JP2005315824A - Cv conversion circuit - Google Patents

Cv conversion circuit Download PDF

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JP2005315824A
JP2005315824A JP2004186160A JP2004186160A JP2005315824A JP 2005315824 A JP2005315824 A JP 2005315824A JP 2004186160 A JP2004186160 A JP 2004186160A JP 2004186160 A JP2004186160 A JP 2004186160A JP 2005315824 A JP2005315824 A JP 2005315824A
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voltage source
operational amplifier
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Minoru Sudo
稔 須藤
Mitsuo Shoda
光男 鎗田
Kenji Kato
健二 加藤
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Seiko Instruments Inc
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Seiko Instruments Inc
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a CV conversion circuit capable of measuring a plurality of capacities by reduced circuit components. <P>SOLUTION: This CV conversion circuit is constituted to measure a plurality of capacity values by the reduced circuit components, by impressing signals different in phases and frequencies to the capacities. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

この発明は、複数の静電容量の値を電圧に変換するＣＶ変換回路に関する。   The present invention relates to a CV conversion circuit that converts a plurality of capacitance values into voltages.

従来のＣＶ変換回路としては、図８に示されるような回路が知られていた。即ち、非反転入力端子が接地された演算増幅器１と、前記演算増幅器１の出力端子と、反転入力端子の間に接続された抵抗３と、一端が前記演算増幅器１の反転入力端子に接続され、他端が信号電圧源４に接続された、検出すべき容量２があり、前記信号電圧源４には、ある電圧振幅Ｖとある角周波数ωの信号が与えられている。すなわち、信号電圧源４の信号電圧をＶｓとすれば、（１）式で表される。   As a conventional CV conversion circuit, a circuit as shown in FIG. 8 has been known. That is, the operational amplifier 1 whose non-inverting input terminal is grounded, the output terminal of the operational amplifier 1, the resistor 3 connected between the inverting input terminals, and one end thereof are connected to the inverting input terminal of the operational amplifier 1. The other end is connected to a signal voltage source 4 and has a capacitor 2 to be detected. The signal voltage source 4 is given a signal having a certain voltage amplitude V and a certain angular frequency ω. That is, if the signal voltage of the signal voltage source 4 is Vs, it is expressed by the equation (1).

Ｖｓ＝Ｖ・ｓｉｎ（ωｔ） …（１）
図８において、反転入力端子は仮想接地されているため、非反転入力端子の接地電位に等しくなっている。仮に、この接地電位を０Ｖとすれば、容量２に流れる電流Ｉは、容量２の値をＣとすれば、（２）式で与えられる。 Vs = V · sin (ωt) (1)
In FIG. 8, since the inverting input terminal is virtually grounded, it is equal to the ground potential of the non-inverting input terminal. If the ground potential is 0 V, the current I flowing through the capacitor 2 is given by the equation (2) if the value of the capacitor 2 is C.

Ｉ＝ｊωＣ・Ｖ・ｓｉｎ（ωｔ） …（２）
従って、演算増幅器１の出力端子５には、抵抗３の抵抗値をＲとすれば、（３）式で与えられる電圧Ｖｏが発生する。 I = jωC · V · sin (ωt) (2)
Therefore, if the resistance value of the resistor 3 is R, the voltage Vo given by the equation (3) is generated at the output terminal 5 of the operational amplifier 1.

Ｖｏ＝−ｊωＣ・Ｒ・Ｖ・ｓｉｎ（ωｔ） …（３）
（３）式より、演算増幅器１の出力電圧の振幅Ｖｏは、容量２の値に比例するため、前記振幅Ｖｏを測定する事で、容量２の値を測定する事ができる。 Vo = −jωC · R · V · sin (ωt) (3)
From the equation (3), the amplitude Vo of the output voltage of the operational amplifier 1 is proportional to the value of the capacitor 2, so that the value of the capacitor 2 can be measured by measuring the amplitude Vo.

図９に、図８のＣＶ変換回路の各部の時間に対する電圧・電流波形を示す。図９（Ａ）は、信号電圧源４の信号電圧を示している。ここでは、正弦波を与えている。図９（Ｂ）は、容量２及び抵抗３に流れる電流波形であり、図９（Ｃ）は、演算増幅器１の出力端子５に現れる電圧波形である。   FIG. 9 shows voltage / current waveforms with respect to time of each part of the CV conversion circuit of FIG. FIG. 9A shows the signal voltage of the signal voltage source 4. Here, a sine wave is given. FIG. 9B shows a current waveform flowing through the capacitor 2 and the resistor 3, and FIG. 9C shows a voltage waveform appearing at the output terminal 5 of the operational amplifier 1.

複数の容量の値を測定する場合、図８の回路を、測定する容量の数だけ用意する事で、複数の容量値を測定する事ができる（例えば、特許文献１参照。）。
特開2001-124807号公報（図２） When measuring a plurality of capacitance values, a plurality of capacitance values can be measured by preparing the circuit of FIG. 8 by the number of capacitances to be measured (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 2001-124807 (FIG. 2)

従来のＣＶ変換回路では、測定する容量の数だけ、ＣＶ変換回路が必要となり、複数の容量を測定すると回路の規模が大きくなるという課題があった。   The conventional CV conversion circuit requires CV conversion circuits as many as the number of capacitances to be measured, and there is a problem in that the circuit scale increases when a plurality of capacitances are measured.

そこで、この発明の目的は従来のこのような課題を解決するために、少ない回路規模で複数の容量を測定することを目的としている。   Accordingly, an object of the present invention is to measure a plurality of capacitors with a small circuit scale in order to solve such a conventional problem.

本願発明にかかるＣＶ変換回路は、非反転入力端子が接地された演算増幅器と、
一端が前記演算増幅器の出力に接続され、他端が前記演算増幅器の反転入力端子に接続された抵抗と、
一端が前記演算増幅器の反転入力端子に接続され、他端が第一の信号電圧源に接続された第一の容量と、
一端が前記演算増幅器の反転入力端子に接続され、他端が第二の信号電圧源に接続された第二の容量とを有し、
前記第一の電圧源の信号周波数と前記第二の電圧源の信号周波数が等しく、かつ、前記第一の信号電圧源と前記第二の信号電圧源の信号周波数の位相が９０度ずれているＣＶ変換回路。
さらに、本願発明にかかるＣＶ変換回路は、前記第一の信号電圧源の信号周波数に対して前記第二の信号電圧源の信号周波数が整数倍であることを特徴とする。
また、本願発明にかかるＣＶ変換回路は、非反転入力端子が接地された演算増幅器と、
一端が前記演算増幅器の出力に接続され、他端が前記演算増幅器の反転入力端子に接続された抵抗と、
一端が前記演算増幅器の反転入力端子に接続され、他端が第一の信号電圧源に接続された第一の容量と、
一端が前記演算増幅器の反転入力端子に接続され、他端が第ニの信号電圧源に接続された第ニの容量と、
一端が前記演算増幅器の反転入力端子に接続され、他端が第三の信号電圧源に接続された第三の容量とを有し、
前記第一の電圧源の信号周波数と前記第二の信号電圧源の信号周波数が等しく、かつ、前記第一の信号電圧源と前記第二の信号電圧源の信号周波数の位相が９０度ずれて、かつ、
前記第一と前記第二の信号電圧源の信号周波数に対して、前記第三の信号電圧源の信号周波数が整数倍であることを特徴とする。 The CV conversion circuit according to the present invention includes an operational amplifier having a non-inverting input terminal grounded,
A resistor having one end connected to the output of the operational amplifier and the other end connected to the inverting input terminal of the operational amplifier;
A first capacitor having one end connected to the inverting input terminal of the operational amplifier and the other end connected to a first signal voltage source;
A second capacitor having one end connected to the inverting input terminal of the operational amplifier and the other end connected to a second signal voltage source;
The signal frequency of the first voltage source and the signal frequency of the second voltage source are equal, and the phase of the signal frequency of the first signal voltage source and that of the second signal voltage source are shifted by 90 degrees. CV conversion circuit.
Furthermore, the CV conversion circuit according to the present invention is characterized in that the signal frequency of the second signal voltage source is an integral multiple of the signal frequency of the first signal voltage source.
A CV conversion circuit according to the present invention includes an operational amplifier having a non-inverting input terminal grounded,
A resistor having one end connected to the output of the operational amplifier and the other end connected to the inverting input terminal of the operational amplifier;
A first capacitor having one end connected to the inverting input terminal of the operational amplifier and the other end connected to a first signal voltage source;
A second capacitor having one end connected to the inverting input terminal of the operational amplifier and the other end connected to a second signal voltage source;
A third capacitor having one end connected to the inverting input terminal of the operational amplifier and the other end connected to a third signal voltage source;
The signal frequency of the first voltage source and the signal frequency of the second signal voltage source are equal, and the phase of the signal frequency of the first signal voltage source and the second signal voltage source is shifted by 90 degrees. ,And,
The signal frequency of the third signal voltage source is an integral multiple of the signal frequency of the first and second signal voltage sources.

また、本願発明にかかるＣＶ変換回路は、非反転入力端子が接地された演算増幅器と、
一端が前記演算増幅器の出力に接続され、他端が前記演算増幅器の反転入力端子に接続された抵抗と、
一端が前記演算増幅器の反転入力端子に接続され、他端が第一の信号電圧源に接続された第一の容量と、
一端が前記演算増幅器の反転入力端子に接続され、他端が第二の信号電圧源に接続された第二の容量と、
一端が前記演算増幅器の反転入力端子に接続され、他端が第三の信号電圧源に接続された第三の容量とを有し、
前記第一の信号電圧源の信号周波数と前記第二の信号電圧源の信号周波数が等しく、かつ、前記第一の信号電圧源と前記第二の信号電圧源の信号周波数の位相が９０度ずれて、かつ、
前記第一と前記第二の信号電圧源の信号周波数に対して、前記第三の信号電圧源の信号周波数が整数分の１であることを特徴とする。 A CV conversion circuit according to the present invention includes an operational amplifier having a non-inverting input terminal grounded,
A resistor having one end connected to the output of the operational amplifier and the other end connected to the inverting input terminal of the operational amplifier;
A first capacitor having one end connected to the inverting input terminal of the operational amplifier and the other end connected to a first signal voltage source;
A second capacitor having one end connected to the inverting input terminal of the operational amplifier and the other end connected to a second signal voltage source;
A third capacitor having one end connected to the inverting input terminal of the operational amplifier and the other end connected to a third signal voltage source;
The signal frequency of the first signal voltage source and the signal frequency of the second signal voltage source are equal, and the phase of the signal frequency of the first signal voltage source and that of the second signal voltage source are shifted by 90 degrees. And once
The signal frequency of the third signal voltage source is 1 / integer of the signal frequency of the first and second signal voltage sources.

本願発明にかかるＣＶ変換回路は、複数の容量の値を少ない回路で測定できるという効果がある。   The CV conversion circuit according to the present invention has an effect that a plurality of capacitance values can be measured with a small number of circuits.

上記課題を解決するために、この発明ではＣＶ変換回路において、位相の９０度異なる信号を容量に印加するようにした。さらに、別の容量には、整数倍の周波数の信号を、容量に印加するようにした。   In order to solve the above-described problem, in the present invention, signals having a phase difference of 90 degrees are applied to the capacitor in the CV conversion circuit. Further, a signal having an integer multiple of frequency is applied to the capacitor as another capacitor.

以下に、本発明の実施例を図面に基づいて説明する。図１は、本発明の第一の実施例を示すＣＶ変換回路である。従来の図８との違いは、２つの容量２と１２の値を、１つの演算増幅器１と、抵抗３によって検出している。   Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a CV conversion circuit showing a first embodiment of the present invention. The difference from the conventional FIG. 8 is that the values of two capacitors 2 and 12 are detected by one operational amplifier 1 and a resistor 3.

第一の容量２は、従来と同様に、演算増幅器１の反転入力端子と、第一の信号電圧源４の間に接続されている。一方、第二の容量１２は、演算増幅器１の反転入力端子と、第二の信号電圧源１４の間に接続されている。   The first capacitor 2 is connected between the inverting input terminal of the operational amplifier 1 and the first signal voltage source 4 as in the prior art. On the other hand, the second capacitor 12 is connected between the inverting input terminal of the operational amplifier 1 and the second signal voltage source 14.

第一の信号電圧源４の電圧Ｖｓ１は、従来と同様に、（１）式で与えられる。一方、第二の信号電圧源１４の電圧Ｖｓ２は、前記第一の信号電圧源４の電圧に対して、位相を９０度ずらしている。即ち、（４）式で与えられる。   The voltage Vs1 of the first signal voltage source 4 is given by the equation (1) as in the conventional case. On the other hand, the voltage Vs2 of the second signal voltage source 14 is 90 degrees out of phase with the voltage of the first signal voltage source 4. That is, it is given by equation (4).

Ｖｓ２＝＝Ｖ・ｓｉｎ（ωｔ−π／４） …（４）
この時の、図１の各部の横軸時間に対する電圧・電流波形を図２に示す。
図２（Ａ）は、第一の信号電圧源４の信号波形を示している。ここでは、正弦波を与えている。図２（Ｂ）は、容量２に流れる電流波形である。図２（Ｃ）は、第二の信号電圧源１４の信号波形を示している。ここでは、正弦波を与えている。図２（Ａ）と（Ｃ）から明らかなように、信号電圧源４と信号電圧源１４の信号の周波数は等しく、位相が９０度ずれている。図２（Ｄ）は、容量１２に流れる電流波形である。図２（Ｅ）は、抵抗２に流れる電流波形であり、図２（Ｂ）と図２（Ｄ）の和である。図２（Ｆ）は、演算増幅器１の出力端子５に現れる電圧波形である。 Vs2 == V · sin (ωt−π / 4) (4)
FIG. 2 shows voltage / current waveforms at this time with respect to time on the horizontal axis of each part in FIG.
FIG. 2A shows the signal waveform of the first signal voltage source 4. Here, a sine wave is given. FIG. 2B shows a current waveform flowing through the capacitor 2. FIG. 2C shows a signal waveform of the second signal voltage source 14. Here, a sine wave is given. As is clear from FIGS. 2A and 2C, the signals of the signal voltage source 4 and the signal voltage source 14 have the same frequency and are 90 degrees out of phase. FIG. 2D shows a current waveform flowing in the capacitor 12. FIG. 2E shows a current waveform flowing through the resistor 2, which is the sum of FIG. 2B and FIG. FIG. 2F shows a voltage waveform appearing at the output terminal 5 of the operational amplifier 1.

即ち、演算増幅器１の出力端子５の電圧Ｖｏは、容量２の値をＣ１、容量１２の値をＣ２とすれば、（５）式で与えられる。   That is, the voltage Vo at the output terminal 5 of the operational amplifier 1 is given by equation (5), where C1 is the value of the capacitor 2 and C2 is the value of the capacitor 12.

Ｖｏ＝ｊωＣ１・Ｒ・Ｖ・ｓｉｎ（ωｔ）
+ｊωＣ２・Ｒ・Ｖ・ｓｉｎ（ωｔ―π／４） …（５）
従って、信号電圧源４に対して、位相を９０度ずらした信号（図２（G））で、演算増幅器１の出力を同期検波し、その出力を平均化すれば、容量２の値を測定する事が可能となり、信号電圧源４と同じ位相（図２（H））で、演算増幅器１の出力を同期検波し、その出力を平均化すれば、容量１２の値を測定する事が可能となる。 Vo = jωC1, R, V, sin (ωt)
+ jωC2 · R · V · sin (ωt−π / 4) (5)
Therefore, the value of the capacitor 2 is measured by synchronously detecting the output of the operational amplifier 1 with a signal (FIG. 2G) whose phase is shifted by 90 degrees with respect to the signal voltage source 4, and averaging the output. It is possible to measure the value of the capacitor 12 by synchronously detecting the output of the operational amplifier 1 with the same phase as that of the signal voltage source 4 (FIG. 2 (H)) and averaging the output. It becomes.

同期検波回路の例を図３に示す。スイッチS1〜S4があり、S1とS3及び、S2とS4は相補的にON/OFFする。すなわち、S1がONの時には、S3がOFF、S2がOFFの時には、S4がONとなるように動作する。   An example of the synchronous detection circuit is shown in FIG. There are switches S1 to S4, and S1 and S3 and S2 and S4 are turned ON / OFF in a complementary manner. That is, when S1 is ON, S3 is OFF, and when S2 is OFF, S4 is ON.

いま、図２（Ｇ）の信号で、図３の回路のスイッチのS1〜S4を制御することで、図１の容量２の値を検波することができ、図２（Ｈ）の信号で、図３の回路のスイッチのS1〜S4を制御することで、図１の容量１２の値を検波することができる。図３の検波回路は、検出する容量の数だけ必要になる。   Now, by controlling the switches S1 to S4 of the circuit of FIG. 3 with the signal of FIG. 2 (G), the value of the capacitor 2 of FIG. 1 can be detected. With the signal of FIG. By controlling the switches S1 to S4 of the circuit of FIG. 3, the value of the capacitor 12 of FIG. 1 can be detected. The detection circuit of FIG. 3 is required for the number of capacitors to be detected.

図２（Ｇ）の信号が禰狽フ時に、図３のS2とS3をON(S1とS4をOFF)とし、図２（Ｇ）の信号が猫狽フ時に、図３のS1とS4をON(S2とS3をOFF)とすることで、図１の容量２の値を検波する。   When the signal in Fig. 2 (G) is off, S2 and S3 in Fig. 3 are set to ON (S1 and S4 are OFF), and when the signal in Fig. 2 (G) is on the cat, S1 and S4 in Fig. 3 are turned on. By turning ON (S2 and S3 are OFF), the value of the capacitor 2 in FIG. 1 is detected.

同様に、図２（H）の信号が禰狽フ時に、図３のS1とS4をON(S2とS3をOFF)とし、図２（Ｇ）の信号が猫狽フ時に、図３のS2とS3をON(S1とS4をOFF)とすることで、図１の容量１２の値を検波する。   Similarly, when the signal in FIG. 2 (H) is off, S1 and S4 in FIG. 3 are turned on (S2 and S3 are off), and when the signal in FIG. 1 and S3 are turned on (S1 and S4 are turned off), thereby detecting the value of the capacitor 12 in FIG.

すなわち、一つの演算増幅器と一つの抵抗で、２つの容量値の測定が可能となる。   That is, two capacitance values can be measured with one operational amplifier and one resistor.

図４は、本発明の第二の実施例を示すＣＶ変換回路の各部の横軸時間に対する電圧・電流波形ある。図４（Ａ）と（Ｂ）は、図２のそれらと同じである。図２との違いは、図４（Ｃ）の第二の信号電圧源１４の信号波形が、第一の信号電圧源４の信号周波数の整数倍となっている点である。仮に、第二の信号電圧源１４の信号周波数を、第一の電圧源４の信号周波数の２倍とすれば、第二の信号電圧源１４の電圧Ｖｓ２は（６）式で与えられる。   FIG. 4 shows voltage / current waveforms with respect to time on the horizontal axis of the respective parts of the CV conversion circuit according to the second embodiment of the present invention. 4A and 4B are the same as those in FIG. The difference from FIG. 2 is that the signal waveform of the second signal voltage source 14 in FIG. 4C is an integral multiple of the signal frequency of the first signal voltage source 4. If the signal frequency of the second signal voltage source 14 is twice the signal frequency of the first voltage source 4, the voltage Vs2 of the second signal voltage source 14 is given by equation (6).

Ｖｓ２＝＝Ｖ・ｓｉｎ（２ωｔ） …（６）
図４（Ｄ）は、容量１２に流れる電流波形である。図４（Ｅ）は、抵抗２に流れる電流波形であり、図４（Ｂ）と図３（Ｄ）の和である。図４（Ｆ）は、演算増幅器１の出力端子５に現れる電圧波形である。 Vs2 == V · sin (2ωt) (6)
FIG. 4D shows a current waveform flowing through the capacitor 12. FIG. 4E shows a current waveform flowing through the resistor 2, which is the sum of FIG. 4B and FIG. FIG. 4F shows a voltage waveform appearing at the output terminal 5 of the operational amplifier 1.

即ち、演算増幅器１の出力端子５の電圧Ｖｏは、容量２の値をＣ１，容量１２の値をＣ２とすれば、（７）式で与えられる。   That is, the voltage Vo at the output terminal 5 of the operational amplifier 1 is given by equation (7), where C2 is the value of the capacitor 2 and C2 is the value of the capacitor 12.

Ｖｏ＝ｊωＣ１・Ｒ・Ｖ・ｓｉｎ（ωｔ）
+ｊωＣ２・Ｒ・Ｖ・ｓｉｎ（２ωｔ） …（７）
従って、信号電圧源４に対して、位相を９０度ずらした信号（図４（G））で、演算増幅器１の出力を同期検波し、その出力を平均化すれば、容量２の値を測定する事が可能となり、信号電圧源１４に対して、位相を９０度ずらした信号（図４（H））で、演算増幅器１の出力を同期検波し、その出力を平均化すれば、容量１２の値を測定する事が可能となる。 Vo = jωC1, R, V, sin (ωt)
+ jωC2 · R · V · sin (2ωt) (7)
Therefore, the value of the capacitor 2 is measured by synchronously detecting the output of the operational amplifier 1 with a signal (FIG. 4G) whose phase is shifted by 90 degrees with respect to the signal voltage source 4 and averaging the output. If the output of the operational amplifier 1 is synchronously detected with a signal whose phase is shifted by 90 degrees with respect to the signal voltage source 14 (FIG. 4H) and the output is averaged, the capacitance 12 It is possible to measure the value of.

すなわち、一つの演算増幅器と一つの抵抗で、２つの容量値の測定が可能となる。   That is, two capacitance values can be measured with one operational amplifier and one resistor.

図５は、本発明の第三の実施例を示すＣＶ変換回路である。図１との違いは、第三の容量２２が、演算増幅器１の反転入力端子と、第三の信号電圧源２４の間に接続されている点である。   FIG. 5 is a CV conversion circuit showing a third embodiment of the present invention. The difference from FIG. 1 is that the third capacitor 22 is connected between the inverting input terminal of the operational amplifier 1 and the third signal voltage source 24.

第一の信号電圧源４及び第二の信号電圧源１４の信号電圧は、実施例１と同等とする。また、第三の電圧源の信号周波数を第一及び第二の電圧源の信号周波数の倍とする。この時の、図５の各部の横軸時間に対する電圧・電流波形を図６に示す。図６（Ａ）〜（Ｄ）は、図２（Ａ）〜（Ｄ）と同等である。図６（Ｅ）は、図６（Ｂ）と図６（Ｄ）の電流波形の和を示している。図６（Ｆ）は、第三の信号電圧源２４の電圧波形を示している。図６（Ｇ）は、第三の容量２２に流れる電流波形を示している。図６（Ｈ）は、抵抗３に流れる電流波形（図６（Ｅ）と（Ｇ）の和）を示している。図６（Ｉ）は、演算増幅器１の出力端子５に現れる電圧波形である。   The signal voltages of the first signal voltage source 4 and the second signal voltage source 14 are the same as those in the first embodiment. Further, the signal frequency of the third voltage source is set to be twice the signal frequency of the first and second voltage sources. FIG. 6 shows voltage / current waveforms with respect to time on the horizontal axis of the respective parts in FIG. 5 at this time. 6A to 6D are the same as FIGS. 2A to 2D. FIG. 6E shows the sum of the current waveforms of FIG. 6B and FIG. 6D. FIG. 6F shows the voltage waveform of the third signal voltage source 24. FIG. 6G shows a current waveform flowing through the third capacitor 22. FIG. 6H shows a current waveform flowing through the resistor 3 (the sum of FIGS. 6E and 6G). FIG. 6I shows a voltage waveform appearing at the output terminal 5 of the operational amplifier 1.

即ち、演算増幅器１の出力端子５の電圧Ｖｏは、容量２の値をＣ１、容量１２の値をＣ２、容量２２の値をＣ３とすれば、（８）式で与えられる。   That is, the voltage Vo at the output terminal 5 of the operational amplifier 1 is given by equation (8), where C1 is the value of the capacitor 2, C2 is the value of the capacitor 12, and C3 is the value of the capacitor 22.

Ｖｏ＝ｊωＣ１・Ｒ・Ｖ・ｓｉｎ（ωｔ）+ｊωＣ２・Ｒ・Ｖ・ｓｉｎ
（ωｔ―π／４）＋ｊ・２・ωＣ３・Ｒ・Ｖ・ｓｉｎ（２ωｔ） …（８）
従って、信号電圧源４に対して、位相を９０度ずらした信号で、演算増幅器１の出力を同期検波し、その出力を平均化すれば、容量２の値を測定する事が可能となり、信号電圧源４と同じ位相で、演算増幅器１の出力を同期検波し、その出力を平均化すれば、容量１２の値を測定する事が可能となり、信号電圧源２４に対して、位相を９０度ずらした信号で、演算増幅器１の出力を同期検波し、その出力を平均化すれば、容量２２の値を測定する事が可能となる。 Vo = jωC1, R, V, sin (ωt) + jωC2, R, V, sin
(Ωt−π / 4) + j · 2 · ωC3 · R · V · sin (2ωt) (8)
Therefore, if the output of the operational amplifier 1 is synchronously detected with a signal whose phase is shifted by 90 degrees with respect to the signal voltage source 4, and the output is averaged, the value of the capacitor 2 can be measured. If the output of the operational amplifier 1 is synchronously detected with the same phase as that of the voltage source 4 and the outputs are averaged, the value of the capacitor 12 can be measured, and the phase of the signal voltage source 24 is 90 degrees. By synchronously detecting the output of the operational amplifier 1 with the shifted signal and averaging the output, the value of the capacitor 22 can be measured.

すなわち、一つの演算増幅器と一つの抵抗で、３つの容量値の測定が可能となる。   That is, three capacitance values can be measured with one operational amplifier and one resistor.

図７は、本発明の第四の実施例を示すＣＶ変換回路の各部の横軸時間に対する電圧・電流波形である。図６との違いは、信号電圧源２４の信号周波数が、異なる点である。   FIG. 7 shows voltage / current waveforms with respect to time on the horizontal axis of the respective parts of the CV conversion circuit according to the fourth embodiment of the present invention. The difference from FIG. 6 is that the signal frequency of the signal voltage source 24 is different.

第一の信号電圧源４及び第二の信号電圧源１４の信号電圧は、実施例３と同等とする。また、第三の電圧源の信号周波数を第一及び第二の電圧源の信号周波数の1/2倍とする。この時の、図５の各部の横軸時間に対する電圧・電流波形を図７に示す。図７（Ａ）〜（Ｅ）は、図６（Ａ）〜（Ｅ）と同等である。図７（Ｆ）は、第三の信号電圧源２４の電圧波形を示している。図７（Ｇ）は、第三の容量２２に流れる電流波形を示している。図７（Ｈ）は、抵抗３に流れる電流波形を示している。図７（Ｉ）は、図５の演算増幅器１の出力端子５に現れる電圧波形である。   The signal voltages of the first signal voltage source 4 and the second signal voltage source 14 are the same as those in the third embodiment. Further, the signal frequency of the third voltage source is set to ½ times the signal frequency of the first and second voltage sources. FIG. 7 shows voltage / current waveforms with respect to the time on the horizontal axis of the respective parts in FIG. 5 at this time. 7A to 7E are equivalent to FIGS. 6A to 6E. FIG. 7F shows the voltage waveform of the third signal voltage source 24. FIG. 7G shows a waveform of a current flowing through the third capacitor 22. FIG. 7H shows a waveform of a current flowing through the resistor 3. FIG. 7I shows a voltage waveform appearing at the output terminal 5 of the operational amplifier 1 of FIG.

即ち、演算増幅器１の出力端子５の電圧Ｖｏは、容量２の値をＣ１、容量１２の値をＣ２、容量２２の値をＣ３とすれば、（９）式で与えられる。   That is, the voltage Vo at the output terminal 5 of the operational amplifier 1 is given by equation (9), assuming that the value of the capacitor 2 is C1, the value of the capacitor 12 is C2, and the value of the capacitor 22 is C3.

Ｖｏ＝ｊωＣ１Ｒ・Ｖ・ｓｉｎ（ωｔ）+ｊωＣ２Ｒ・Ｖ・ｓｉｎ（ωｔ―π／４）
＋ｊ・０．５・ωＣ３Ｒ・Ｖ・ｓｉｎ（０．５ωｔ） …（９）
従って、信号電圧源４に対して、位相を９０度ずらした信号で、演算増幅器１の出力を同期検波し、その出力を平均化すれば、容量２の値を測定する事が可能となり、信号電圧源４と同じ位相で、演算増幅器１の出力を同期検波し、その出力を平均化すれば、容量１２の値を測定する事が可能となり、信号電圧源２４に対して、位相を９０度ずらした信号で、演算増幅器１の出力を同期検波し、その出力を平均化すれば、容量２２の値を測定する事が可能となる。 Vo = jωC1R · V · sin (ωt) + jωC2R · V · sin (ωt−π / 4)
+ J · 0.5 · ωC3R · V · sin (0.5ωt) (9)
Therefore, if the output of the operational amplifier 1 is synchronously detected with a signal whose phase is shifted by 90 degrees with respect to the signal voltage source 4, and the output is averaged, the value of the capacitor 2 can be measured. If the output of the operational amplifier 1 is synchronously detected with the same phase as that of the voltage source 4 and the outputs are averaged, the value of the capacitor 12 can be measured, and the phase of the signal voltage source 24 is 90 degrees. By synchronously detecting the output of the operational amplifier 1 with the shifted signal and averaging the output, the value of the capacitor 22 can be measured.

すなわち、一つの演算増幅器と一つの抵抗で、３つの容量値の測定が可能となる。   That is, three capacitance values can be measured with one operational amplifier and one resistor.

以上、実施例１〜４では、演算増幅器１の非反転入力端子は全て、０Ｖに接地しているが、０Ｖである必要はなく、ある任意の電圧であれば、その任意の電圧を基準に、演算増幅器１の出力電圧が発生する。以上説明したように、本発明によればＣＶ変換回路おいて、少ない回路で複数の容量を測定することが可能となる。   As described above, in the first to fourth embodiments, all the non-inverting input terminals of the operational amplifier 1 are grounded to 0V, but need not be 0V, and any arbitrary voltage can be used as a reference. The output voltage of the operational amplifier 1 is generated. As described above, according to the present invention, a plurality of capacitors can be measured with a small number of circuits in a CV conversion circuit.

本発明のＣＶ変換回路は、少ない回路部品で複数の容量を測定する技術として利用可能である。   The CV conversion circuit of the present invention can be used as a technique for measuring a plurality of capacitors with a small number of circuit components.

本発明の第一の実施例のＣＶ変換回路である。1 is a CV conversion circuit according to a first embodiment of the present invention. 本発明の第一の実施例のＣＶ変換回路の電圧電流波形である。It is a voltage-current waveform of the CV conversion circuit of the first embodiment of the present invention. 同期検波回路の例である。It is an example of a synchronous detection circuit. 本発明の第二の実施例のＣＶ変換回路の電圧電流波形である。It is a voltage-current waveform of the CV conversion circuit of the 2nd Example of this invention. 本発明の第三の実施例のＣＶ変換回路である。It is a CV conversion circuit of the third embodiment of the present invention. 本発明の第三の実施例のＣＶ変換回路の電圧電流波形である。It is a voltage-current waveform of the CV conversion circuit of the 3rd Example of this invention. 本発明の第四の実施例のＣＶ変換回路の電圧電流波形である。It is a voltage-current waveform of the CV conversion circuit of 4th Example of this invention. 従来のＣＶ変換回路である。This is a conventional CV conversion circuit. 従来のＣＶ変換回路の電圧電流波形である。It is the voltage current waveform of the conventional CV conversion circuit.

符号の説明Explanation of symbols

１ 演算増幅器
２，１２，２２ 容量
３ 抵抗
４，１４，２４ 信号電圧源 1 operational amplifier 2, 12, 22 capacity 3 resistance 4, 14, 24 signal voltage source

Claims (4)

非反転入力端子が接地された演算増幅器と、
一端が前記演算増幅器の出力に接続され、他端が前記演算増幅器の反転入力端子に接続された抵抗と、
一端が前記演算増幅器の反転入力端子に接続され、他端が第一の信号電圧源に接続された第一の容量と、
一端が前記演算増幅器の反転入力端子に接続され、他端が第二の信号電圧源に接続された第二の容量とを有するＣＶ変換回路において、
前記第一の信号電圧源の信号周波数と前記第二の信号電圧源の信号周波数が等しく、かつ、前記第一の電圧源と前記第二の信号電圧源の信号周波数の位相が９０度ずれていることを特徴とするＣＶ変換回路。 An operational amplifier with a non-inverting input terminal grounded;
A resistor having one end connected to the output of the operational amplifier and the other end connected to the inverting input terminal of the operational amplifier;
A first capacitor having one end connected to the inverting input terminal of the operational amplifier and the other end connected to a first signal voltage source;
In a CV conversion circuit having one end connected to the inverting input terminal of the operational amplifier and the other end connected to a second signal voltage source,
The signal frequency of the first signal voltage source and the signal frequency of the second signal voltage source are equal, and the phase of the signal frequency of the first voltage source and the second signal voltage source is shifted by 90 degrees. A CV conversion circuit characterized by comprising: 前記第一の信号電圧源の信号周波数に対して前記第二の信号電圧源の信号周波数が整数倍であるＣＶ変換回路。   A CV conversion circuit in which the signal frequency of the second signal voltage source is an integral multiple of the signal frequency of the first signal voltage source. 非反転入力端子が接地された演算増幅器と、
一端が前記演算増幅器の出力に接続され、他端が前記演算増幅器の反転入力端子に接続された抵抗と、
一端が前記演算増幅器の反転入力端子に接続され、他端が第一の信号電圧源に接続された第一の容量と、
一端が前記演算増幅器の反転入力端子に接続され、他端が第二の信号電圧源に接続された第二の容量と、
一端が前記演算増幅器の反転入力端子に接続され、他端が第三の信号電圧源に接続された第三の容量とを有するＣＶ変換回路において、
前記第一の信号電圧源の信号周波数と前記第二の信号電圧源の信号周波数が等しく、かつ、前記第一の信号電圧源と前記第二の信号電圧源の信号周波数の位相が９０度ずれて、かつ、
前記第一と前記第二の信号電圧源の信号周波数に対して、前記第三の信号電圧源の信号周波数が整数倍であることを特徴とするＣＶ変換回路。 An operational amplifier with a non-inverting input terminal grounded;
A resistor having one end connected to the output of the operational amplifier and the other end connected to the inverting input terminal of the operational amplifier;
A first capacitor having one end connected to the inverting input terminal of the operational amplifier and the other end connected to a first signal voltage source;
A second capacitor having one end connected to the inverting input terminal of the operational amplifier and the other end connected to a second signal voltage source;
In a CV conversion circuit having a third capacitor having one end connected to the inverting input terminal of the operational amplifier and the other end connected to a third signal voltage source,
The signal frequency of the first signal voltage source and the signal frequency of the second signal voltage source are equal, and the phase of the signal frequency of the first signal voltage source and the second signal voltage source is shifted by 90 degrees. And once
The CV conversion circuit, wherein the signal frequency of the third signal voltage source is an integral multiple of the signal frequency of the first and second signal voltage sources. 非反転入力端子が接地された演算増幅器と、
一端が前記演算増幅器の出力に接続され、他端が前記演算増幅器の反転入力端子に接続された抵抗と、
一端が前記演算増幅器の反転入力端子に接続され、他端が第一の信号電圧源に接続された第一の容量と、
一端が前記演算増幅器の反転入力端子に接続され、他端が第二の信号電圧源に接続された第二の容量と、
一端が前記演算増幅器の反転入力端子に接続され、他端が第三の信号電圧源に接続された第三の容量とを有するＣＶ変換回路において、
前記第一の信号電圧源の信号周波数と前記第二の信号電圧源の信号周波数が等しく、かつ、前記第一の信号電圧源と前記第二の信号電圧源の信号周波数の位相が９０度ずれて、かつ、
前記第一と前記第二の信号電圧源の信号周波数に対して、前記第三の信号電圧源の信号周波数が整数分の１であることを特徴とするＣＶ変換回路。 An operational amplifier with a non-inverting input terminal grounded;
A resistor having one end connected to the output of the operational amplifier and the other end connected to the inverting input terminal of the operational amplifier;
A first capacitor having one end connected to the inverting input terminal of the operational amplifier and the other end connected to a first signal voltage source;
A second capacitor having one end connected to the inverting input terminal of the operational amplifier and the other end connected to a second signal voltage source;
In a CV conversion circuit having a third capacitor having one end connected to the inverting input terminal of the operational amplifier and the other end connected to a third signal voltage source,
The signal frequency of the first signal voltage source and the signal frequency of the second signal voltage source are equal, and the phase of the signal frequency of the first signal voltage source and that of the second signal voltage source are shifted by 90 degrees. And once
The CV conversion circuit, wherein the signal frequency of the third signal voltage source is 1 / integer of the signal frequency of the first and second signal voltage sources.
JP2004186160A 2004-03-31 2004-06-24 Cv conversion circuit Withdrawn JP2005315824A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7444870B2 (en) 2006-02-07 2008-11-04 Seiko Instruments Inc. Angular velocity sensor having one amplifying circuit for amplifying plural detection signals
CN115184686A (en) * 2022-07-20 2022-10-14 燕麦(杭州)智能制造有限公司 Capacitance test circuit and circuit board

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7444870B2 (en) 2006-02-07 2008-11-04 Seiko Instruments Inc. Angular velocity sensor having one amplifying circuit for amplifying plural detection signals
CN115184686A (en) * 2022-07-20 2022-10-14 燕麦(杭州)智能制造有限公司 Capacitance test circuit and circuit board

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