical vibrators 13 and 23 vibrate, the first vibrator filter 1 and the second vibrator filter 2 have a frequency that matches the mechanical natural frequency of each of the mechanical vibrators 13 and 23. Permeate only. Therefore, even when a received signal having a frequency indicated by symbol A in FIG. 1 is input to the voltage → vibration conversion unit 3, the first detection electrode 41 corresponds to the carrier band in the vibration → voltage conversion unit 4. Vibration (see symbol B in FIG. 1) is detected, and the second detection electrode 42 detects the vibration (see symbol C in FIG. 1) corresponding to the channel band including the carrier wavelength as a reference frequency. Will be detected. Note that the vibrations detected by the first detection electrode 41 and the second detection electrode 42 both include the wavelength of the carrier serving as the reference frequency, but the input electrode 31 is compared with the mechanical vibrators 13 and 23. Since the first detection electrode 41 and the second detection electrode 42 are arranged at the same relative position, the wavelengths of the carriers common to each other are also opposite in phase. It will be a thing.
[0031]
The vibration detected by the first detection electrode 41, that is, the vibration of the carrier band frequency is transmitted to the mechanical vibrator 43 after DC boosting of the vibration → voltage conversion unit 4. Since DC boosting may be performed using a known technique, the description thereof is omitted here. On the other hand, vibration detected by the second detection electrode 42, that is, vibration having a frequency in the channel band is transmitted to the fixed electrode 44.
[0032]
At this time, the following operations are performed between the mechanical vibrator 43 and the fixed electrode 44. Normally, when an alternating current (AC) signal is supplied from one of the electrodes between the MEMS mechanical vibrator and the fixed electrode associated therewith, filtering by resonance vibration is performed. However, when different frequencies f1 and f2 are input to both electrodes, mixing occurs between the two electrodes, and frequencies of | f1 + f2 | and | f1-f2 | are generated. When the resonance frequency of the mechanical vibrator coincides with, for example, | f1-f2 |, frequency conversion corresponding to | f1-f2 | is performed, and then a signal having the converted frequency is output. Will be. From these facts, when the vibration of the carrier band frequency is transmitted to the mechanical vibrator 43 and the vibration of the channel band frequency is transmitted to the fixed electrode 44, each of the mechanical vibrator 43 and the fixed electrode 44 has each of them. The vibrations are mixed, and the vibrations of the carrier wavelengths that are common to each other and opposite in phase are cancelled. In addition, based on the resonance frequency of the mechanical vibrator 43, frequency conversion for the vibration after mixing is also performed at the same time.
[0033]
Therefore, the vibration → voltage conversion unit 4 corresponds to the vibration of the channel band excluding the wavelength of the carrier, and the signal after the frequency conversion that matches the vibration to the specific frequency component (see symbol D in FIG. 1). ) Is extracted and output as a baseband signal which is a signal of a specific frequency component. This baseband signal is equivalent to a communication signal processed by a conventional direct conversion signal processing device. For example, if the communication device is a mobile phone, it corresponds to an audio signal to be output from the mobile phone. To do. Note that the conversion to the voltage signal performed when the baseband signal is output may be performed using a known technique, and thus the description thereof is omitted here.
[0034]
As described above, in the signal processing device described in the present embodiment and the communication device equipped with the signal processing device, the mechanical filter using the micro-vibrator created using the MEMS technology has extremely high wavelength selectivity. By utilizing this, a carrier band component signal is extracted from the received signal and mixed with the received signal to demodulate the received signal. In other words, the extraction of the carrier band component from the received signal and the extraction of the baseband signal by mixing the received signal and the carrier band component are all realized by a mechanical vibration propagation mechanism composed of minute mechanical vibrators. The Therefore, even when demodulating a received signal, functions in these electronic elements are not required without requiring additional electronic elements such as a bandpass filter, a PLL (phase adjuster), a VCO, a mixer, and an IF filter. Can be integrated into a single MEMS structure, and the RF receiving module can be completely integrated into a single chip, which makes it very easy to downsize the apparatus. In addition, since all demodulation processing can be performed with passive elements, a significant reduction in power consumption can be expected as compared with the prior art.
[0035]
In the signal processing apparatus described in the present embodiment, the channel band that is the transmission frequency band in the second vibrator filter 2 includes the carrier band that is the transmission frequency band in the first vibrator filter 1. In addition, since the voltage-to-vibration conversion unit 3 excites vibration so that the phases of the first and second vibrator filters 1 and 2 are reversed, the MEMS structure is used. Even so, the extraction of the carrier band component and the extraction of the baseband signal by mixing the received signal and the carrier band component can be performed easily and reliably. In addition, as described above, if the vibration-to-voltage converter 4 includes the mechanical vibrator 43 and the fixed electrode 44, it is possible to perform frequency conversion on the extraction result while using the MEMS structure. This is even more preferable in realizing downsizing of the apparatus.
[0036]
As a matter of course, this embodiment is merely a preferred specific example of the present invention, and the technical scope of the present invention is not limited thereto. Of course, the configuration is not limited to the configuration of the signal processing apparatus shown in FIG.
[0037]
【The invention's effect】
As described above, according to the signal processing device and the communication device according to the present invention, by utilizing the MEMS technology, it is possible to integrate functions necessary for demodulation of the received signal in a very small area, As a result, the signal processing device can be realized as a single chip, so that it is very easy to reduce the size and cost of the device.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an outline of a reception processing system of a signal processing apparatus according to the present invention.
FIG. 2 is a plan view showing a specific configuration example of a reception processing system of the signal processing apparatus according to the present invention.
FIG. 3 is a block diagram illustrating an example of a schematic configuration of a signal processing device used in a communication device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... 1st vibrator filter, 2 ... 2nd vibrator filter, 3 ... Voltage-> vibration conversion part, 4 ... Vibration-> voltage conversion part, 13, 23 ... Mechanical vibrator, 31 ... Input electrode, 41 ... First detection electrode, 42 ... second detection electrode, 43 ... mechanical vibrator, 44 ... fixed electrode

Claims (2)

A first mechanical vibrator having a transmission frequency band as a carrier band of a communication signal in which a channel band component is superimposed on a carrier band component;
A second mechanical vibrator whose transmission frequency band is a frequency band including the channel band component in addition to the carrier band component;
Excitation means for exciting vibrations of opposite phase simultaneously to the first mechanical vibrator and the second mechanical vibrator by application of the communication signal;
Detecting means for simultaneously detecting and synthesizing vibrations having opposite phases transmitted through each of the first mechanical vibrator and the second mechanical vibrator and extracting a baseband signal in the communication signal;
A signal processing apparatus comprising: A communication device having a communication signal reception function in which a channel band component is superimposed on at least a carrier band component ,
A first mechanical vibrator having a transmission frequency band as a carrier band of the communication signal;
A second mechanical vibrator whose transmission frequency band is a frequency band including the channel band component in addition to the carrier band component ;
Excitation means for exciting vibrations of opposite phase to the first mechanical vibrator and the second mechanical vibrator simultaneously by application of the communication signal;
Detecting means for simultaneously detecting and synthesizing vibrations having opposite phases transmitted through each of the first mechanical vibrator and the second mechanical vibrator and extracting a baseband signal in the communication signal;
A communication device comprising:

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