JPS5880717A - Reference voltage circuit - Google Patents

Abstract

PURPOSE:To ensure the designing flexibility and to obtain the reference voltage of a low noise level, by varying the connection between the transistors and the resistances which are connected between a reference voltage output terminal and an earth terminal and then setting the reference voltage and the temperature coefficient independently of each other. CONSTITUTION:A reference voltage output 3 is connected to a power supply terminal 1 via a current supply circuit 2, and an end of each of resistances 4 and 7 is connected to the terminal 3. At the same time, the collectors of transistor (TR) 5, and TR10, TR11 are connected to the terminal 3. The other end of the resistance 4 is connected to the base of the TR5 as well as to an earth terminal 14 via the collector of a TR6. The emitter of the TR5 is connected to the terminal 14 via the resistances 15 and 12, and the joint of the resistances 15 and 12 is connected to the base of a TR8. The emitter of the TR8 is connected to the terminal 14 by a resistance 9. Then the other end of the resistance 7 is connected to the collectors of TRs 8 and 10 as well as to the base of the TR10. The emitter of the TR10 is connected to the terminal 14 by resistances 16 and 13, and the joint between the emitter of the TR10 and the terminal 14 is connected to the base of the TR11. 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, as a reference voltage circuit for a semiconductor integrated circuit, a constant voltage circuit using a Zener diode and a constant voltage circuit using a no-gun gap regulator are generally used. The former uses the breakdown voltage of a Zener diode, which is approximately 5
It is widely used when obtaining a reference voltage of V or higher. However, in this case, the breakdown voltage of the Zener diode is determined during the process of manufacturing the semiconductor integrated circuit, and therefore, when fabricating a Zener diode with a low breakdown voltage of approximately 5 V or less into the semiconductor integrated circuit, a new Additional manufacturing steps are required, leading to an increase in costs. Furthermore, the Zener voltage has drawbacks such as a large noise voltage due to its characteristics and a large temperature coefficient of the Zener voltage. The latter method takes advantage of the fact that the temperature coefficients of the base-.phi.-emitter voltages of transistors with different current sensitivities are different, and a specific example of the one-path configuration will be explained with reference to FIG. In FIG. 1, the power supply terminal 1 is connected to the reference voltage output terminal 3 through the current supply circuit 2 via L7, and from the reference voltage output terminal 3 to one end of each of a resistor 4 and a resistor 7, The connections to the collectors of transistors 5, 10 and 11 are respectively removed. The other end of the resistor 4 is connected to the common connection point of the base transistor 6 of the transistor 5.
The emitter JI of the transistor 5, the base of the range nut 6, and the base of the trough 2 and 8 are commonly connected, and the common connection point is connected via a resistor 12.

[7] is connected to the ground terminal 14. The other end of the resistor 7 is connected to the collector of a transistor 8 and further to the base of a transistor 10. The emitter of the transistor 10 is connected to the ground terminal 1 through a resistor 13.
Connected to 4. The emitters of transistors 6 and 11 are directly connected to ground terminal 14, and the emitter of transistor 8 is connected to ground terminal 14 through resistor 9. here,
The current supply circuit 2 is composed of, for example, a current source or a voltage source and a resistor. Moreover, since this circuit is made of a semiconductor integrated circuit, each of the above elements operates at the same junction temperature, and each transistor 5, 6, 8, 10 and 1
The ratio of saturation currents of 1 is proportional to their structure. Furthermore, the relative ratio of the resistance values of each resistor 4.7 and 9 can be determined accurately. Since the band gag regulator shown in FIG. 1 has the above-mentioned configuration, the voltage VR at the reference voltage output terminal 3
EF is expressed as equation (1), and the voltage at each operating point,
(2) to (γ) hold true for the current. vREF=■2xFL7+vBglO+vBE11
−°°−(i) VBE6 = VBEa +L+ x1
% +++ −(z) However, VREF: Voltage VB of reference voltage output terminal 3: )
Base-emitter voltage VBEa of transistor: lBE6 of transistor 8:
Base-emitter voltage Vnglo of transistor 5 IVBEII of transistor 10
: ) 11 of transistor 11 56 m) Saturation current of transistor ■S8:) U〉' 1 of transistor 8 ■s5: 1 of transistor 5 ISIO: ) 1 of transistor 10 1 Sll: 1 of transistor 11 5-11 m F transistor Current flowing in ■2: I into transistor 8. I n2: Resistance value of resistor 4. R7: Resistor 7. R9: Resistance 9. R12: I R of resistor 12. 3: I of resistor 13. γ: Electron charge: Boltzmann's constant T: Absolute temperature Here, if the base-emitter junction area of transistor 8 is N times that of transistor 6, then IS, = N @ IS6・・・・・・
...(8) holds true. By substituting equations (8), (4), and (8) into equation (2), it is obtained. Here vBg 6 and VBEII and VBEa and VB
Since the operating points are selected so that EIO is approximately equal to 6-, equation (9) can be expressed as follows. Substituting this into equation (1) yields. This is the formula for determining the voltage VREF at the reference voltage output terminal 3. Partially differentiating the above equation 01) with respect to temperature T, θVagto/
a 'r-δVngt 17a T= a (!:
>< This is the formula for determining the temperature coefficient of VREF. Typical values for -VBEl O, VBE 11 here are about 0.65V at T=300', and the temperature coefficient of each, or α, is about -2mV/°C. the above(
As can be seen from Equation 14, the second term on the right side is negative, so if the resistance ratios R7/I't 9 and R7/R4 of the first term on the right side and the area ratio N of transistor 6 and transistor 80 are appropriately selected, the reference voltage can be obtained. Temperature coefficient θVR of voltage VREF of output terminal 3
up/aT can be made zero. All right, above (
] By setting the left side of the equation to zero, the following equation is obtained. If we choose each constant to satisfy this equation, we can obtain VREF that is stable against temperature fluctuations.
kΩ Ru. As a specific example, R4=1.2, Ry=12
, Rs=300° and N=1, then VnEp-2.5V
...No. 0). However, the biggest drawback of this circuit is that the reference voltage output terminal 3
The voltage VREP is uniquely determined by the temperature coefficient of VBE1 (h'VBE11 and %).Here, according to equations 01 and 12, aVREF/aT=
(VREp-Vat< l+)-VB E l 1
)/P+ 2 a-=cm, and VREF with the temperature coefficient of VRE'F as a value becomes the voltage value of the equation 04-) even if the combination of the above valley parameters is used.If we try to deviate from this, VRgFe becomes ( It has the temperature coefficient of equation 15). If you try to obtain a voltage value of VREF=3V, T-30
Near 0° (D V. 1. A stable reference voltage can be obtained using the table, but if the reference voltage VREF is changed, it will have a temperature coefficient, so a stable reference voltage without temperature dependence cannot be obtained over a wide range, and this is a major constraint in terms of calculation. The object of the present invention is to overcome the above-mentioned drawbacks and to provide a reference voltage circuit suitable for semiconductor integrated circuits that supplies a stable reference voltage over a wide range. 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 current source is connected to the IT terminal and its power supply terminal. a first series circuit consisting of a first resistor connected between the output terminal and the ground terminal, a constant current voltage element, and this first series circuit. a second string circuit including a second resistor, a first transistor, and a third resistor connected in parallel with each other; the base is connected to the connection point of the second resistor and the first transistor; A second transistor is connected to the ground terminal through fourth and fifth resistors connected in series, and the base is connected to the connection point of the fourth and fifth resistors, and a collector-emitter current path is formed. A reference voltage circuit characterized in that it has a third transistor inserted between a current source and a ground terminal.
I will clarify. FIG. 2 is a circuit diagram of a reference voltage circuit showing one embodiment of the present invention. In FIG. 2, the same company rules and symbols as in the conventional example shown in FIG. The emitter of transistor 10 is connected to a common connection point between the 10- base of transistor 11 and one end of resistor 13 through resistor 16, and the other points are the same. If this circuit is made with a semiconductor cold product circuit, the first
As in the conventional example shown in the figure, each device operates at the same junction temperature, and transistors 5, 6, 8, 10, and 11
The ratio of the saturation currents of is proportional to their structural area. Furthermore, the relative ratios of the resistance values of each resistor 4.7.9.12, 13.15 and 16 are also accurately taken. Since such a reference voltage circuit differs from the above-described configuration, the voltage VREF at the reference voltage output terminal 3 can be expressed as in the conventional example as shown in the following equation. However, R13 is the resistance value of the resistor 13, ■t16 is the resistance value of the resistor 16, and the rest is the same as in the case of FIG. By partializing the above equation Q6) with temperature T, dVBElo/
aT=aVBE//l17I';αtoot, which is the formula for determining the temperature coefficient of VREF. Here, the output voltage V'REF at which the temperature coefficient of the voltage VREF of the reference voltage output terminal 3 is equal to 0 is determined by setting the left side of the equation 7) to zero and using the parameter 4! r resistance ratio R7/I (9, R
By setting 7/R4 and Rq s/R1g and the area ratio N of the transistor 6 and the transistor 80 so as to be the same, the following voltage value can be obtained. As a result, by setting each parameter so as to satisfy equation (g), the voltage at the reference voltage output terminal 3 at which the temperature coefficient drops to zero, V k E F! , is the resistance ratio R16/Rs a that can be varied to obtain any voltage value.3 As a specific example, VBEI (h The typical value of VBE41 is '
1' = approximately 0.65 V at 300 K, each temperature coefficient is approximately -27°C, R4 = 1.2" R7 = 12
If kn, R9=250'', It13 is set to Ω-5+R16==2k, and N=1, then 'VRgp=3V...
...(goods). That is, at the reference voltage output terminal 3,
A reference voltage with a temperature coefficient of zero and an output voltage of 3V can be obtained. Further, α6) equation and equation (17) are combined with the following equation (1+). From the above equation (g), it can be seen that in the conventional system, the reference voltage and its temperature coefficient are uniquely determined. In this case, the desired reference voltage VREF #+I and the temperature coefficient can be obtained using the resistance ratio (1i 6/Rls) as a parameter. In the embodiment shown in FIG.
A similar effect can be obtained by connecting the emitter of transistor 5 directly to the common connection point of transistor 6.8. Also, although the formula for calculating the voltage VREF of the reference voltage output terminal 3 and its temperature coefficient is complicated, it is necessary to calculate the voltage VREF of the reference voltage output terminal 3 and its temperature coefficient.
A similar effect can be obtained when the collector and base of the transistor 6 are directly connected to form a diode connection without using the transistor 6. FIG. 3 shows a circuit diagram of a constant voltage generating circuit with an output voltage of 3 V, which was demonstrated using the embodiment shown in FIG. In FIG. 3, the same reference numerals are used for parts corresponding to the reference voltage circuit in FIG. 2, and different points will be explained. In FIG. 3, the resistor 17, transistor 18, and diode 19.20 constitute a start circuit when the tt power is turned on, and when the output voltage VREF of the output terminal 3 reaches 3■, the transistor 18 is turned off and the It no longer contributes to the operation as a voltage generating circuit. Transistors 22, 23.
26 resistors 21, 24.25 are the current/supply circuit j1 in Fig. 2
The transistor 23 constitutes a constant current source corresponding to the transistor 82, and a bias is applied to the transistor 23 from the output terminal 3. The transistor 27 functions as a current amplification transistor subjected to negative feedback in order to improve voltage stability. The capacitor 28 is a 14-capacitor for preventing oscillation. Now, when the output voltage of this constant voltage generation circuit becomes higher than the constant set value, this voltage passes through the resistor 7 and raises the base potential of the transistor 10, and further raises the base potential of the transistor 11. , transistor 1
1's collector current increases. As a result, the base current of the transistor 27 decreases, and the voltage at the output terminal 3 decreases to a steady state at a predetermined value. As explained above, according to the present invention, a reference voltage circuit with a circuit configuration suitable for semiconductor integrated circuits can be obtained, and the advantage of being able to set the reference voltage and its temperature coefficient independently increases the degree of freedom in design. It can be taken. Furthermore, since no Zener diode is used, there is an advantage that a low-noise reference voltage can be obtained. It should be noted that the present invention is not limited to the above embodiments, and for example, the power supply terminal 1 and the ground terminal 14 may have a certain predetermined bias potential, and a resistor may be inserted at an appropriate predetermined position for matching the circuit. . 15-

[Brief Description of the Drawings] Fig. 1 is a circuit diagram showing an example of a conventional band gap regulator, and Fig. 2 is a reference voltage 11 showing an embodiment of the present invention.
FIG. 3 shows a constant voltage generation circuit diagram based on the reference voltage circuit of the present invention. ■・・・Power terminal, 3・・・Output terminal, 1
4...Ground terminal, 2...° constant current source, 4
．． 7.9.12.13.15.16, 17.21.24
．． 25°・Pa・・Resistance, 5.6.8.10, 11.18
．． 22.23.26.27°=°) transistor, 19.
20... Diode)", 28... Capacitor. -16- ÷ Graduation) 1\Il Hayabusa 2 figure ′ → Hi-kushi 3 figure

Claims (1)

[Claims] a first voltage terminal; an output terminal coupled to the first voltage terminal via a first current supply means;
A base is connected to a second voltage terminal connected through a series (b) path between the resistor and the second current supply means, and a connection point between the first resistor and the second current supply means. The first
transistor, second and third resistors connected in series and having one end connected to the emifter of the first transistor and the other end connected to the second voltage terminal, respectively;
The base is connected to the connection point of the resistor, and the collector-emitter current path includes a second transistor inserted between the first current supply means and the second voltage terminal. Reference voltage circuit.