JP2006270641A - Oscillation circuit - Google Patents

Oscillation circuit Download PDF

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Publication number
JP2006270641A
JP2006270641A JP2005087173A JP2005087173A JP2006270641A JP 2006270641 A JP2006270641 A JP 2006270641A JP 2005087173 A JP2005087173 A JP 2005087173A JP 2005087173 A JP2005087173 A JP 2005087173A JP 2006270641 A JP2006270641 A JP 2006270641A
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current
oscillation
circuit
multivibrator
vbe
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Tsuyoshi Nakazato
剛志 中里
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New Japan Radio Co Ltd
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New Japan Radio Co Ltd
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a multivibrator type oscillator wherein temperature variations in an oscillated frequency oscillated on the basis of a base-emitter voltage Vbe can be cancelled. <P>SOLUTION: The oscillation circuit with a multivibrator for oscillating a frequency f expressed by f=I1/(4Vbe×C1), wherein I1 is an operating current, C1 is a capacity related to oscillation, and Vbe is a base-emitter voltage of a transistor related to the oscillation, a reference current I5 is generated by applying a voltage generated in a plurality of diode-connection transistors Q21 to Q2n connected in series to a resistor R3 and a current obtained by adjusting the reference current I5 is supplied to the multivibrator as the operating current I1. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

本発明は、マルチバイブレータの動作電流を制御することにより発振周波数を制御できる発振回路に係り、特に発振周波数の温度依存性を無くした発振回路に関するものである。   The present invention relates to an oscillation circuit that can control an oscillation frequency by controlling an operating current of a multivibrator, and more particularly to an oscillation circuit that eliminates the temperature dependence of the oscillation frequency.

図3は従来から使用されているマルチバイブレータ型発振器の回路図(例えば、特許文献1、非特許文献1参照)である。NPNトランジスタQ1〜Q4、抵抗R1〜R2、ダイオードDl〜D2、容量C1、電流源I1〜I4で構成される。   FIG. 3 is a circuit diagram of a conventional multivibrator oscillator (see, for example, Patent Document 1 and Non-Patent Document 1). NPN transistors Q1 to Q4, resistors R1 to R2, diodes D1 to D2, a capacitor C1, and current sources I1 to I4.

図3において、トランジスタQ1がオンし、ダイオードD1に電流がながれている時、トランジスタQ2はオフしているため、電流源I2の吸い込み電流I2によって電位VBが徐々に低下する。この電位VBが電位VAと比較し1Vbe(トランジスタQ2のベース・エミッタ間電圧)分低下した時、今度はトランジスタQ2がオンするため、トランジスタQ3がオフしてトランジスタQ1がオフする。トランジスQ1がオフした時、電位VAはトランジスタQ1がオンしていた時よりも1Vbeだけ高い電圧にあり、そこから電流源I1の吸い込み電流I1によって徐々に低下する。かくして、電位VAとVBの波形は図4に示すようになり、差分VA−VBを取り出すことにより発振出力を得ることができる。   In FIG. 3, when the transistor Q1 is turned on and the current is flowing to the diode D1, the transistor Q2 is turned off, so that the potential VB gradually decreases due to the sink current I2 of the current source I2. When this potential VB decreases by 1 Vbe (base-emitter voltage of the transistor Q2) compared to the potential VA, the transistor Q2 is turned on this time, so that the transistor Q3 is turned off and the transistor Q1 is turned off. When the transistor Q1 is turned off, the potential VA is at a voltage higher by 1 Vbe than when the transistor Q1 is turned on, and gradually decreases by the sink current I1 of the current source I1. Thus, the waveforms of the potentials VA and VB are as shown in FIG. 4, and an oscillation output can be obtained by extracting the difference VA−VB.

以上から、1周期にかかる時間は、
T=4Vbe×C1/I1
となるから、この発振器の発振周波数は、
f=I1/(4Vbe×C1) (1)
で決定される。なお、I1=I2である。
特開平4−117019号公報 JOSEPH F.KUKIELKA and ROBERT G. MEYER,”A High-Frequency Temperature-Stable Monolithic VCO” IEEE JOURNAL OF SOLID-STATE CIRCUITS,VOL.SC-16,NO.16,DECEMBER p639-647 1981
From the above, the time required for one cycle is
T = 4Vbe × C1 / I1
Therefore, the oscillation frequency of this oscillator is
f = I1 / (4Vbe × C1) (1)
Determined by Note that I1 = I2.
Japanese Patent Laid-Open No. 4-11709 JOSEPH F.KUKIELKA and ROBERT G. MEYER, “A High-Frequency Temperature-Stable Monolithic VCO” IEEE JOURNAL OF SOLID-STATE CIRCUITS, VOL.SC-16, NO.16, DECEMBER p639-647 1981

ところが、上記発振器では、発振周波数の式がf=I1/(4Vbe×Cl)であり、これを決める要素であるVbeは温度係数を持つため、発振周波数が周囲温度に対し大きく依存してしまう。Vbeは温度が高くなるほどその値が小さくなるので、結局温度が高くなると、発振周波数が高くなるという問題があった。   However, in the oscillator, the oscillation frequency formula is f = I1 / (4Vbe × Cl), and Vbe, which is an element that determines this, has a temperature coefficient, and therefore the oscillation frequency greatly depends on the ambient temperature. Since the value of Vbe decreases as the temperature increases, there is a problem that the oscillation frequency increases as the temperature eventually increases.

本発明の目的は、上記問題点を改善し、Vbeによる発振周波数の温度変動をキャンセルしたマルチバイブレータ型の発振器を提供することである。   An object of the present invention is to provide a multivibrator type oscillator that improves the above-described problems and cancels temperature fluctuations of the oscillation frequency due to Vbe.

上記課題を解決するために、本発明は、動作電流をI1とし、発振に関わる容量をC1とし、発振に関わるトランジスタのベース・エミッタ間電圧をVbeとするとき、f=I1/(4Vbe×C1)で表される周波数fを発振するマルチバイブレータを有する発振回路において、前記Vbeの成分に相当する電流を生成し、該電流を前記動作電流I1として前記マルチバイブレータに供給する手段を設けたことを特徴とする。   In order to solve the above problems, the present invention provides f = I1 / (4Vbe × C1) where the operating current is I1, the capacitance relating to oscillation is C1, and the base-emitter voltage of the transistor relating to oscillation is Vbe. In the oscillation circuit having a multivibrator that oscillates at a frequency f expressed by (2), there is provided means for generating a current corresponding to the component of Vbe and supplying the current to the multivibrator as the operating current I1. Features.

ここで、前記手段は、1又は2以上直列接続されたダイオード接続のトランジスタに発生する電圧を所定の抵抗に印加して基準電流を生成する基準電流生成回路と、該基準電流生成回路で生成された基準電流の値を調整する電流増幅回路とからなり、該電流増幅回路から得られた電流を前記動作電流I1として前記マルチバイブレータに供給することが望ましい。   Here, the means is generated by a reference current generating circuit that generates a reference current by applying a voltage generated in one or two or more diode-connected transistors connected in series to a predetermined resistor, and the reference current generating circuit generates the reference current. It is desirable that the current amplifying circuit for adjusting the value of the reference current is supplied, and the current obtained from the current amplifying circuit is supplied to the multivibrator as the operating current I1.

本発明によれば、f=I1/(4Vbe×C1)で表される周波数fにかかわる動作電流I1を、Vbeの成分に相当する成分を含む電流としてマルチバイブレータに供給するので、Vbeの成分をキャンセルすることができ、発振周波数の温度依存性をなくすることができる。   According to the present invention, the operating current I1 related to the frequency f represented by f = I1 / (4Vbe × C1) is supplied to the multivibrator as a current including a component corresponding to the component of Vbe. The frequency dependence of the oscillation frequency can be eliminated.

図1は本発明の実施例のマルチバイブレーター型発振器を示す回路図である。図1において、1は図3に示したのと同じマルチバイブレータである。2はこのマルチバイブレータ1の駆動電流を増幅する電流増幅回路であり、トランジスタQ5〜Q10から構成されている。3はキャンセル用の温度係数をもつ基準電流を生成する基準電流生成回路であり、オペアンプOP1、トランジスタQ10、Q21〜Q2n、抵抗R3、R4から構成されている。   FIG. 1 is a circuit diagram showing a multivibrator oscillator according to an embodiment of the present invention. In FIG. 1, 1 is the same multivibrator as shown in FIG. Reference numeral 2 denotes a current amplifying circuit for amplifying the driving current of the multivibrator 1 and is composed of transistors Q5 to Q10. Reference numeral 3 denotes a reference current generation circuit that generates a reference current having a canceling temperature coefficient, and includes an operational amplifier OP1, transistors Q10, Q21 to Q2n, and resistors R3 and R4.

基準電流生成回路3では、オペアンプOP1の非反転入力端子(+)と接地間に、n個のダイオード接続のトランジスタQ21〜Q2nが接続されているので、その非反転入力端子(+)には、抵抗R4を介して流れる電流により発生するn×Vbeの電圧が印加する。Vbeは各トランジスタQ21〜Q2nのベース・エミッタ間電圧である。そして、このオペアンプOP1の出力がトランジスタQ10にベースに入力し、このトランジスタQ10のエミッタの抵抗R3に生じた電圧がオペアンプOP1の反転入力端子(−)に入力している。このとき、オペアンプOP1の特性により、抵抗R3に生じる電圧は、n×Vbeとなる。よって、トランジスタQ10のコレクタにはn×Vbe/R3の電流I5が流れる。つまり、基準電流生成回路3ではn×Vbe/R3の電流I5が生成される。   In the reference current generation circuit 3, since n diode-connected transistors Q21 to Q2n are connected between the non-inverting input terminal (+) of the operational amplifier OP1 and the ground, the non-inverting input terminal (+) A voltage of n × Vbe generated by the current flowing through the resistor R4 is applied. Vbe is a base-emitter voltage of each of the transistors Q21 to Q2n. The output of the operational amplifier OP1 is input to the base of the transistor Q10, and the voltage generated in the resistor R3 of the emitter of the transistor Q10 is input to the inverting input terminal (−) of the operational amplifier OP1. At this time, due to the characteristics of the operational amplifier OP1, the voltage generated in the resistor R3 is n × Vbe. Therefore, a current I5 of n × Vbe / R3 flows through the collector of the transistor Q10. That is, the reference current generation circuit 3 generates an n × Vbe / R3 current I5.

この電流I5は、電流増幅回路2のトランジスタQ8,Q9によるカレントミラー動作により電流I6となってトランジスタQ7に供給される。このトランジスタQ7はトランジスタQ5,Q6とカレントミラー接続されているので、そのトランジスタQ5,Q6を流れる電流I1,I2は電流I6に応じた電流となる。いま、トランジスタQ8,Q9によるカレントミラー回路のカレントミラー比をa、トランジスタQ5〜Q7によるカレントミラー回路のカレントミラー比をbとすれば、
I1=I2=a×b×n×Vbe/R3 (2)
となる。
This current I5 is supplied as a current I6 to the transistor Q7 by the current mirror operation of the transistors Q8 and Q9 of the current amplifier circuit 2. Since the transistor Q7 is current mirror connected to the transistors Q5 and Q6, the currents I1 and I2 flowing through the transistors Q5 and Q6 are currents corresponding to the current I6. Now, if the current mirror ratio of the current mirror circuit by the transistors Q8 and Q9 is a and the current mirror ratio of the current mirror circuit by the transistors Q5 to Q7 is b,
I1 = I2 = a * b * n * Vbe / R3 (2)
It becomes.

前記したように、マルチバイブレータ1で発生する周波数fの式(1)には、4Vbeの項が含まれていたので、式(2)のa×b×nを、「a×b×n=4」となるように設定すれば、式(2)は、
I1=I2=4Vbe/R3 (3)
となり、式(1)にこの式(3)を代入すれば、4Vbeの項がキャンセルされる。以上により、温度変動の影響を受けるVbeが発振周波数と無関係になるので、発振周波数が温度補償されることになる。
As described above, since the expression (1) of the frequency f generated in the multivibrator 1 includes the term of 4 Vbe, a × b × n in the expression (2) is changed to “a × b × n = If it is set to “4”, equation (2) becomes
I1 = I2 = 4Vbe / R3 (3)
If this equation (3) is substituted into equation (1), the term of 4Vbe is canceled. As described above, Vbe, which is affected by temperature fluctuations, is independent of the oscillation frequency, so that the oscillation frequency is temperature compensated.

図2は図1に示した発振回路を具体化した回路図である。ここでは、電流増幅回路2の前段のカレントミラー回路としてトランジスタQ8,Q9の他にエミッタホロワのトランジスタQ12も加え、また後段のカレントミラー回路としてトランジスタQ5〜Q7の他にエミッタホロワトランジスタQ11も加えて、それらのカレントミラー回路におけるカレントミラー比の精度を高めている。また、オペアンプOP1はトランジスタQ13〜Q16と抵抗R5により構成している。   FIG. 2 is a circuit diagram embodying the oscillation circuit shown in FIG. In this example, an emitter follower transistor Q12 is added in addition to the transistors Q8 and Q9 as a current mirror circuit in the previous stage of the current amplifier circuit 2, and an emitter follower transistor Q11 is added in addition to the transistors Q5 to Q7 as a current mirror circuit in the subsequent stage. The accuracy of the current mirror ratio in these current mirror circuits is increased. The operational amplifier OP1 is composed of transistors Q13 to Q16 and a resistor R5.

なお、以上ではダイオード接続のトランジスタをQ21〜Q2nに示すようにn個使用したが、これは1個であってもよい。この場合は、電流増幅回路2のカレントミラー回路のカレントミラー比の設定のみにより、動作電流I1として4Vbeの成分をもつ電流を生成すればよい。   In the above description, n diode-connected transistors are used as indicated by Q21 to Q2n. However, this may be one. In this case, a current having a component of 4 Vbe may be generated as the operating current I1 only by setting the current mirror ratio of the current mirror circuit of the current amplifier circuit 2.

本発明の実施例の発振回路のブロック図である。It is a block diagram of the oscillation circuit of the Example of this invention. 本発明の実施例の発振回路の具体的な回路図である。It is a specific circuit diagram of the oscillation circuit of the embodiment of the present invention. 従来の発振回路の回路図である。It is a circuit diagram of the conventional oscillation circuit. 図3の発振回路の動作波形図である。FIG. 4 is an operation waveform diagram of the oscillation circuit of FIG. 3.

符号の説明Explanation of symbols

1:マルチバイブレータ
2:電流増幅回路
3:基準電流生成回路
1: Multivibrator 2: Current amplification circuit 3: Reference current generation circuit

Claims (2)

動作電流をI1とし、発振に関わる容量をC1とし、発振に関わるトランジスタのベース・エミッタ間電圧をVbeとするとき、f=I1/(4Vbe×C1)で表される周波数fを発振するマルチバイブレータを有する発振回路において、
前記Vbeの成分に相当する電流を生成し、該電流を前記動作電流I1として前記マルチバイブレータに供給する手段を設けたことを特徴とする発振回路。
A multivibrator that oscillates at a frequency f represented by f = I1 / (4Vbe × C1), where I1 is an operating current, C1 is a capacitance related to oscillation, and Vbe is a base-emitter voltage of a transistor related to oscillation. In an oscillation circuit having
An oscillation circuit comprising means for generating a current corresponding to the component of Vbe and supplying the current to the multivibrator as the operating current I1.
請求項1に記載の発振回路において、
前記手段は、1又は2以上直列接続されたダイオード接続のトランジスタに発生する電圧を所定の抵抗に印加して基準電流を生成する基準電流生成回路と、該基準電流生成回路で生成された基準電流の値を調整する電流増幅回路とからなり、該電流増幅回路から得られた電流を前記動作電流I1として前記マルチバイブレータに供給することを特徴とする発振回路。
The oscillation circuit according to claim 1,
The means includes a reference current generation circuit that generates a reference current by applying a voltage generated in one or more diode-connected transistors connected in series to a predetermined resistor, and a reference current generated by the reference current generation circuit An oscillation circuit comprising: a current amplifying circuit that adjusts a value of the current; and supplying a current obtained from the current amplifying circuit to the multivibrator as the operating current I1.
JP2005087173A 2005-03-24 2005-03-24 Oscillation circuit Pending JP2006270641A (en)

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Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5523615A (en) * 1978-08-07 1980-02-20 Hitachi Ltd Voltage control type multivibrator of emitter coupling
JPS61267409A (en) * 1985-05-22 1986-11-27 Hitachi Ltd Voltage controlled oscillator circuit
JPS62289010A (en) * 1986-06-09 1987-12-15 Hitachi Ltd Current control oscillator
JPH03175813A (en) * 1989-12-05 1991-07-30 Oki Electric Ind Co Ltd Voltage controlled oscillator
JPH04117019A (en) * 1990-09-03 1992-04-17 Nec Ic Microcomput Syst Ltd Oscillation circuit
JPH09121143A (en) * 1995-10-26 1997-05-06 Hitachi Ltd Temperature compensated variable frequency oscillator
JPH11340797A (en) * 1998-05-27 1999-12-10 Matsushita Electric Ind Co Ltd Voltage-controlled oscillator

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5523615A (en) * 1978-08-07 1980-02-20 Hitachi Ltd Voltage control type multivibrator of emitter coupling
JPS61267409A (en) * 1985-05-22 1986-11-27 Hitachi Ltd Voltage controlled oscillator circuit
JPS62289010A (en) * 1986-06-09 1987-12-15 Hitachi Ltd Current control oscillator
JPH03175813A (en) * 1989-12-05 1991-07-30 Oki Electric Ind Co Ltd Voltage controlled oscillator
JPH04117019A (en) * 1990-09-03 1992-04-17 Nec Ic Microcomput Syst Ltd Oscillation circuit
JPH09121143A (en) * 1995-10-26 1997-05-06 Hitachi Ltd Temperature compensated variable frequency oscillator
JPH11340797A (en) * 1998-05-27 1999-12-10 Matsushita Electric Ind Co Ltd Voltage-controlled oscillator

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