JPH02241219A - Emitter coupling type multivibrator - Google Patents

Abstract

PURPOSE:To stabilize the oscillation frequency against a temperature variation by inputting a signal outputted to an emitter of a first differential pair and a signal outputted to an emitter of a transistor for constituting a second differential pair to a base of a second transistor and a base of a first transistor, respectively. CONSTITUTION:Transistors Q7, Q8 constitute a differential pair by connecting the emitters in common, and its emitter is connected to an earth through a current source A5, and also, connected to an output terminal T1 and a base of a transistor Q2, as well. Transistors Q9, Q10 constitute a differential pair by connecting the emitters in common, and its emitter is connected to an earth through a current source A6, and also, connected to an output terminal T2 and a base of a transistor Q1, as well. When the transistors Q7, Q8 consist of the same structure, a base emitter voltage becomes VBB7=VBE. Accordingly, amplitude DELTAV of an oscillation signal inputted to the base of the transistor Q2 becomes DELTAV=Vcc-V1, and this amplitude voltage is not brought to temperature variation.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an emitter-coupled multivibrator suitable for IC implementation.

[Conventional technology]

An example of a conventional emitter-coupled multivibrator is shown in Part 8.
As shown in the figure. In the same figure, Q1 to Q6 are transistors, C
1 is the capacitance, R1 and R2 are the resistances, A1-A4 are the current sources, and V
CC is a voltage source, and T1 and T2 are output terminals. A capacitor C1 is connected between the emitters of transistors Q1 and Q2,
The collectors of transistors Q1 and Q2 are each resistor R1.
, R2 to voltage source vCC, and transistors Q5. Emitter of Q6 and transistor Q3
．． Each is connected to the base of Q4. transistor Q
5. The base and collector of Q6 are connected to voltage source vCC, and transistors Q3. The collector of Q4 is also connected to voltage source vCC. The emitter of transistor Q3 is connected to voltage source A3
The emitter of the transistor Q4 is grounded via the current source A4 and is also connected to the base of the transistor Q2 and the output terminal T2, respectively. . Also, the transistor Ql.

The emitters of Q2 are grounded via current sources A1 and A2, respectively.

Regarding the operation of the above conventional circuit, please refer to Hideo Tsunoda's "Basics and Applications of PLL" (Tokyo Denki University Press) pp78-80.
It is described in detail in JP-A No. 52-77565, etc., and the detailed explanation here will be omitted and will be briefly explained below.

In FIG. 8, the oscillation frequency f of the conventional circuit is the current source A1
, A2 both supply equal current I.

If the capacitance value of the capacitor C□ is the C1 oscillation output amplitude and ■, then it is expressed by the following formula.

f=−Ri1 (1) CAV Here, the oscillation output amplitude, ■, is the transistor Q5.
The amplitude is limited by Q6. That is, in the range in which transistors Q5 and Q6 operate as diodes, if the voltage between the base and emitter of transistors Q5 and Q6 is VBB, then a V = V Bv and by substituting it into the above equation (1), the following equation is obtained.

f=-mu... (2) 4 CVBx [Problem to be solved by the invention] As is well known, the base-emitter voltage of a transistor ■
. varies with temperature. The fluctuation is approximately -2mV/℃
It is. That is, as is clear from equation (2) above, the conventional circuit shown in FIG. 8 has the disadvantage that the oscillation frequency fluctuates as the temperature changes. For example, if the temperature increases by 100'C, VBI! is approximately 0.7
V to 0.5V, and the oscillation frequency increases by +40%.

An object of the present invention is to provide an emitter-coupled multivibrator whose oscillation frequency is stable against temperature changes.

[Means to solve the problem]

Basic means for solving the problem will be explained with reference to FIG.

A capacitor (C1) is connected between the emitters of the first and second transistors (Q1, Q2), and each emitter is connected to a reference potential via a constant current source (A1, A2). First and second resistors (R1, R2) are provided on the current path that supplies collector current from the first voltage source (VCC) to the respective collectors of the second transistors (Q1, Q2).
), and the first and second transistors (Q1, Q
In the astable multivibrator in which the output is taken out from each base side of 2), the emitters are interconnected and connected to the reference potential via the constant current source (A5), the collectors are interconnected, and the A first differential pair consisting of third and fourth transistors (Q7, Q8) connected to one voltage source (VCC), and a constant current source (86) whose emitters are interconnected.
a fifth voltage source, the collectors of which are interconnected and connected to the first voltage source (VCC);
, a second differential pair consisting of sixth transistors (Q9, Q10) and a second voltage source (■1) are provided, and the bases of the third and sixth transistors (Q7, Q10) are both connected to the The bases of the fourth and fifth transistors (Q8 and Q9) are connected to a second voltage source (V1), respectively.
The first signal connected to the second resistor (R1°R2) and output to the emitters of the third and fourth transistors (Q7, Q8) is connected to the base of the second 1-transistor (Q2). , an emitter-coupled multivibrator in which a second signal output to the emitters of the fifth and sixth transistors (Q9, Q10) is inputted to the base of the first transistor (Q1), respectively. It is a basic means for solving problems, and achieves the above objectives.

[Effect]

The differential pair consisting of the third and fourth transistors (Q7, Q8) limits the amplitude of the oscillation signal generated at the first resistor (R1) and outputs it to the base of the second transistor (Q2). .

Further, the fifth and sixth transistors (Q9, Q10)
The differential pair also limits the amplitude of the oscillation signal generated at the second resistor (R2) and
Output to the base of. In other words, the above-mentioned 4. When the base potential of the fifth transistor (Q8, Q9) reaches the maximum potential at the same potential as the potential vCC of the first voltage source (VCC),
The third and sixth transistors (Q7, Q10) are turned off, and the first and sixth transistors (Q7, Q10) are turned off. The second 1-transistor (Q1, Q
The base potential VsH of 2) is expressed by the following formula.

Val(=Vcc VBg--(3) Also, conversely, when the base potential of the fourth and fifth transistors (Q8, Q9) becomes the potential of the second voltage source (V1) ■1 or less, The fourth and fifth transistors (Q8 and Q9) are turned off, and the first and second transistors (Q1, Q9) are turned off.
The base potential of 2) is expressed by the following formula.

V3L=V I VnE・=−(4) Therefore, the first
．． The second transistor (Ql.

The oscillation output amplitude AV output to the base of Q2) is expressed as follows.

°　8　.

ΔV=Vcc-V, (5) That is,
The oscillation output amplitude does not increase or decrease even if the temperature changes, and as is clear from the above equation (1), the oscillation frequency can be stabilized against temperature changes.

〔Example〕

Examples of the present invention will be described below.

FIG. 1 is a circuit diagram showing an embodiment of an emitter-coupled multivibrator according to the present invention. Components that are the same as those of the conventional circuit shown in FIG. Explanation will be omitted.

In FIG. 1, Q7 to Q10 are transistors, A5. A
6 is a current source, and vl is a voltage source. Transistor Q7.
The emitters of Q8 are commonly connected to form a differential pair, and the emitters are connected to ground via current source A5 and also to the output terminal T1 and the base of transistor Q2. Transistors Q9 and Q10 have their emitters connected in common to form a differential pair, whose emitters are connected to ground via current source A6 and also to output terminal T2 and the base of transistor Q1. transistor Q8
．． The bases of Q9 are connected to resistors R1 and R2, respectively,
The bases of transistors Q7 and Q10 are both connected to voltage source 1. Transistor Q7. The collectors of QB, Q9, and Q10 are all connected to voltage source vcc.

Next, the operation of this embodiment will be explained. FIG. 2 shows signal waveforms at various parts in the circuit of FIG. 1. In the same figure, VQ
8B represents the base potential of transistor Q8, VQ2B represents the base potential of transistor Q2, and the horizontal axis t represents time. The operation of the circuit shown in FIG. 1 will be explained below using FIG. 2. In order to simplify the explanation, the following current sources A1, A
The two currents are both equal■. The operation will be explained assuming that.

An oscillation signal generated in resistor R1 is applied to the base of transistor Q8. The upper limit voltage of this oscillation signal amplitude is Vc
c, and the amplitude is 2·■, the sum of the currents of the current sources A1 and A2 in the resistor R1 when the transistor Q2 is turned off. This is the voltage drop when . On the other hand, transistor Q7. Q8. Current source A
5. The voltage source v1 limits the lower limit value of the oscillation signal amplitude and outputs it to the base of the transistor Q2. That is, when the base potential of the transistor Q8 is the voltage source V ca, the transistor Q7 is turned off and the base potential of the transistor Q2 becomes ■cc-■B□8. Here, vnpa is the base-emitter voltage of transistor Q8. Also,
When the base potential of the transistor Q8 decreases and becomes lower than the voltage of the voltage source v1, the transistor Q8 is turned off and the base potential of the transistor Q2 becomes 1V n E ? The potential will not go below this limit.

V B E here? is the base-emitter voltage of transistor Q7, and transistor Q7. If Q8 has the same structure, V Bl! ? = V BEE. Therefore, the amplitude of the oscillation signal input to the base of transistor Q2.

(2) is aV=Vcc-V, and this amplitude voltage does not change with temperature. Furthermore, the operation of the transistors Q9 and Q109 and the current source A6 is clear from the above operation description.
Similarly, an oscillation signal whose amplitude does not change with temperature is input to the base of the transistor Q1. Therefore, as is clear from the above equation (1), this embodiment has the effect of stabilizing the oscillation frequency against temperature changes.

Next, other embodiments according to the present invention will be described in order from FIG. 3 onwards, but in each case, FIG.

Components that are the same as or have the same functions as those shown in FIGS. 1 and 2 are given the same reference numerals, and detailed explanation thereof will be omitted.

FIG. 3 shows another embodiment of the present invention, and FIG. 4 shows signal waveforms at various parts in the circuit shown in FIG. In the same figure, V! l
E5 indicates the base-emitter voltage of the one-herald transistor Q5. The operation of this embodiment will be explained below. An oscillation signal generated in resistor R1 is applied to the base of transistor Q8. A diode-connected transistor Q5 is connected in parallel to the resistor R1. Therefore, the oscillation signal amplitude is the base-emitter voltage V B E of transistor Q5.
It never exceeds 5. That is, transistor Q1
The collector voltage of is never lower than Vcc VBE5. Therefore, the resistance value of the resistor R1 and the current values of the current sources A1 and A2 may be arbitrary values, and the transistor 12.

The voltage between the collector and base of star Q1 is reverse biased and there is no possibility of malfunction. In other words, the degree of freedom in design is high.

On the other hand, the voltage v1 of the voltage source 1 is the limit voltage V c
c Set to a potential higher than VBE5. As a result, the amplitude voltage (■) of the oscillation signal applied to the base of the transistor Q2 is Vcc-V as in the embodiment shown in FIG.
, so it is clear that the temperature does not change.

That is, according to this embodiment, there is an effect that the degree of freedom in design is high and it can be applied to various purposes.

Next, another embodiment of the present invention shown in FIG. 5 will be described. In FIG. 5, Q11 to Q18 are transistors, and A7 to A10 are current sources. Transistor Q1
The emitter of transistor Q1 is grounded via current source A7 and connected to the base of transistor Q7. transistor Q
12. The emitters of Q13 and Q14 are respectively connected to current source A8.
．． A9.A10 are connected to ground through transistors Q8. Connected to the bases of Q9 and Q10.

The bases of transistors Q11 and Q14 are both voltage source ■1
are connected to transistors Q12. The bases of Q13 are connected to resistors R1 and R2, respectively.

Transistors Q11, Q12. Q13. The collectors of Ql4 are both connected to voltage source Vcc. Transistor Q1
5. The collector and base of Q17 are both connected to CC. The collector and base of transistor 016 are both connected to the emitter of transistor Q15, and transistor Q
18 collectors.

The bases are both connected to the emitter of transistor Q17, and transistors Q16. The emitters of Q18 are connected to resistors R1 and R2, respectively.

FIG. 6 shows signal waveforms at various parts in the circuit shown in FIG. In the figure, VQ12B indicates the base potential of transistor Q12. Also, v11EI□.

V B E 12 t V B E 15 t V B
E t s are transistors Q11, Q12 .
Q15. The voltage between the base and emitter of Ql6 is shown. The operation of this embodiment will be explained below.

Transistors Q11, Q12. Q13. Ql4 and current source A7. A8. A9. A10 constitutes an emitter follower, respectively. Also, transistor Q15. Q16 and transistor Q17. Q18 limits the oscillation amplitude output to R1 and R2, respectively, and
This prevents the collector-base voltage of No. 2 from becoming reverse biased.

That is, as is clear from the explanation of the operation of the embodiment shown in FIGS. 1 and 3, this embodiment also has a high degree of freedom in design, and the oscillation frequency is stable against temperature changes.

On the other hand, consider increasing the oscillation frequency. In this case resistance R1
The time constant between and its parasitic capacitance becomes dominant. Here, the transistor Q8 is repeatedly turned on and off depending on its base potential, and it is generally known that the base-emitter capacitance of a transistor increases rapidly when it is off. That is, if the base of transistor Q8 and resistor R1 are directly connected, it will be difficult to increase the speed of the oscillator. In this embodiment, an emitter follower constituted by a transistor Q12 is connected between the base of the transistor Q8 and the resistor R1, and when the transistor Q8 is turned off, the effect that the base-emitter capacitance has on the time constant of the resistor R1 is If the current amplification factor of Q12 is hfe, then 1/h
f Reduce to e.

That is, according to this embodiment, there is an effect that it becomes easy to increase the oscillation frequency.

Next, another embodiment according to the present invention shown in FIG. 7 will be described. In FIG. 7, Q1, 9 to Q22 are transistors, and A11 to A13 are current sources. Transistor Q19. The emitters of Q20 are commonly connected to form a differential pair, and the emitters are grounded via a current source A11. Also, transistor Q, 19. The collectors of Q20 are connected to the emitters of transistors Q1 and Q2, respectively. The collector and base of transistor Q21 are both connected to the base of transistor Q2, and its emitter is grounded via current source A12 and connected to the base of transistor Q19. Furthermore, transistor Q
The collector and base of 22 are both connected to the base of transistor Q1, and its emitter is connected to ground via current source A13 and to the base of transistor Q20.

In this embodiment, current IQ of current source A11 is connected to transistor Q19. Switched by a differential pair consisting of Q20,
The capacitor C1 is charged and discharged. In this embodiment as well, the oscillation frequency f is similar to the above equation (1) and is expressed by the following equation.

However, in this embodiment, only one current source is sufficient.

■Compared to the above example. The same oscillation frequency can be obtained with a smaller amount of current.

That is, this embodiment has the effect of easily reducing power consumption.

〔Effect of the invention〕

According to the present invention, the oscillation frequency of the emitter-coupled multivibrator can be stabilized against temperature changes.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram showing one embodiment of the present invention, and Fig. 2 is a circuit diagram showing an embodiment of the present invention.
3 is a circuit diagram showing another embodiment of the present invention, FIG. 4 is a signal waveform diagram of the embodiment shown in FIG. 3, and FIG. 5 is a further embodiment of the present invention. 6 is a signal waveform diagram of the embodiment shown in FIG. 5, FIG. 7 is a circuit diagram showing still another embodiment of the present invention, and FIG. 8 is a diagram of a multivibrator circuit. FIG. 2 is a circuit diagram showing a conventional example. Q1 to Q22...transistors. R1, R2...Resistance. C1... Capacity. A1-A13...Current source. Vcc, Vl...voltage source.

Claims (1)

[Claims] A capacitor (C1) is connected between the emitters of the first and second transistors (Q1, Q2), and each emitter is connected to a reference potential through a constant current source (A1, A2). A first and second load element (R
1, R2), and the first and second transistors (
In the astable multivibrator whose output is taken out from each base side of Q1, Q2), the emitters are interconnected and connected to the reference voltage via the constant current source (A5), the collectors are interconnected and A first differential pair consisting of third and fourth transistors (Q7, Q8) connected to the first voltage source (VCC) and whose emitters are interconnected and connected via a constant current source (A6). a fifth, whose collectors are interconnected and connected to the first voltage source (VCC);
A second differential pair consisting of a sixth transistor (Q9, Q10) and a second voltage source (V1) are provided;
The bases of the transistors (Q7, Q10) are both connected to the second voltage source (V1), and the bases of the fourth and fourth transistors (Q8, Q9) are connected to the first and second voltage sources, respectively.
The first signal connected to the load element (R1, R2) and output to the emitters of the third and fourth transistors (Q7, Q8) is connected to the base of the second transistor (Q2). 5. An emitter-coupled multivibrator, characterized in that the second signal output to the emitters of the sixth transistors (Q9, Q10) is input to the bases of the first transistor (Q1), respectively. 2. The emitter-coupled multivibrator according to claim 1, wherein each emitter is connected to the first and second load elements (R1
, R2), the respective bases and collectors of the seventh and eighth transistors (Q5, Q6) are connected to the first and eighth transistors (Q5, Q6). An emitter-coupled multivibrator characterized in that it is connected to the other ends of two load elements (R1, R2). 3. The emitter-coupled multivibrator according to claim 1 or 2, wherein between the second voltage source (V1) and each base of the third and sixth transistors (Q1, Q2), between the first load element (R1) and the base of the fourth transistor (Q8), and between the second load element (R2) and the fifth
between the base of the transistor (Q9) and the first, second, third, and fourth emitter follower circuits (Q11), respectively.
-A7, Q12-A8, Q13-A9, Q14-A10
) is connected to the emitter-coupled multivibrator.