JPS626313A - Reference voltage generator - Google Patents

Abstract

PURPOSE:To obtain the stable output reference voltage with high accuracy by using the 1st transistor which has a negative temperature slope of the base- emitter voltage and setting a proper ratio between the 1st and 2nd resistances of the emitter. CONSTITUTION:A reference voltage generating circuit consists of the 1st and 2nd NPN transistors Tr 1 and 2 having different emitter areas, the 3rd-6th Tr 3-6, the 1st and 2nd resistances 7 and 8, a load resistance 9 and a resistance 10. Here the Tr 5 and 6 form a current mirror circuit, and the reference voltages Vout 11 and 12 having minute temperature coefficients are delivered from both ends of the resistances 9 and 10 respectively. Thus, it is possible to obtain the reference voltage having a minute temperature coefficient in the form of a reference potential equal to the sum of the voltage drop VR2 of the resistance 8 and the base-emitter voltage VBE1 of the Tr 1 by setting the resistance ratio R2/R1 of both resistances 7 and 8 at a proper level.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a reference voltage generating means often used in integrated circuit devices, and in particular to maintaining a constant output voltage against temperature changes and current/voltage changes. This invention relates to a reference voltage generating device that can perform

Conventional technology A conventional reference voltage generation circuit will be explained below.

Figure 3 shows a conventional band gap type reference voltage generation circuit, in which 14, 15.16 are NPN transistors, 17.1
8 is an NPN transistor, 19°20.21.22 is a resistor, 13 is a constant current source that supplies current to the bandgap reference voltage circuit composed of the above transistors, 23 is an output reference voltage, and the NPN transistor 16 is ,NP
A constant current circuit composed of N transistors 17 and 18 and a resistor 22 is connected.

Regarding the band gap type reference voltage circuit configured as above, for example, rlEEE, JOURNAL O
F 5OLID-8TATE CIRCUITJ
VOL, 5C-6, No. 11971), and its operation will be explained below.

First, the NPN transistors 14 and 15 operate at different current densities, and a voltage having a positive temperature gradient is generated across the resistor 21 and the resistor 20. Furthermore, NPN) transistor 1
6 is added to the voltage generated across the resistor 20 to produce an output voltage 2
Generate 3. As a result, the output voltage 'J out
is the voltage V at the base-emitter of the NPN transistor 160
BE and the temperature-dependent voltage generated in the resistor 20 are added together and output as a voltage. If the output voltage V Q u t is set to the bandgap voltage of silicon (approximately 1.2 V), the voltage generated across the resistor 20 will compensate for the temperature coefficient of the base-emitter voltage VBH of the NPN transistor 16 and change due to temperature changes. A constant output reference voltage 23 can be obtained.

Problems to be Solved by the Invention However, in the above configuration, the low current source 13 is required to configure the reference voltage circuit, which not only makes the circuit configuration complicated (and the current value is If it does not match the circuit current of the reference voltage circuit, the output reference voltage 23
This has the problem of causing errors in the results.

The present invention solves the above problems, does not require a constant current source,
The present invention provides a reference voltage generation circuit suitable for an integrated circuit device that makes it possible to obtain a stable reference voltage with a small temperature coefficient with a simple configuration.

Means for Solving the Problems Therefore, the present invention includes first and second transistors each having a different emitter area, and the first transistor connects the emitter of the second transistor to the second transistor through the first resistor. A third transistor is connected to the emitter and grounded via a second resistor, a third transistor is diode-grounded to its collector, and a current proportional to the collector current of the second transistor is connected to the collector of the third transistor. and a current mirror circuit that supplies the third transistor;
By connecting the base and collector of the third transistor to a fourth transistor whose bases are commonly connected, a constant voltage is generated in the load connected between the emitter of the fourth transistor and the ground terminal. It is.

Effect According to the above configuration, the base-emitter voltage of the first transistor has a negative temperature gradient, and by appropriately setting the first and second resistance ratios, the voltage drop at the second resistor can be reduced. A reference voltage with a small temperature coefficient can be obtained as a reference potential obtained by adding the base-emitter voltage of the transistor. Further, a fourth transistor is connected to the connection point between the third transistor and the current mirror circuit, and outputs an output reference voltage across the load resistor, so the output reference voltage is the base-emitter voltage of the third transistor and the fourth transistor. The base-emitter voltages of the transistors cancel each other out, and the output voltage can be a reference voltage with a small temperature coefficient.

Embodiment Hereinafter, a reference voltage generation circuit according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows a reference voltage generating circuit according to a first embodiment of the invention. In FIG. 1, 1°2 is an NPN transistor having a different emitter area, and
The collector and base of the PN transistor 1 are connected, and the bases of the second NPN transistor 2 are commonly connected. 3 is an NPN transistor diode-connected to the NPN transistor 1; 4 is an output NPN transistor that outputs a reference voltage to its emitter terminal; its base is commonly connected to the third NPN transistor 3;

5 and 6 are PNP transistors forming a current mirror circuit that supplies a current proportional to the collector current of transistor 2 to transistors 3 and 1; 7 and 8 are PNP transistors having a voltage having a positive temperature gradient across them; Reference voltages Vout and vout having a desired small temperature coefficient are output across the resistors 9 and 10.

In the embodiment configured as above, when the emitter area ratio of NPN transistors 1 and 2 is configured to be 1:N, if the current flowing through transistor 1 is IEI, and the current flowing through transistor 2 is II2, then Base-emitter voltage VBE of transistors 1 and 2
I, VBE2 are expressed as. (Here, K is the Boltzmann constant, T is the absolute temperature, g is the electron charge, ■o is the transistor reverse saturation current, and AE is the emitter area.

) By the way, the above IEI and II2 are connected to ■ Old = IE2 by a current mirror circuit composed of PNP transistors 5.6
holds true. Therefore, from equations 3 and 4 above, the differential voltage △VBE generated across the resistor 7 becomes
When and (1112) are determined, it is expressed as follows.Furthermore, since the emitter currents IEI and II2 are combined and flow through the resistor 8, the resistance value of the resistor 8 is set as R, and the voltage drop VR2 at R2 is determined.

Here, if we differentiate the formula (■) with respect to the temperature T, we get N
When >1 is established, the voltage VR2 becomes a voltage having a positive temperature coefficient.

On the other hand, in equation (3) above, the base of the transistor
The emitter voltage VBEI is -3000PPM (-2m
V/℃), and the resistor 7
By appropriately setting the resistance ratio R2/Rt of resistor 8 and 8, the voltage drop VR2 at resistor 8 and V of transistor 1 are
A reference potential with BEI added can be obtained.

Furthermore, in the present invention, a diode-connected NPN
Transistor 3 is cascade-connected to NPN transistor 1 and connected to PNP transistor 5 of the current mirror circuit, and an output NPN transistor 4 is connected from the connection point to output reference voltage V OII t across load resistor 9.
Output. Here, the output reference voltage vo ut is
Base-emitter voltage of transistor 3 and output NPN
The base and emitter voltages of transistor 4 cancel each other out,
V out = vrer
-(9) is established, and the output voltage V out can obtain a reference voltage with a small temperature coefficient.

Furthermore, the collector of the output NPN transistor 4 is connected to the resistor 1.
By connecting the resistor 10 to the power supply via 0, a reference voltage Vout' having a small temperature coefficient can be obtained across the resistor 10.

FIG. 2 shows a second embodiment of the present invention, in which an NPN transistor 24 for supplying base current is provided to configure an output circuit with high precision and large current capacity.

Effects of the Invention As detailed above (according to the present invention, a constant current source is not required, a reference voltage circuit with a small temperature coefficient suitable for integration can be constructed with a simple configuration, and the present invention has the following advantages) In contrast to the conventional reference voltage generation circuit whose output reference voltage changes depending on the current value of the constant current source, it is possible to obtain a stable and highly accurate reference voltage.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a reference voltage generator according to a first embodiment of the present invention, FIG. 2 is a circuit diagram of a reference voltage generator according to a second embodiment of the present invention, and FIG. 3 is a circuit diagram of a reference voltage generator according to a second embodiment of the present invention. It is a circuit diagram of a generator. 1...First transistor, 2...Second transistor, 3...Third transistor, 4...Fourth transistor, 5, 6...
...Transistor for current mirror circuit, 7...1st
resistance, 8... second resistance, 9... load resistance. Name of agent: Patent attorney Toshio Nakao and 1 other person/---
Transistor 111 2-11 Transistor 2 3 ---1 Transistor 4-11 4th F transistor 1;, 6 --- tt Transistor 9-11 Choudou ＼ magazine breasts

Claims (2)

[Claims] (1) first and second transistors each having a different emitter area; the first transistor has its collector and base connected, and the second transistor and the base are commonly connected; The first transistor has an emitter connected to the emitter of the second transistor through a first resistor and grounded through the second resistor, and further has a diode-connected second transistor connected to the collector of the first transistor. No. 3 transistors are connected in series, and a current circuit is connected to the collector of the transistor for supplying a current proportional to the collector current of the second transistor to the first and third transistors, and the third transistor is connected in series. , the base and collector of which are connected, a fourth transistor and the base are connected, and a constant voltage is generated in the load of the fourth transistor. (2) The reference voltage generating device according to claim 1, wherein the collector of the fourth transistor is connected to a current terminal via a load resistor, and a constant voltage is generated across the load resistor.