KR101369909B1 - Complex coefficient transversal filter and frequency converter - Google Patents

Abstract

The present invention relates to a complex coefficient transversal filter and a frequency converter using a surface acoustic wave (SAW) filter, and the complex coefficient transverse filter according to the present invention causes mechanical distortion due to piezoelectricity by inputting an RF signal. A first SAW transducer that excites a surface acoustic wave and a second SAW transducer that generates a real part and an imaginary part of a complex signal by polymerizing and integrating based on an impulse response of a right function and an odd function for the surface acoustic wave; And at least one of the second SAW converters is a four-phase unidirectional converter, thereby realizing miniaturization of the size and preventing variations in the propagation track.

Description

COMPLEX COEFFICIENT TRANSVERSAL FILTER AND FREQUENCY CONVERTER}

1 is a view showing the structure of a conventional complex coefficient universal filter.

2 is a view showing a schematic configuration of a full complex frequency converter according to an embodiment of the present invention.

3 is an explanatory diagram showing a configuration of a complex coefficient universal filter according to a first embodiment of the present invention.

4A is an explanatory diagram showing a configuration of a bidirectional transducer (single electrode).

4B is an explanatory diagram showing a configuration of a bidirectional converter (double electrode).

5 is an explanatory diagram showing a configuration of a four-phase unidirectional converter according to an embodiment of the present invention.

FIG. 6 is an explanatory view showing a partially enlarged view of FIG. 5. FIG.

7 is a perspective view showing the configuration of a four-phase unidirectional converter according to an embodiment of the present invention.

8 is an explanatory diagram showing an embodiment of a group type converter.

9 is an explanatory diagram showing a partially enlarged view of FIG. 8.

10 is an explanatory diagram showing another embodiment of a group type converter.

FIG. 11 is an explanatory diagram showing a partially enlarged view of FIG. 10. FIG.

Figure 12 shows the frequency-amplitude characteristics of the complex coefficient transverse filter according to the present invention.

Figure 13 shows the frequency-phase characteristics of a complex coefficient transverse filter according to the present invention.

14 shows image suppression characteristics of a complex coefficient transversal filter according to the present invention.

15 is an explanatory diagram showing a configuration of a single-phase unidirectional converter according to an embodiment of the present invention.

Fig. 16 is an explanatory diagram showing a configuration of a complex coefficient universal filter according to a second embodiment of the present invention.

17 and 18 are explanatory diagrams showing a configuration of a complex coefficient universal filter according to a third embodiment of the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a complex coefficient transversal filter and a frequency converter. In particular, a surface acoustic wave (SAW) filter suitable for implementing a complex coefficient filter of a high frequency band such as a high performance wireless communication terminal is provided. The present invention relates to a complex coefficient transversal filter used and a frequency converter using the same.

The Double Quadrature Frequency Converter, which is used in high-performance wireless communication terminals, receives a RF signal and generates a complex signal by having a 90-degree phase difference by a complex coefficient filter, and generates the complex signal by using a double quadrature mixer. By frequency downconverting, a high image suppression ratio can be obtained. Here, the complex coefficient filter may be implemented using a transversal SAW filter. The complex coefficient filter can be realized not only by the SAW filter but also by a switched capacitor circuit, a charge region device, and the like. However, the SAW filter is suitable for implementing a high frequency complex coefficient filter.

1 is a view showing the structure of a SAW filter described in Japanese Patent Application No. 2005-117458 filed by the applicant of the present application. The SAW filter 10 is composed of a piezoelectric substrate 11 and comb-shaped electrodes (hereinafter referred to as inter-digital transducers (IDTs) 12 to 15) provided on the piezoelectric substrate 11 and having different crossing widths for each position. have. Each comb-shaped portion is also called an electrode finger. The IDTs 12 and 14 are connected to the input terminals, and when an RF signal is applied, they cause mechanical distortion by piezoelectricity to excite the surface acoustic waves, and the surface acoustic waves propagate in the left and right directions of the piezoelectric substrate 11. The IDT 13 is connected to the output terminal I which outputs the real axis component, and is provided in the position which can receive the surface acoustic wave propagated from the IDT 12. As shown in FIG. The IDT 15 is connected to an output terminal Q that outputs the imaginary shrinkage component, and is provided at a position capable of receiving surface acoustic waves propagated from the IDT 14.

The SAW filter 10 made as above is composed of propagation tracks of independent surface acoustic waves, respectively, in order to obtain the complex signals I and Q. That is, one propagation track is constituted by the IDT 12 and the IDT 13 to obtain the complex signal I, and another propagation track is performed by the IDT 14 and the IDT 15 to obtain the complex signal Q. Configure In such a configuration, since two transverse SAW filters are required, there is a problem that the size thereof becomes large. In addition, since the propagation tracks are independent, there is a problem that characteristic variations due to manufacturing variations between the propagation tracks occur.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a complex-coefficient transversal filter and a frequency converter using the same, which are capable of miniaturizing the size and preventing the variation of the propagation track characteristics. There is.

The complex coefficient transverse filter according to the present invention for solving the above technical problem is a first function and an odd function for the first SAW converter and the surface acoustic wave that excite a surface acoustic wave by causing mechanical distortion due to piezoelectricity by inputting an RF signal. And a second SAW transducer for generating a real part and an imaginary part of a complex signal by polymerizing and integrating based on an impulse response of the signal, wherein at least one of the first SAW converter and the second SAW converter is a four-phase unidirectional converter. do.

The first SAW transducer is a bidirectional transducer for propagating the surface acoustic wave in both directions, and the second SAW transducer is a four-phase unidirectional antenna installed at a position capable of receiving one of the surface acoustic waves propagating in both directions. It may be characterized in that the converter. By using the bidirectional converter as described above, broadband characteristics can be realized as compared with the case of using the single-phase unidirectional converter.

The first SAW transducer is a single-phase unidirectional transducer that propagates the surface acoustic wave in one direction, and the second SAW transducer is a four-phase unidirectional transducer installed at a position capable of receiving the propagated surface acoustic wave. can do. Single-phase unidirectional transducers have narrowband characteristics compared to bidirectional transducers, but signal loss can be reduced because they propagate surface acoustic waves in one direction only and receive all the propagated surface waves with four-phase unidirectional transducers.

In addition, the first SAW transducer is a bidirectional transducer for propagating the surface acoustic wave in both directions, and the second SAW transducer is two four-phase unidirectional transducers respectively installed at positions capable of receiving each of the surface acoustic waves propagating in both directions. It can be characterized by. According to this configuration, the broadband characteristics can be realized by using the bidirectional transducer, which propagates the surface acoustic waves in both directions and receives the propagated surface acoustic waves by two four-phase unidirectional transducers. This can reduce signal loss.

In addition, the four-phase unidirectional converter may be characterized by having at least four electrodes in which the center distance of each electrode is arranged in a quarter wavelength within one period.

The four-phase unidirectional converter may include four output terminals and at least four electrodes, and each of the at least four electrodes may be connected to each of the four output terminals.

In addition, the four-phase unidirectional converter may be characterized in that the group type converter.

The four-phase unidirectional converter may include four output terminals, a ground terminal, and a plurality of electrodes, and the plurality of electrodes may include a predetermined number of electrodes as a group, and the electrodes in each group may be used as the four output terminals. It may be characterized in that it is arranged connected to the output terminal and the ground terminal corresponding to each of the groups.

The frequency converter according to the present invention for solving the above other technical problem is the first SAW converter and the surface function wave and the impulse of the right function and the odd function for the first SAW converter and the surface acoustic wave to excite the surface wave by causing mechanical distortion due to piezoelectricity as an RF signal input A complex coefficient transverse filter having a second SAW converter that polymerizes and integrates based on the response to produce a real part and an imaginary part of the complex signal, wherein at least one of the first SAW converter and the second SAW converter is a four-phase unidirectional converter A local oscillator for generating a local signal of a predetermined frequency and the complex coefficient transverse filter and the local oscillator, and multiplying the complex signal output from the complex coefficient transverse filter and the local signal output from the local oscillator Characterized by including a complex mixer to convert the frequency .

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description and the accompanying drawings, the substantially identical components are represented by the same reference numerals, and thus redundant description will be omitted.

2 is a diagram showing a schematic configuration of a full complex frequency converter 100 according to an embodiment of the present invention.

The full complex frequency converter 100 according to the present embodiment includes the antenna 111, the LNA 112, the complex coefficient transversal filter 120, the complex complex mixer 130, the LPFs 141 and 144, and the AGC 142. 145 and ADCs 143 and 146. 1 shows only the components necessary for the present embodiment, and illustration and description of other components not listed above are omitted.

The low noise amplifier (LNA) 112 is an amplifier that amplifies the RF signal input from the antenna 111. The complex coefficient transverse filter 120 is a filter for suppressing a positive frequency or a negative frequency component. Details of the complex coefficient universal filter 120 will be described later with reference to FIG. 3.

The entire complex mixer 130 performs frequency conversion by mixing the local signal with the complex signal from the complex coefficient transversal filter 120. The precomplex mixer 130 includes a precomplex mixer 130 including first to fourth multipliers 131, 132, 133, and 134 and first and second adders (or subtractors) 135 and 136. The complex mixer 130 receives a real axis local signal cos from a local oscillator 137 generating a local signal and an imaginary axis local signal -sin from the local oscillator 137. The precomplex mixer 130 performs a frequency conversion on the complex signal input from the complex coefficient transversal filter 120 to become frequency zero or near zero and outputs a complex signal.

The low pass filter (LPF) 141 removes high frequency components of the complex signal. The complex signal from which the high frequency component is removed through the LPF 141 is output stage I as a real axis component of the complex baseband signal through the AGC (Auto Gain Contro1) 142 and the ADC (Analog / Digital Converter) 143. Is output via Similarly, LPF 144 also removes high frequency components of the complex signal. The complex signal from which the high frequency component is removed through the LPF 144 is output through the output terminal Q as the imaginary axis component of the complex baseband signal through the AGC 145 and the ADC 146.

The full complex frequency converter 100 according to the exemplary embodiment of the present invention has been described above. Hereinafter, the complex coefficient transverse filter 120 which is a characteristic component of the present invention among the components of the full complex frequency converter 100 will be described.

First, the principle of the complex coefficient transverse filter will be described. The impulse response of a SAW signal output as a surface acoustic wave when an impulse electric signal is applied is determined by the weight function (cross width) Wi at each electrode finger, the distance xi from each electrode finger, and the phase velocity v of the surface acoustic wave. The frequency transfer function H (ω) of the impulse response is represented by the following equation. The equation below is a linear combination of the weight function Wi and is the same as the basic principle of a transverse filter.

The transverse filter having the frequency transfer function H (ω) as described above can independently control the amplitude characteristics and the phase characteristics through the design of Wi and xi. Therefore, by designing Wi and xi of the transversal SAW filter, a complex coefficient transversal filter with desired characteristics can be realized. The transducer connected to the output terminal I which outputs the component of the real axis performs the weighting corresponding to the impulse response of the real part, that is, the even symmetrical impulse response (weighting corresponding to the transfer function HI (ω)), so that the center of the envelope Each electrode finger is provided to be even symmetrical with respect to. The transducer connected to the output terminal Q which outputs the imaginary axis component performs weighting corresponding to the impulse response of the imaginary part, that is, the odd symmetric impulse response (weighting corresponding to the transfer function HQ (ω)), so that the center of the envelope Each electrode finger is provided so as to be odd symmetric with respect to. This configuration makes it possible to convert a real RF signal into a complex RF signal having a phase difference of 90 degrees between the real part and the imaginary part.

An object of the present invention is to realize a miniaturization of size in a double quadrature frequency converter or the like used in a high-performance wireless communication terminal and to prevent characteristic deviation of a radio wave track. To this end, in the frequency converter according to the present invention, at least one of a SAW converter having a propagation function HI (ω) and a transfer function HQ (ω) composed of one propagation track and disposed on one propagation track Is characterized by consisting of a four-phase unidirectional converter. Hereinafter, as a specific embodiment of the complex coefficient transverse filter 120, the complex coefficient vertical filter 120-1, the first embodiment, the complex coefficient vertical filter 120-2, the second embodiment, and the complex coefficient transversal The filter 120-3 and the third embodiment will be described in order.

As shown in FIG. 3, the complex coefficient transversal filter 120-1 according to the first embodiment of the present invention includes a bidirectional transducer 200 installed at an input side and a four phase one-way transducer 300 provided at an output side. It is composed by. The bidirectional transducer 200 excites a surface acoustic wave to propagate in both directions. The four-phase unidirectional converter 300 is connected to the output terminals I + and I- for outputting the real axis component and the output terminals Q + and Q- for outputting the imaginary axis component, and is propagated from the bidirectional converter 200. The directivity is directed toward the bidirectional transducer 200 so as to efficiently receive the surface acoustic wave. Since the complex coefficient transversal filter 120-1 according to the first embodiment is composed of one propagation track as shown in Fig. 2, its size is very small compared to the configuration of Fig. 1 described above. Hereinafter, the configuration of the bidirectional converter 200 and the configuration of the four-phase one-way converter 300 will be described in more detail.

As shown in FIGS. 4A and 4B, the bidirectional transducer 200-1 and the bidirectional transducer 200-2 are comb-shaped electrodes (inter-digital transducers) formed of negative and negative electrode fingers disposed on a piezoelectric substrate and arranged in a symmetrical direction. : IDT). The yin-yang electrode finger is generally composed of one set as shown in Fig. 4A or two sets as shown in Fig. 4B, and is called single electrode (Fig. 4A) and double electrode (Fig. 4B), respectively. It can also be designed so that the crossover width varies from place to place in order to weight.

The IDT 210 shown in FIG. 4A is connected to the input terminal 220 and the ground terminal 230. When an electrical signal is applied to the input terminal 220, mechanical distortion is caused by piezoelectricity in the IDT 210 to excite the surface acoustic wave, and the surface acoustic waves 250 and 260 are in the left and right directions of the piezoelectric substrate, that is, in FIG. Propagates in the horizontal direction of the ground.

Similarly, the IDT 215 shown in FIG. 4B is connected to the input terminal 225 and the ground terminal 235. When an electrical signal is applied to the input terminal 225, mechanical distortion is caused by piezoelectricity to excite the surface acoustic wave to the IDT 215, and the surface acoustic waves 255 and 265 are in the left and right directions of the piezoelectric substrate, that is, in FIG. Propagates in the horizontal direction of the ground.

Meanwhile, as the four-phase unidirectional converter 300 shown in FIG. 3, a four-phase transducer or a group-type transducer composed of at least four electrodes in which the center distance between the electrodes is arranged at a quarter wavelength within one cycle may be used. have. Hereinafter, it demonstrates in order.

5 is an explanatory diagram illustrating a four-phase converter 310 as an embodiment of the four-phase unidirectional converter 300 of FIG. 3. FIG. 6 is an explanatory view showing an enlarged portion of reference numeral A shown in FIG. 5. FIG. 6 shows four electrodes 310a, 310b, 310c and 310d in which the center distance between each electrode is arranged at a quarter wavelength within one cycle. Here, the width of each electrode is 1/8 wavelength. In addition, the electrode 310a is connected to the output terminal I−, the electrode 310b is connected to the output terminal Q +, the electrode 310c is connected to the output terminal I +, and the electrode 310b is It is connected to the output terminal Q-. As shown in FIGS. 5 and 6, the four-phase converter 310 is a unit in which the four electrodes 310a, 310b, 310c, and 310d are arranged in one unit. Each electrode is applied with an electric field of a quarter wavelength difference from each other to receive surface acoustic waves.

On the other hand, referring to the reference numeral B of FIG. 6, it can be seen that the electrode 310d connected to the output terminal Q− intersects with the output terminal Q + in three dimensions. For this reason, the output terminal Q + is formed three-dimensionally in the shape of a bridge at the place where it intersects with the electrode 310d. FIG. 7: is explanatory drawing which shows the bridge shape formed in the output terminal Q + and the output terminal I-. In FIG. 7, the bridge shape is exaggerated for the convenience of explanation. Similarly, the electrode 310c connected to the output terminal I + intersects three-dimensionally between the output terminals I-. For this reason, the output terminal I- is formed three-dimensionally in the shape of a bridge at the place where it cross | intersects the electrode 310c.

The four-phase converter 310 according to the embodiment of FIG. 5 is superior in characteristics to the group type converters 320 and 330 according to the embodiments of FIGS. 8 and 10 to be described later. However, since the group type converter according to the embodiments of FIGS. 8 and 10 does not need to adopt a three-dimensional bridge shape as in the embodiment of FIG. 5, it is relatively easy to manufacture.

8 and 10 are explanatory diagrams showing a group type converter as another embodiment of the four-phase unidirectional converter 300 of FIG. 3.

FIG. 8 is an embodiment of a group type converter, and FIG. 9 is an explanatory diagram showing an enlarged reference numeral C shown in FIG. 8. 9 illustrates electrodes 320a, 320b, 320c, 320d, 320e, 320f, 320g, 320h and 320i which are one group constituting the group type converter 320. The group of electrodes shown in FIG. 9 corresponds to the output terminal I-. The electrodes 320a, 320b, 320e, 320f are connected to the output terminal I-, and the electrodes 320c, 320d, 320g, 320h, 320i are connected to the ground terminal GND. In addition, for the other output terminals Q−, I +, Q +, a group of electrodes corresponds to the same. In the group type converter 320, the width of each electrode is 1/8 wavelength, and the center distance between the electrodes is arranged at 1/4 wavelength.

FIG. 10 is another embodiment of a group type converter, and FIG. 11 is an explanatory diagram showing an enlarged reference numeral D shown in FIG. 10. 11 illustrates electrodes 330a, 330b, 330c, and 330d as one group constituting the group type converter 330. The group of electrodes shown in FIG. 11 corresponds to the output terminal I-. The electrodes 330a and 330c are connected to the output terminal I-, and the electrodes 330b and 330d are connected to the ground terminal GND. In addition, for the other output terminals Q−, I +, Q +, a group of electrodes corresponds to the same. In the group type converter 330, the widths of the electrodes 330a, 330b, and 330c are 1/4 wavelength, and the width of the electrode 330d is 1/2 wavelength. In addition, the center distance between electrodes of 1/4 wavelength width is 1/2 wavelength.

The group type converter according to the embodiment of FIG. 8 has superior characteristics as compared to the group type converter according to the embodiment of FIG. 10 since the reflected waves of each electrode cancel each other in the converter. However, in the group type converter according to the embodiment of FIG. 10, the width of the electrode is wider than that of the embodiment of FIG. 8, and thus it is relatively easy to manufacture.

Next, the operation of the complex coefficient universal filter 120-1 according to the first embodiment of the present invention will be described. When a real RF signal is input to the input terminals (in +, in-), mechanical distortion due to piezoelectricity is generated in the bidirectional transducer 200 to excite the surface acoustic wave, and the surface acoustic wave propagates in both directions of the bidirectional transducer 200. . The surface acoustic wave signal propagated from the bidirectional transducer 200 is received by the four-phase unidirectional transducer 300 installed in the propagation direction, and is converted into an electrical signal while polymerization integration is performed based on the impulse responses of the right and the odd functions. do.

At this time, in the four-phase unidirectional converter 300, the real component of the complex signal is output from the output terminals I + and I-, and the imaginary component of the complex signal is output from the output terminals Q + and Q-. Thereby, the filter which can raise the suppression ratio with respect to the non-target signal on the frequency side in which the target signal exists while suppressing a negative frequency can be obtained.

According to the complex coefficient transversal filter according to the first embodiment as described above, a good image suppression characteristic is obtained, and its size is very small because it is composed of one propagation track. In addition, by using the bidirectional converter 200, the broadband characteristics can be realized as compared with the case of using the single-phase unidirectional converter.

As shown in FIG. 16, the complex coefficient transverse filter 120-2 according to the second embodiment of the present invention includes a single-phase one-way converter 400 installed at an input side and a four-phase one-way converter 300 installed at an output side. It is configured by The single phase unidirectional transducer 400 excites the surface acoustic wave to propagate in both directions. The four-phase unidirectional transducer 300 is installed so that the directionality is directed toward the single-phase unidirectional transducer 400 so that the surface acoustic wave propagated from the single-phase unidirectional transducer 400 can be efficiently received. As the four-phase unidirectional converter 300, a configuration as shown in FIGS. 5 to 11 may be adopted as in the first embodiment. Since the complex coefficient transverse filter 120-2 according to the second embodiment is constituted by one propagation track as shown in FIG. 14, its size is very small compared to the configuration of FIG. 1 described above. Hereinafter, the configuration of the single-phase one-way converter 400 will be described in more detail.

The single-phase unidirectional transducer 400 may include internal reflection, bank type reflector, difference in magnitude of electromechanical coupling coefficient, crystal anisotropy, and the like. Asymmetry is used.

As an example, the single-phase unidirectional transducer 400 has a comb-tooth shape consisting of two 1/8 wavelength electrode fingers and one 3/8 wavelength electrode finger in one cycle (wavelength) provided on the piezoelectric substrate as shown in FIG. 15. It is composed of an electrode (Single Phase Unidirectional Transducer: SPUDT) 410, an input terminal 420 and a ground terminal 430. It can also be designed so that the crossover width varies from place to place in order to weight.

The SPUDT 410 is connected to the input terminal 420 and the ground terminal 430. When an electrical signal is applied to the input terminal 420, the surface acoustic wave is excited by the mechanical distortion caused by piezoelectricity in the SPUDT 410, and the surface acoustic wave is reflected on the right side of the piezoelectric substrate by the reflection of the thick electrode, that is, FIG. Propagates to the right side of the page. The bandwidth in which unidirectionality appears depends on the reflection coefficient of the thick electrode and is generally difficult to widen, and thus can be used in a relatively narrow bandwidth system.

Next, the operation of the complex coefficient universal filter 120-2 according to the second embodiment of the present invention will be described. When a real RF signal is input to the input terminals in + and in-, mechanical distortion due to piezoelectricity occurs in the single-phase unidirectional converter 400 to excite the surface acoustic wave, and the surface acoustic wave propagates in one direction. The surface acoustic wave signal propagated from the single-phase unidirectional transducer 400 is received by the four-phase unidirectional transducer 300 installed in the propagation direction, and is again subjected to polymerization integration based on the impulse response of the right function and the odd function. Is converted into a signal.

At this time, in the four-phase unidirectional converter 300, the real component of the complex signal is output from the output terminals I + and I-, and the imaginary component of the complex signal is output from the output terminals Q + and Q-. Thereby, the filter which can raise the suppression ratio with respect to the non-target signal on the frequency side in which the target signal exists while suppressing a negative frequency can be obtained.

According to the complex coefficient transverse filter according to the second embodiment as described above, similarly to the first embodiment described above, a good image suppression characteristic can be obtained, and since the structure is composed of one propagation track, its size is very large. small. In addition, although the single-phase unidirectional transducer 400 has narrower band characteristics than the bidirectional transducer, the surface acoustic wave propagates only in one direction and receives all the surface acoustic waves propagated by the four-phase unidirectional transducer. Can be reduced.

The complex coefficient transversal filter 120-3 according to the third embodiment of the present invention has a bidirectional transducer 200 provided on the input side and two four phase one-way filters provided on the output side, as shown in Figs. It is comprised by the converters 300-1 and 300-2. The bidirectional transducer 200 excites a surface acoustic wave to propagate in both directions. The four-phase unidirectional transducers 300-1 and 300-2 direct the respective directions in the direction of the bidirectional transducer 200 so as to efficiently receive the surface acoustic waves propagating in both directions from the bidirectional transducer 200. As the bidirectional transducer 200 and the four-phase unidirectional transducers 300-1 and 300-2, the same configuration as that shown in FIGS. 4A to 11 may be adopted as in the above-described first embodiment. Since the complex coefficient transverse filter 120-3 according to the third embodiment is constituted by one propagation track as shown in FIGS. 17 and 18, the size of the complex coefficient transverse filter 120-3 is very large compared to the configuration of FIG. 1. small.

As such, the complex coefficient transversal filter according to the third embodiment includes two four-phase one-way transducers 300-1 and 300-2. In the first embodiment as shown in FIG. 3, the surface acoustic wave signal output from the bidirectional transducer 200 to the opposite side of the four-phase unidirectional transducer 300 may not be effectively used. However, according to the configuration of the complex coefficient transverse filter according to the third embodiment as described above, all surface acoustic wave signals propagating in both directions can be effectively used. The image suppression is also very small in size, as in the first embodiment, because good characteristics are obtained and are composed of one propagation track.

12 shows the frequency-amplitude characteristics of the complex coefficient transverse filter 120 according to the present invention. Looking at S21 (passing characteristics from the input terminal to the I terminal) and S31 (passing characteristics from the input terminal to the Q terminal), it can be seen that the frequency-amplitude characteristics are almost identical and have good characteristics.

13 shows the frequency-phase characteristics of the complex coefficient transverse filter 120 according to the present invention. Looking at S21 (passing characteristics from the input terminal to the I terminal) and S31 (passing characteristics from the input terminal to the Q terminal), it can be seen that a phase difference of 90 degrees occurs for an arbitrary frequency and thus has good characteristics.

14 shows image suppression characteristics of the complex coefficient transverse filter 120 according to the present invention, that is, the attenuation characteristics of the negative frequency domain. In Fig. 14, USB (Upper Sideband) represents a characteristic in the positive frequency domain, and LSB (Lower Sideband) represents a characteristic in the negative frequency domain, taking the absolute value of the frequency and taking the frequency in the positive and negative frequency domain- The amplitude characteristics are simultaneously shown. As can be clearly seen from Fig. 14, it can be seen that the suppression ratio (image suppression degree) in the negative frequency region has a very good characteristic as 68 dB.

As mentioned above, although the preferred embodiment of the complex coefficient universal filter and the frequency converter which concerns on this invention was demonstrated referring an accompanying drawing, this invention is not limited to these embodiments. It will be apparent to those skilled in the art that various changes or modifications can be made within the scope of the technical idea described in the claims, and that these naturally belong to the technical scope of the present invention.

For example, in the above-described embodiment, as a specific configuration example of the complex coefficient transversal filter 120, the complex coefficient vertical filter 120-1 (first embodiment) and the complex coefficient vertical filter 120-2, the second embodiment Example) and the complex coefficient transversal filter 120-3 (third embodiment) are described, but the present invention is not limited to these embodiments. That is, a first SAW transducer that excites a surface acoustic wave and a second SAW transducer that generates a real part and an imaginary part of a complex signal by performing polymerization integration on the surface acoustic wave based on an impulse response. The present invention can be applied to all complex-coefficient transversal filters and at least one of two SAW transducers composed of four-phase unidirectional transducers.

In addition, in the above embodiment, as a specific embodiment of the four-phase unidirectional converter, the four-phase converter 310 and the group type converters 320 and 330 have been described. However, the present invention is not limited thereto, and four other configurations may be used. It goes without saying that a phase unidirectional transducer can be employed.

According to the present invention, a complex coefficient transverse filter is composed of a SAW transducer that excites a surface acoustic wave and a SAW transducer that generates a real part and an imaginary part of a complex signal by polymerizing and integrating based on an impulse response, and at least one of each SAW converter By constructing a four-phase unidirectional converter, it is possible to provide a complex-coefficient transversal filter and a frequency converter using the same, which can reduce the size and at the same time prevent the variation of the propagation track.

Claims (16)

A first SAW converter which inputs an RF signal and causes surface acoustic waves to cause mechanical distortion by piezoelectricity; and And a second SAW converter for polymerizing and integrating the surface acoustic wave based on the impulse responses of the right function and the odd function to generate the real part and the imaginary part of the complex signal. At least one of the first SAW transducer and the second SAW transducer is a four-phase unidirectional transducer composed of four or more electrodes. The method of claim 1, The first SAW transducer is a bidirectional transducer that propagates the surface acoustic wave in both directions. And the second SAW transducer is a four-phase unidirectional transducer installed at a position capable of receiving a surface acoustic wave of any one of the surface acoustic waves propagating in both directions. The method of claim 1, The first SAW transducer is a single-phase unidirectional transducer that propagates the surface acoustic wave in one direction. And the second SAW transducer is a four-phase unidirectional transducer installed at a position capable of receiving the propagated surface acoustic wave. The method of claim 1, The first SAW transducer is a bidirectional transducer that propagates the surface acoustic wave in both directions. And said second SAW transducers are two four-phase unidirectional transducers respectively installed at positions capable of receiving respective surface acoustic waves propagating in both directions. 5. The method according to any one of claims 1 to 4, And said four-phase unidirectional transducer comprises at least four electrodes in which a center distance between each electrode is arranged at a quarter wavelength within one period. 5. The method according to any one of claims 1 to 4, The four-phase unidirectional transducer has four output terminals and at least four electrodes, And wherein each of said at least four electrodes is connected to each of said four output terminals and arranged. 5. The method according to any one of claims 1 to 4, And said four-phase unidirectional transducer is a group type transducer. 5. The method according to any one of claims 1 to 4, The four-phase unidirectional converter has four output terminals, a ground terminal and a plurality of electrodes, The plurality of electrodes, the predetermined number of electrodes as a group of electrodes in each group is arranged to be connected to the output terminal and the ground terminal corresponding to each of the four output terminals of the complex coefficients, characterized in that Transversal filter. The first SAW transducer, which causes mechanical distortion due to piezoelectricity to excite surface acoustic waves by inputting an RF signal, and polymerizes and integrates the surface acoustic wave based on the impulse response of the right function and the odd function, thereby real and imaginary parts of the complex signal. A second coefficient SAW transducer, wherein at least one of the first SAW transducer and the second SAW transducer is a four-phase unidirectional transducer; A local oscillator for generating a local signal of a predetermined frequency; And a complex mixer connected to the complex coefficient transversal filter and the local oscillator and converting the frequency by multiplying the complex signal output from the complex coefficient transversal filter and the local signal output from the local oscillator. Frequency converter. 10. The method of claim 9, The first SAW transducer is a bidirectional transducer that propagates the surface acoustic wave in both directions. And the second SAW transducer is a four-phase unidirectional transducer installed at a position capable of receiving the surface acoustic wave of any one of the surface acoustic waves propagating in both directions. 10. The method of claim 9, The first SAW transducer is a single-phase unidirectional transducer that propagates the surface acoustic wave in one direction. And said second SAW transducer is a four-phase unidirectional transducer installed at a position capable of receiving the propagated surface acoustic wave. 10. The method of claim 9, The first SAW transducer is a bidirectional transducer that propagates the surface acoustic wave in both directions. And said second SAW transducers are two four-phase unidirectional transducers respectively installed at positions capable of receiving respective surface acoustic waves propagating in both directions. 13. The method according to any one of claims 9 to 12, And said four-phase unidirectional converter comprises at least four electrodes in which a center distance between each electrode is arranged at a quarter wavelength within one period. 13. The method according to any one of claims 9 to 12, The four-phase unidirectional transducer has four output terminals and at least four electrodes, And each of said at least four electrodes is connected to and arranged in each of said four output terminals. 13. The method according to any one of claims 9 to 12, And said four-phase unidirectional converter is a group type converter. 13. The method according to any one of claims 9 to 12, The four-phase unidirectional converter has four output terminals, a ground terminal and a plurality of electrodes, The plurality of electrodes, the predetermined number of electrodes as a group of electrodes in each group are arranged in connection with the output terminal corresponding to each group of the four output terminals and the ground terminal is arranged .

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