JPH0578845B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a reference voltage generation circuit that is independent of changes in ambient temperature or fluctuations in power supply voltage and is capable of generating a low-voltage reference voltage.

(b) Conventional technology Pages 1-6 and 1-7 of the book "Voltage Regulator Handbook" published by Seibundo Shinkosha on September 10, 1980, describe the base and emitter of a transistor. A reference voltage generation circuit is described that is capable of generating a reference voltage based on the difference in voltage between the two. FIG. 2 shows the reference voltage generation circuit, in which the current density of the diode-connected first transistor 1 is made larger than the current density of the second transistor 2, so that the voltage between the base and emitter of both transistors is A voltage difference is generated across the first resistor 3, and a reference voltage corresponding to the voltage difference is generated at the output terminal 4. Now, if the current flowing through the first resistor 3 is I ₁ , then V _BE1 = V _BE2 + R ₁ I ₁ ...(1) [However, V _BE1 is the base-emitter voltage of the first transistor 1, and V _BE2 is the voltage between the base and emitter of the first transistor 1. The base-emitter voltage R ₁ of the transistor 2 is the resistance value of the first resistor 3], and the reference voltage Vref obtained at the output terminal 4 is Vref = V _BE3 + R ₂ I ₁ ...(2) [However, V _BE3 is The base-emitter voltage R ₂ of the third transistor 5 is the resistance value of the second resistor 6. Therefore, from equations (1) and (2) above, Vref=V _BE3 +R ₂ /R ₁ (V _BE1 −V _BE2 ) = V _BE3 +R ₂ /R ₁・kT/qlnJ ₁ /J ₂ (3) ) [where k is the Boltzmann constant, T is the absolute temperature, q is the electron charge, and J ₁ and J ₂ are the current densities of the first and second transistors 1 and 2]. In the above equation (3), in order to obtain a stable reference voltage against changes in ambient temperature, it is sufficient to set dVref/dT=0, and dVref/dT=dV _BE3 /dT+R ₂ /R ₁・k/qlnJ ₁ /J ₂ ...(4), so change the first and second resistors 3 and 6 so that dV _BE3 /dT=-R ₂ /R ₁・k/qlnJ ₁ /J ₂ ...(5) By setting a value, the reference voltage is stable against changes in ambient temperature.
You can get Vref.

(c) Problems to be solved by the invention However, the reference voltage generation circuit shown in FIG.
It is only possible to obtain a reference voltage of at least 1.3V,
It is not possible to obtain a low reference voltage below 1V,
There was a problem. That is, since dV _BE3 /dT is normally -2 mV, from the above equation (5), R ₂ /R ₁ ·k/qlnJ ₁ /J ₂ = 2 (mV) ...(6), and the above equation (6) ) is substituted into the above equation (3), Vref=V _BE3 +2T...(7). At room temperature (300〓), V _BE3 is approximately 700m
Therefore, from the above equation (7), Vref is approximately
The voltage becomes 1.3V, and it is not possible to obtain a reference voltage lower than this with the circuit configuration shown in Figure 2.

(d) Means for solving the problems The present invention has been made in view of the above points.
In order to obtain a reference voltage that does not have temperature dependence of 1V or less, a current generation circuit that generates a band gap current, a diode-connected third transistor and a second resistor are each supplied with the current obtained from the current generation circuit. , characterized in that third and fourth resistors are provided which are connected in series between the collector of the third transistor and one end of the second resistor.

(e) Effect According to the present invention, the voltage having the predetermined temperature characteristic obtained at the collector of the third transistor and the
The reference voltage is obtained by dividing the voltage obtained at one end of the resistor with a predetermined temperature characteristic by the third and fourth resistors, so if the values of the first to fourth resistors are appropriately set, the ambient It is possible to generate a low-voltage reference voltage that is independent of temperature changes.

(F) Embodiment FIG. 1 is a circuit diagram showing an embodiment of the present invention.
7 is a diode-connected first transistor; 8
9 is a second transistor connected to the first transistor 7 in a current mirror relationship; 9 is a first transistor connected between the emitter of the second transistor 8 and ground;
A resistor 10 is a diode-connected third transistor to which a current equal to the collector current of the second transistor 8 is supplied; 11 is a second resistor to which a current equal to the collector current of the second transistor 8 is supplied; 12 and 13 are third and fourth resistors connected in series between the collector of the third transistor 10 and one end of the second resistor 11; and 14.
is an output terminal connected to the connection midpoint of the third and fourth resistors 12 and 13. Note that the fourth, fifth, and sixth transistors 15, 16, and 17 form a feedback path for causing a current equal to the collector current of the second transistor 8 to flow to the diode-connected seventh transistor 18. 8th, 9th and 10th
Transistors 19, 20 and 21 are connected to the seventh transistor 18 in a current mirror relationship. Further, the resistor 22 and capacitor 23 are arranged to prevent oscillation.

Now, if the area ratio of the emitters of the first and second transistors 7 and 8 is set to 1:n (where n>1), the current I ₁ flowing through the first resistor 9 is I ₁ =V _BE1 − V _BE2 /R ₁ ...(8) [where V _BE1 is the base-emitter voltage of the first transistor 7 V _BE2 is the base-emitter voltage of the second transistor 8 R ₁ is the resistance value of the first resistor 9] , the current I ₁ also flows through the diode-connected seventh transistor 18 and the eighth to tenth transistors 19 to 21 connected to the seventh transistor 18 in a current mirror relationship. Therefore, the voltage V _A at one end A of the second resistor 11 is V _A = R ₂ / R ₁ (V _BE1 − V _BE2 ) = R ₂ / R ₁・kT/qlnn...(9) [However, R ₂ is the resistance value of the second resistor 11]. On the other hand, since the collector voltage of the third transistor 10 is V _BE3 , the reference voltage Vref obtained at the output terminal 14 is Vref=R ₄ /R ₃ +R ₄ V _BE3 +R ₃ /R ₃ +R ₄・R ₂ / R ₁ ·kT/qlnn (10) [where R ₃ is the resistance value of the third resistor 12 and R ₄ is the resistance value of the fourth resistor 13]. Reference voltage Vref obtained at output terminal 14
_{In order for _ _ _ _ _ 1}・k/qlnn _{... ( 11} ) Therefore, the third and _fourth resistors ₁₂ are By setting the values of and 13, the reference voltage Vref becomes independent of the ambient temperature. The reference voltage Vref at that time is
From equations (10) and (12), Vref=1/1-dT/dV _BE3・R ₂ /R ₁・k/qlnn・
R ₂ /R ₁ · k / q (T - dT / dV _BE3 · V _BE3 ) lnn...(13). By the way, n=10, R ₁ = 620Ω, R ₂ =
3.9 kΩ, dV _BE3 /dT = -1.8 mV/°C, then from the above equation (12), R ₄ /R ₃ = 0.695, and the reference voltage at that time is 0.515V from the above equation (13).

Therefore, by using the circuit shown in Figure 1, a low reference voltage of 1V or less can be applied to the first voltage regardless of the ambient temperature.
This can be obtained only by setting the fourth resistors 9 to 13. It is also clear from equation (13) that the reference voltage Vref does not depend on changes in the power supply voltage V _CC .

(G) Effects of the Invention As described above, according to the present invention, it is possible to provide a reference voltage generation circuit that can generate a reference voltage that does not depend on changes in ambient temperature or fluctuations in power supply voltage. According to the present invention, it is possible to provide a reference voltage generation circuit that can generate a low reference voltage of 1V or less. At this time, the reference voltage can be obtained by simply setting the values of the first to fourth resistors, so the present invention can provide a reference voltage generation circuit suitable for integrated circuit implementation.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, and FIG. 2 is a circuit diagram showing a conventional reference voltage generation circuit. 7...First transistor, 8...Second transistor, 9...First resistor, 10...Third transistor, 11...Second resistor, 12...Third resistor, 13
...Fourth resistance.

Claims (1)

[Claims] 1. Current generation that generates a predetermined current by a first transistor connected as a diode, a second transistor connected to the first transistor in a current mirror relationship, and a first resistor connected to the emitter of the second transistor. a diode-connected third transistor to which a current obtained from the current generation circuit is supplied; a second resistor to which the current obtained from the current generation circuit is supplied; a collector of the third transistor; third and fourth resistors connected in series between one end of the two resistors;
the collectors of the second and third transistors and the second
a plurality of transistors each having a collector-emitter path connected in a current mirror relationship between one end of the resistor and a power source, the transistors supplying the current obtained from the current generating circuit to the third transistor and the second resistor; A reference voltage generating circuit comprising: a reference voltage generating circuit which generates a reference voltage at a connection midpoint between the third and fourth resistors.