JPS5811648B2 - Denatsu Dentatsu Cairo - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a voltage transmission circuit that can transmit a constant voltage to a desired location as it is.

When a constant voltage circuit is constructed using an IC (integrated circuit), it is required to prevent the constant voltage from changing due to changes in temperature.

The temperature characteristics of a general-purpose diode (silicon diode) are as shown in the characteristic curve in Figure 1, for example, 2 to 3 mV.
/°C, which is a negative temperature characteristic.

On the other hand, the temperature characteristic of a Zener diode is as shown in the characteristic curve of FIG. 2, and exhibits a positive temperature characteristic of, for example, +2.3 mV/°C.

Incidentally, Fig. 1 is a voltage-current characteristic curve diagram of a diode with temperature as a parameter, and Fig. 2 is a voltage-current characteristic curve diagram of a Zener diode with temperature as a parameter.
℃, T2℃, and T3℃ indicate the temperature, respectively.

The relationship is C> T2'C> T3°C.

Therefore, as shown in FIG. 3, by connecting the diode D1 and the Zener diode DZ in series and applying the DC voltage from the power supply element B to this series circuit through the resistor R8, the voltage-current characteristics are It is known that it is possible to obtain a constant voltage circuit SP that is not affected by changes in , that is, has no temperature characteristics.

In this constant voltage circuit SP, resistor R8 and diode D1
A constant voltage output ■s having no temperature characteristics between the output terminal t1 derived from the midpoint of the connection with the ground and the ground is obtained.

However, in general, it is not preferable to allow too much current to flow in an IC, and the same can be said for such a constant voltage circuit SP.

Further, particularly in such a constant voltage circuit SP, the larger the value of the resistor R8, the more effective the removal of noise components contained in the power supply voltage becomes.

Therefore, a resistor R8 of relatively high resistance must be used.

Now, by providing such a constant voltage circuit SP in one IC,
When this constant voltage circuit SP is to be shared as a constant voltage circuit for another IC, if the output terminal of this constant voltage circuit SP is directly connected to the constant voltage input terminal of the other IC, the resistor R8 of the constant voltage circuit SP Power (current) due to the large resistance value of
This means that you won't be able to get much.

In view of these points, the present invention is capable of transmitting a constant voltage from a constant voltage circuit without drawing a large current from the constant voltage circuit with zero temperature characteristics, and also reduces the amount of electric power (
The purpose of this paper is to propose a voltage transmission circuit that can extract current.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the drawings.

First, referring to FIG. 4, a first embodiment will be described.

4, parts corresponding to those in FIG. 3 will be described with the same reference numerals.

In FIG. 4, 1 and 2 indicate separate ICs (monolithic), and in this case, the IC 1 is provided with a constant voltage circuit SP similar to that in FIG. 3.

This constant voltage circuit SP has a configuration similar to that shown in FIG. 3, so its explanation will be omitted, but it supplies constant voltage to IC1, and
A voltage transmission circuit VT according to the present invention is provided which supplies a constant voltage to other IC2 as well, and in particular to IC2.

The IC1 is provided with terminals t1, t2, and t3 in connection with the constant voltage circuit SP.

Terminal t1 is derived from the connection midpoint between resistor R8 and the series circuit of diode D1 and Zener diode DZ.

This terminal t1 has a Zener diode D7. A capacitor CP for bypassing white noise generated by this is externally connected between the ground and the ground.

The terminal t2 is led out from the power supply element B.

Terminal t3 is grounded. IC2 has the above-mentioned terminal t1.
, t2 and t3, respectively, terminals t5, t7 and t
6 is provided.

Next, the voltage transfer circuit VT will be explained.

A constant voltage output terminal t0 of the constant voltage circuit SP is grounded through the collector-emitter of the first constant current transistor Q1.

That is, the collector of transistor Q1 is connected to terminal t5, and the emitter is connected to terminal t6 via resistor R5.

The base of the transistor Q1 is connected to the base of a transistor Q2 having a diode configuration in which the collector and base are directly connected, and also to the base of a transistor Q3, and these transistors Q1, Q2, and Q3 form a current mirror C1. Ru.

The emitters of transistors Q2 and Q3 are grounded through resistors R6 and R7, and the collector of transistor Q2 is connected to t7 through resistor R1.

-Furthermore, this constant voltage output terminal t1 is connected through a diode D2 to the base of an impedance conversion transistor Q6 having the same temperature characteristics as this diode D2.

This transistor Q6 constitutes an emitter follower type power amplifier that is said to have high input impedance and low output impedance, and its emitter is grounded through a load resistor R2 and is connected to a constant voltage output terminal t4. is derived, and its collector is further connected to power source B via terminals t7 and t2.

The base of the transistor Q6 is connected to the power supply element B via the resistor R4 and terminals t7 and t2 between the collector and emitter of the second constant current transistor Q5.

The base of the transistor Q4 whose collector and base are connected is connected to the base of the transistor Q5, thereby forming a Karen mirror circuit C2.

The emitter of transistor Q4 is connected to terminal t7 via resistor R3.

The current mirror circuit C1 described above is provided with a transistor Q3 whose base is connected to the base of the transistor Q2, and the collector of the transistor Q4 is connected to the collector of the transistor Q3.

The emitter of transistor Q3 is grounded via resistor R7.

Here, the values of the resistors R3 to R7 are made equal.

The first and second constant current transistors Q1 and Q
5 are made almost equal, and the diode D
The value of the above-mentioned constant current is set so that the forward drop voltage of transistor Q2 and the base-emitter voltage of transistor Q6 are equal to each other.

Next, the operation of the voltage transfer circuit VT in FIG. 4 will be explained with reference also to the equivalent circuit in FIG. 5.

In FIG. 5, 3 indicates a constant current circuit corresponding to the first constant current transistor Q1, and 4 indicates a constant current circuit corresponding to the second constant current transistor Q5. ■.

flows. The constant voltage obtained between the terminals t1 and t3 of the constant voltage circuit SP is supplied to the voltage transmission circuit VT via the terminals t6 and t6 of IC2, with the white noise generated from the Zener diode removed by the capacitor CP. be done.

A constant current is applied to the diode D2 by a constant current circuit 3.4 so that its forward voltage drop is equal to the base-emitter voltage of the transistor Q6.

is washed away. Furthermore, the diode D2 and the transistor Q6 are formed in the same IC, and their temperature characteristics, especially the forward drop voltage of the diode D2 and the temperature characteristics of the base-emitter voltage of the transistor Q6, are made equal.

Therefore, the voltage across the diodes D1 and D2 is VD,
(-〇, 7V), VD2 (=0.7V), the voltage across the Zener diode DZ is ■DZ (-5, 5V), the voltage between the base and emitter of transistor Q6 is ■be6 (
-0,7), the output voltage t4 derived to the output terminal t4 is expressed by the following equation.

■t4-■D1+■DZ+■D2-Vbo6-■.

t+VI)z(=6.2V) ・・・・・・・・・
...(1) That is, the voltage Vt4 generated at the output terminal t4 is I
The voltage generated at the terminal t of C1 becomes equal to t1.

Also, as mentioned above, the diode D2 and the transistor Q6
Since the temperature characteristics are the same as that of the output voltage Vt4, the output voltage Vt4 does not change due to temperature changes.

The characteristics of the circuit shown in FIG. 4 are as follows.

That is, the constant voltage generated at the constant voltage output terminal t1 of IC1 is
The signal can be directly transmitted to the output terminal t4 of C2 without being affected by the temperature characteristics of elements such as transistors.

Since the transistor Q6 constitutes an emitter follower type amplifier, its large input impedance eliminates the need to draw a large amount of current from the constant voltage circuit SP, and its small output impedance allows a large output from the output terminal t4. Electric power (output current) can be extracted.

Since the collector-emitter of the first and second constant current transistors Q1 and Q2 exhibits high impedance,
The input impedance of the voltage transfer circuit VT is determined by the input impedance of the emitter follower type amplifier constituted by the transistor Q6, and exhibits a high input impedance as described above.

By connecting a capacitor CP between the terminal D1 and the ground, the white noise generated by the Zener diode DZ in IC1 is bypassed and removed, but this terminal t1 is used to transfer the voltage from IC1 to IC2. can be transmitted.

Next, another embodiment of the present invention will be described with reference to FIG.

In FIG. 6, parts corresponding to those in FIG. 4 are designated by the same reference numerals, and redundant explanation will be omitted.

In this example, the diode D2 and the impedance converting transistor Q6 shown in FIG. 4 are each constituted by the same number of Darlington-connected transistors, and in this example, each is constituted by two transistors.

That is, the diode D2 is composed of transistors Q7 and Q8 connected in a Darlington manner.

Transistor Q6 is composed of transistors Q9 and Q10 connected in a Darlington manner.

The load connected to the emitter of the transistor Q6 is composed of a constant current transistor Q11 whose base is connected to the base of the transistor Q2, whose collector is connected to the emitter of the transistor Q1o, and from which the output terminal is connected. Derive t4.

Next, Darlington connected transistors Q9, Q, Q
Consider compensation for the temperature characteristics of transistor Q6.

The respective pace-emitter voltages of transistors Qg and Q1o are expressed as ■be9, ■be1o1 transistor Q9,
The collector current of each QIO is IC9, and the collector saturation current of ■c1o1 transistors Q0, Q, and O is ■sa□9
, ■sa□lQi When the electron charge is 91 and the Boltzmann constant is 1 and the temperature is T, the voltage Vbeo between the base of transistor Q9 and the emitter of transistor Qto is expressed by the following equation (2).

■beO-■be9+■be10 From formula (2), ■beo is ■.

9. ■It is understood that it depends on the CIO.

Therefore, ■1) To compensate for the temperature characteristics of eo.

9.■ A collector current equal to o1o flows.

A Darlington connection circuit consisting of two transistors must be provided.

That is, Darlington connected transistors Q9 and Qlo
Transistors Q and Q8 are used to compensate for the temperature characteristics of
The temperature characteristics of the transistors Q10 and Q7 are made to be the same as that of the transistors Q10 and Q7.

In the circuit of FIG. 6, if the voltage across the diode D0 is .

If the pressure across the Zenider DZ is ``DZ1'', the voltage between the base of transistor Q8 and the emitter of transistor Q is ``beo1'', and the voltage between the base of transistor Q and the emitter of transistor QIO is ``beo'', then the output is The voltage ■t4 generated at the terminal t4 can be expressed as in equation (3).

■ −■ ′+■o, 10■D□−■5e.

t4 beO (3) Here, as mentioned above, since Vbeo'-■boo is established, ■14 can be expressed as in the following equation (4).

vt4-vD1+VDZ ……………(4)
That is, the voltage ■14 generated at the output terminal t4 is the block (1
) is equal to the voltage ■11 occurring at the terminal t.

Further, as described above, since the influence of the temperature characteristics of the transistors Q9 and Qlo is compensated by the transistors Q8 and Q7, this voltage 14 is not affected by the temperature characteristics of elements such as transistors.

Therefore, the characteristics of the circuit shown in FIG. 6 can be described as follows.

The voltage generated at the constant voltage output terminal t1 of the ICI can be transmitted to the output terminal t4 of the IC2 without being affected by the temperature characteristics of elements such as transistors.

Since the transistor Q6 is composed of a plurality of transistors connected in a Darlington connection, the transistors Q9,
The input impedance of the emitter follower multiplier consisting of Qlo becomes larger.

Therefore, the current flowing out from the constant voltage circuit SP can be further reduced.

The voltage generated at the constant voltage output terminal t of IC1 can be transmitted to the output terminal t4 of IC2 without being affected by the temperature characteristics of elements such as transistors.

Transistor Q6 is composed of a plurality of Darlington-connected one-herald transistors, so transistor Q0
, Qlo, the input impedance of the emitter-follower amplifier is even larger.

Therefore, the current flowing out from the constant voltage circuit SP can be further reduced.

According to the above-described voltage transfer circuit of the present invention, the constant voltage from the constant voltage circuit is supplied via the diode to the impedance conversion transistor having the same temperature characteristics as the diode, and the forward drop voltage of the diode and the impedance conversion transistor are Since the voltage between the base and emitter of the constant voltage circuit is equalized using a constant current circuit, the constant voltage from the constant voltage circuit can be transmitted with zero temperature characteristics without drawing a large current from the constant voltage circuit. At the same time, electric power (current) can be extracted.

Furthermore, since the above-mentioned diodes and impedance conversion transistors are each composed of a plurality of Darlington-connected transistors of the same number, the input impedance of the voltage transmission circuit becomes even larger, and the current extracted from the constant voltage circuit can be further reduced. can.

Note that the number of Darlington-connected transistors constituting the above-mentioned diode and impedance conversion transistor may be three or more.

In the above, the diode D1 and the Zener diode D
Although we have described the transmission of a constant voltage obtained across Z, even if this voltage is any voltage that can be varied, the input terminal t4
Since voltage can be transmitted between the output terminal t5 and the output terminal t5, the present invention can also be applied to a general voltage transmission path.

[Brief explanation of the drawing]

Figure 1 is a characteristic curve diagram showing the temperature characteristics of the diode, Figure 2 is a characteristic curve diagram showing the temperature characteristics of the diode.
The figure is a characteristic curve diagram showing the temperature characteristics of a Zener diode.
Fig. 3 is a circuit diagram showing a conventional constant voltage circuit, Fig. 4 is a circuit diagram showing an embodiment of the present invention, Fig. 5 is an equivalent circuit diagram of Fig. 4, and Fig. 6 is a circuit diagram showing another embodiment of the present invention. FIG. 2 is a circuit diagram showing an example. SP is a constant voltage circuit, tl is a constant voltage output terminal, t4 is an output terminal, Ql is a first constant current transistor, Q5 is a second constant current transistor, Q6 is an impedance conversion transistor N, Q7, Q8, and Q . and Q, 0 is a Darlington connected transistor, VT
is a voltage transfer circuit.

Claims (1)

[Claims] 1. The constant voltage output terminal of the constant voltage circuit is grounded through the collector-emitter of the first constant current transistor, and is also connected to the base of the impedance conversion transistor having the same temperature characteristics as the diode through the diode. The base of the impedance conversion transistor is connected to the power supply through the collector-emitter of the second constant current transistor, the collector of the impedance conversion transistor is connected to the power supply, and the output terminal is connected to the emitter of the impedance conversion transistor. is derived so that the constant currents of the first and second constant current transistors are approximately equal, and the forward drop voltage of the diode and the base-emitter voltage of the impedance conversion transistor are equal to each other. A voltage transfer circuit characterized in that the value of the constant current is selected so that a constant voltage equal to the constant voltage of the constant voltage output terminal is obtained at the output terminal. 2. The voltage transfer circuit according to claim 1, wherein the diode and the impedance converting transistor are each made up of a plurality of Darlington-connected transistors of the same number.