Equivalent circuit

Abstract

To provide an equivalent circuit capable of obtaining characteristics approximate to the characteristics of a laminated capacitor of an actual product.SOLUTION: An equivalent circuit 1 includes: a first electrostatic capacitance portion 5 having a first electrostatic capacitance; a circuit portion 11 having an inductor component, an electrostatic capacitance component, and a resistor, the inductor component, the electrostatic capacitance component, and the resistor being connected in series, the circuit portion being connected in parallel with the first electrostatic capacitance portion 5; and a second electrostatic capacitance portion 7 provided between the first electrostatic capacitance portion 5 and the circuit portion 11, and having a second electrostatic capacitance, in which the first capacitance portion 5 has a first capacitance that changes in accordance with the voltage value of a DC voltage applied to the first capacitance portion 5, and the second capacitance unit has a second capacitance that changes in accordance with the voltage value of the DC voltage applied to the first capacitance portion 5 and has a positive second capacitance that is N times (N>0) the first capacitance of the first capacitance portion 5.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an equivalent circuit for simulating a multilayer capacitor. [Background technology]

[0002] Patent Document 1 discloses a circuit simulation model of a capacitor to which a DC bias is applied, the circuit simulation model comprising: a non-linear voltage-controlled voltage source in which the change characteristics due to the DC bias of circuit elements included in a predetermined basic equivalent circuit of the capacitor are obtained by actual measurement, and the obtained change characteristics are defined by a polynomial and replaced with the corresponding circuit elements; a filter that extracts a DC bias component from the voltage applied to the capacitor and supplies it to the non-linear voltage-controlled voltage source; a calculation circuit that uses each output voltage of the non-linear voltage-controlled voltage source to calculate a circuit equation related to voltage and current established based on the basic equivalent circuit; and a linear voltage-controlled voltage source that couples the voltage applied to the capacitor to the calculation circuit. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2012-150579 A Summary of the Invention [Problem to be solved by the invention]

[0004] In an actual multilayer capacitor (hereinafter simply referred to as a "multilayer capacitor"), when the voltage value of the applied direct current voltage (DC bias) changes, the impedance value (other than the peak) changes in a graph showing the relationship between frequency and impedance. Specifically, in a multilayer capacitor, when the voltage value of the direct current voltage increases, the absolute value of the impedance increases.

[0005] Furthermore, in a multilayer capacitor, when a DC voltage is applied, a peak appears in the impedance in a graph showing the relationship between frequency and impedance. The peaks include a peak due to resonance (a downward peak) and a peak due to anti-resonance (an upward peak). In a multilayer capacitor, when a DC voltage is applied, multiple peaks appear. In a multilayer capacitor, when the voltage value of the DC voltage changes, the frequency at which a peak appears in the impedance (resonant frequency, anti-resonant frequency) changes. Specifically, in a multilayer capacitor, when the voltage value of the DC voltage increases, the frequency at which a peak appears in the impedance is offset to the high frequency side. In a conventional equivalent circuit, it was not possible to obtain the characteristic that the frequency at which a peak appears in the impedance changes when the voltage value of the DC voltage changes.

[0006] An object of one embodiment of the present invention is to provide an equivalent circuit that can provide characteristics that are similar to those of an actual multilayer capacitor product. [Means for solving the problem]

[0007] (1) An equivalent circuit according to one embodiment of the present invention includes a first capacitance section having a first capacitance, a circuit section having an inductor component, a capacitance component, and a resistance component, the inductor component, the capacitance component, and the resistance component being connected in series and connected in parallel to the first capacitance section, and a second capacitance section provided between the first capacitance section and the circuit section and having a second capacitance, wherein the first capacitance section changes its first capacitance in response to a voltage value of a DC voltage applied to the first capacitance section, and the second capacitance section changes its second capacitance in response to a voltage value of a DC voltage applied to the first capacitance section and has a positive second capacitance that is N times (N>0) the first capacitance of the first capacitance section.

[0008] In an equivalent circuit according to an embodiment of the present invention, the first capacitance of the first capacitance section changes according to the voltage value of the DC voltage applied to the first capacitance section. As a result, the equivalent circuit can obtain a characteristic in which the impedance value (other than the peak) changes according to the change in the voltage value of the applied DC voltage. In addition, in the equivalent circuit, the circuit section is configured by connecting an inductor component, a capacitance component, and a resistance component in series. As a result, the equivalent circuit can obtain a characteristic in which a peak (resonance, anti-resonance) appears in the impedance. In addition, the equivalent circuit includes a second capacitance section. The second capacitance section has a second capacitance that changes according to the voltage value of the DC voltage applied to the first capacitance section, and has a positive second capacitance that is N (N>0) times the first capacitance of the first capacitance section. As a result, the equivalent circuit can obtain a characteristic in which the frequency (resonance frequency, anti-resonance frequency) at which a peak appears in the impedance changes when the voltage value of the DC voltage changes. Therefore, the equivalent circuit can obtain a characteristic that is close to the characteristic of a stacked capacitor of an actual product.

[0009] (2) The equivalent circuit of (1) above may further include a control unit provided between the second capacitance unit and the circuit unit, for controlling the current flowing through the circuit unit based on the voltage value of the DC voltage. In this configuration, when the voltage value of the DC voltage is small, the current flowing through the circuit unit becomes small (no current flows through the circuit unit), and when the voltage value of the DC voltage is large, the current flowing through the circuit unit becomes large. When the current flowing through the circuit unit becomes small, no peak appears in the impedance. This makes it possible to obtain a characteristic in which no peak appears in the impedance when the DC voltage is 0V.

[0010] (3) In the equivalent circuit of (2) above, the control unit may be a transformer. In this configuration, the current flowing through the circuit unit can be controlled based on the voltage value of the DC voltage.

[0011] (4) In any one of the equivalent circuits (1) to (3) above, the second capacitance of the second capacitance section may be 0.5 to 1.0 times the first capacitance of the first capacitance section. With this configuration, it is possible to obtain a characteristic that, when the voltage value of the DC voltage changes, the frequency at which a peak appears in the impedance (resonant frequency, anti-resonant frequency) changes. Effect of the Invention

[0012] According to one aspect of the present invention, it is possible to obtain characteristics that are similar to those of an actual multilayer capacitor product. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a diagram showing an equivalent circuit according to the first embodiment. [Diagram 2] FIG. 2 is a graph showing an example of the relationship between frequency and impedance of a multilayer capacitor. [Diagram 3] FIG. 3 is a diagram showing an equivalent circuit according to the second embodiment. [Figure 4] FIG. 4 is a diagram showing an equivalent circuit according to the third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same or corresponding elements are designated by the same reference numerals, and duplicated explanations will be omitted.

[0015] [First embodiment] Fig. 1 is a diagram showing an equivalent circuit according to the first embodiment. The equivalent circuit 1 shown in Fig. 1 is a circuit used, for example, in simulation of circuit design and analysis using electronic components, and is applied to a circuit design (analysis) program executed in a computer.

[0016] As shown in FIG. 1, the equivalent circuit 1 includes a first terminal 3a, a second terminal 3b, a third terminal 3c, and a fourth terminal 3d, a first capacitance section 5, a second capacitance section 7, a transformer section (control section) 9, and a circuit section 11.

[0017] The first terminal 3a, the second terminal 3b, the third terminal 3c, and the fourth terminal 3d may be connected to other circuits, etc. The first terminal 3a and the second terminal 3b may be input terminals. The third terminal 3c and the fourth terminal 3d may be output terminals.

[0018] The first capacitance unit 5 is connected between the first terminal 3a and the second terminal 3b. The first capacitance unit 5 has a first capacitance C1. The first capacitance C1 is a so-called damping capacitance. The first capacitance C1 changes according to the voltage value of the DC voltage applied to the first capacitance unit 5.

[0019] The second capacitance section 7 is provided between the first capacitance section 5 and the transformer section 9. The second capacitance section 7 has a second capacitance C2. The second capacitance C2 is a positive capacitance. The second capacitance C2 changes according to the voltage value of the DC voltage applied to the first capacitance section 5. The second capacitance C2 is N times the capacitance of the first capacitance C1 (C2=N×C1). N is greater than 0 (N>0). The second capacitance C2 is 0.5 times to 1.0 times the first capacitance C1 (0.5C≦N≦1.0). Preferably, the second capacitance C2 is 0.7 times to 0.9 times the first capacitance C1 (0.7≦N≦0.9).

[0020] The transformer unit 9 is provided between the second capacitance unit 7 and the circuit unit 11. The transformer unit 9 controls the current flowing through the circuit unit 11. The transformer unit 9 controls the current flowing through the circuit unit 11 according to the voltage value of the DC voltage applied to the equivalent circuit 1. Specifically, the transformer unit 9 increases the current flowing through the circuit unit 11 when the voltage value of the DC voltage increases, and decreases the current flowing through the circuit unit 11 when the voltage value of the DC voltage decreases.

[0021] In this embodiment, the circuit unit 11 has a first circuit 13 and a second circuit 15. The number of circuits in the circuit unit 11 is set according to the number of peaks that appear in the impedance graph. For example, when two peaks appear in the impedance graph, two circuits are provided.

[0022] The first circuit 13 is connected in parallel to the first capacitance section 5. The first circuit 13 is connected in parallel to the first capacitance section 5 via the transformer section 9. The first circuit 13 has an inductor (inductor component) 13A, a capacitor (capacitance component) 13B, and a resistor (resistance component) 13C. The inductor 13A, the capacitor 13B, and the resistor 13C are connected in series to form an RCL series circuit. The inductor 13A is an equivalent inductance and represents a parasitic inductance due to the internal electrodes, the connecting conductors, etc. The capacitor 13B is an equivalent capacitance. The resistor 13C is a resonant resistance and represents a conductor loss due to the internal electrodes, the connecting conductors, etc.

[0023] The second circuit 15 is connected in parallel to the first capacitance section 5. The second circuit 15 is connected in parallel to the first capacitance section 5 via the transformer section 9. The second circuit 15 is connected in parallel to the first circuit 13. The second circuit 15 has an inductor (inductor component) 15A, a capacitor (capacitance component) 15B, and a resistor (resistance component) 15C. The inductor 15A, the capacitor 15B, and the resistor 15C are connected in series to form an RCL series circuit. The inductor 15A is an equivalent inductance and represents a parasitic inductance due to the internal electrodes, the connecting conductors, and the like. The capacitor 15B is an equivalent capacitance. The resistor 15C is a resonant resistance and represents a conductor loss due to the internal electrodes, the connecting conductors, and the like.

[0024] Fig. 2 is a graph showing an example of the relationship between frequency and impedance of a multilayer capacitor. In Fig. 2, the horizontal axis indicates frequency f [Hz], and the vertical axis indicates impedance Z [Ω]. Impedance Z is an absolute value. In Fig. 2, the measurement result when the DC voltage value is "0V" is shown by a solid line, the measurement result when the DC voltage value is "20V" is shown by a dashed line, and the measurement result when the DC voltage value is "40V" is shown by a dashed line.

[0025] As shown in Figure 2, when the DC voltage value is "0V", no peak appears. When the DC voltage value is "20V" and "40V", downward and upward peaks appear. The downward peaks indicate resonance. The upward peaks indicate anti-resonance. When the DC voltage value is "20V" and "40V", multiple peaks appear. The higher the DC voltage value, the larger the peaks become, and they appear on the high frequency side. The absolute value of the impedance (other than the peaks) becomes larger as the DC voltage value increases.

[0026] The peak occurs when a DC voltage is applied to a multilayer capacitor, causing it to undergo electrostrictive deformation. The reason that no peak appears when the DC voltage value is "0V" is because there is almost no mechanical deformation when voltage is applied when the voltage value is near 0V. The reason that the absolute value of the impedance (other than the peak) increases as the DC voltage value increases is that when the DC voltage value increases, the electrostatic capacitance of the multilayer capacitor decreases due to the DC bias characteristics, causing the impedance to decrease.

[0027] In the equivalent circuit 1, the phenomenon in which an upward peak appears after a downward peak appears when viewed from the low frequency side is represented by the circuit portion 11. The phenomenon in which multiple peaks (for example, two) appear is represented by connecting two circuits, the first circuit 13 and the second circuit 15, in parallel. The phenomenon in which impedance changes depending on the voltage value of the DC voltage is represented by the first capacitance portion 5 in which the first capacitance C1 changes depending on the voltage value of the DC voltage.

[0028] In equivalent circuit 1, the phenomenon where no peak appears when the voltage value of the DC voltage is "0V" but multiple peaks appear when a DC voltage is applied is represented by transformer unit 9. When the voltage value of the DC voltage is small, transformer unit 9 does not pass current to circuit unit 11, but when the voltage value of the DC voltage is large, current passes through circuit unit 11. As a result, in equivalent circuit 1, no peak appears when the voltage value of the DC voltage is "0V", but multiple peaks appear when a DC voltage is applied.

[0029] In the equivalent circuit 1, the phenomenon in which the position (frequency) of the peak changes when the voltage value of the DC voltage changes is represented by the second capacitance section 7 having a positive second capacitance C2.

[0030] As described above, in the equivalent circuit 1 according to this embodiment, the first capacitance C1 of the first capacitance section 5 changes according to the voltage value of the DC voltage applied to the first capacitance section 5. As a result, the equivalent circuit 1 can obtain a characteristic in which the impedance value (other than the peak) changes according to the change in the voltage value of the applied DC voltage. In addition, in the equivalent circuit 1, the first circuit 13 of the circuit section 11 is configured by connecting an inductor 13A, a capacitor 13B, and a resistor 13C in series, and the second circuit 15 of the circuit section 11 is configured by connecting an inductor 15A, a capacitor 15B, and a resistor 15C in series. As a result, the equivalent circuit 1 can obtain a characteristic in which a peak (resonance, anti-resonance) appears in the impedance.

[0031] The equivalent circuit 1 also includes a second capacitance section 7. The second capacitance section 7 has a second capacitance C2 that changes according to the voltage value of the DC voltage applied to the first capacitance section 5, and has a positive second capacitance C2 that is N (N>0) times the first capacitance C1 of the first capacitance section 5. This allows the equivalent circuit 1 to obtain a characteristic in which, when the voltage value of the DC voltage changes, the frequency at which a peak appears in the impedance (resonant frequency, anti-resonant frequency) changes. Therefore, the equivalent circuit 1 can obtain a characteristic that is close to the characteristic of a stacked capacitor that is an actual product.

[0032] The equivalent circuit 1 according to this embodiment includes a transformer section 9. The transformer section 9 is provided between the second capacitance section 7 and the circuit section 11, and controls the current flowing through the circuit section 11 based on the voltage value of the DC voltage. In this configuration, when the voltage value of the DC voltage is small, the current flowing through the circuit section 11 becomes small (no current flows through the circuit section 11), and when the voltage value of the DC voltage is large, the current flowing through the circuit section 11 becomes large. When the current flowing through the circuit section 11 becomes small, no peak appears in the impedance. This makes it possible to obtain a characteristic in which no peak appears in the impedance when the DC voltage is 0V.

[0033] In the equivalent circuit 1 according to this embodiment, the second capacitance C2 of the second capacitance section 7 is 0.5 to 1.0 times the first capacitance C1 of the first capacitance section 5, and preferably 0.7 to 0.9 times the first capacitance C1. With this configuration, it is possible to obtain a characteristic that when the voltage value of the DC voltage changes, the frequency at which a peak appears in the impedance (resonant frequency, anti-resonant frequency) changes.

[0034] [Second embodiment] Next, an equivalent circuit according to the second embodiment will be described. Fig. 3 is a diagram showing an equivalent circuit according to the second embodiment. As shown in Fig. 3, an equivalent circuit 1A according to the second embodiment includes a first terminal 3a, a second terminal 3b, a third terminal 3c, and a fourth terminal 3d, a first capacitance section 5, a second capacitance section 7, a switch section (control section) 17, and a circuit section 11. The equivalent circuit 1A differs from the equivalent circuit 1 of the first embodiment in the configuration of the switch section 17.

[0035] The switch unit 17 is provided between the second capacitance unit 7 and the circuit unit 11. The switch unit 17 controls the current flowing through the circuit unit 11. The switch unit 17 controls the current flowing through the circuit unit 11 according to the voltage value of the DC voltage applied to the equivalent circuit 1A. Specifically, the switch unit 17 increases the current flowing through the circuit unit 11 when the voltage value of the DC voltage increases, and decreases the current flowing through the circuit unit 11 when the voltage value of the DC voltage decreases.

[0036] The switch unit 17 detects a voltage value between one end (first terminal 3a) and the other end (second terminal 3b) of the first capacitance unit 5, and turns the switch on and off based on the detected voltage value. The switch unit 17 turns the switch on when the detected voltage value is equal to or greater than a predetermined value, and turns the switch off when the detected voltage value is less than the predetermined value.

[0037] As described above, in the equivalent circuit 1A according to this embodiment, the first capacitance C1 of the first capacitance section 5 changes according to the voltage value of the DC voltage applied to the first capacitance section 5. As a result, in the equivalent circuit 1A, a characteristic can be obtained in which the impedance value (other than the peak) changes according to the change in the voltage value of the applied DC voltage. In addition, in the equivalent circuit 1A, the first circuit 13 of the circuit section 11 is configured by connecting an inductor 13A, a capacitor 13B, and a resistor 13C in series, and the second circuit 15 of the circuit section 11 is configured by connecting an inductor 15A, a capacitor 15B, and a resistor 15C in series. As a result, in the equivalent circuit 1A, a characteristic can be obtained in which a peak (resonance, anti-resonance) appears in the impedance.

[0038] The equivalent circuit 1A also includes a second capacitance section 7. The second capacitance section 7 has a second capacitance C2 that changes in response to the voltage value of the DC voltage applied to the first capacitance section 5, and has a positive second capacitance C2 that is N (N>0) times the first capacitance C1 of the first capacitance section 5. This allows the equivalent circuit 1A to obtain a characteristic in which, when the voltage value of the DC voltage changes, the frequency at which a peak appears in the impedance (resonance frequency, anti-resonance frequency) changes. Therefore, the equivalent circuit 1A can obtain a characteristic that is close to the characteristic of a stacked capacitor that is an actual product.

[0039] The equivalent circuit 1A according to this embodiment includes a switch section 17. The switch section 17 is provided between the second capacitance section 7 and the circuit section 11, and controls the current flowing through the circuit section 11 based on the voltage value of the DC voltage. In this configuration, when the voltage value of the DC voltage is small, the current flowing through the circuit section 11 becomes small (no current flows through the circuit section 11), and when the voltage value of the DC voltage is large, the current flowing through the circuit section 11 becomes large. When the current flowing through the circuit section 11 becomes small, no peak appears in the impedance. This makes it possible to obtain a characteristic in which no peak appears in the impedance when the DC voltage is 0V.

[0040] [Third embodiment] Next, an equivalent circuit according to the third embodiment will be described. Fig. 4 is a diagram showing an equivalent circuit according to the third embodiment. As shown in Fig. 4, an equivalent circuit 1B according to the third embodiment includes a first terminal 3a, a second terminal 3b, a third terminal 3c, and a fourth terminal 3d, a first capacitance section 5, a second capacitance section 7, and a circuit section 11. The equivalent circuit 1B differs in configuration from the equivalent circuit 1 of the first embodiment and the equivalent circuit 1A of the second embodiment in that it does not include a control section.

[0041] In the equivalent circuit 1B according to this embodiment, the first capacitance C1 of the first capacitance section 5 changes according to the voltage value of the DC voltage applied to the first capacitance section 5. As a result, in the equivalent circuit 1B, a characteristic can be obtained in which the impedance value (other than the peak) changes according to the change in the voltage value of the applied DC voltage. In addition, in the equivalent circuit 1B, the first circuit 13 of the circuit section 11 is configured by connecting an inductor 13A, a capacitor 13B, and a resistor 13C in series, and the second circuit 15 of the circuit section 11 is configured by connecting an inductor 15A, a capacitor 15B, and a resistor 15C in series. As a result, in the equivalent circuit 1B, a characteristic can be obtained in which a peak (resonance, anti-resonance) appears in the impedance.

[0042] Furthermore, the equivalent circuit 1B includes a second capacitance section 7. The second capacitance section 7 has a second capacitance C2 that changes according to the voltage value of the DC voltage applied to the first capacitance section 5, and has a positive second capacitance C2 that is N (N>0) times the first capacitance C1 of the first capacitance section 5. As a result, the equivalent circuit 1B can obtain a characteristic in which, when the voltage value of the DC voltage changes, the frequency at which a peak appears in the impedance (resonance frequency, anti-resonance frequency) changes. Therefore, the equivalent circuit 1B can obtain a characteristic that is close to the characteristic of a stacked capacitor that is an actual product.

[0043] Although the embodiment of the present invention has been described above, the present invention is not necessarily limited to the above-described embodiment, and various modifications are possible without departing from the gist of the present invention.

[0044] In the above embodiment, an example has been described in which there is one second capacitance section 7. However, the second capacitance section 7 may be composed of a plurality of elements.

[0045] In the above embodiment, an example has been described in which the circuit unit 11 includes the first circuit 13 and the second circuit 15. However, the number of circuits in the circuit unit 11 may be appropriately set depending on the number of peaks that appear in the impedance graph.

[0046] In the above embodiment, the control unit that controls the current flowing through the circuit unit 11 based on the voltage value of the DC voltage is the transformer unit 9 or the switch unit 17. However, the control unit may be another element. [Explanation of symbols]

[0047] 1, 1A, 1B... equivalent circuit, 5... first capacitance section, 7... second capacitance section, 9... transformer section (control section), 11... circuit section, 13A, 15A... inductor (inductor component), 13B, 15B... capacitor (capacitance component), 13C, 15C... resistor (resistance component), 17... switch section (control section), C1... first capacitance, C2... second capacitance.

Claims

1. a first capacitance portion having a first capacitance; a circuit section having an inductor component, a capacitance component, and a resistance, the inductor component, the capacitance component, and the resistance being connected in series and connected in parallel to the first capacitance section; a second capacitance unit provided between the first capacitance unit and the circuit unit and having a second capacitance, the first capacitance section changes in first capacitance in response to a voltage value of a DC voltage applied to the first capacitance section, An equivalent circuit in which the second capacitance section changes in response to the voltage value of the DC voltage applied to the first capacitance section, and the second capacitance section has a positive second capacitance that is N times (N>0) the first capacitance of the first capacitance section.

2. 2 . The equivalent circuit according to claim 1 , further comprising a control unit provided between the second capacitance unit and the circuit unit, the control unit controlling a current flowing through the circuit unit based on a voltage value of the DC voltage.

3. The equivalent circuit according to claim 2 , wherein the control unit is a transformer.

4. 3 . The equivalent circuit according to claim 1 , wherein the second capacitance of the second capacitance section is 0.5 to 1.0 times the first capacitance of the first capacitance section.

Images