JP2007183878A - Electromagnetic circuit cooperation analysis program, record medium, analysis method, and analysis device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electromagnetic circuit cooperation analysis program, a record medium, a cooperation analysis method, and a cooperation analysis device for performing circuit analysis while four terminals are floating even when an analysis object includes a mutual inductor. <P>SOLUTION: Two corresponding terminals (b) and (d) of an inductively coupled coil are interconnected virtually, and are grounded. The electric field can be obtained in the electromagnetic field analysis based on the voltage difference between the terminals obtained by applying circuit analysis to this equivalent circuit. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention stores an electromagnetic field circuit linkage analysis program and an electromagnetic field circuit linkage analysis program for causing a computer to execute a linkage analysis combining an electromagnetic field analysis method based on a time domain finite difference method and a circuit analysis method based on a transient electrical circuit analysis. The present invention relates to a recording medium, an analysis method and an analysis apparatus for cooperative analysis.

  In electromagnetic field circuit linkage analysis, analysis is performed while associating an electric field or magnetic field defined in electromagnetic field analysis with a voltage or current defined in circuit analysis. Numerical simulation that combines electromagnetic field analysis and circuit analysis has the characteristic that the characteristics of circuit elements and surrounding electromagnetic field phenomena can be analyzed in a unified manner, which is very useful for analyzing high-frequency signals propagating in a circuit. It is generally known to be useful.

  The time domain finite difference method (hereinafter referred to as FDTD (Finite Difference Time Domain) method), which is one of the methods of electromagnetic field analysis as described above, divides the analysis region into grids and places unknown electromagnetic fields at grid points. To do. In the FDTD method, analysis is performed using a structure called a Yee lattice in which a lattice in which an unknown electric field is arranged and a lattice in which an unknown magnetic field is arranged are shifted by half the width of the lattice. The FDTD method derives a relational expression that works between these unknown electric field and magnetic field and the adjacent unknown magnetic field and electric field by differentiating Maxwell's electromagnetic field equation, and based on that, the unknown electric field and magnetic field are converted to a certain time. This is an analysis method for obtaining the entire electromagnetic field behavior by updating the steps in units. According to this analysis method, the electric field and the magnetic field can be obtained alternately by updating the electric field at a certain time step, updating the magnetic field after ½ time step, and updating the electric field after one time step. .

  Currently, a SPICE (Simulation Program with Integrated Circuit Emphasis) simulator developed by the University of California, Berkeley is known as a transient electrical circuit analysis tool. The tool provides an efficient way to simulate processes in very complex electronic devices.

  Non-Patent Document 1 proposes a method combining a FDTD method and a circuit simulator such as SPICE as a method of simulating a circuit such as an integrated circuit. In the electromagnetic field circuit linkage analysis combining the conventional FDTD method and a circuit simulator (SPICE in this case), a circuit element is incorporated in a cell of the FDTD, and a current source is connected between terminals corresponding to one side of the cell. A technique (current source method) that combines the FDTD method and circuit analysis by arranging capacitors is used.

When handling an N-terminal circuit element by this current source method, it is necessary to generate an equivalent circuit in which a current source is inserted between the terminals. In Non-Patent Document 2, when an N-terminal circuit element is subjected to electromagnetic circuit cooperation analysis, a current source and a capacitor are set in parallel between a terminal connected to a signal line and a terminal connected to a ground line, whereby the FDTD method and the circuit are set. A method for combining analysis is shown. In such a conventional electromagnetic field circuit cooperative analysis method, when an N-terminal circuit element is handled, either the current source or the terminal into which the capacitor is inserted is connected to the ground.
A. Thomas, et al .: The use of SPICE lumped circuits as sub-grid models for FDTD analysis, IEEE Microwave Guided Wave Letters, vol. 4, pp. 141-143 (1994). C. Kuo, B. Houshmand, and T. Itoh: Full-wave analysis of packaged microwave circuits with active and nonlinear devices: An FDTD approach, IEEE Transactions on Microwave Theory Techniques, vol. 45, pp. 819-826 (1997) .

  FIG. 9 is a diagram illustrating an example of a mutual inductor. As shown in FIG. 9, the mutual inductor includes, for example, a coil 52 having terminals a and b and a coil 54 having terminals c and d. In addition, let M be the mutual inductance of the two coils.

  Although such a mutual inductor is generally used as a component of a circuit, not only the conventional electromagnetic field circuit cooperation analysis as described above but also a general circuit analysis as shown in FIG. In a state that is not connected in a direct current, that is, in a so-called floating state, the DC potential cannot be determined, and therefore circuit analysis cannot be performed.

  FIG. 10 is a diagram showing a case where a high resistance 35 is inserted in the circuit of FIG. 9 so that the mutual inductor of FIG. 9 can be analyzed in general circuit analysis.

In general, in circuit analysis such as SPICE, for circuit analysis of a circuit element in a floating state, for example, as shown in FIG. 10, a high resistance 35 that does not hinder circuit operation between b and d is virtually set. Added, and the analysis is performed without the floating terminal. This modification allows the potential of each terminal to be determined in a DC manner, allowing analysis. In order to combine this mutual inductor with the FDTD analysis, circuit elements are connected to receive information from the FDTD. It is necessary to add a current source and a capacitor between the terminals corresponding to the FDTD cell.

  FIG. 12 shows a conventional electromagnetic field circuit cooperative analysis method in which a current source is connected between terminals where circuit elements of the circuit of FIG. 9 are arranged in order to couple the mutual inductor added with the high resistance of FIG. 10 with the FDTD method. It is a figure which shows the case where a capacitor is added.

  Referring to FIG. 12, the addition of a current source and a capacitor between terminals corresponding to the FDTD cell connecting circuit elements will be described. In order to add a current source and a capacitor between terminals where circuit elements of the circuit of FIG. 9 are arranged, a current source 32a and a capacitor 33a are added between a and b, and a current source 32b and a capacitor 33b are added between cd and d. Add Furthermore, the high resistance 35 added above needs to be changed by adding the current source 32c and the capacitor 33c.

  FIG. 12 is a table illustrating a net list. 12A is a table corresponding to FIG. 9, FIG. 12B is a table corresponding to FIG. 10, and FIG. 12C is a table corresponding to FIG.

  In FIG. 12, the first column shows the element name, the second column shows the node number of the + terminal, the third column shows the node number of the-terminal, and the fourth column shows information such as the element value. When the high resistance 35 is inserted, as shown in FIG. 12C, besides the insertion of the current source 32a (I1), current source 32b (I2), capacitor 33a (C1), and capacitor 33b (C2) corresponding to the inductor. Therefore, it is necessary to describe the current source 32c and the capacitor 33c for the high resistance 35 as well.

  This is because, in the FDTD method, an electric field and a magnetic field are calculated on each side of the cell. Therefore, when the FDTD method and circuit analysis are performed in combination, for example, the magnetic field on the side of the FDTD cell is replaced with a current. In the circuit analysis, a circuit analysis is performed with a lumped constant model for a circuit network including a current source expressing the current and a capacitor corresponding to one side of the cell, and the voltage value obtained from the result of the circuit analysis is This is because it is necessary to assume that the circuit element is in one cell in order to return to the electric field of the cell of the FDTD method instead of the electric field.

  As described above, the electromagnetic field circuit linkage analysis of the N-terminal circuit element in the floating state requires a current source and a capacitor to be added to a high resistance that does not exist originally, and thus the netlist must be changed. In addition, the amount of calculation increased as the current source increased, which required calculation time.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an electromagnetic field circuit linkage analysis program for performing circuit analysis while the four terminals of the mutual inductor are floating. It is to provide a linkage analysis method and a linkage analysis device.

  According to one aspect of the present invention, there is provided a program for causing a computer having an arithmetic processing unit to execute electromagnetic field circuit linkage analysis, wherein the arithmetic processing unit is configured to perform an electric field in a region in an analysis target region divided into cells. Alternatively, the first electromagnetic field analysis step for the magnetic field and the arithmetic processing unit are given by the first electromagnetic field analysis step for the equivalent circuit represented by the net list of the circuit elements included in the cell. A step of setting one of a voltage source or a current source based on one of an electric field or a magnetic field and performing circuit analysis, and the step of performing circuit analysis includes an inductively coupled mutual inductor included in the analysis target of the arithmetic processing unit When analyzing the operation of the inductor circuit, the arithmetic processing unit analyzes that the corresponding two terminals of the mutual inductor are connected An analysis step, the arithmetic processing unit calculates the other of the electric field or magnetic field of the cell including the circuit element based on the result of the circuit analysis, and performs a second electromagnetic field analysis on the electric field or magnetic field of the region; The arithmetic processing unit further includes a step of repeating the first electromagnetic field analysis step, the circuit analysis step, and the second electromagnetic field analysis step until a predetermined condition is satisfied. And the step of performing the second electromagnetic field analysis is performed between the two terminals to which the arithmetic processing unit is connected when the arithmetic processing unit analyzes the operation of the inductively coupled mutual inductor included in the analysis target. Inductor region analysis step for analyzing by opening.

  Preferably, the step of performing the circuit analysis includes a step of changing the net list so that the arithmetic processing unit virtually connects two terminals corresponding to the mutual inductor when the cell includes the mutual inductor.

  Preferably, the inductor circuit analyzing step includes a step in which the arithmetic processing unit analyzes a voltage between the terminals of the mutual inductor based on the virtually changed netlist, and the inductor region analyzing step is performed by the arithmetic processing unit. The step of converting the voltage of the cell into an electric field is included based on the analysis result in the step of analyzing the voltage, assuming that the two terminals that are connected are open.

  Preferably, the computer further includes a storage unit, the analysis target region includes a circuit board, and an equivalent circuit of the circuit element arranged on the circuit board includes a CR element, a coil element without inductive coupling, an induction When the time step Δt includes the coupled coil elements and the time step Δt is determined in advance, the step of performing the first electromagnetic field analysis is performed by the arithmetic processing unit dividing the region to be analyzed into cells and dividing the electric field and the magnetic field. A step of spatially shifting by half a cell, a step in which an arithmetic processing unit obtains a magnetic field in a region at time t, and a step in which the arithmetic processing unit obtains a current of a cell including a circuit element based on the obtained magnetic field. In the case where the circuit element included in the cell is an inductively coupled coil element, the arithmetic processing unit virtually includes two corresponding terminals of the inductively coupled coil element. And changing the netlist so as to connect to the network, and the arithmetic processing unit sets a current source for the netlist or the changed netlist based on the current obtained in the step of obtaining the current, and The step of obtaining the voltage at time t + 1 / 2Δt between the two terminals and the step of the arithmetic processing unit updating the time t to t + 1 / 2Δt, and the step of performing the second electromagnetic field analysis include: Based on the circuit analysis step, the electric field of the cell including the circuit element is calculated, the step of obtaining the electric field in the region at time t + 1 / 2Δt, and the arithmetic processing unit stores the obtained electric field and the obtained magnetic field in the storage unit. And a step in which the arithmetic processing unit updates the time t to t + 1 / 2Δt in the electromagnetic field analysis.

  When the other situation of this invention is followed, the computer-readable recording medium which stored the said electromagnetic field circuit cooperation analysis program is provided.

  According to still another aspect of the present invention, there is provided an electromagnetic field circuit linkage analyzing apparatus including an electromagnetic field analysis unit for performing electromagnetic field analysis, wherein the electromagnetic field analysis unit is a region divided into cells to be analyzed. Means for performing a first electromagnetic field analysis on the electric field or magnetic field of the electric field applied to the equivalent circuit represented by the net list of the circuit elements included in the cell. When the circuit analysis unit further analyzes the operation of the inductively coupled mutual inductor included in the analysis target by setting one of the voltage source or the current source based on one of the magnetic fields and performing circuit analysis. Including an inductor circuit analysis means for analyzing that the corresponding two terminals of the mutual inductor are connected, and an analysis control unit for controlling the electromagnetic field analysis unit and the circuit analysis unit; The electromagnetic field analysis unit calculates the other of the electric field or magnetic field of the cell in which the equivalent circuit exists based on the result of the circuit analysis unit, and performs a second electromagnetic field analysis on the electric field or magnetic field of the region; Inductor region analysis means for performing first and second electromagnetic field analysis by opening the two connected terminals when analyzing the operation of the inductively coupled mutual inductor included in the analysis target The analysis control unit satisfies the predetermined condition for each analysis by the means for performing the first electromagnetic field analysis, the means for performing the circuit analysis, and the means for performing the second electromagnetic field analysis. Means for controlling the electromagnetic field analysis unit and the circuit analysis unit so as to repeat.

  According to still another aspect of the present invention, there is provided an electromagnetic field circuit cooperative analysis method, comprising: performing a first electromagnetic field analysis on an electric field or a magnetic field of a region in a cell-divided analysis target region; A step of setting a voltage source or a current source and performing a circuit analysis based on one of an electric field or a magnetic field given by an electromagnetic field analysis step for an equivalent circuit represented by a net list of circuit elements including And the step of analyzing the circuit includes an inductor circuit analyzing step of analyzing that the corresponding two terminals of the mutual inductor are connected when analyzing the operation of the inductively coupled mutual inductor included in the analysis target. And calculate the other of the electric field or magnetic field of the cell in which the equivalent circuit exists based on the result of the circuit analysis. Performing a second electromagnetic field analysis step on the magnetic field, a first electromagnetic field analysis step, a circuit analysis step, and a second electromagnetic field analysis step until a predetermined condition is satisfied. The step of performing the first and second electromagnetic field analysis includes a step between two terminals that are assumed to be connected when analyzing the operation of the inductively coupled mutual inductor included in the analysis target. Inductor region analysis step for analyzing by opening.

  According to the present invention, since the terminals of the mutual inductors are in a floating state and can be handled by circuit analysis with little increase in resistance and current source, it is possible to reduce the amount of calculation of electromagnetic field circuit linkage analysis. In addition, since the amount of work for changing the netlist of circuit analysis that has occurred can be reduced as compared with the case of adding a resistor, the processing time required for preparation for electromagnetic field circuit linkage analysis can be reduced.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

  As will be apparent from the following description, in the electromagnetic field circuit cooperative analysis program and the cooperative analysis method of the present invention, the electric field and magnetic field in the circuit board are analyzed by electromagnetic field analysis such as the FDTD method, and the electric circuit element is a circuit such as SPICE. When the circuit analysis is performed by the simulator, the terminals of the N-terminal circuit element that does not have the common electrode included in the circuit board are handled by the circuit analysis while floating. Therefore, the electromagnetic field circuit linkage analysis can be performed without changing the netlist of the circuit analysis and adding the circuit element, which is further generated as compared with the case of handling the N-terminal circuit element having the common electrode.

(1. System configuration of the present invention)
FIG. 1 is a conceptual diagram showing an example of a computer 100 that executes the cooperation analysis program of the present invention.

  In FIG. 1, a computer 100 for executing a program for cooperative analysis includes an optical disk drive 108 for reading information on an optical disk such as a CD-ROM (Compact Disc Read-Only Memory) 118 and a flexible disk (Flexible Disk). , FD) 116, a computer main body 102 having an FD drive 106 for reading and writing information, a display 104 as a display device connected to the computer main body 102, and an input device also connected to the computer main body 102. A keyboard 110 and a mouse 112 are provided.

FIG. 2 is a block diagram showing the configuration of the computer 100. As shown in FIG.
As shown in FIG. 2, in addition to the optical disk drive 108 and the FD drive 106, the computer main body 102 constituting the computer 100 includes a CPU (Central Processing Unit) 120 connected to the bus 105 and a ROM (Read Only). A memory 122 including a memory (RAM) and a random access memory (RAM), a direct access memory device such as a hard disk 124, and a communication interface 128 for exchanging data with the outside are included. An optical disk such as a CD-ROM 118 is loaded in the optical disk drive 108. An FD 116 is attached to the FD drive 106.

  In the hard disk 124, circuit board data 134 in which parameters representing the physical properties of the board such as the shape of the board, the dielectric constant of the board, etc. are stored for the circuit board to be analyzed, and electromagnetic analysis in the time domain A program 135 for executing FDTD which is one of the techniques for performing the above, a program 136 for executing circuit analysis, and the like are stored. Here, for example, the circuit board data may be supplied from an external database via the communication interface 128. Each program may be supplied by a recording medium such as the FD 116 or the CD-ROM 118, or may be supplied by another computer via a communication line. The execution of FDTD or circuit analysis may be executed by an external computer via the communication interface 128 and the result may be stored in the hard disk 124.

  In addition, in a storage area of the storage device, for example, the hard disk 124, an electric field value storage area for temporarily storing electric field values and magnetic field values as analysis results during the electromagnetic field analysis, and updating those values in the next step. 137 and a magnetic field value storage area 138 are provided.

  Here, the program 135 for executing FDTD and the program 136 for executing circuit analysis are collectively referred to as an electromagnetic field circuit cooperation analysis program.

  Therefore, in the following description, it is assumed that time domain electromagnetic field analysis and circuit analysis are executed in cooperation within one computer device. However, the electromagnetic field analysis and the circuit analysis may be executed by separate computer devices, and data may be exchanged between the separate computer devices via the communication interface 128 to perform the cooperative analysis.

  The CPU 120 functioning as an arithmetic processing unit uses the memory 122 as a working memory to execute processing corresponding to the above-described program 135 for executing FDTD and the program 136 for executing circuit analysis.

  The CD-ROM 118 may be another medium, such as a DVD-ROM (Digital Versatile Disc) or a memory card, as long as it can record information such as a program installed in the computer main body. In this case, the computer main body 102 is provided with a drive device that can read these media.

  The program 135 for executing FDTD and the program 136 for executing circuit analysis are software executed by the CPU 120 as described above. Generally, such software is stored and distributed in a recording medium such as the CD-ROM 118 and the FD 116, read from the recording medium by the CD-ROM drive 108 or the FD drive 106, and temporarily stored in the hard disk 124. Alternatively, when the computer 100 is connected to the network, it is temporarily copied from the server on the network to the hard disk 124. Then, the data is further read from the hard disk 124 to the RAM in the memory 122 and executed by the CPU 120. In the case of network connection, the program may be directly loaded into the RAM and executed without being stored in the hard disk 124.

  The computer hardware itself and its operating principle shown in FIGS. 1 and 2 are general. Therefore, an essential part for realizing the functions of the present invention is software stored in a recording medium such as the FD 116, the CD-ROM 118, and the hard disk 124.

  As a general tendency, various program modules are prepared as a part of a computer operating system, and an application program generally calls a module in a predetermined arrangement to advance processing. . In such a case, the software itself does not include such a module, and the electromagnetic field circuit linkage analysis is possible only when the computer cooperates with the operating system. However, as long as a general platform is used, it is not necessary to distribute software including such modules, and the software itself not including these modules and the recording medium storing the software (and the software distributes on the network). Data signal) can be considered to constitute the embodiment.

(2. Electromagnetic circuit linkage analysis method)
Hereinafter, an electromagnetic field circuit cooperation analysis method according to the present invention will be described.

(2.1 Cooperative analysis method between electromagnetic field analysis and circuit analysis)
First, the FDTD method, which is one of methods for performing electromagnetic field analysis, will be described, and then the current source method used for cooperative analysis will be described.

  The FDTD method is a numerical calculation method by differentiating Maxwell's electromagnetic field equation. First, an analysis region is divided by a lattice, and an electric field is arranged at the center of each side of the lattice, and a magnetic field is arranged at the center of each surface. Then, when Maxwell's equations are differentiated, the electric and magnetic fields are arranged at positions that are spatially shifted by half a cell and temporally by a half time step. Here, the following equations (1) and (2) can be obtained by deriving the unknown electric field to be obtained, the known electric field adjacent to the unknown magnetic field one time step before, and the relational expression that works between the known magnetic fields from the Maxwell equation based on electromagnetism. It becomes like this.

In the formula, bold indicates that the variable is a vector.
Equation (1) is an electric field E (vector) of n time steps, and equation (2) is a relational equation of magnetic field H (vector) of (n + 1/2) time steps. However, Δt, μ, ε, and σ are time step, magnetic permeability, dielectric constant, and conductivity, respectively.

  By updating the unknown electric field and unknown magnetic field in units of a certain time step Δt based on these, the electromagnetic field behavior of the entire analysis region can be obtained in the time domain.

  As described above, in the FDTD method, the time domain electromagnetic field response to be analyzed can be analyzed by sequentially calculating the unknown electric field and the unknown magnetic field in the analysis region by the explicit method.

  Next, the current source method, which is a method for directly combining the FDTD method and circuit analysis, which is used in the electromagnetic field circuit cooperation analysis of the present invention will be described.

  FIG. 3 is a schematic diagram of cooperative analysis by the current source method. FIG. 3A is a diagram showing an FDTD cell including a circuit element to be subjected to circuit analysis, and FIG. 3B shows an equivalent circuit of the current source method corresponding to the cell of FIG. FIG. 3C is a diagram showing a schematic processing flow of the current source method.

  The current source method will be described with reference to FIG. In FIG. 3A, the electric field is assigned along the side of the lattice cell indicated by the solid line, and the magnetic field is assigned perpendicularly to the center of the surface of the lattice cell indicated by the dotted line. Δx, Δy, Δz indicate the length of each side of the FDTD cell, and the solid grid cell and the dotted grid cell are shifted from each other by 1 / 2Δx, 1 / 2Δy, 1 / 2Δz. The arrows indicate the directions of the electric field and magnetic field. Here, it is assumed that a circuit element to be subjected to operation analysis by circuit analysis is arranged on a side ab where an electric field is present.

  With reference to FIG. 3C, the flow of processing in the current source method will be described. First, the magnetic field of the cell is calculated by the FDTD method (step S300).

  Then, by applying Ampere's law to the cell including the circuit element and expanding the z component, the following expression (3) is obtained.

However, J _L is the density of the conductive current flowing through the element.
Here, assuming that ε (ΔxΔy) / Δz in the first term on the left side of Equation (3) is equivalently the capacitance C ₀ of the parallel plate capacitor, and the right side is the total current I flowing through the cell, Equation (3) is (4) can be rewritten.

Where V _L is the voltage across the circuit element, and I _L is the total current flowing through the circuit element.
The total current I flowing in the cell can be obtained by circular integration of the magnetic field around the element along the surface 31 using Ampere's law. However, since the magnetic field is constant, I can be considered as a constant current source. . As shown in FIG. 3B, equation (4) can be considered as an equivalent circuit including a current source 32, a capacitor 33, and a network 34.

Returning to FIG. 3C again, the current I is calculated from the magnetic field H obtained by FDTD, and passed to the circuit analysis as the current source value I (step S302), thereby obtaining V _L and I _L by the circuit analysis. I can do it. Then, a V _L by a circuit analysis, passes the V _L to calculate the electric field of the cell sides of the circuit elements in the FDTD method (step S304), in step S306, the electric field E is calculated.

  As described above, the circuit analysis and the FDTD method are directly coupled. Thereby, the coupling with the electromagnetic field can be analyzed considering only the input / output terminals of the circuit.

  Here, although the current source method formulated based on Ampere's law is shown as the cooperative analysis method, the voltage source method, which is a method based on Faraday's law, may be used.

(2.2 Electromagnetic Circuit Cooperative Analysis Method of the Present Invention)
Below, the outline | summary of the cooperation analysis method of this invention is demonstrated.

FIG. 4 is a diagram illustrating an example of a two-dimensional electromagnetic model of a circuit board including an RC network.
With reference to FIG. 4, first, a model of a circuit board including a mutual inductor, which is an object of electromagnetic field circuit cooperation analysis of the present invention will be described.

  In order to perform electromagnetic field analysis by the FDTD method, a circuit board is divided into cells and an electromagnetic field model is created. FIG. 4 is a two-dimensional electromagnetic field model in which the circuit board 1 is divided into cells. In the electromagnetic field model, for example, a metal, a dielectric, or the like is set as a substance contained in each cell. Each cell in FIG. 4 includes a conductor 2, a dielectric 4, and a resistor 6a and a capacitor 6b as circuit elements. Further, the coil 52 (not shown) is included in the cell 12 between a and b, and the coil 54 (not shown) is included in the cell 14 between cd, and the terminal a and terminal c, and the terminal b and terminal. d is not directly connected. The substrate 1 also includes a ground 8 indicating a ground electrode and a power supply 10.

  FIG. 5 is a diagram illustrating an example of a cooperative analysis model of inductively coupled coils. FIG. 5A is a diagram showing a substrate model meshed by the FDTD method, FIG. 5B is a diagram showing an equivalent circuit in a circuit simulator for performing circuit analysis, and FIG. 5 (B) is a netlist.

  With reference to FIG. 5, an outline of a method for particularly analyzing the cooperation of the coils 52 and 54 of the circuit board of FIG. 4 will be described.

  The inductively coupled coils 52 and 54 whose operation is to be analyzed by circuit analysis are shown in FIG. 5A, respectively, the side ab where the electric field of the cell 12 is arranged and the side where the electric field of the cell 14 is arranged. It is assumed that it is arranged in cd.

  In the cooperative analysis by the current source method, what is given to the FDTD method from the circuit analysis is a potential difference between ab and cd, and based on this, the electric field of the cell side ab and the side cd is calculated by the FDTD method. To do. However, in order to obtain an electric field by the FDTD method, it is sufficient to give a potential difference between ab and cd. Therefore, in the circuit analysis, an equivalent circuit in which floating terminals are virtually connected is analyzed, and in the FDTD method, the above-described connection is released to perform electromagnetic field analysis.

  Specifically, the following method is taken. As shown in FIG. 5A, in the FDTD method model, the terminal b and the terminal d are not directly connected. However, in order to analyze the circuit, as shown in FIG. Create an equivalent circuit that is grounded. Further, the net list is changed as shown in FIG. Based on this equivalent circuit, circuit analysis is performed and the obtained voltage difference is given to the FDTD method. At this time, since the terminal b and the terminal d are connected in the circuit analysis, the potential difference between the terminals b and d is 0, but when reflected in the model of the FDTD method, the terminals b and d are opened, and the circuit Of the potential difference obtained by the analysis, only the potential difference between the terminals a and b and the potential difference between the terminals cd is set as a voltage on the substrate, and the potential difference between the terminals b and d and the terminals a and c is FDTD. The electromagnetic field analysis is performed using the values obtained in step 1 as they are.

  As described above, when analyzing the mutual inductance in the floating state in the electromagnetic field circuit linkage analysis, create and analyze an equivalent circuit in which the terminals that should be floating are connected and grounded, and specify from the analysis results By performing the process of transferring only the potential difference between the terminals to the FDTD method, it is possible to perform the electromagnetic field circuit linkage analysis of the circuit board including the mutual inductor.

  The flow of the cooperative processing between the electromagnetic field analysis and the circuit analysis by the current source method is as described in (2.1).

(3. Implementation on computer 100)
The cooperative analysis method according to the above invention can be implemented as computer software by the following procedure.

The procedure is summarized below.
FIG. 6 is a flowchart specifically showing the flow of the cooperative analysis process shown in FIG.

  With reference to FIG. 6, the flow of the cooperative analysis process will be described. Steps S7100 to S7120 are processes according to the program 135 that executes FDTD, and steps S7200 to S7212 are processes according to the program 136 that executes circuit analysis.

  3C corresponds to steps S7100 to S7102, step S302 corresponds to steps S7104 to 7106, step S304 corresponds to steps S7200 to S7212, and step S306 corresponds to steps S7108 to S7120.

The flow of FDTD processing will be described.
First, the CPU 120 reads analysis conditions from the circuit board data 134 stored in the hard disk 124 (step S7100). The analysis conditions include the size of the lattice cell, the time step of FDTD analysis, the time step of circuit analysis, the analysis time, the electric field in the analysis region, the initial value of the magnetic field, the current of the circuit element, the initial value of the voltage, and the analysis region. They are the dielectric, the coordinate value of the conductor, the net list of the circuit element, and the maximum analysis time Tmax.

  Further, the CPU 120 sets the analysis time t to zero, secures a storage area corresponding to the analysis area size and cell size of the analysis condition in the memory 122, and analyzes the coefficients of the analysis area cell based on the arranged conductor and dielectric information. Term calculation is performed (step S7101). The electric field and magnetic field values are set based on predetermined electric field and magnetic field initial values.

  Subsequently, the CPU 120 calculates and updates the total magnetic field H of the analysis region cell (step S7102). Based on the magnetic field updated in step S7102, the CPU 120 converts the magnetic field H in the vicinity of the cell including the circuit element (hereinafter referred to as a circuit cell) into a current value I using the following amperage formula (5) (step S1102). S7104).

  Here, the CPU 120 uses the current value I as a current source value to be added to the netlist for circuit analysis.

  The CPU 120 gives the current source value of step S7104 to the circuit analysis (step S7106). The process flow of the circuit analysis that has received the current source value will be described later.

  In step S7108, the CPU 120 advances the current analysis time t by half of the FDTD time step, and calculates and updates the total electric field E in the analysis region (step S7110).

  Next, the CPU 120 receives a voltage calculated by circuit analysis (step S7112). However, if the circuit analysis target is an inductively coupled coil, the voltage difference value is received. If it has not been calculated yet, the process is suspended until it is calculated.

  In step S7114, the CPU 120 converts the voltage value received from the circuit analysis into an electric field value of the circuit cell by the following equation (6).

  Δy is the length of the FDTD cell in the Y direction. Although the circuit elements are arranged in the Y direction here, they can be arranged in any direction.

  Then, the CPU 120 sets the voltage value obtained in step S7114 as the electric field value at the place where the circuit element in the electromagnetic field analysis region is inserted (step S7116).

  In step S7118, CPU 120 advances the current analysis time t by half of the time step of FDTD. Further, the electric field in the analysis area at the analysis time t is stored in the electric field value storage area 137 in the hard disk 124, and the magnetic field information is stored in the magnetic field value storage area 138 in the hard disk 124.

  In step S7120, CPU 120 compares current analysis time t with maximum analysis time Tmax. If analysis time t is smaller than maximum analysis time Tmax (No in step S120), the process returns to step S7102. Otherwise (Yes in step S7120), the storage area of the memory 122 used for analysis is released, and the calculation is terminated.

Next, the flow of circuit analysis processing will be described.
First, the CPU 120 secures a storage area in the memory 122 based on a predetermined netlist, and generates a circuit matrix in which a current source and a capacitor are added by a current source method based on element connection information (step S7200). ). At this time, if the element is a mutual inductance, a circuit matrix in which the corresponding two terminals are connected as described above is generated. The analysis time is set to zero.

  In step S7202, CPU 120 receives the current source value from the electromagnetic field analysis. The process is suspended until the current source value is received.

  Next, the CPU 120 updates the current source value to the current source value received in step S7202 (step S7204), and performs circuit analysis from the analysis time Δt (n−1 / 2) to Δt (n + 1/2). The voltage is obtained (step S7206).

  Furthermore, CPU 120 gives the voltage value at time Δt (n + 1/2) to the electromagnetic field analysis (step S7208). However, when the object of circuit analysis is mutual inductance, a voltage difference value is given. In addition, the CPU 120 stores the current and voltage values at time Δt (n + 1/2) in the hard disk 124.

  In step S7210, CPU 120 advances current analysis time t by a circuit analysis time step, and stores the voltage or voltage difference between analysis time t and circuit element terminals in hard disk 124.

  Then, CPU 120 compares current analysis time t with maximum analysis time Tmax (step S7212). If analysis time t is smaller than maximum analysis time Tmax (No in step S7212), the process returns to step S7202. If not (Yes in step S7212), the storage area of the memory 122 used for analysis is released and the calculation is terminated.

  As described above, in the present invention, the electromagnetic field circuit linkage analysis including the mutual inductance circuit is performed.

  In the above description, the analysis process has been described as being completed on the condition that the maximum analysis time has been exceeded. However, as an analysis process termination condition, other conditions such as an electric field and a magnetic field are in a steady state. It is also possible to use whether or not a condition that a predetermined time has elapsed since the time is satisfied.

  As described above, the electromagnetic field analysis and the circuit analysis are performed by the CPU 120 according to the program 135 for executing the FDTD and the program 136 for executing the circuit analysis, but are executed by a plurality of CPUs connected via the communication interface 128. The result may be exchanged through the computer 100. The electromagnetic field analysis and the circuit analysis may be analyzed using a single CPU, but the analysis area may be divided into a plurality of areas and analyzed using a plurality of CPUs.

(4. Example of analysis results)
Hereinafter, an example of the result of analyzing two coils inductively coupled using the method of the present invention will be shown.

FIG. 7 is a diagram showing port input waveforms at terminals a and c in FIG.
FIG. 8 is a diagram showing port output waveforms at terminals b and d in FIG.

  FIG. 7 and FIG. 8 show that differential input signals having a phase shift are input to the terminals a and c and are corrected at the terminals b and d. Here, the dotted line graph is a voltage value obtained by the electromagnetic field circuit cooperation analysis program of the present invention, and the solid line graph is a result of analyzing the SPICE alone with the same settings. As a result, in the cooperative analysis program of the present invention, it is understood that the analysis of the coil is accurately incorporated in the electromagnetic field analysis even if the analysis is performed based on the voltage difference between the input and output terminals in the case of the inductively coupled coil.

  As described above, according to the present invention, since the circuit between the terminals of the mutual inductor is in a floating state and can be handled by circuit analysis with little increase in resistance and current source, it is possible to reduce the calculation amount of electromagnetic field circuit linkage analysis. In addition, since the amount of work for changing the netlist of circuit analysis that has occurred can be reduced as compared with the case of adding a resistor, the processing time required for preparation for electromagnetic field circuit linkage analysis can be reduced.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a conceptual diagram which shows an example of the computer 100 which performs the cooperation analysis program of this invention. It is a figure which shows the structure of this computer 100 in a block diagram format. It is a schematic diagram of the cooperative analysis by the current source method. It is a figure which shows the example of the two-dimensional electromagnetic field model of a circuit board including RC network. It is a figure which shows the example of the cooperation analysis model of the inductively coupled coil. It is the flowchart which showed concretely the flow of the process of a cooperation analysis shown in FIG.3 (C). It is a figure which shows the port input waveform of the terminals a and c of FIG. It is a figure which shows the port output waveform of the terminals b and d of FIG. It is a figure which shows the example of a mutual inductor. FIG. 10 is a diagram showing a case where a high resistance 35 is inserted in the circuit of FIG. 9 in order to enable analysis of the mutual inductor of FIG. 9 in a general circuit analysis method. In the conventional electromagnetic field circuit linkage analysis method, a current source and a capacitor are added between terminals where the circuit elements of the circuit of FIG. 9 are arranged in order to couple the mutual inductor added with the high resistance of FIG. 10 with the FDTD method. It is a figure which shows a case. It is the table | surface which illustrated the net list.

Explanation of symbols

  1 circuit board, 2 conductors, 4 dielectric, 6a resistance, 8 ground, 10 power supply, 12, 14 cells, 31 magnetic field, 32a, 32b, 32c current source, 6b, 33a, 33b, 33c capacitor, 34 circuit network, 35 High resistance, 52, 54 coil, 100 computer, 102 computer body, 104 display, 106 FD drive, 108 optical disk drive, 110 keyboard, 112 mouse, 116 FD, 118 CD-ROM, 120 CPU, 122 memory, 124 hard disk, 128 Communication interface, 134 circuit board data, 135 program for executing FDTD, 136 program for executing circuit analysis, 137 electric field value storage area, 138 magnetic field value storage area.

Claims (7)

A program for causing a computer having an arithmetic processing unit to execute electromagnetic field circuit linkage analysis,
The arithmetic processing unit performs a first electromagnetic field analysis on an electric field or a magnetic field of the region in a cell-divided region to be analyzed;
The arithmetic processing unit, based on one of the electric field or the magnetic field given by the step of performing the first electromagnetic field analysis on an equivalent circuit represented by a net list of circuit elements included in the cell, Setting one of the current sources and performing circuit analysis,
The step of performing the circuit analysis includes: when the arithmetic processing unit analyzes the operation of the inductively coupled mutual inductor included in the analysis target, the arithmetic processing unit is connected to the corresponding two terminals of the mutual inductor. Including an inductor circuit analysis step to analyze as
The arithmetic processing unit calculates the other of the electric field or magnetic field of the cell including the circuit element based on the result of the circuit analysis, and performs a second electromagnetic field analysis on the electric field or magnetic field of the region;
The arithmetic processing unit further includes the step of performing the first electromagnetic field analysis, the step of performing the circuit analysis, and the step of performing the second electromagnetic field analysis until a predetermined condition is satisfied. Prepared,
In the step of performing the first and second electromagnetic field analysis, the arithmetic processing unit is connected when the arithmetic processing unit analyzes the operation of the inductively coupled mutual inductor included in the analysis target. An electromagnetic field circuit linkage analysis program for causing a computer to execute analysis processing, including an inductor region analysis step for analyzing by opening between two terminals. The step of performing the circuit analysis includes:
The electromagnetic field according to claim 1, wherein when the cell includes the mutual inductor, the arithmetic processing unit includes a step of changing the netlist so as to virtually connect two terminals corresponding to the mutual inductor. Circuit linkage analysis program. The inductor circuit analyzing step includes a step in which the arithmetic processing unit analyzes a voltage between terminals of the mutual inductor based on the virtually changed netlist.
In the inductor region analyzing step, the voltage of the cell is changed to an electric field based on the analysis result in the step of analyzing the voltage, assuming that the arithmetic processing unit is open between the two terminals that are connected. The electromagnetic field circuit cooperation analysis program according to claim 2, further comprising a step of converting into an electromagnetic field circuit. The computer further includes a storage unit,
The region to be analyzed includes a circuit board,
An equivalent circuit of circuit elements disposed on the circuit board includes a CR element, a coil element without inductive coupling, and an inductively coupled coil element,
When the time step Δt is predetermined,
The step of performing the first electromagnetic field analysis includes:
The arithmetic processing unit divides the region to be analyzed into cells and arranges the electric field and the magnetic field spatially shifted by a half cell; and
The arithmetic processing unit obtaining a magnetic field of the region at time t;
The arithmetic processing unit includes a step of obtaining a current of the cell including the circuit element based on the obtained magnetic field;
The step of performing the circuit analysis includes:
When the circuit element included in the cell is the inductively coupled coil element, the arithmetic processing unit displays the netlist so as to virtually connect two corresponding terminals of the inductively coupled coil element. Steps to change,
The arithmetic processing unit sets a current source for the netlist or the changed netlist based on the current obtained in the step of obtaining the current, and the time t + 1 / between the two terminals of the circuit element. Obtaining a voltage at 2Δt;
The arithmetic processing unit updates the time t to t + 1 / 2Δt,
The step of performing the second electromagnetic field analysis includes:
The arithmetic processing unit calculates an electric field of a cell including the circuit element based on the step of performing the circuit analysis, and obtains an electric field of the region at the time t + 1 / 2Δt;
The arithmetic processing unit storing the obtained electric field and the obtained magnetic field in the storage unit;
The electromagnetic circuit integration analysis program according to claim 1, wherein the arithmetic processing unit includes a step of updating the time t to t + 1 / 2Δt in electromagnetic field analysis.   A computer-readable recording medium storing the electromagnetic circuit cooperation analysis program according to claim 1. An electromagnetic field circuit linkage analysis device,
Equipped with an electromagnetic field analysis unit that performs electromagnetic field analysis,
The electromagnetic field analysis unit
Means for performing a first electromagnetic field analysis on the electric field or magnetic field of the region in the cell-divided region to be analyzed;
One of the voltage source and the current source is set based on one of the electric field or magnetic field given by the means for performing the first electromagnetic field analysis on the equivalent circuit represented by the net list of the circuit elements included in the cell. And a circuit analysis unit for performing circuit analysis,
The circuit analysis unit
When analyzing the operation of the inductively coupled mutual inductor included in the analysis target, including an inductor circuit analyzing means for analyzing that the corresponding two terminals of the mutual inductor are connected,
An analysis control unit that controls the electromagnetic field analysis unit and the circuit analysis unit;
The electromagnetic field analysis unit
Means for calculating the other of the electric field or magnetic field of the cell in which the equivalent circuit exists based on the result of the circuit analysis unit, and performing a second electromagnetic field analysis on the electric field or magnetic field of the region;
When analyzing the operation of the inductively coupled mutual inductor included in the analysis target, the inductor that opens the two terminals assumed to be connected and performs the first and second electromagnetic field analysis It further includes area analysis means,
The analysis control unit
The electromagnetic field analysis so that each analysis by the means for performing the first electromagnetic field analysis, the means for performing the circuit analysis, and the means for performing the second electromagnetic field analysis is repeated until a predetermined condition is satisfied. And an electromagnetic field circuit cooperation analyzing apparatus including means for controlling the circuit analyzing unit and the circuit analyzing unit. Performing a first electromagnetic field analysis on the electric field or magnetic field of the region in the cell-divided region to be analyzed;
One of a voltage source and a current source is set based on one of an electric field or a magnetic field given by the step of performing the electromagnetic field analysis on an equivalent circuit represented by a net list of circuit elements included in the cell, An analysis step,
The circuit analysis step includes an inductor circuit analysis step of analyzing that the corresponding two terminals of the mutual inductor are connected when analyzing the operation of the inductively coupled mutual inductor included in the analysis target. Including
Calculating the other of the electric field or magnetic field of the cell in which the equivalent circuit exists based on the result of the circuit analysis, and performing a second electromagnetic field analysis on the electric field or magnetic field of the region;
Further comprising the step of performing the first electromagnetic field analysis, the step of performing the circuit analysis, and the step of performing the second electromagnetic field analysis until a predetermined condition is satisfied,
In the step of performing the first and second electromagnetic field analysis, when analyzing the operation of the inductively coupled mutual inductor included in the analysis target, the two terminals that are connected are opened. An electromagnetic field circuit linkage analysis method including an inductor region analysis step for analysis.

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