JPS5880716A - Reference voltage circuit - Google Patents

Abstract

PURPOSE:To ensure the designing flexibility and to obtain the reference voltage of a low noise level, by providing a current supply circuit connected in series to a transistor between a power supply terminal and an earth terminal in addition to a prescribed current supply circuit and therefore setting the reference voltage and the temperature coefficient independently of each other. CONSTITUTION:A power supply terminal 11 is connected to a reference voltage output terminal 14 via a current supply circuit 13, and an end of each of resistances 15 and 16 is connected to the terminal 14. At the same time, the collector of a transistor TR23 is connected to the terminal 14. The other end of the resistance 15 is connected to the collector of a TR17, and the base of the resistance 15 is connected to the base of a TR18. The emitters of the TRs 17 and 18 are connected to an earth terminal 24 directly via a resistance 19 respectively. At the same time, the other end of the resistance 16 is connected to the emitter of the TR18 and to the base of a TR20, and the emitter of the TR20 is connected to the terminal 11 via a current supply circuit 12. Then the base of the TR23 is connected to the joint between a circuit 12 and the TR20 via a resistance R21. The emitter of the TR23 and a resistance 22 connected to a resistance 21 are connected to the terminal 24. Thus the reference voltage and the temperature coefficient are set independently of each other.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a reference voltage circuit most suitable as a constant voltage source used in a semiconductor integrated circuit.

Conventionally, the breakdown voltage of a Zener diode or the forward voltage of a diode is generally used as a reference voltage source for a semiconductor integrated circuit. The former is widely used to obtain a reference voltage of about 5cm or higher. However, in this case, the breakdown of Zener dimer during the manufacturing process of semiconductor integrated circuits is
The voltage is regulated by law, and therefore, when building a Zener diode with a low voltage breakdown voltage of about 5V or less into a semiconductor integrated circuit, an additional manufacturing process is required, which increases the cost. Make 1. Moreover, the runner-up is tp, 2, which has a large noise voltage due to its characteristics.

Also, the presenter is a convenience to low voltage ￥L υ; fiIf? :but,
The temperature coefficient is -2/°C to -47°C, which is a large deficiency.

In view of the above points, several constant voltage circuits using a bandgap regulator have been proposed in which the temperature coefficient of output is zero and the reference voltage circuit is set to 15, which is suitable for the L1 semiconductor integrated circuit. This constant voltage circuit utilizes the fact that transistors having different current densities have different temperature coefficients of forward voltages between bases and emitters, and an example of a specific circuit configuration will be described with reference to FIG.

In FIG. 1, a power supply terminal 1 is coupled to a reference voltage output terminal 3 via a current supply circuit 2), and the reference voltage output terminal 3 is connected to one end of each of a resistor 4 and a resistor 5, and further to a transistor 9. A connection is made to each collector. The other end of the resistor 4 is connected to a common connection point between the collector and base of the transistor 6, and is also connected to the base of the transistor 7. The other end of the resistor 5 is connected to the collector of the transistor 7 and further connected to the base of the transistor 9. The emitters of transistors 6 and 9 are connected directly, and the emitter of transistor 7 is connected directly to resistor 8.
are respectively connected to the ground terminal 10 via. Here, the current supply circuit 2 is composed of, for example, a current or voltage source and a resistor. Further, since this circuit is made of a semiconductor integrated circuit, each of the above elements operates at the same junction temperature, and the relative ratio of the resistance values of the resistors 4.5 and 8 is accurately determined.

When using this circuit, the base-emitter forward voltage VBE of each of transistor 6 and transistor 7 is 6%V.
BE7 cD difference' is pressure △VBg (=Vngs-VBB7
) to determine the ``torque pressure''btEp of the reference voltage output terminal 3.
``If you add 4 bales, you get equation (1).

However, R6: Resistance value of resistor 5 R8m Resistance value of resistor 8 BE9: Base-emitter forward voltage of transistor 9 In equation (1), the temperature coefficient of △VBK is the current flowing through transistors 6 and 7. 17 is positive under the conditions of I5)I7, while VBE9 has a negative temperature coefficient, so the temperature coefficient of VREF can be made zero by appropriately choosing sR6/Ra.

5- However, in this circuit, the temperature coefficient approaches zero only for constant reference voltage values.

For fLjt, transistors with the same characteristics are used as transistors 6, 7 and 9, the resistance value R4 of resistor 4 is set to Ω = 600, the resistance value of resistor 5 is set to Rfi = 6, and VBBg at absolute temperature T = 300K is set to 0. 65V
, for a circuit where the temperature coefficient of VIIE9 is -27°C, by changing the resistance value R8 of resistor 8, the reference voltage VREF and its temperature coefficient α REF /
Figure 2 shows the calculation of αT.

As is clear from Figure 2, R4=600, VREF”
At 1.25V, αV RE F,/(Xi' is zero. For reference voltages higher than 1.25V, it has a positive temperature coefficient s. For reference voltages lower than 1.25V, it has a negative temperature coefficient. The constant reference voltage at which the temperature coefficient becomes zero varies depending on the manufacturing process of semiconductor integrated circuits.
Since the BKG and its temperature coefficient are different, the value will be slightly different, but the value will be approximately between 12 and 1.3V.

As explained above, according to the conventional bandgap regulator, the reference voltage is stable at about 1 with respect to temperature.
A stable reference voltage of 2 to 1.3 V, which is independent of temperature, cannot be obtained over a wide range. This has the disadvantage of being a major design constraint.

SUMMARY OF THE INVENTION An object of the present invention is to provide a reference voltage circuit suitable for a semiconductor integrated circuit that supplies a stable reference voltage over a wide range, without the above-mentioned drawbacks.

Another object of the present invention is to provide a reference voltage circuit that can arbitrarily set the output voltage and its temperature coefficient.

According to the present invention, a power supply terminal, an output terminal coupled to the power supply terminal via the first current source, a first resistor and a constant voltage means connected between the output terminal and the ground terminal. 1st
a series circuit, a second resistor connected in parallel to the first series circuit, a second resistor, a first transistor, and a second resistor.
The base is connected to the self-effect N path and the connection point between the second resistor and the first transistor, and the base is connected to the power supply terminal via the second current source, and the fourth and fifth A second transistor is connected to the ground terminal via a resistor, and the collector is connected to the ground terminal, and the base is connected to the connection point between the fourth and fifth resistors, and the collector-emitter current path is connected to the first transistor. and a third transistor inserted between the current source and the ground terminal.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 3 is a circuit diagram of a reference voltage circuit showing one embodiment of the present invention. In FIG. 3, power supply terminal 11 is coupled to reference voltage output terminal 14 via current/supply circuit 13, and from reference voltage output terminal 14 there are resistors 15 and 16.
are connected to one end of each of the transistors 23 and to the collector of the transistor 23. The other end of the resistor 15 is connected to a common connection point between the collector and base of the transistor 17, and is also connected to the base of the transistor 18. The other end of resistor 16 is connected to the collector of transistor 18 and the base of transistor 2o. The emitter of the transistor 20 is connected to the power supply terminal 11 through the current supply circuit 12 and a resistor 21 connected in series.
．． 22 to a ground terminal 24. resistance 2
The common connection point of transistors 1 and 22 is connected to the base of transistor 23, and the emitters of transistors 17 and 23 and the collector of transistor 20 are connected to the 1 self, and the emitter of transistor 18 is connected to ground terminal 24 through resistor 19, respectively. It is connected. Here, the xi supply circuits 12 and 13 are composed of, for example, a voltage source and a resistor. Me, since this circuit is made with a semiconductor integrated circuit, the above % elements operate at the same junction temperature, and the relative ratio of the resistance values of each resistor 15, 16, 19, 21 and 22 is not accurate. I can do it.

Since this reference voltage circuit has the above-described configuration, the voltage VREF at the reference voltage terminal 14 is expressed as in equation (2).

However, 9- Rl6 : Resistance value R1 of resistor 16, : Resistance value R21 of resistor 19 : Resistance value R22 of resistor 21 : Resistance value of resistor 22 △VBE : ) 7 Forward voltage between base and emitter of transistor 17 and transistor 18 The difference voltage between the base and emitter forward voltage of transistor 20 is VNG2o; ) The base-emitter forward voltage of transistor 20 is VBE23; ) The base-emitter forward voltage of transistor 23 is Although it is difficult to maintain the same characteristics on a semiconductor integrated circuit due to transistors, by appropriately selecting the base-emitter junction area of each transistor, the forward voltage between each base-emitter can be made almost the same. Therefore, equation (2) can be approximated as shown in equation (8) below.

10- In equation (8), the temperature coefficient of △VBE is the transistor 17
and the currents 117 and 118 flowing through 18 are 117〉
Under the condition of 118, it is positive, while vnE2g has a negative temperature coefficient.

From this equation (8), it is possible to set the voltage and temperature coefficient of the voltage VREF of the reference voltage output terminal 14 separately by appropriately setting the resistance ratios R16/R, 19 and 21/R22. I understand.

That is, as mentioned above, the reference voltage, voltage v, E in FIG.
1? is expressed by equation (1), and the temperature coefficient of VREF becomes zero only at a certain constant value of the base f voltage by adjusting the resistance ratio 1t5/R9, whereas equation (3) So, (
If the first term on the right-hand side of equation (8) and equation (1) are set to be equivalent, the temperature coefficient of the second term is V, which has a negative temperature coefficient.
The resistance ratio of BE211 is R2L/kL22 times) IL
By adjusting zl/1jz2, any temperature coefficient can be preferred.

This means that the temperature coefficient of VRIEF in equation (8) is the resistance ratio 1'
By setting L21/R22>1, it becomes negative, and by setting the resistance ratio R21/R22<1, it becomes positive.

Therefore, by adjusting the resistance ratio L2t/R22, the temperature coefficient can be made zero at any reference voltage.

Therefore, if the reference voltage circuit shown in Fig. 3 is used, the reference voltage EE whose thermal coefficient is zero will have a resistance ratio of 21/R22''.
1, the voltage exceeds 1.25 V, and the resistance ratio is 1 (21
/R22 and a separate voltage circuit having 1.25 V or less at 10 o'clock can be easily realized. In this way, a reference voltage with a temperature coefficient of zero is undesirable in the example, and -C is fixed at a certain reference voltage value, but in this example, an arbitrary base voltage value can be used. can get.

FIG. 4 shows an embodiment of a constant voltage generating circuit with an output voltage of 1.times., which is based on the embodiment shown in FIG. R3.

In FIG. 4, parts that are the same as those in the embodiment in FIG. 3 are designated by the same reference numerals.
lII4. In Figure 4, resistance 31.34.37
．． 38, 40, 42. The diode 32.33%, the transistor 35.36%, and the 39.41% 43 constitute a constant current source, and current is supplied to the collectors of the deer transistors 39, 41, and 43, respectively. The collector of the transistor 41 is connected to the common connection point of the transistor 20 and the resistor 21, and the collector of the transistor 43 is connected to the collector of the transistor 23 and the transistor 440.
connected to the base. The transistor 44 acts as a current amplification transistor to which negative feedback is applied in order to improve regulation. Reference voltage output terminal 1
4 is connected to the base of transistor 450 and the collector of transistor 48 through resistor 15, and the emitter of transistor 45 is connected to the ground terminal 24 through the collector of transistor 39 and a series circuit of resistors 46 and 47. The bases of transistors 48 and 18 are connected to the common connection point of resistors 46 and 47, and the collector of transistor 45 and the emitter of transistor 48 are connected to ground terminal 24. Capacitor 49 is an oscillation prevention capacitor.

Constant current supply path of transistor 39, transistor 45
, resistors 46, 47, resistors 15 and 16
13- It is provided to set the operating point so that the voltage across the terminal is approximately the same.

The voltage V at the reference voltage output terminal 14 of this constant voltage generation circuit
REF is equivalent to the case of FIG. 3 and is expressed by the above-mentioned equation (8). Here, transistor 48 and transistor 18
Since the base-to-emitter forward voltage is expressed as the ratio N of the base-to-emitter junction area of the transistor 17 to the base-to-emitter junction area of the transistor 48, it can be expressed as the following equation (4).

(Tatashi, vT is the thermal voltage vT - KV'e) Here, the fourth
The resistance value of each resistor in the diagram corresponds to the subscript of the R symbol: R31=50" Ω Rs 4=Ra 11=R40=R42=100R37
=800゜R46''421:2kQ R47'''几22 = 2.5 to 0 14- J5 = 6000 ) 1.16 = 6krl ■ Also □ 9 = 7500, and the difference in selection with N22 is the base of Trumpan Star 23. The typical value of emitter voltage VBE23 is '1'
= 0.65 V at 300°K, so the formula (4) is: VIEF=lv. Finally, a reference voltage with a temperature coefficient of zero and an output voltage of 1 V can be obtained at the reference voltage output terminal 14.As has been observed above, the present invention provides a reference voltage circuit with a circuit configuration suitable for semiconductor integrated circuits. This has the advantage that the reference voltage and its thermal coefficient can be set independently, allowing for a greater degree of freedom in installation.

In particular, a highly stable reference voltage circuit with an arbitrary voltage comparable to or lower than the one-way voltage of the diode can be obtained.

Furthermore, since no Zener diode is used, there is an advantage that a low-noise reference voltage is eliminated.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram showing an example of a conventional pan)/gag regulator, and Fig. 2 is a characteristic diagram showing the reference voltage and its temperature coefficient of the circuit of Fig. 1 with different resistance value R8. FIG. 3 is a constant voltage circuit diagram showing an embodiment of the present invention, and FIG. 4 is a constant voltage circuit diagram applying the standard 1=pressure N path of the present invention. 1, 1l...Power terminal, 2, 12, 13...
゜゛Current supply circuit, 3, 14...Reference voltage output terminal, 10, 24...Ground terminal, 4, 5, 8,
15, i6, 19, 21, 22, 31, 34, 37, 3
8, 40, 42, 46, 47...Resistance, 6,
7, 9, 1γ, 18, 20, 23, 36, 35,
39, 41, 43, 44, 45, 4B...transistor, 32, 33...diode, 49.
...Capacitor.

Claims (2)

[Claims] (1) a first voltage terminal; an output terminal coupled to the first voltage terminal via a first current supply means; a first resistor and a first transistor connected to the output terminal; a second voltage terminal connected to the base of the first transistor through a first series circuit including a second voltage terminal; a second transistor connected to the terminal and the second voltage terminal, respectively; a base is connected to the collector of the second transistor; and an emitter is connected to the 10' voltage via a second current supply means. A third transistor is connected in series with a third transistor whose collector is connected to the second voltage terminal and whose one end is connected to the third voltage terminal.
fourth and fifth resistors whose other ends are respectively connected to the emitter of the transistor and the second voltage terminal;
The base is connected to the connection point of the resistor No. 5, and the collector-emitter current path is connected to the first current supply means and the second current supply means.
a fourth transistor inserted at 101 and a voltage terminal, and is configured to output a fundamental pressure between the output terminal and the second voltage terminal. circuit. (2) The base is connected to a common connection point between the first resistor and the collector of the first transistor, and the emitter is connected to the third transistor.
is connected in series with a fifth transistor whose collector is connected to the second voltage terminal of iσ, and one end of which is connected to the voltage terminal of kIJl through the second voltage terminal of iσ.
sixth and seventh resistors whose other ends are respectively connected to the emitter of the transistor and the second voltage terminal;
1. The reference voltage circuit according to item 1 of Patent H1.1, characterized in that the base of the first transistor is connected to the connection point of the resistor.