JP2007072590A - Bandpass filter design support system, method for designing bandpass filter, and bandpass filter design support program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To design a bandpass filter that shows a broad passband characteristic and a steep attenuation characteristic in the vicinity of a passband. <P>SOLUTION: A bandpass filter design support system includes: a resonator library 5 for storing data about the plurality of structure models of a resonator each consisting of a tap part formed by a first distribution constant line and a stab part formed by a second distribution constant line connected to the first distribution constant line in an area other than ends, and data about the relationship of resonator characteristics with the parameters of the distribution constant lines in each structure model; and a filter design support apparatus 2 which refers to the resonator library 5 at the input of the required specifications for the bandpass filter, so as to select the resonator satisfying the required requirements; virtually constructs a bandpass filter with the selected resonator connected in multiple steps between an input end and an output end by a third distribution constant line; simulates the characteristics of the bandpass filter; and outputs simulation results to an output device 4. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a design support system, a bandpass filter design method, and a bandpass filter design support program that support the design of a bandpass filter suitable for application to a UWB wireless communication system.

In recent years, studies for practical application of a UWB (Ultra Wideband) wireless communication system that realizes a high-speed communication speed of several hundred megabits / second have been energetically advanced. Because of having a wide frequency component, there is a possibility of interference with existing communication service signals. From such a background, it is necessary to use a bandpass filter in the UWB wireless communication system in order to regulate the radiation level.
JP 2000-357903 A

  However, so far, there is a report example of a bandpass filter that can be used in a high frequency region such as a microwave band (see Patent Document 1), but it can be applied to a UWB wireless communication system, There are few reported examples of bandpass filters that exhibit a wide bandpass band characteristic and a steep attenuation characteristic near the passband, and there are no reported examples of those that can easily adjust the characteristics of the bandpass filter. Under such circumstances, there is an urgent need to provide a system and a design method that support the design of a bandpass filter suitable for application to a UWB wireless communication system.

  The present invention has been made to solve the above-described problems, and its object is to support design of a bandpass filter capable of designing a bandpass filter exhibiting a wide passband characteristic and a steep attenuation characteristic in the vicinity of the passband. To provide a system, a bandpass filter design method, and a bandpass filter design support program.

  As a result of intensive research, the inventors of the present invention have developed a resonator configured by connecting a tap portion formed by a distributed constant line to a side surface of a stub portion formed by a distributed constant line. It was found that by connecting multiple stages with distributed constant lines and changing parameters such as characteristic impedance and line length of these distributed constant lines, the passband width and the position of the attenuation pole in the vicinity of the passband can be controlled. Furthermore, it has also been found that when a distributed constant tap type resonator is connected to the distributed constant line, even if a plurality of resonators are used, the characteristic is simply added.

  One aspect of the design support system for a bandpass filter according to the present invention conceived from such knowledge is a bandpass filter that outputs only a signal in a desired frequency band from an output end among signals input to an input end. A band-pass filter design support system for supporting the design of the second distributed constant line connected to the first distributed constant line in a region other than the tap portion and the end formed by the first distributed constant line A resonator library for storing data of a plurality of structural models of a resonator including a stub portion formed by the method, a data of a relationship of a resonator characteristic with respect to a parameter of a distributed constant line for each structural model, and a bandpass filter According to the input of the required specification, the resonator satisfying the required specification is selected with reference to the resonator library, and the selected resonator is selected as the third distributed constant. The band-pass filters connected in multiple stages between input and output ends by the road virtually constructed to simulate the characteristics of the band-pass filter, and a control unit for outputting a simulation result.

  In addition, one aspect of the design method of the bandpass filter according to the present invention is a design method of a bandpass filter that outputs only a signal in a desired frequency band from the output end among the signals input to the input end, In response to the input of the required specification of the bandpass filter, the tap portion formed by the first distributed constant line and the second distributed constant line connected to the first distributed constant line in a region other than the end portion Refer to the resonator library that stores the data of multiple structural models of the resonator consisting of the formed stub part and the data of the relationship of the resonator characteristics to the parameters of the distributed constant line for each structural model. A step of selecting a satisfactory resonator, and a band-pass filter in which the selected resonator is connected in multiple stages between the input end and the output end by a third distributed constant line are virtually configured, It has a step of simulating the characteristic of the band-pass filter, and a step of designing a band-pass filter with reference to the results of the simulation.

  In addition, one aspect of the bandpass filter design support program according to the present invention is a bandpass filter design support program that outputs only a signal of a desired frequency band from the output terminal among the signals input to the input terminal. The second distributed constant connected to the first distributed constant line in a region other than the tap portion and the end formed by the first distributed constant line in response to the input of the required specification of the bandpass filter Requested by referring to a resonator library that stores data of multiple structural models of resonators composed of stubs formed by lines, and data on the relationship of resonator characteristics to distributed constant line parameters for each structural model A process of selecting a resonator satisfying the specifications and a bandpass filter in which the selected resonator is connected in multiple stages between the input end and the output end by a third distributed constant line are temporarily installed. To configure, simulate the characteristics of the bandpass filter, to perform the process of outputting the simulation results to a computer.

  According to the bandpass filter design support system, the bandpass filter design method, and the bandpass filter design support program according to the present invention, a desired characteristic having a wideband passband characteristic and a steep attenuation characteristic in the vicinity of the passband. The bandpass filter can be easily designed.

  Hereinafter, the configuration of a filter design support system according to an embodiment of the present invention will be described with reference to the drawings.

[Configuration of filter design support system]
As shown in FIG. 1, a filter design support system 1 according to an embodiment of the present invention includes a filter design support device 2 configured by a general-purpose information processing device such as a workstation or a personal computer, a keyboard, a mouse pointer, and the like. The main component includes an input device 3, an output device 4 such as a display device or a printer device, and a resonator library 5 and an element library 6 configured by known information storage devices.

  In the filter design support apparatus 2, a CPU (Central Processing Unit) 7 loads a computer program stored in a ROM (Read Only Memory) 8 into a RAM (Random Access Memory) 9, and the loaded computer program is loaded. By executing this, various processes for supporting the design of the bandpass filter are executed. In the present embodiment, the ROM 8 stores a known circuit simulation program 10 and an electromagnetic field simulation program 11 for executing circuit simulation and electromagnetic field simulation in filter design support processing described later.

  The resonator library 5 classifies and stores data of a plurality of types of resonators according to the position of the attenuation pole, the number of realizations, the bandwidth, and the frequency band. More specifically, in this embodiment, as shown in FIG. 2, the resonator library 5 includes a structural model of a distributed constant tap coupled resonator, such as a double-ended open model, a double-ended ground model, a single-ended ground model, and a structural model. The relationship of the resonator characteristics to the parameters of each distributed constant line is stored.

  As shown in FIG. 2, the distributed constant tap coupled resonator includes a tap portion 15 formed by a first distributed constant line and a first distributed constant line connected to the first distributed constant line in a region other than the end portion. Means a resonator connected to the third distributed constant line connecting the input end and the output end of the bandpass filter via the tap portion 15. The distributed constant tap coupled resonator of the open both ends model means a resonator in which both ends of the stub portion 16 are open.

  Also, the distributed constant tap coupled resonator of the both-end grounded model means a resonator in which both ends of the stub portion 16 are grounded. In addition, the distributed constant tap coupled resonator of the one-end grounded model means a resonator in which one end of the stub portion 16 is grounded. In this embodiment, the parameter of the distributed constant line means the line length, the line width, and the characteristic impedance of the distributed constant line forming the tap part 15 and the stub part 16. The resonator characteristic means the attenuation characteristic (S21) and the input reactance characteristic (Xin) of the resonator, and the position (frequency) of the attenuation pole is confirmed by extracting the frequency at which the input reactance characteristic becomes zero. be able to.

  The element library 6 stores information related to elements to which the resonator is connected. In addition, although mentioned later in detail, in this embodiment, the filter design assistance apparatus 2 virtually connects a bandpass filter by connecting the resonator in multiple stages with a third distributed constant line between the input end and the output end. Since it is configured (see FIG. 4), the element library 6 stores information on parameters (line length, line width, characteristic impedance, etc.) of the third distributed constant line.

  In the filter design support system 1 having such a configuration, the filter design support apparatus 2 performs the following filter design support processing, thereby obtaining a wide band pass band characteristic and a steep attenuation characteristic in the vicinity of the pass band. Make the path filter designable. The operation of the filter design support apparatus 2 when executing this filter design support process will be described below with reference to the flowchart shown in the drawing.

[Filter design support processing]
The flowchart shown in FIG. 3 starts when the operator inputs an execution instruction for the filter design support process to the filter design support apparatus 2 via the input device 3, and the filter design support process proceeds to the process of step S1.

  In the process of step S1, the filter design support apparatus 2 performs the center frequency, the lower and upper limit frequencies of the pass band, the frequency band of the out-of-band suppression (low band side and high band side), and the suppression level of the out-of-band suppression (low band). Prompts the operator to enter the required specifications for the bandpass filter, such as the location and number of attenuation pole frequencies (low frequency side, high frequency side). Then, in response to the operator inputting the required specification via the input device 3, the filter design support device 2 advances the filter design support processing to the processing in step S2.

  In the process of step S2, the filter design support apparatus 2 refers to the resonator library 5 and the types and number of resonators satisfying the required specifications input by the process of step S1, and the structure of the distributed constant line (microstrip line). , Strip line, coplanar line), range of circuit constants due to variations in manufacturing accuracy, and details of the substrate (dielectric constant, size, single layer or multilayer). Information about the structure of the distributed constant line, the range of circuit constants, and details of the substrate is stored in advance in the filter design support device 2 or specified by the operator when executing the filter design support processing. And Thereby, the process of step S2 is completed, and the filter design support process proceeds to the process of step S3.

  In the process of step S3, the filter design support apparatus 2 refers to the element library 6 and arranges the third distributed constant line on the substrate determined by the process of step 2, and the third distributed constant line includes the third distributed constant line. A band-pass filter is virtually configured by connecting resonators determined by processing. According to such processing, for example, a band-pass filter 21 as shown in FIG. 4 is virtually configured. 4 includes a dielectric substrate 22 and a distributed constant line (third distributed constant line) connecting the input transmission line 23 and the output transmission line 24 formed on the dielectric substrate 22. ) Tap portions 26a, 26b, 26c, 26d composed of 25a, 25b, 25c and first distributed constant lines connected to the distributed constant lines 25a, 25b, 25c at the ends, and tap portions 26a in the regions other than the ends. , 26b, 26c, and 26d, a resonator having stub portions 27a, 27b, 27c, and 27d composed of second distributed constant lines, and four resonators between the input transmission line 23 and the output transmission line 24. Are multi-stage connected (multi-stage coupled) by distributed constant lines 25a, 25b, and 25c. The bandpass filter 21 resonates at a frequency corresponding to the passband in response to a signal being input to the input transmission line 23, so that only a signal in a desired frequency band is output to the output transmission line. 24. Thereby, the process of step S3 is completed, and the filter design support process proceeds to the process of step S4.

  In the process of step S4, the filter design support device 2 executes a circuit simulation and an electromagnetic field simulation of the bandpass filter virtually configured by the process of step S3. Thereby, the process of step S4 is completed, and the filter design support process proceeds to the process of step S5.

  In step S5, the filter design support apparatus 2 refers to the simulation result in step S4 to determine whether or not the bandpass filter satisfies the required specifications. If the required specification is not satisfied as a result of the determination, the filter design support apparatus 2 changes the width, length, and characteristic impedance of the distributed constant line as the process of step S6, and then performs the filter design support process. The process returns to S3.

  Specifically, the filter design support device 2 changes the line width of the distributed constant line 25a shown in FIG. 4, and reflects the change in the reflection characteristics accompanying the change in the line width as shown by the broken line in FIG. Ensure that the characteristics meet the required specifications. As is apparent from FIG. 5, it can be seen that the attenuation characteristic of the pass band is improved and reduced by making the reflection characteristic satisfy the required specification.

  On the other hand, if the required specifications are satisfied, the filter design support device 2 outputs the structural information of the virtually constructed bandpass filter to the output device 4, and then ends the series of filter design support processing. Thereafter, the operator actually manufactures the band pass filter with reference to the output structure information.

  As mentioned above, although embodiment which applied the invention made by the present inventors was described, this invention is not limited by the description and drawing which make a part of indication of this invention by this embodiment. That is, it should be added that other embodiments, examples, operation techniques, and the like made by those skilled in the art based on the above-described embodiments are all included in the scope of the present invention.

It is a block diagram which shows the structure of the filter design assistance system used as embodiment of this invention. It is a figure which shows an example of an internal structure of the resonator library shown in FIG. It is a flowchart figure which shows the flow of the filter design assistance process used as embodiment of this invention. It is a figure which shows an example of a structure of the band pass filter comprised virtually by the filter design assistance process shown in FIG. It is a figure which shows the change of the attenuation | damping characteristic and reflection characteristic of a band pass filter accompanying the change of the line width of a distributed constant line.

Explanation of symbols

1: Filter design support system 2: Filter design support device 3: Input device 4: Output device 5: Resonator library 6: Element library 7: CPU
8: ROM
9: RAM
10: Circuit simulation program 11: Electromagnetic field simulation program

Claims (4)

A bandpass filter design support system that supports the design of a bandpass filter that outputs only a signal in a desired frequency band from an output end among signals input to an input end,
A plurality of structural models of a resonator comprising a tap portion formed by a first distributed constant line and a stub portion formed by a second distributed constant line connected to the first distributed constant line in a region other than the end portion And a resonator library for storing data on the relationship of the resonator characteristics to the parameters of the distributed constant line for each structural model,
In response to the input of the required specifications of the bandpass filter, the resonator library is selected with reference to the resonator library, and the selected resonator is input by the third distributed constant line. A band-pass filter having a multi-stage connection between the output end and the output end, a controller that simulates the characteristics of the band-pass filter and outputs a simulation result. Support system. A design support system for a bandpass filter according to claim 1,
If the characteristic of the bandpass filter does not satisfy the required specification as a result of the simulation, the control unit changes any of the parameters of the first to third distributed constant lines, and the characteristic of the bandpass filter satisfies the required specification. A design support system for a band-pass filter, which performs simulation repeatedly until satisfied. A method for designing a band-pass filter that outputs only a signal in a desired frequency band from an output end among signals input to an input end,
The second distributed constant line connected to the first distributed constant line in a region other than the tap portion and the end formed by the first distributed constant line in response to the input of the required specifications of the bandpass filter Requested by referring to a resonator library that stores data of a plurality of structural models of a resonator composed of stub portions formed by the above and data of the relationship of the resonator characteristics to the parameters of the distributed constant line for each structural model. Selecting a resonator that satisfies the specifications; and
Virtually configuring a bandpass filter in which the selected resonator is connected in multiple stages between the input end and the output end by a third distributed constant line, and simulating the characteristics of the bandpass filter;
And a step of designing a bandpass filter with reference to a result of the simulation. A design support program for a bandpass filter that outputs only a signal in a desired frequency band from an output end among signals input to an input end,
A second distributed constant line connected to the first distributed constant line in a region other than the tap portion and the end formed by the first distributed constant line in response to the input of the required specifications of the bandpass filter. Requested by referring to a resonator library that stores data of a plurality of structural models of a resonator composed of stub portions formed by the above and data on the relationship of the resonator characteristics to the parameters of the distributed constant line for each structural model. A process of selecting a resonator that satisfies the specifications;
A band-pass filter in which the selected resonator is connected in multiple stages between the input end and the output end by a third distributed constant line is virtually configured, the characteristics of the band-pass filter are simulated, and the simulation result is output. Processing,
A program for supporting the design of a band-pass filter, characterized in that a computer is executed.

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