JP4227756B2 - Smoothing capacitor characteristic measurement device - Google Patents

Description

【００１６】
Ｌｓについて：
【数２】

【００１７】
Ｃについて：
【数３】

この計算は、ｉ（ｔ）下降時のＶ（ｔ）から各成分を算出する方法であるが、もちろん時刻ｔｎを中心としてｉ（ｔ）上昇時のＶ（ｔ）から各成分を算出することも同様に可能である。
【００１８】
図５は、既知の鋸歯状波電流ｉ（ｔ）を被測定コンデンサに流し、Ｖ（ｔ）を測定する装置の構成を示す。これは、オシロスコープなどの波形観測機器２４によりＶ（ｔｍ−τ）とＶ（ｔｍ＋τ）を読み取る場合を示している。図５の電流電圧変換器２３は、カレントトランス、カレントプローブ、電流検出抵抗器と差動増幅器で構成したものなどを用いる。
【００１９】
この装置においては、鋸歯状波電流源２１より上記鋸歯状波電流を被測定コンデンサ１３に供給する。そして、その両端に生じる電圧Ｖ（ｔ）を電圧検出器２２にて検出し、波形表示装置２４に入力する。また、鋸歯状波電流ｉ（ｔ）を上記電流電圧変換器２３にて検出し、電流ｉ（ｔ）に比例した電圧として波形表示装置２４に入力する。従って、波形表示装置２４では、被測定コンデンサ１３に流れる電流ｉ（ｔ）と、その両端に生じる電圧Ｖ（ｔ）とを、対比して表示することができる。
【００２０】
図６は、サンプリング回路を付加して、自動測定する場合の構成である。即ち、波形表示装置２４に代えて、サンプルホールド回路２５ａ，２５ｂおよびＡ／Ｄコンバータ２６ａ，２６ｂおよびデジタル演算表示回路２７を用いたものである。電流電圧変換器２３で検出された鋸歯状波電流ｉ（ｔ）は、サンプルホールド回路２５ａによりサンプルホールドされたアナログ値がＡ／Ｄコンバータ２６ａによりデジタル値に変換され、デジタル演算表示回路２７に入力される。また、電圧変換器２２で検出された被測定コンデンサ１３の両端電圧Ｖ（ｔ）は、同様にサンプルホールド回路２５ｂによりサンプルホールドされたアナログ値がＡ／Ｄコンバータ２６ｂによりデジタル値に変換され、デジタル演算表示回路２７に入力される。これにより、図４および上記計算式に示す、各測定値が演算表示回路２７により自動的に演算して表示される。ここで、発振回路およびタイミング調整回路２８は、鋸歯状波電流源２１および演算表示回路２７をタイミング制御する。
【００２１】
図７は、このサンプリング及び演算、表示のタイミング例を示す。図示するように、電流ｉ（ｔ）および電圧Ｖ（ｔ）は、時刻ｔａ、ｔｍ、ｔｂの近傍でサンプリングされ、図４に示すのと等価なデータがデジタル演算により得られる。
【００２２】
次に、被測定コンデンサを実装して測定に供する基板上の導体パターンについて述べる。
図８は基本的な接続パターンの構成例を示す。比較的大電流で微小な直列等価抵抗Ｒｓなどを測定するため、電流パターン３１ａ，３１ｂと、電圧検出パターン３２ａ，３２ｂを分離した４端子測定を行う必要がある。図８のＲとＣは被測定コンデンサ１３の交流成分のみを取り出すフィルタであり、差動増幅器２２を図８のように接続することにより、Ｖ（ｔ）の交流成分のみを増幅する。これは、測定のダイナミックレンジを上げるための構成である。
等価直列インダクタンスＬｓを正確に測定するためには、電圧検出パターン３２ａ，３２ｂの間隔ｄは、被測定コンデンサ１３の電極幅にとるのが望ましいが、後述のように等価直列インダクタンスＬｓが大きいと等価直列抵抗Ｒｓの測定精度が上がらないため、等価直列抵抗Ｒｓ測定時には後述の別パターンを使用することが望ましい。
【００２３】
図９は、等価直列インダクタンスＬｓの影響によるコンデンサ両端電圧波形例を示す。等価直列インダクタンスによる電圧は電流変化点での段差ΔＶＬとなって現れる。
等価直列インダクタンスＬｓが大きく、等価直列抵抗Ｒｓが比較的に小さいと、図９の上段に示すように、Ｖ（ｔｍ＋τ）−Ｖ（ｔｍ−τ）の値がＶｐ-ｐに比較して小さくなってしまう。これに対して、等価直列インダクタンスＬｓが小さく、等価直列抵抗Ｒｓが相対的に大きくなると、図９の下段に示すように、Ｖ（ｔｍ＋τ）−Ｖ（ｔｍ−τ）の値がＶｐ-ｐに比較して大きくなる。従って、Ｖ（ｔ）を増幅する増幅器のダイナミックレンジを考慮すると、なるべく等価直列インダクタンスＬｓ成分の影響を小さくしたほうが図９の下段に示すように等価直列抵抗Ｒｓの測定精度が向上する。
【００２４】
次に、等価直列インダクタンスＬｓの影響を低減するための電圧検出パターンの構成例について述べる。
図１０は、電圧を検出する導体パターン３３ａ，３３ｂを回路基板の表裏面に、交差するように配置してある。電圧検出パターン３３ａ，３３ｂを交差させることにより、コンデンサを流れる電流変化ｄｉ（ｔ）／ｄｔが等価直列インダクタンスＬｓによって発生させるＶＬ（ｔ）を、ｉ（ｔ）に磁気的に結合した電圧検出パターンに誘起する電圧で相殺することができる。
【００２５】
次に、図１１は交差する電圧検出パターン３４ａ，３４ｂを平面状ではなく立体的に構成したものである。図示するように、電圧検出導体３４ａ，３４ｂが三次元的に配置され、コンデンサ電極に接続された二本の導体が互いに磁気的に結合するように配置されている。図１０の平面パターンより結合を上げられるので相殺の効率が高い。ただし、渦電流が発生しないように電流パターンに水平な部分はなるべく細い導体で籠状に構成するのが望ましい。
【００２６】
図１２は、等価直列インダクタンスＬｓの影響を打ち消すための補正コイル３５を設けた構成例である。補正コイル３５は電流パターン３１ａ，３１ｂを流れる電流が作る磁束と図中矢印Ｍで示す向きで磁気結合させる。
【００２７】
図１３は、補正コイル３５に加え、不平衡増幅器３６を用いた構成例である。この例では、電流パターン３１ａ側のＧＮＤと増幅器３６のＧＮＤの間のパターン抵抗が、測定すべき被測定コンデンサの等価直列抵抗Ｒｓより十分に小さくなければならない。
【００２８】
図１４は、補正用コイル３５の電圧を独立した差動増幅器３７ａ，３７ｂで増幅した後、加算器３８によりＶ（ｔ）と加算するものである。差動増幅器のダイナミックレンジは広くなければならないが、差動増幅器３７ａ，３７ｂのゲインを調節することによりΔＶＬの大きさが任意に決められる利点を有する。
【００２９】
図１５は、不平衡型の増幅器３６ａ，３６ｂで図１４と同様の補正をかける構成である。この場合、電流パターン３１ａ側のＧＮＤと増幅器３６ｂのＧＮＤの間のパターン抵抗が、測定すべき被測定コンデンサの等価直列抵抗Ｒｓより十分に小さくなければならない。
【００３０】
次に、被測定コンデンサ１３を基板に実装せずに、テストフィクスチャーを使用する場合の、電流電極について述べる。この構造は、被測定コンデンサ１３の電極１４ａ，１４ｂにプローブ４０を用いて接続するものである。電流を電極１４ａ，１４ｂへなるべく均一に流すため、複数のコンタクトピン（プローブ）４０を用いることが望ましいが、ピン先端と電極間の接触抵抗ｒにぱらつきが生じると各ピンに均一の電流が流れない。そこで、図１６（ｃ）に示すように、電流プローブ４０に直列に電流均一化抵抗Ｒを接続して電流の均一化を図ることが望ましい。電流均一化抵抗Ｒは接触抵抗ｒに対して十分大きい必要がある。
【００３１】
図１７は、針状の電流プローブ４０の代わりに水銀などのきわめて導電性の良い液体４１を使用する例である。これにより、接触電位差を極めて小さくすることが可能である。
【００３２】
図１８に他の実施形態の測定回路を示す。スイッチング制御回路で２つのＦＥＴを交互にＯＮ／ＯＦＦして鋸歯状波電流源２１を構成し、被測定コンデンサ１３に鋸歯状波電流を流す。疑似負荷４４は、安定に定常電流を流す目的と、被測定コンデンサ１３に直流バイアス電圧をかける目的で挿入されている。
【００３３】
これまで本発明の一実施形態について説明したが、本発明は上述の実施形態に限定されず、その技術的思想の範囲内において種々異なる形態にて実施されてよいことは言うまでもない。
【００３４】
【発明の効果】
本発明によれば、鋸歯状波電流を被測定コンデンサへ導く電流パターンと、これに分離して被測定コンデンサの両端の電圧波形を観測または測定に供する電圧検出パターンを設けて、観測されたまたは測定された電圧波形を対称成分と非対称成分に分解して、該成分の値よりコンデンサの等価直列抵抗または等価直列インダクタンスまたは等価直列静電容量を算出している。このことにより、実際のコンピュータ直流電源等に用いられるＤＣ／ＤＣコンバータと同様の動作状態での、平滑用コンデンサの等価直列抵抗、等価直列インダクタンス、等価直列静電容量の測定が可能となる。特に、損失評価に必要な等価直列抵抗の値を正確に測定できる。
【図面の簡単な説明】
【図１】ＣＰＵ直流電源用ＤＣ／ＤＣコンバータの基本回路を示す図である。
【図２】平滑コンデンサの等価回路（その１）を示す図である。
【図３】平滑コンデンサの等価回路（その２）を示す図である。
【図４】平滑コンデンサに流す鋸歯状波電流波形及び各部の電圧波形を示す図である。
【図５】本発明の実施形態の測定装置のブロック構成（波形）を示す図である。
【図６】図５の変形例の測定装置を示す図である。
【図７】サンプリングおよび演算、表示のタイミングを示す図である。
【図８】被測定コンデンサを実装した図（基本図）であり、（ａ）は側面図であり、（ｂ）は上面図である。
【図９】検出された電圧波形例を示す波形図である。
【図１０】等価直列抵抗Ｒｓ測定精度向上のための変形実施例を示す図で、（ａ）は側面図であり、（ｂ）は上面図であり、（ｃ）は等価回路図である。
【図１１】等価直列抵抗Ｒｓ測定精度向上のための変形実施例を示す図で、（ａ）は側面図であり、（ｂ）は上面図であり、（ｃ）は等価回路図である。
【図１２】等価直列抵抗Ｒｓ測定精度向上のための変形実施例を示す図で、（ａ）は側面図であり、（ｂ）は上面図であり、（ｃ）はその等価回路である。
【図１３】等価直列抵抗Ｒｓ測定精度向上のための変形実施例を示す図で、（ａ）は側面図であり、（ｂ）は上面図であり、（ｃ）はその等価回路である。
【図１４】等価直列抵抗Ｒｓ測定精度向上のための変形実施例を示す図で、（ａ）は側面図であり、（ｂ）は上面図であり、（ｃ）はその等価回路である。
【図１５】等価直列抵抗Ｒｓ測定精度向上のための変形実施例を示す図で、（ａ）は側面図であり、（ｂ）は上面図であり、（ｃ）はその等価回路である。
【図１６】デストフィクスチャを使用する場合の、電流を供給する接続構造を説明する図であり、（ａ）は側面図であり、（ｂ）は上面図であり、（ｃ）は電流均一化のため抵抗Ｒを接続した図である。
【図１７】図１６の変形例を説明する図である。
【図１８】本発明の他の実施例の測定回路を示す図である。
【符号の説明】
１１ ＤＣ／ＤＣコンバータ
１２ ＣＰＵ
１３ 平滑用コンデンサ
２１ 鋸歯状波電流源
２２ 電圧検出器
２３ 電流電圧変換器
２４ 波形表示装置[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a smoothing capacitor of a DC / DC converter used in a power supply circuit of a personal computer, and more particularly to a measuring apparatus and a measuring method for measuring the equivalent series resistance, equivalent series inductance, and equivalent series capacitance. In particular, the present invention relates to a measuring apparatus that can measure the above-mentioned constants with high accuracy and has high measurement accuracy.
[0002]
[Prior art]
In recent years, especially in notebook personal computers and the like, the voltage of CPU chips has been lowered, but a relatively high DC voltage of about +10 to +15 V is supplied from a DC power supply. Therefore, as shown in FIG. 1, the DC / DC converter 11 using the sawtooth current is converted into a low DC voltage suitable for the CPU chip 12, and the voltage is smoothed and smoothed by the smoothing capacitor 13. Accumulating and supplying power to the CPU chip 12. The DC / DC converter 11 for such a use has a low voltage and a large current, and in order to reduce the loss, the smoothing capacitor 13 is required to have a low loss.
[0003]
As shown in FIG. 2, the smoothing capacitor 13 used in the DC / DC converter is represented by an equivalent circuit including an equivalent series resistance Rs, an equivalent series inductance Ls, and an equivalent series capacitance C. Conventionally, these constants have been measured by an LCR meter or an impedance analyzer. However, the measurement waveform of the LCR meter or the impedance analyzer is a sine wave, and the current is as small as several tens of mA or less. However, the current flowing through the smoothing capacitor of an actual DC / DC converter is a sawtooth wave having a high frequency, and its value ranges from several to several tens of A. For this reason, the equivalent series resistance Rs, equivalent series inductance Ls, and equivalent series capacitance C obtained with an LCR meter or an impedance analyzer are measured under conditions that are far different from those in actual use.
[0004]
Furthermore, since LCR meters and impedance analyzers calculate equivalent series resistance, equivalent series inductance, and equivalent series capacitance from sinusoidal current, voltage, and phase difference, especially with smoothing capacitors used in DC / DC converters. There is a problem that the measurement accuracy of the equivalent series resistance that directly affects the loss is poor.
[0005]
[Problems to be solved by the invention]
To provide a measuring apparatus capable of measuring the equivalent series resistance, equivalent series inductance, and equivalent series capacitance of a smoothing capacitor used in a DC power supply circuit of a personal computer or the like with high accuracy in a state close to actual use. Objective.
[0006]
[Means for Solving the Problems]
In order to solve the above problems, a measuring apparatus of the present invention includes a sawtooth wave current source that generates a sawtooth wave current, a current-voltage converter that converts the sawtooth wave current into a voltage, and outputs the voltage to a waveform display device. A current pattern for guiding the sawtooth wave current to the capacitor to be measured and a device to be measured, comprising: a substrate on which the capacitor to be measured is mounted; and a voltage detector that amplifies the voltage across the capacitor to be measured and outputs it to the waveform display device. It has a voltage detection pattern that leads to observation or measurement of the voltage waveform at both ends of the capacitor, and the voltage waveform observed or measured through the voltage detection pattern is divided into two equal parts of the rising or falling period of the sawtooth current It is broken down into a symmetric component and an asymmetric component with the time of the point as the central axis, and the equivalent series resistance, equivalent series inductance, and equivalent series capacitance of the measured capacitor are determined from the values of the symmetric component and the asymmetric component . And calculating the quantity .
[0007]
It is preferable to arrange a low-pass filter composed of a resistor and a capacitor at the output end of the voltage detection pattern, and output a voltage waveform at both ends of the resistor to output only a change (AC component) waveform. Thereby, the dynamic range of observation and measurement can be expanded.
[0008]
Further, the measuring device for measuring the equivalent series resistance or equivalent series inductance or equivalent series capacitance of the capacitor has a voltage detection pattern that is a pair of conductor patterns formed to intersect the front surface and the back surface of the substrate, or The correction coil is composed of a conductor plane pattern formed on the substrate and a correction coil, and the correction coil has a voltage detection pattern arranged at a position magnetically coupled to the current pattern, or is three-dimensionally formed on the substrate. It is preferable to have a voltage detection pattern composed of a pair of intersecting structures. Thereby, it is possible to accurately measure the equivalent series resistance Rs by canceling the influence of the voltage generated by the equivalent series inductance.
[0009]
A first sample-and-hold circuit that receives the output of the current-voltage converter; a first A / D converter that receives the output of the first sample-and-hold circuit; and an output of the voltage detector. And a second A / D converter having the output of the second sample and hold circuit as an input, and calculating the constants of the capacitor by digital calculation. preferable. As a result, the equivalent series resistance, equivalent series inductance, or equivalent series capacitance of the capacitor can be digitally calculated and automatically obtained.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 3 to 18.
[0011]
In the present invention, the equivalent series capacitance C, equivalent series inductance Ls, and equivalent series resistance Rs of the capacitor are measured according to the following principle. First, a terminal voltage when a sawtooth current is passed through a capacitor is assumed.
As shown in FIG. 3, when a current i (t) is supplied to each component of the equivalent series capacitance C, equivalent series inductance Ls, and equivalent series resistance Rs, the voltage Vc (t) (C) corresponding to this current is supplied. ), VL (t) (corresponding to Ls), and VR (t) (corresponding to Rs) indicate characteristic waveforms as shown in FIG. Of course, the capacitance C, the equivalent series inductance Ls, and the equivalent series resistance Rs are not concentrated in the capacitor to be measured, but are considered to be distributed throughout, but depending on the size of each component, In considering how the voltage waveform V (t) changes, it can be considered separately.
[0012]
As shown in FIG. 4, when a sawtooth wave current such as a current waveform is passed through a capacitor to be measured, (2) a capacitance component both-ends voltage V C (t), (3) an inductance component both-ends voltage VL (t ), (4) A voltage corresponding to each component such as a resistance component both-end voltage VR (t) appears. The sum of these becomes (5) the voltage V (t) across the smoothing capacitor. What should be noted here is the waveform feature that each component gives to V (t).
[0013]
In FIG. 4, ta is a time when the current i (t) turns from rising to falling, and tb is a time when the current i (t) turns from falling to rising. tc is the time when it starts to fall again. In a steady state, i (ta) = i (tc), Vc (ta) = Vc (tc), VL (ta) = VL (tc), VR (ta) = VR (tc ), V (ta) = V (tc), tm is the time of the bisector of ta and tb, and tn is the time of the bisector of tb and tc. Vc (t) and VL (t) are axisymmetric with respect to tm or tn as the central axis, and only VR (t) is asymmetric.
[0014]
Therefore, the asymmetric component of tm or tn of V (t), which is a simple addition of Vc (t), VL (t), and VR (t), may be attributed to VR (t). When a known current i (t) is applied to the measured capacitor, Vc (t), VL (t), and VR (t) cannot be measured independently, but the waveform of V (t) is observed. Focusing on the asymmetry, it can be decomposed into Vc (t), VL (t), and VR (t) components.
[0015]
Based on this principle, each component can be calculated as follows.
About Rs:
[Expression 1]

[0016]
About Ls:
[Expression 2]

[0017]
About C:
[Equation 3]

This calculation is a method of calculating each component from V (t) when i (t) is lowered. Of course, each component is calculated from V (t) when i (t) is increased around time tn. Is possible as well.
[0018]
FIG. 5 shows a configuration of an apparatus for measuring V (t) by passing a known sawtooth wave current i (t) through a capacitor to be measured. This shows a case where V (tm−τ) and V (tm + τ) are read by a waveform observation device 24 such as an oscilloscope. The current-voltage converter 23 of FIG. 5 uses a current transformer, a current probe, a current detection resistor and a differential amplifier.
[0019]
In this apparatus, the sawtooth current is supplied from the sawtooth current source 21 to the capacitor 13 to be measured. The voltage V (t) generated at both ends is detected by the voltage detector 22 and input to the waveform display device 24. The sawtooth wave current i (t) is detected by the current-voltage converter 23 and input to the waveform display device 24 as a voltage proportional to the current i (t). Therefore, the waveform display device 24 can display the current i (t) flowing through the capacitor to be measured 13 and the voltage V (t) generated at both ends thereof in comparison.
[0020]
FIG. 6 shows a configuration in the case where a sampling circuit is added and automatic measurement is performed. That is, instead of the waveform display device 24, sample hold circuits 25a and 25b, A / D converters 26a and 26b, and a digital arithmetic display circuit 27 are used. The sawtooth wave current i (t) detected by the current-voltage converter 23 is converted into a digital value by the A / D converter 26 a after the analog value sampled and held by the sample-and-hold circuit 25 a is input to the digital arithmetic display circuit 27. Is done. Similarly, the voltage V (t) across the capacitor 13 to be measured detected by the voltage converter 22 is converted into a digital value by the analog value sampled and held by the sample and hold circuit 25b by the A / D converter 26b. It is input to the calculation display circuit 27. Thereby, each measured value shown in FIG. 4 and the above calculation formula is automatically calculated and displayed by the calculation display circuit 27. Here, the oscillation circuit and timing adjustment circuit 28 controls the timing of the sawtooth current source 21 and the calculation display circuit 27.
[0021]
FIG. 7 shows an example of timing of this sampling, calculation and display. As shown in the figure, the current i (t) and the voltage V (t) are sampled in the vicinity of the times ta, tm, and tb, and data equivalent to that shown in FIG. 4 is obtained by digital calculation.
[0022]
Next, a description will be given of a conductor pattern on a substrate to be measured by mounting a capacitor to be measured.
FIG. 8 shows a configuration example of a basic connection pattern. In order to measure a small series equivalent resistance Rs and the like with a relatively large current, it is necessary to perform four-terminal measurement in which the current patterns 31a and 31b and the voltage detection patterns 32a and 32b are separated. R and C in FIG. 8 is a filter for extracting only AC Ingredient of the measured capacitor 13, by connecting a differential amplifier 22 as shown in FIG. 8, to amplify only the AC component of V (t). This is a configuration for increasing the dynamic range of measurement.
In order to accurately measure the equivalent series inductance Ls, the distance d between the voltage detection patterns 32a and 32b is preferably set to the electrode width of the capacitor 13 to be measured, but it is equivalent if the equivalent series inductance Ls is large as will be described later. Since the measurement accuracy of the series resistance Rs does not increase, it is desirable to use another pattern described later when measuring the equivalent series resistance Rs.
[0023]
FIG. 9 shows an example of the voltage waveform across the capacitor due to the influence of the equivalent series inductance Ls. The voltage due to the equivalent series inductance appears as a step ΔVL at the current change point.
When the equivalent series inductance Ls is large and the equivalent series resistance Rs is relatively small, the value of V (tm + τ) −V (tm−τ) becomes smaller than Vp-p as shown in the upper part of FIG. End up. On the other hand, when the equivalent series inductance Ls is small and the equivalent series resistance Rs is relatively large, the value of V (tm + τ) −V (tm−τ) becomes Vp-p as shown in the lower part of FIG. It becomes large compared. Therefore, considering the dynamic range of the amplifier that amplifies V (t), the measurement accuracy of the equivalent series resistance Rs is improved as shown in the lower part of FIG. 9 if the influence of the equivalent series inductance Ls component is reduced as much as possible.
[0024]
Next, a configuration example of a voltage detection pattern for reducing the influence of the equivalent series inductance Ls will be described.
In FIG. 10, conductor patterns 33a and 33b for detecting a voltage are arranged on the front and back surfaces of the circuit board so as to intersect with each other. A voltage detection pattern in which VL (t) generated by the equivalent series inductance Ls by the current change di (t) / dt flowing through the capacitor is magnetically coupled to i (t) by intersecting the voltage detection patterns 33a and 33b. Can be canceled by the voltage induced in the.
[0025]
Next, FIG. 11 shows a configuration in which the intersecting voltage detection patterns 34a and 34b are three-dimensional rather than planar. As shown in the figure, the voltage detection conductors 34a and 34b are three-dimensionally arranged so that the two conductors connected to the capacitor electrode are magnetically coupled to each other. Since the coupling can be raised from the planar pattern of FIG. 10, the cancellation efficiency is high. However, it is desirable that the horizontal portion of the current pattern is formed in a bowl shape with as thin a conductor as possible so that eddy currents are not generated.
[0026]
FIG. 12 is a configuration example in which a correction coil 35 for canceling the influence of the equivalent series inductance Ls is provided. The correction coil 35 is magnetically coupled with the magnetic flux generated by the current flowing through the current patterns 31a and 31b in the direction indicated by the arrow M in the figure.
[0027]
FIG. 13 shows a configuration example using an unbalanced amplifier 36 in addition to the correction coil 35. In this example, the pattern resistance between the GND on the current pattern 31a side and the GND of the amplifier 36 must be sufficiently smaller than the equivalent series resistance Rs of the capacitor to be measured.
[0028]
In FIG. 14, the voltage of the correction coil 35 is amplified by independent differential amplifiers 37 a and 37 b and then added to V (t) by an adder 38. Although the dynamic range of the differential amplifier must be wide, there is an advantage that the magnitude of ΔVL can be arbitrarily determined by adjusting the gains of the differential amplifiers 37a and 37b.
[0029]
FIG. 15 shows a configuration in which the same correction as that of FIG. 14 is performed by the unbalanced amplifiers 36a and 36b. In this case, the pattern resistance between the GND on the current pattern 31a side and the GND of the amplifier 36b must be sufficiently smaller than the equivalent series resistance Rs of the capacitor to be measured.
[0030]
Next, the current electrode when the test fixture is used without mounting the measured capacitor 13 on the substrate will be described. This structure is connected to the electrodes 14 a and 14 b of the capacitor 13 to be measured using the probe 40. It is desirable to use a plurality of contact pins (probes) 40 in order to flow the current to the electrodes 14a and 14b as uniformly as possible. Absent. Therefore, as shown in FIG. 16C, it is desirable to connect the current equalizing resistor R in series with the current probe 40 to equalize the current. The current equalizing resistance R needs to be sufficiently larger than the contact resistance r.
[0031]
FIG. 17 shows an example in which a highly conductive liquid 41 such as mercury is used instead of the needle-like current probe 40. Thereby, the contact potential difference can be made extremely small.
[0032]
FIG. 18 shows a measurement circuit according to another embodiment. The sawtooth wave current source 21 is configured by alternately turning on and off the two FETs by the switching control circuit, and a sawtooth wave current is passed through the capacitor 13 to be measured. The pseudo load 44 is inserted for the purpose of flowing a steady current stably and for applying a DC bias voltage to the capacitor 13 to be measured.
[0033]
Although one embodiment of the present invention has been described so far, it is needless to say that the present invention is not limited to the above-described embodiment, and may be implemented in various forms within the scope of the technical idea.
[0034]
【The invention's effect】
According to the present invention, a current pattern for leading a sawtooth wave current to the capacitor to be measured and a voltage detection pattern for separating or observing the voltage waveform at both ends of the capacitor to be measured are provided. The measured voltage waveform is decomposed into a symmetric component and an asymmetric component, and the equivalent series resistance, equivalent series inductance, or equivalent series capacitance of the capacitor is calculated from the value of the component. This makes it possible to measure the equivalent series resistance, equivalent series inductance, and equivalent series capacitance of the smoothing capacitor in the same operating state as a DC / DC converter used in an actual computer DC power supply or the like. In particular, the value of the equivalent series resistance necessary for loss evaluation can be accurately measured.
[Brief description of the drawings]
FIG. 1 is a diagram showing a basic circuit of a DC / DC converter for CPU DC power supply.
FIG. 2 is a diagram illustrating an equivalent circuit (part 1) of a smoothing capacitor.
FIG. 3 is a diagram showing an equivalent circuit (part 2) of the smoothing capacitor.
FIG. 4 is a diagram illustrating a sawtooth current waveform flowing through a smoothing capacitor and a voltage waveform of each part.
FIG. 5 is a diagram showing a block configuration (waveform) of the measuring apparatus according to the embodiment of the present invention.
6 is a view showing a measuring apparatus according to a modification of FIG.
FIG. 7 is a diagram illustrating timings of sampling, calculation, and display.
8A and 8B are diagrams (basic view) in which a capacitor to be measured is mounted, in which FIG. 8A is a side view and FIG. 8B is a top view.
FIG. 9 is a waveform diagram showing an example of a detected voltage waveform.
10A and 10B are diagrams showing a modified embodiment for improving the measurement accuracy of the equivalent series resistance Rs, where FIG. 10A is a side view, FIG. 10B is a top view, and FIG. 10C is an equivalent circuit diagram.
11A and 11B are diagrams showing a modified embodiment for improving the measurement accuracy of the equivalent series resistance Rs, where FIG. 11A is a side view, FIG. 11B is a top view, and FIG. 11C is an equivalent circuit diagram.
12A and 12B are diagrams showing a modified embodiment for improving the measurement accuracy of the equivalent series resistance Rs, where FIG. 12A is a side view, FIG. 12B is a top view, and FIG. 12C is an equivalent circuit thereof.
13A and 13B are diagrams showing a modified embodiment for improving the measurement accuracy of the equivalent series resistance Rs, where FIG. 13A is a side view, FIG. 13B is a top view, and FIG. 13C is an equivalent circuit thereof.
14A and 14B are diagrams showing a modified embodiment for improving the measurement accuracy of the equivalent series resistance Rs, where FIG. 14A is a side view, FIG. 14B is a top view, and FIG. 14C is an equivalent circuit thereof.
FIGS. 15A and 15B are diagrams showing a modified embodiment for improving the measurement accuracy of the equivalent series resistance Rs, where FIG. 15A is a side view, FIG. 15B is a top view, and FIG. 15C is an equivalent circuit thereof.
FIGS. 16A and 16B are diagrams for explaining a connection structure for supplying a current when a destination fixture is used; FIG. 16A is a side view, FIG. 16B is a top view, and FIG. It is the figure which connected resistance R for conversion.
FIG. 17 is a diagram illustrating a modification of FIG.
FIG. 18 is a diagram showing a measurement circuit according to another embodiment of the present invention.
[Explanation of symbols]
11 DC / DC converter 12 CPU
13 Smoothing Capacitor 21 Sawtooth Wave Current Source 22 Voltage Detector 23 Current-Voltage Converter 24 Waveform Display Device

Claims (6)

A sawtooth current source for generating a sawtooth current;
A current-voltage converter for converting the sawtooth current into a voltage and outputting the voltage to a waveform display device;
A substrate on which the capacitor to be measured is mounted;
A voltage detector that amplifies the voltage across the capacitor to be measured and outputs it to the waveform display device;
A current pattern that leads the sawtooth current to the capacitor to be measured and a voltage detection pattern that leads to observation or measurement of the voltage waveform at both ends of the capacitor to be measured;
The voltage waveform observed or measured via the voltage detection pattern is decomposed into a symmetric component and an asymmetric component with the time at the bisection point of the rising or falling section of the sawtooth current as the central axis ,
An apparatus for measuring characteristics of a smoothing capacitor, wherein an equivalent series resistance, an equivalent series inductance, and an equivalent series capacitance of a capacitor to be measured are calculated from the values of the symmetric component and the asymmetric component. The smoothing capacitor according to claim 1, wherein a filter that passes a low- frequency component composed of a resistor and a capacitor is disposed at an output end of the voltage detection pattern, and a voltage waveform at both ends of the resistor is output. Characteristic measuring device.   2. The smoothing capacitor characteristic measuring apparatus according to claim 1, wherein the voltage detection pattern is a pair of conductor patterns formed so as to intersect the front surface and the back surface of the substrate.   2. The voltage detection pattern includes a conductor plane pattern formed on a substrate and a correction coil, and the correction coil is disposed at a position magnetically coupled to the current pattern. The characteristic measuring apparatus of the smoothing capacitor as described.   2. The characteristic measuring apparatus for a smoothing capacitor according to claim 1, wherein the voltage detection pattern is a pair of intersecting structures formed three-dimensionally on a substrate. A first sample-and-hold circuit that receives the output of the current-voltage converter, a first A / D converter that receives the output of the first sample-and-hold circuit, and an output of the voltage detector A second sample-and-hold circuit, and a second A / D converter that receives the output of the second sample-and-hold circuit.
2. The smoothing capacitor characteristic measuring apparatus according to claim 1, wherein various constants of the capacitor are calculated by digital calculation.

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