JPS58112112A - Reference voltage circuit - Google Patents

Abstract

PURPOSE:To ensure a stable supply of the reference voltage over a wide range, by putting a resistance between the base of an output transistor of a band gap regulator and an earth to obtain a variable negative temperature coefficient. CONSTITUTION:A power supply terminal 1 is connected to an output terminal 3 of the reference voltage via a current supply circuit 2, and the terminal 3 is connected to an end of each of resistances 5 and 7 as well as to the collector of a transistor (TR)10 respectively. A common contact of the collector of a TR8 and the resistance 7 is connected to an earth terminal via a resistance 11. The negative temperature coefficient of an equation showing the reference voltage is variable by a resistance ratio R7/R11, and an optional negative temperature coefficient is obtained. Therefore the zero temperature coefficient is obtained for the reference output voltage by controlling the ratio R7/R11.

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 bandgap 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 manufacturing process of the semiconductor integrated circuit, and therefore the breakdown voltage of the Zener diode is approximately 5.
If a Zener diode with a low breakdown voltage of V or less is to be fabricated into a semiconductor integrated circuit, a new and additional manufacturing process will be required, leading to an increase in cost. However, there are disadvantages such as high noise, high soldering pressure, and high temperature coefficient of Zener voltage.

Also, the latter is electric current! This circuit utilizes transistors having different temperature coefficients of base-emitter voltages at different temperatures, and an example of a specific circuit configuration thereof will be described with reference to FIG.

#I1 In the diagram, the power supply terminal l is coupled to the reference voltage output terminal 3 via the current supply circuit 2, and the reference voltage output terminal 3 is connected to one end of a resistor 5 and a resistor 7, and further to a transistor. Connections are made to each of the 10 collectors. The other end of the resistor 5 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 8. The other end of the resistor 7 is connected to the collector of the transistor 8, and further connected to the collector of the transistor 10.
It is also connected to the base of n. transistors 6 and l
The emitter of the transistor 8 is directly connected to the ground terminal 4 via a resistor 9.

Here, the current supply circuit 2 is composed of, for example, a current source or a voltage source and a resistor.

Also, since this circuit is made of a semiconductor integrated circuit, each of the above elements operates at the same junction temperature, and each resistor 5#7
The comparison of the resistance values of 9 and 9 is exactly 9.

Since the bandgap regulator shown in Fig. 1 has the above configuration, the voltage at the reference voltage output terminal 3 is
1mν is expressed as tL as in equation (1), n is expressed as in equation (1) for the voltage and current at each operating point, and (2) to (5) for voltage and current at each operating point. ) formula holds true.

■RIP ” ”! ×R? +VBI11゜・
・・・・・・・・・・・・(1) ■1! ! +1 = ■1
1111 + 工、×R9””””””(”9 dashi.

■, □: Voltage of reference voltage output terminal 3, ■□6: Transistor 60 base, 2 f, voltage between terminals, ■□ - 2 transistor 80 base, terminal (voltage between terminals).

vmmto : ) Voltage between base and emitter of transistor 10 s ``@@ ' ) Saturation current of transistor 10 *
"@@" Saturation current s of transistor 8 1sxo:)
? y series x 1 O gun sum current, 11 Nidrangistoro's llc current, i, :): 9y Current h flowing in y series 8
'3: Transistor 10 (lllln current full-
* 'y' Resistance value of resistor 7* flL+1 'Resistance value of resistor 9 %q: Electron charge, K: Boltzmann constant,
T: Absolute temperature, where is the base-emitter junction m product of transistor 8? If n is made with an area N times that of transistor 6, nbal gN@I , , , , ,
, , , , 811 sg holds true. (3), (4) and (6) to equation (2)
) by substituting the expression. By substituting this into the equation f'Lt(1), we get: Here, the temperature change in the first term on the right side is positive, and the temperature change in VBN in the second term is negative (approximately -2 mV/'O for silicon transistors), so the temperature change in the first term = 2 mV/'O.
”0=-〇VB11G ,,,,,,,,(
By selecting and changing each constant so that 9>θT, an output voltage VIIIF that is stable against temperature fluctuations can be obtained. As a specific example, using a transistor with the same characteristics as transistor 6e8*10, R, = 600Ω. =6 to Ω,
R・-600Ω and Δ=1 and each para V 1.25
V......(lO)! II
It is IIF.

However, in this circuit, the temperature coefficient becomes zero only for a constant reference voltage value.

Here, by partially differentiating (8), the temperature coefficient of the reference voltage θVRIc
F/δTt - Find a VRIF/a T = (VIIP - Vileso)
,, + 11 Vsw/aT・・・・・・・・・(
11) Then, the temperature coefficient θ is. , /θT is set to zero, and it is logically determined by v882 and its temperature coefficient.

As a result, the voltage value is given by equation (10), and if one tries to obtain RICr t- which deviates from n, the temperature coefficient is given by equation (11').

If V is set to = 1.5V, T-3000
Nearby VR,! The temperature coefficient of iF is 0.83mV/”O
I'm sure you'll like it.

As explained above, with the conventional bandgap regiator, a reference voltage of about 1.25 V can be obtained that is stable with respect to temperature, but if the reference voltage vR1F is changed, the ffi degree coefficient will be affected, resulting in temperature dependence. This had the drawback that a stable reference voltage could not be established over a wide range, and this was a major design constraint.

SUMMARY OF THE INVENTION An object of the present invention is to overcome the above-mentioned drawback 1 and provide a reference voltage circuit suitable for conductive integrated circuits.

Another object of the present invention is to provide a reference voltage circuit 1m in which the output voltage and its temperature coefficient can be arbitrarily set.

According to the present invention, a power supply terminal, an output terminal coupled to the power supply terminal via a current #, a series circuit of a first resistor and a constant voltage element, and a series circuit of a second resistor and a first a ground terminal connected through a series circuit of a transistor and a third resistor; a fourth resistor connected to a connection point between the second resistor and the first transistor and the ground terminal;
A reference voltage circuit having a base connected to the collector of the second transistor, and a third transistor whose collector current path is inserted between the current source and the ground terminal. get.

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 2 is a circuit diagram of a reference voltage circuit showing one embodiment of the present invention.

In Figure 11G2, the same parts as in the conventional example in Figure 1 are given the same symbols, and the only difference is that the common connection point between the collector of transistor 8 and resistor 7 is connected to the ground via resistor 11. Everything else is exactly the same.

And if this circuit is made with a semiconductor integrated circuit, @1
As in the conventional example shown in the figure, each element operates at the same junction temperature, and the ratio of the saturation currents of each transistor 6#8 and 10 is
are proportional to their structural area. Furthermore, each resistance 5=
The relative ratio of the resistance values of 7.9 and 11 is also accurately taken.

Since this reference voltage circuit has the above-mentioned configuration, the voltage VRmF of the reference voltage output terminal 3 holds true, and the formulas (2), . . . I() also hold true.

It becomes as shown in equation (12).

V□1° However, %R11 is the resistance value of resistor 11, and the others are the same as in the $1 diagram. If each constant is selected so that the positive temperature coefficient pair value of the first term on the right side is equal, an output voltage that is stable against temperature fluctuations can be obtained.

The major difference between the above equation (12) and the conventional example (8) is as follows.

Since a coefficient larger than 1 is added to the second term □, this value is variable depending on the resistance ratio Ry /R, , so that any negative temperature coefficient can be obtained.

Therefore, by adjusting R and /R1, a zero temperature coefficient can be obtained at any output voltage equal to or higher than VR1F, at which the temperature coefficient of the conventional example remains zero.

FIG. 3 is a circuit connection diagram showing another embodiment of the present invention, in which the current ratio 1°/Is flowing through transistors 6 and 8 is set to a value that does not fluctuate with temperature changes, so that the output is The present invention provides a reference voltage circuit which makes it easy to select a predetermined temperature coefficient of +1 that is constant even over a wide range of temperature fluctuations as the temperature coefficient of the voltage ■IIF.

In the embodiment of FIG. 2, the current ratio L! 71. It can be seen that n has a temperature fluctuation.

This means that even if it is set directly to a certain value, it will fluctuate from the predetermined value over a wide range of temperatures. Therefore, the output voltage of the embodiment shown in FIG. 2 can have a temperature coefficient of zero near the arbitrary temperature mentioned above, but it has a temperature coefficient at a temperature far away from the arbitrary humidity layer.'''A6.
,,j,l,j.

Now, in FIG. 3, the difference from the embodiment shown in FIG. 2 is that the base-collector connection point of the transistor 60 is connected to the resistor 12.
It is connected to the ground terminal 4 via. The output voltage VRIF of the reference voltage circuit having the above configuration is expressed by the above equation (12) as in the embodiment shown in FIG.

Here, the current flowing through the transistors 6 and 8 can be made to have a temperature coefficient of 11/I of zero by selecting the resistance value of each transistor 12 to be 11/I. However, VB1$-VII□. Let us set the emitter' surge density so that.

The output voltage VBIP when satisfying formula (16) is ・VBi
ml. ......(17) Therefore, the positive fif coefficient in the first term on the right side is determined only by the resistance ratio and area ratio of LFi and does not include the temperature parameter, so it remains constant even over a wide range of temperature fluctuations. Each constant can be easily selected so that the absolute value is equal to the negative temperature coefficient (constant with respect to temperature). Note that the temperature coefficient is expressed by the following equation (18).

It goes without saying that in this embodiment as well, it is possible to obtain an arbitrary output voltage that is stable against temperature fluctuations, as in the embodiment shown in FIG.

Figure 84 shows the output voltage 1. realized using the embodiment of Figure 3.
FIG. 2 is a circuit connection diagram showing a 5V constant voltage generation circuit.

In FIG. 4, the same reference numerals are used for parts corresponding to the reference voltage circuit in FIG. 3, and the differences will be explained. In FIG. 4, resistor 13. )? 14. The diode 15 * 16 constitutes a start circuit when the power is turned on, and when the output voltage m1ey at the output terminal reaches 1.5 V, the transistor 14 turns off and does not contribute to the operation as a constant voltage generation circuit. It disappears. Transistor 18*19
I22-resistor 17*20s21 constitutes a constant current source corresponding to 2 in FIG. 3, and transistor 19 is biased from the output terminal. The transistor 23 functions as a current amplification transistor to which negative feedback is applied in order to improve regulation. The capacitor 24 is a capacitor for preventing oscillation.

Now, when the output voltage of this constant voltage generation circuit becomes higher than a predetermined set value, this voltage is passed through the resistor 7 to the transistor l.
In order to raise the base potential of O, its collector current increases. As a result, the base current of the transistor 23 decreases, and the voltage line of the output terminal 3 decreases to a steady state at a predetermined value.

Here, corresponding to the subscript of the symbol of the resistance value t-H of each resistor, R, = 6000-By = 1.2 and Ω-R, = 1000-
'o = 6 k < 1 + )Ll, =t, 3
kΩ, R,,z 59 kΩ.

kL1? = k21 = 2000"go = 6000, and if N; 5 is selected, the transistor is 100 base.
Typical value of electrical voltage ■11110 is T-300
' Since it is 0.65V, from equation (17), VR liver 81
-5V, that is, a reference voltage with a temperature coefficient of zero and an output voltage of 1.5V is obtained at the reference voltage output terminal 3. It is sufficient to select not only the constants described above but also to satisfy the above-mentioned equations (16), I(17), and (1B).

As explained above, the present invention provides a reference voltage circuit with a circuit configuration suitable for semiconductor integrated circuits, and has the advantage that the reference voltage and its temperature coefficient can be set independently, allowing a greater degree of freedom in design. . or.

Since no Zener diode is used, there is an advantage that a low-noise reference voltage can be obtained.

1. The present invention is not limited to the above-mentioned implementation, and for example, the power terminal 1 and the ground terminal 4 may have a predetermined bias potential, or a resistor may be inserted at an appropriate predetermined position to secure the circuit. good.

[Brief explanation of drawings]

Fig. 1 is a circuit connection diagram showing an example of a conventional band gear and preregulator, Fig. 2 is a circuit connection diagram of a reference voltage circuit showing an embodiment of the present invention, and Fig. 3 is another embodiment of the present invention. FIG. 4 shows a circuit connection diagram of a constant voltage generation circuit which is a specific embodiment of the reference voltage circuit of the present invention. l...Power terminal, 3...Output terminal, 4
...Ground terminal, 2...Constant current source, 5t
7 years 9 * 11-12 + 13 * 17 + 20 e
21"""Resistance%6.8t10114+18*19t2
2+23...transistor, 15*16...
...Diode, 24...Capacitor. Figure 1 Figure 2 Figure 3 Figure 4

Claims (2)

[Claims] (1) all voltage terminals, an output terminal coupled to the first voltage terminal via a current supply means, and a first transistor diode-connected to a first resistor to the output terminal; The second voltage terminals are connected in series through a series circuit, with one end being the output terminal and the other end being the second voltage terminal. The collector is connected to the connection point between the second and third resistors, and the base of the first transistor is connected to the second resistor.
transistor, the emitter of the second transistor and the fit! a fourth resistor connected between the two voltage terminals; and a third transistor inserted between the second voltage terminal and the second voltage terminal of the second and third resistors. Characteristic reference voltage circuit. (2) The reference voltage circuit according to claim 1, wherein a connection point between the first resistor and the first transistor is connected to the second voltage terminal via a fifth resistor.