JPH0256849B2 - - Google Patents
Info
- Publication number
- JPH0256849B2 JPH0256849B2 JP58038678A JP3867883A JPH0256849B2 JP H0256849 B2 JPH0256849 B2 JP H0256849B2 JP 58038678 A JP58038678 A JP 58038678A JP 3867883 A JP3867883 A JP 3867883A JP H0256849 B2 JPH0256849 B2 JP H0256849B2
- Authority
- JP
- Japan
- Prior art keywords
- constant current
- current source
- amplifier
- output
- positive
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K3/00—Circuits for generating electric pulses; Monostable, bistable or multistable circuits
- H03K3/02—Generators characterised by the type of circuit or by the means used for producing pulses
- H03K3/023—Generators characterised by the type of circuit or by the means used for producing pulses by the use of differential amplifiers or comparators, with internal or external positive feedback
- H03K3/0231—Astable circuits
Description
【発明の詳細な説明】
この発明は増幅器の正帰還ループに容量素子を
設けると共に、正定電流源と負定電流源を互いに
切り換えて上記容量素子に定電流を供給すること
によつて浮遊容量の影響をなくする無安定マルチ
バイブレータにおいて、上記正負の定電流源の端
子間容量に起因する誤差をなくする無安定マルチ
バイブレータに関する。Detailed Description of the Invention The present invention provides a capacitive element in the positive feedback loop of an amplifier, and also switches between a positive constant current source and a negative constant current source to supply a constant current to the capacitive element, thereby reducing stray capacitance. The present invention relates to an astable multivibrator that eliminates the error caused by the capacitance between the terminals of the positive and negative constant current sources.
＜従来技術の説明＞
出願人は特願昭57−98740号「無安定マルチバ
イブレータ」において、増幅器の正帰還ループに
容量素子を設け、正定電流源と負定電流源を交互
に切り換えて上記容量素子に定電流を供給する構
成の、浮遊容量の影響を受けない無安定マルチバ
イブレータを提供した。第１図に基づいてまずこ
の回路を説明する。<Description of Prior Art> In Japanese Patent Application No. 57-98740 "Astable Multivibrator," the applicant provided a capacitive element in the positive feedback loop of an amplifier, and alternately switched between a positive constant current source and a negative constant current source to increase the capacitance. We have provided an astable multivibrator that is unaffected by stray capacitance and has a configuration that supplies constant current to the elements. This circuit will first be explained based on FIG.
第１図において１は増幅器、２は発振周波数を
決定するためのコンデンサ、３は浮遊容量、４は
正電圧源端子、５は負電圧源端子、６は正定電流
源、７は負定電流源である。８，９，１０，１１
はスイツチ素子であり、スイツチ素子８，９は縦
接続されて正定電流源６、負定電流源７の間に接
続され、スイツチ素子１０は正定電流源６と負電
圧源端子５の間にスイツチ素子１１は正電圧源端
子４と負定電流源７の間に接続されている。スイ
ツチ素子８，９の共通接続点は増幅器１の入力端
子に接続されている。これらのスイツチ素子は増
幅器１の出力によつて制御される。すなわち増幅
器１の出力が「Ｈ」のときはスイツチ素子９，１
０が導通、同８，１１が不導通になる。また増幅
器１の出力が「Ｌ」のときは上記の逆に制御され
る。 In Figure 1, 1 is an amplifier, 2 is a capacitor for determining the oscillation frequency, 3 is a stray capacitance, 4 is a positive voltage source terminal, 5 is a negative voltage source terminal, 6 is a positive constant current source, and 7 is a negative constant current source It is. 8,9,10,11
is a switch element, the switch elements 8 and 9 are connected vertically between the positive constant current source 6 and the negative constant current source 7, and the switch element 10 is connected between the positive constant current source 6 and the negative voltage source terminal 5. Element 11 is connected between positive voltage source terminal 4 and negative constant current source 7. The common connection point of the switch elements 8, 9 is connected to the input terminal of the amplifier 1. These switch elements are controlled by the output of amplifier 1. That is, when the output of amplifier 1 is "H", switch elements 9, 1
0 is conductive, and 8 and 11 are non-conductive. Further, when the output of the amplifier 1 is "L", the control is performed in the opposite manner to the above.
次に動作を説明する。増幅器１の出力が零から
＋Ｅに変化すると、増幅器１の入力端すなわちＡ
点の電位lAはそのスレツシユホールドレベルに
対して
lA＝Ｃ／Ｃ＋CsＥ ……(1)
だけ上昇する。Ｃ，Csはそれぞれコンデンサ２
浮遊容量３の容量である。このときスイツチ素子
９が導通し、Ａ点は負定電流源に接続されるので
Ａ点の電位は一定の割合で下降し、増幅器１のス
レツシユホールドレベル以下になるとその出力は
反転する。今度はＡ点の電位は上記のlAだけ下
降する。またスイツチ素子８が導通してＡ点は正
電圧源端子に接続されるので、その電位は一定の
割合で上昇し、スレツシユホールドレベルに達す
ると再び増幅器１の出力は反転してもとにもど
る。このような動作を繰り返して自励発振を行
う。今Ａ点の電位が上昇して再びスレツシユホー
ルドレベルにもどる時間をｔ１、負定電流源７の
電流をｉ１とすると
lA・（Ｃ＋Cs）＝i1・t1 ……(2)
が成立する。これを前記の(1)式に代入すると
t1＝Ｃ・Ｅ／i1 ……(3)
となる。すなわち発振周波数は浮遊容量Csに依
存しなくなる。尚定電流源６，７はスイツチ素子
１０，１１によつて、その出力端子がＡ点に接続
されていないときは、それぞれ電圧端子５，４に
接続している。このため定電流源は常時電流を出
力している。 Next, the operation will be explained. When the output of amplifier 1 changes from zero to +E, the input terminal of amplifier 1, that is, A
The potential lA at the point increases by lA=C/C+CsE (1) with respect to its threshold level. C and Cs are each capacitor 2
This is the capacitance of stray capacitance 3. At this time, switch element 9 becomes conductive and point A is connected to a negative constant current source, so that the potential at point A falls at a constant rate, and when it falls below the threshold level of amplifier 1, its output is reversed. This time, the potential at point A drops by the amount of lA above. Also, since the switch element 8 becomes conductive and the point A is connected to the positive voltage source terminal, its potential increases at a constant rate, and when it reaches the threshold level, the output of the amplifier 1 is reversed again and returns to the original state. Return. Self-oscillation is performed by repeating these operations. Now, if the time for the potential at point A to rise and return to the threshold level again is t1, and the current of the negative constant current source 7 is i1, lA.(C+Cs)=i1.t1...(2) holds true. Substituting this into equation (1) above gives t1=C・E/i1...(3). In other words, the oscillation frequency no longer depends on the stray capacitance Cs. The constant current sources 6 and 7 are connected to voltage terminals 5 and 4 by switch elements 10 and 11, respectively, when their output terminals are not connected to point A. Therefore, the constant current source always outputs current.
このように第１図記載の無安定マルチバイブレ
ータは、その発振周波数が浮遊容量に依存しない
ので、増幅器１の出力Ｅ、定電流源の出力電流ｉ
１を一定にすると、発振周波数は正確にコンデン
サ２の容量に比例する。またスイツチ素子１０，
１１により定電流源は常時電流を出力しているの
で、スイツチ素子を切り換えたときでもその出力
電流は変化しないので、発振周波数がさらに安定
になるという効果もある。 In this way, the astable multivibrator shown in FIG.
1 is kept constant, the oscillation frequency is exactly proportional to the capacitance of the capacitor 2. Moreover, the switch element 10,
11, the constant current source always outputs current, so even when the switch element is switched, the output current does not change, which has the effect of further stabilizing the oscillation frequency.
しかしながらこの従来例には以下に示すような
欠点がある。第２図は増幅器１の高いレベル出力
をＥ、そのスレツシユホールドレベルの電位を
0.5E、負電圧端子５の電位を零にしたときの正定
電流源６の出力端子の電位を示す。時点ｔ１でス
イツチ素子８が導通、スイツチ素子１０が不導通
制御されると、正定電流源６の出力端子の電位は
瞬間的に零から（0.5E−lA）（lAは前記(1)式で示
した値）に変化する。この電位は一定の割合で上
昇し、時点ｔ２でスレツシユホールドレベルに達
するるとスイツチ素子８が不導通、同１１が導通
し、瞬間的に零電位に低下する。すなわち時点ｔ
１，ｔ２で電位は瞬間的に大きく変化する。負定
電流源７の出力端子の電位も同様に変化する。そ
のため正負定電流源６，７の端子間容量を通して
逆相電流が流れ、発振周波数が変化する。正負定
電流源の端子間容量をCGとし、増幅器１のスレ
ツシユホールドレベルを0.5Eとすると、前記(1)(2)
式は下記(4)(5)式で置き換えなければならない。(4)
式の第２項が逆相電流による影響を表わす。 However, this conventional example has the following drawbacks. Figure 2 shows the high level output of amplifier 1 as E, and its threshold level potential as E.
0.5E, which indicates the potential of the output terminal of the positive constant current source 6 when the potential of the negative voltage terminal 5 is set to zero. When the switch element 8 is turned on and the switch element 10 is turned off at time t1, the potential at the output terminal of the positive constant current source 6 instantly changes from zero to (0.5E-lA) (where lA is expressed in equation (1) above). the value shown). This potential increases at a constant rate, and when it reaches the threshold level at time t2, switch element 8 becomes non-conductive, switch element 11 becomes conductive, and the potential drops instantaneously to zero. That is, time t
1, the potential changes greatly instantaneously at t2. The potential of the output terminal of the negative constant current source 7 changes similarly. Therefore, a negative phase current flows through the capacitance between the terminals of the positive and negative constant current sources 6 and 7, and the oscillation frequency changes. If the capacitance between the terminals of the positive and negative constant current sources is CG, and the threshold level of amplifier 1 is 0.5E, then (1) and (2) above are obtained.
The formula must be replaced with the following formulas (4) and (5). (Four)
The second term in the equation represents the influence of negative sequence current.
lA＝Ｃ／Ｃ＋CS＋CGＥ＋CG／Ｃ＋CS＋CG（−0.5）
……(4)
lA・（Ｃ＋CS＋CG）＝i1・t1 ……(5)
従つて前記(3)式に相当する発振周期を表わす式
は次のようになる。lA=C/C+CS+CGE+CG/C+CS+CG(-0.5)...(4) lA・(C+CS+CG)=i1・t1...(5) Therefore, the equation representing the oscillation period corresponding to the above equation (3) is as follows. Become.
t1＝（ｃ−0.5CG）・Ｅ／i1 ……(6)
すなわち発振周波数はコンデンサ２の容量Ｃだ
けでなく、定電流源６，７の端子間容量CGにも
依存するようになる。CGは素子によつてばらつ
きがあり、また周囲環境の変化によつても変化す
るので、発振周波数が不安定になる原因となる。 t1=(c-0.5CG)・E/i1 (6) That is, the oscillation frequency depends not only on the capacitance C of the capacitor 2 but also on the capacitance CG between the terminals of the constant current sources 6 and 7. CG varies depending on the element and also changes due to changes in the surrounding environment, which causes the oscillation frequency to become unstable.
＜発明の概要＞
この発明の目的は増幅器の入力端子に接続され
ていない定電流源の出力端子の電位を該増幅器の
スレツシユホールドレベル近辺に固定することに
よつて、定電流源の端子間容量を通じて流れる逆
相電流による誤差を防止することができる無安定
マルチバイブレータを提供することにある。<Summary of the Invention> An object of the present invention is to fix the potential of the output terminal of a constant current source, which is not connected to the input terminal of an amplifier, near the threshold level of the amplifier, thereby reducing the potential between the terminals of the constant current source. An object of the present invention is to provide an astable multivibrator that can prevent errors caused by negative sequence current flowing through a capacitor.
＜第１実施例＞
第３図にこの発明の第１の実施例を示す。１は
増幅器、２はコンデンサ、３は浮遊容量、４は正
電圧源端子、６，７はそれぞれ正，負定電流源、
８，９，１０，１１はスイツチ素子であり、第１
図従来例と同じ働きをするので説明を省略する。
尚この実施例では特に負電圧源端子を設けず、負
電流源７の一端は共通電位点に接続されている。
この実施例においては正電圧源端子４の電圧を抵
抗１２，１３，１４で分圧し、スイツチ素子１
０，１１の定電流源に接続されていない側の端子
をこれら分圧抵抗の接続点に接続する。抵抗１
２，１３，１４の分圧比は、各抵抗の接続点すな
わちスイツチ素子１０，１１の他端の電位が増幅
器１のスレツシユホールドレベルの近辺になるよ
うに設定される。第２図に対応する正定電流源６
の出力端子の電位を第４図に示す。この図からわ
かるようにスイツチ素子が切り換わつたときの電
位の瞬間的変化はＥ１の程度となり、第２図に比
べて大幅に少なくなる。そのため前記(4)式は下記
の(7)式となり発振周期を表わす前記(6)式となる。<First Embodiment> FIG. 3 shows a first embodiment of the present invention. 1 is an amplifier, 2 is a capacitor, 3 is a stray capacitance, 4 is a positive voltage source terminal, 6 and 7 are positive and negative constant current sources, respectively.
8, 9, 10, 11 are switch elements, and the first
Since the function is the same as that of the conventional example shown in the figure, the explanation will be omitted.
In this embodiment, a negative voltage source terminal is not particularly provided, and one end of the negative current source 7 is connected to a common potential point.
In this embodiment, the voltage at the positive voltage source terminal 4 is divided by resistors 12, 13, and 14, and the switch element 1
The terminals on the side not connected to the constant current sources 0 and 11 are connected to the connection point of these voltage dividing resistors. resistance 1
The voltage division ratios 2, 13, and 14 are set so that the potential at the connection point of each resistor, that is, the other end of the switch elements 10, 11, is near the threshold level of the amplifier 1. Positive constant current source 6 corresponding to Fig. 2
The potential of the output terminal of is shown in FIG. As can be seen from this figure, the instantaneous change in potential when the switch element is switched is on the order of E1, which is much smaller than that in FIG. 2. Therefore, the above equation (4) becomes the following equation (7) and becomes the above equation (6) representing the oscillation period.
lA＝Ｃ／Ｃ＋Cs＋CGＥ＋CG／Ｃ＋Cs＋CG（−E1）
……(7)
t1＝（Ｃ−E1／Ｅ・CG）・Ｅ／i1 ……(8)
すなわち抵抗１２，１３，１４の分圧比を調整
して分圧電圧がスレツシユホールドに近くなるよ
うにしＥ１を小さくすることによつて、定電流源
６，７の端子間容量CGの影響を軽減することが
できる。尚この実施例において、抵抗１３を挿入
してスイツチ素子１０と同１１にかける電圧を異
ならしめたのは、時点ｔ１による電位の瞬間的変
化を小さくするためである。 lA=C/C+Cs+CGE+CG/C+Cs+CG(-E1)...(7) t1=(C-E1/E・CG)・E/i1...(8) In other words, adjust the voltage division ratio of resistors 12, 13, and 14. By making the divided voltage close to the threshold and reducing E1, the influence of the capacitance CG between the terminals of the constant current sources 6 and 7 can be reduced. In this embodiment, the reason why the resistor 13 is inserted and the voltages applied to the switch elements 10 and 11 are made different is to reduce the instantaneous change in potential at time t1.
＜第２実施例＞
第５図に第２の実施例を示す。この実施例では
スイツチ素子１０，１１の代わりにダイオード１
５，１６を接続している。ダイオード１５はその
アノードを正定電源６の出力端子に、カソードを
抵抗１７，１８からなる分圧回路に接続する。ま
たダイオード１６はカソードを負定電流源７の出
力端子に、アノードを抵抗１７，１８からなる分
圧回路に接続している。第４図からわかるように
スイツチ素子８が導通している間（第４図のｔ１
とｔ２の間）は正定電流源６の出力端子の電位は
増幅器１のスレツシユホールドレベルより低くな
るので抵抗１７と１８からなる分圧回路の出力電
圧をスレツシユホールドレベルに等しく設定する
と、分圧回路と正定電流源６の出力端子はダイオ
ード１５により切り換される。またスイツチ素子
８が不導通になると、正定電流源６の出力電流は
ダイオード１５を通して流れる。またダイオード
１６も同様にして動作する。すなわちダイオード
１５，１６は第３図の第１の実施例のスイツチ素
子１０，１１と同じ動作をすることになる。<Second Example> A second example is shown in FIG. In this embodiment, a diode 1 is used instead of the switch elements 10 and 11.
5 and 16 are connected. The diode 15 has its anode connected to the output terminal of the positive constant power supply 6 and its cathode connected to a voltage dividing circuit consisting of resistors 17 and 18. Further, the diode 16 has a cathode connected to the output terminal of the negative constant current source 7 and an anode connected to a voltage dividing circuit consisting of resistors 17 and 18. As can be seen from FIG. 4, while the switch element 8 is conducting (t1 in FIG.
and t2), the potential at the output terminal of the positive constant current source 6 is lower than the threshold level of the amplifier 1, so if the output voltage of the voltage divider circuit consisting of resistors 17 and 18 is set equal to the threshold level, The voltage circuit and the output terminal of the positive constant current source 6 are switched by a diode 15. Further, when the switch element 8 becomes non-conductive, the output current of the positive constant current source 6 flows through the diode 15. The diode 16 also operates in the same manner. That is, the diodes 15 and 16 operate in the same manner as the switch elements 10 and 11 of the first embodiment shown in FIG.
＜第３実施例＞
第６図に第３の実施例を示す。この例ではスイ
ツチ素子としてダイオード１９，２０，２１，２
２を使用している。今増幅器１の出力が「Ｈ」に
なつたとするとインバータ２４の出力「Ｌ」にな
る。そのため正定電流源６の出力電流はダイオー
ド１９を通してインバータ２４へ流れ込む。また
コンデンサ２、浮遊容量３に蓄積された電荷はダ
イオード２１を通して負定電流源７に流れ込む。
増幅器１の出力が「Ｌ」になると負定電流源７に
はインバータ２４から電流が流れ込み、また正定
電流源６からコンデンサ２、浮遊容量３に電荷が
供給される。このようにしてダイオード１９〜２
２は第１の実施例のスイツチ素子８〜１１と同様
の動作をする。この実施例ではさらにインバータ
２４の出力側に抵抗２３が設けられている。この
抵抗の電圧降下により、増幅器１の入力端に接続
されていないときの定電流源６，７の出力端子の
電位を該増幅器のスレツシユホールドレベル近辺
に設定することによつて第１，第２実施例と同様
の効果を得ることができる。尚インバータ２４の
出力は第７図のように抵抗２５，２６で分圧して
ダイオード回路に接続してもよい。<Third Example> A third example is shown in FIG. In this example, diodes 19, 20, 21, 2 are used as switch elements.
2 is used. If the output of the amplifier 1 now becomes "H", the output of the inverter 24 becomes "L". Therefore, the output current of the positive constant current source 6 flows into the inverter 24 through the diode 19. Further, the charges accumulated in the capacitor 2 and the stray capacitance 3 flow into the negative constant current source 7 through the diode 21.
When the output of the amplifier 1 becomes "L", current flows into the negative constant current source 7 from the inverter 24, and charges are supplied to the capacitor 2 and the stray capacitance 3 from the positive constant current source 6. In this way, diodes 19-2
2 operates in the same manner as the switch elements 8 to 11 of the first embodiment. In this embodiment, a resistor 23 is further provided on the output side of the inverter 24. Due to the voltage drop across this resistor, the potential of the output terminals of the constant current sources 6 and 7 when they are not connected to the input terminal of the amplifier 1 is set near the threshold level of the amplifier. The same effects as in the second embodiment can be obtained. The output of the inverter 24 may be divided by resistors 25 and 26 and connected to a diode circuit as shown in FIG.
＜応用例＞
第３図の第１の実施例の無安定マルチバイブレ
ータを用いて２つの容量の和と差との比に比例し
た出力を得る例を第８図に第３図と対応する部分
に同一符号を付けて示す。増幅器１からの発振出
力はｎビツトカウンタ３７に入力されて計数され
カウンタ３７のｎビツト目の出力端子３８はイン
バータ３９を介してまた介することなく直接
NANDゲート２７，２８へ供給される。カウン
タ３７に計数値が2n-2になる前は端子３８が低レ
ベルでゲート２７が開かれ、増幅器１の発振出力
はインバータ３６を通じてNANDゲート２７へ
供給される。NANDゲート２７，２８の各出力
は容量３１ａ，３１ｂの電極３２ａ，３２ｂに接
続される。また電極３２ａ，３２ｂに対向して共
通電極３３が設けられ、増幅器１の非反転入力端
子に接続されると共にスイツチ素子８，９の接続
点に接続される。共通電極３３は測定すべき物理
量によつて移動させられ、そのため容量３１ａ，
３２ｂは互いに逆方向に変位させられる。増幅器
１の非反転入力端子の発振信号は低域通過波器
３４で直流化されると共に、端子３５の基準電圧
と加算されて、しきい値電圧として増幅器１の反
転入力端子へ供給される。NANDゲート２７が
開かれていると増幅器１に容量３１ａが正帰還ル
ープを構成するように接続され、従つてこの容量
に逆比例する周波数ｆ１で発振する。カウンタ３
７の計数値が2n-1に達すると、ｎビツトの端子３
８が「Ｈ」になり、NANDゲート２８が開き容
量３１ｂが増幅器１の正帰還ループに接続され、
この容量に逆比例した周波数ｆ２の発振が発生す
る。カウンタ３７の計数値が2nになると、端子３
８の出力が「Ｌ」になり、以上のことが繰り返さ
れる。従つてカウンタ３７の端子３８の出力は周
波数ｆ１を2n-1個計数している期間は「Ｌ」、周
波数ｆ２を2n-1個計数している期間は「Ｈ」にな
り、これが繰り返される。この出力は平滑回路４
０で平滑され、この平滑出力は、f1−f2／f1＋f2に比例
したアナログ値になる。NANDゲート２７，２
８の出力はNANDゲート２９へも供給され、
NANDゲート２９の出力側は容量は３１ａ，３
１ｂに並列に付加される浮遊容量の影響を除く並
列浮遊容量補償容量素子３０を通じて、増幅器１
の非反転入力端子に接続される。<Application example> An example of obtaining an output proportional to the ratio of the sum and difference of two capacitances using the astable multivibrator of the first embodiment shown in Fig. 3 is shown in Fig. 8, which corresponds to Fig. 3. are shown with the same symbols. The oscillation output from the amplifier 1 is input to an n-bit counter 37 and counted, and the n-th output terminal 38 of the counter 37 is directly inputted via an inverter 39 or not.
It is supplied to NAND gates 27 and 28. Before the count value of the counter 37 reaches 2 n -2, the terminal 38 is at a low level and the gate 27 is opened, and the oscillation output of the amplifier 1 is supplied to the NAND gate 27 through the inverter 36 . Each output of the NAND gates 27 and 28 is connected to electrodes 32a and 32b of capacitors 31a and 31b. Further, a common electrode 33 is provided opposite the electrodes 32a and 32b, and is connected to the non-inverting input terminal of the amplifier 1 and to the connection point of the switch elements 8 and 9. The common electrode 33 is moved by the physical quantity to be measured, so that the capacitances 31a,
32b are displaced in opposite directions. The oscillation signal at the non-inverting input terminal of the amplifier 1 is converted into a DC signal by the low-pass wave generator 34, added to the reference voltage at the terminal 35, and supplied to the inverting input terminal of the amplifier 1 as a threshold voltage. When the NAND gate 27 is open, the capacitor 31a is connected to the amplifier 1 to form a positive feedback loop, and therefore oscillates at a frequency f1 that is inversely proportional to this capacitance. counter 3
When the count value of 7 reaches 2 n-1 , the n-bit terminal 3
8 becomes "H", the NAND gate 28 opens and the capacitor 31b is connected to the positive feedback loop of the amplifier 1.
Oscillation with a frequency f2 that is inversely proportional to this capacitance occurs. When the count value of the counter 37 reaches 2 n , the terminal 3
The output of 8 becomes "L" and the above steps are repeated. Therefore, the output of the terminal 38 of the counter 37 is "L" during the period when 2 n-1 frequencies f1 are counted, and "H" during the period when 2 n-1 frequencies f2 are counted, and this is repeated. It will be done. This output is the smoothing circuit 4
0, and this smoothed output becomes an analog value proportional to f1-f2/f1+f2. NAND gate 27,2
The output of 8 is also supplied to the NAND gate 29,
The output side of the NAND gate 29 has a capacity of 31a, 3
The amplifier 1
is connected to the non-inverting input terminal of
＜発明の効果＞
このようにこの発明では増幅器１の入力端子に
接続されていない側の定電流源の出力端子の電位
を該増幅器のスレツシユホールドレベルの近辺に
維持することによつて、定電流源の出力端子の電
位を急激な変化を小さくしている。そのため定電
流源の端子間容量を通して流れる誤差電流の大き
さが小さくなり、出力周波数が正確にコンデンサ
の容量に比例するという特徴を有する。このよう
な無安定マルチバイブレータは、第８図の応用例
に示したように、物流量を容量に変換してその容
量の大きさを測定することによつて、物理量を測
定する測定装置に用いて特に好適である。<Effects of the Invention> As described above, in this invention, by maintaining the potential of the output terminal of the constant current source that is not connected to the input terminal of the amplifier 1 near the threshold level of the amplifier, Sudden changes in the potential of the output terminal of the current source are minimized. Therefore, the magnitude of the error current flowing through the capacitance between the terminals of the constant current source is reduced, and the output frequency is precisely proportional to the capacitance of the capacitor. As shown in the application example in Figure 8, such an astable multivibrator is used in a measuring device that measures physical quantities by converting the flow rate into capacity and measuring the size of the capacity. This is particularly suitable.
第１図は従来の無安定マルチバイブレータを示
す接続図、第２図は第１図の従来例における正定
電流源の出力端子の電位を示す図、第３図はこの
発明の無安定マルチバイブレータの１実施例を示
す接続図、第４図は第３図実施例における正定電
流源の出力端子の電位を示す図、第５図はこの発
明の無安定マルチバイブレータの第２の実施例を
示す接続図、第６図はこの発明の無安定マルチバ
イブレータの第３の実施例を示す接続図、第７図
は第６図実施例の電圧降下手段の他の実施例、第
８図はこの発明の無安定マルチバイブレータを利
用した２つの容量の和と差の比に比例した出力を
得る装置の接続図である。
１：増幅器、２：コンデンサ、３：浮遊容量、
６：正定電流源、７：負定電流源、８，９，１
０，１１：スイツチ素子、２，４，３，６：イン
バータ。
Fig. 1 is a connection diagram showing a conventional astable multivibrator, Fig. 2 is a diagram showing the potential of the output terminal of the positive constant current source in the conventional example of Fig. 1, and Fig. 3 is a diagram of the astable multivibrator of the present invention. 4 is a diagram showing the potential of the output terminal of the positive constant current source in the embodiment shown in FIG. 3, and FIG. 5 is a connection diagram showing the second embodiment of the astable multivibrator of the present invention. 6 is a connection diagram showing a third embodiment of the astable multivibrator of the present invention, FIG. 7 is another embodiment of the voltage drop means of the embodiment of FIG. 6, and FIG. 8 is a connection diagram showing a third embodiment of the astable multivibrator of the present invention. FIG. 2 is a connection diagram of a device that uses an astable multivibrator to obtain an output proportional to the ratio of the sum and difference of two capacitances. 1: Amplifier, 2: Capacitor, 3: Stray capacitance,
6: Positive constant current source, 7: Negative constant current source, 8, 9, 1
0, 11: switch element, 2, 4, 3, 6: inverter.
Claims (1)
するように接続された容量素子と、正定電流源
と、負定電流源を有し、上記増幅器の出力に応じ
て上記正定電流源と上記負定電流源から交互に上
記容量素子に電流を供給すると共に上記正定電流
源と上記負定電流源のうち上記容量素子に電流を
供給していない側の定電流源の出力端子の電位を
ほぼ上記増幅器のスレツシユホールドレベルに維
持するようにしたことを特徴とする無安定マルチ
バイブレータ。1 comprises an amplifier, a capacitive element connected to the amplifier so as to form a positive feedback loop, a positive constant current source, and a negative constant current source, the positive constant current source and the negative constant current source depending on the output of the amplifier. Current is alternately supplied from the current source to the capacitive element, and the potential of the output terminal of the constant current source that is not supplying current to the capacitive element among the positive constant current source and the negative constant current source is approximately set to the amplifier. An astable multivibrator characterized by maintaining the threshold at a threshold level of .
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP58038678A JPS59165516A (en) | 1983-03-09 | 1983-03-09 | Unstable multivibrator |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP58038678A JPS59165516A (en) | 1983-03-09 | 1983-03-09 | Unstable multivibrator |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS59165516A JPS59165516A (en) | 1984-09-18 |
| JPH0256849B2 true JPH0256849B2 (en) | 1990-12-03 |
Family
ID=12531932
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP58038678A Granted JPS59165516A (en) | 1983-03-09 | 1983-03-09 | Unstable multivibrator |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS59165516A (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0735677B1 (en) * | 1995-03-31 | 1999-12-22 | Co.Ri.M.Me. Consorzio Per La Ricerca Sulla Microelettronica Nel Mezzogiorno | Oscillator circuit having oscillation frequency independent from the supply voltage value |
| US5990753A (en) * | 1996-01-29 | 1999-11-23 | Stmicroelectronics, Inc. | Precision oscillator circuit having a controllable duty cycle and related methods |
-
1983
- 1983-03-09 JP JP58038678A patent/JPS59165516A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS59165516A (en) | 1984-09-18 |
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