JPH0229811A - Voltage source circuit - Google Patents

Abstract

PURPOSE:To optionally set up the temperature characteristics of a 2nd output voltage by impressing a difference current between the output current of a band gap regulator setting up the temperature characteristic of its output voltage to zero and a DC constant current to a resistor and setting up its voltage drop as the 2nd output voltage. CONSTITUTION:A DC constant current source I02 is connected to the collector of a transistor(TR) Q4 to allow current I2 to flow. A resistor R4 is connected to the collector of the TR Q4 and the other end of the resistor R4 of earthed. When the current I2 flowing from the current source I02 is set up to I2>I3, a difference current I4 between the I2 and the I3 (the output current of the band gap regulator) flows into the resistor R4 and the 2nd reference output voltage VREF2 appearing on an output terminal N2 goes VREF2=R4XI4= R4X(I2-I3). When the temperature characteristics of the I2 and the R4 are set up to zero, the temperature characteristics of the VREF2 can be set up by that of the I3.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a voltage source circuit, and more particularly to a DC voltage source circuit equipped with a bandgap regulator.

[Conventional technology]

BACKGROUND ART Conventionally, as a reference voltage generating circuit used on an integrated circuit, a bandgap regulator, which can maintain a constant output voltage even when there is a temperature change, has generally been widely used.

[Problem to be solved by the invention]

, However, in integrated circuits, the transistor's V□(
The base-emitter voltage (voltage between base and emitter) has a temperature characteristic of approximately -2 mV/°C, and in a differential amplifier, its gm (mutual conductance) includes the term 1/T (T is absolute temperature), so the temperature varies from 25°C to If the temperature rises by 100℃ to 125℃,
There are many items that must be corrected for temperature changes, such as the gm value decreasing by a factor of 0.81. Furthermore, due to the specifications of the integrated circuit, the characteristics may change in response to temperature changes. In such cases, it would be a good idea to prepare a reference voltage generation circuit according to the required temperature characteristics, but this would result in redundancy in the circuit and cost (mainly Pele).

The current situation is that the characteristics are compromised due to the conflict with the size (size).

An object of the present invention is to provide a power supply Shobara circuit that can generate a voltage with a substantially zero temperature coefficient and a voltage with a desired temperature coefficient with a simplified configuration.

[Means to solve the problem]

A voltage source circuit according to the present invention includes a first transistor having a collector resistance and an emitter resistance and operating at a first emitter current density, and a second transistor having a collector resistance and operating at a second emitter current density. , a third transistor whose base is connected to the collector of the first transistor, a fourth transistor that provides an operating current to the first and second transistors, an output terminal, and a fourth transistor connected to the output terminal. The fourth transistor is characterized by comprising a resistor, a current source, and means for supplying a difference current between the current of the current source and the current flowing through the fourth transistor to the resistor.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a circuit diagram of an embodiment of the present invention. In FIG. 1, a first DC constant current source is shown. l, NPN transistor Q 1. Q 2 , Q s , Q s and resistance RHe
R! The output of J is taken from the first terminal N.

The first reference output voltage v*xy+ at the terminal N1 is defined as the difference voltage between VBi of transistor Q1 and V□ of transistor Q, that is, the voltage drop across resistor R+, and V□ of transistor Q as ΔV Bl. (Q3) and calculate the collector current of transistor Q2. 2. transistor Q
, the base current is l1ls, the charge amount of the electron is q, the Portzmann constant is T, and the absolute temperature is as follows.

VRIFl=V! 1m (Q3) + (Icz+Igz)
・Rt=V111! <os)+ (ΔVn+
t) 10I ns ・If R2 engineering 1 is sufficiently small, it will be. The temperature characteristic of VY,1 is as follows, and by appropriately setting the values of R2/Rl and R2/Rs, an output voltage without temperature characteristics can be obtained at the output terminal N1. The current flowing to the emitter of transistor Q4, ie, the output current of the band gear and preregulator, is as follows.

Now, the temperature characteristics of a resistor used in an integrated circuit vary depending on the process of configuring the integrated circuit, and also vary depending on the method of forming the resistor. For example, a base resistor, a graft base resistor, and a polysilicon resistor each have different temperature characteristics, and also vary greatly depending on the type and concentration of impurities to be diffused. It is known that the temperature characteristics of the output current I of a bandgap regulator vary by using a resistor having the temperature characteristics as described above.

In FIG. 1, the collector of transistor Q4 is equipped with a DC constant current source according to the present invention. 2 is connected and a current I2 is flowing. Further, a resistor R4 is connected to the collector of the transistor Q4, and the other end of the resistor R4 is grounded. Install a DC constant current source on the circuit shown in Figure 1. Electrical work 2 to flow 2〉■.

By setting , the difference current between I2 and I flows into the resistor R4, and the second reference output voltage VBiA2 appearing at the output terminal N2 becomes VB11F! =R4XI4=R4X (I2 Iri
...(5) is obtained as the value. In equation (5), if the temperature characteristics of 2 and 'R4 are set to zero, the temperature characteristics of V OR 2 can be set according to the temperature characteristics of . When setting the range of change of vex□ with respect to temperature to be small, set the value of resistor R4, which does not have temperature characteristics, to a sufficiently large value with respect to
You can reduce the value of . Also, if you want to set a large variation width of VRKF2 with respect to temperature, set the value of 2 close to the value of 2, make the difference current 2 small, and set the resistance R
You can increase the value of 4.

Therefore, even if the second output voltages VRE and VRE at a certain temperature are the same, the temperature characteristics can be set arbitrarily by appropriately selecting the values of VRE and R4.

Next, the actual operation of the circuit shown in FIG. 1 will be explained. FIG. 3 shows the temperature characteristics of I3 and I3 of FIG. 3 in the circuit of FIG. 1, and FIG. The temperature characteristics of the output voltage Vo,2 at the output terminal N2 at the current value of I4 are shown. Now, as shown in Figure 3, the output current of the bandgap regulator is 500 μA at the reference temperature, increases to 600 μA with a +50°C change from the reference temperature, and 400 μA with a -50°C change. If so, install a constant current source. 2 output current value I zn+ is constant 700 regardless of temperature change.
The value of ω when set to μA is ω, and ■. When the output current value (2) is set to 1500 μA, the value of (2) is shown in FIG. 3 as (2). As can be seen from FIG. 3, by changing the value of 2, the reference current value can be arbitrarily changed without changing the slope of . Next, in Fig. 4, when the current values of I4ur and I4i shown in Fig. 3 are at the reference temperature, ■. 5 for P2. It shows the temperature characteristics when Ov is obtained. As shown in Figure 3, if I4+11=200μA at the reference temperature, set R4 to 25Ω, and if I4(1° is 1000μA, set R4 to 5Ω).
V RRF□ set to Ω in v1A2.1.
It corresponds to V□A, ■. In VYP 2111, the difference from the reference temperature is -50 to -50°C, which is a 5V change, whereas in VYP 2111, a similar temperature change is a 1V change.

By appropriately selecting Work2 and R2 as described above, Vil! F2 can significantly change its temperature characteristics without changing the output voltage at the reference temperature.

FIG. 2 shows another specific embodiment of the present invention.

The same functions as in FIG. 1 are given the same reference numerals as in FIG. That is, transistors Q1 to Q4 and resistors R1 to R
3 constitutes a bandgap regulator whose output terminal is N1. In addition, a constant current source is configured by the transistor Q and the resistor R6, and the transistors Q s and Q
The DC constant current source in Figure 1 is constructed using a current mirror of r. It works the same as 1. The output current of the bandgap regulator becomes the collector current of transistor Q by the current mirror of transistors Q* and Qs. Further, the transistor Q1° and the resistor R6 constitute a direct current constant current source, and a constant current 2 flows through the collector of the transistor Q1°.

In the circuit shown in Fig. 2, I s > I 2 is set, and the difference current l4 (=I3
A second output voltage V, mxyz is applied to the output terminal N2.
Get the powder. vexa, Vigyz=R4XL=R4X (Is I2)
..."(6). That is, the resistances R1 to R in FIG.
If the same resistance as 1 is used in Figure 2, V in Figure 2 will be
REF2 has a temperature characteristic that is opposite in polarity to vytxp□ in FIG. That is, the slope in FIG. 4 is reversed in positive and negative directions.

Furthermore, the circuit shown in FIG. 2 includes a current output circuit consisting of transistors Qll to Q14, a resistor R7, and an output terminal N. A constant current source is constituted by the collector current I3' of the transistor shown in FIG. 2, the transistor Q1□, and the resistor R7,
A constant current I2' is caused to flow. Now 1.1 and engineering,'
The relationship I2'>I! ', and the difference current I4'
(=I!'I3') to transistor Q13#Q14
A current mirror circuit consisting of a current mirror circuit outputs the signal to an output terminal N. In this case, the temperature characteristic of I4' is opposite to that of . In addition, by changing the area ratio of transistors Q13 and Q14 that constitute the current mirror, I and l can reset the range of change in the temperature characteristics of the output current, and by changing them to current output, the differential amplifier can be regulated. Effective when used as a current.

〔Effect of the invention〕

As explained above, the present invention applies the difference current between the output current of a bandgap regulator with zero temperature characteristics of the output voltage and a constant DC current to a resistor, and converts the voltage drop into a second
By setting the output voltage to , the temperature characteristics of the second output voltage can be arbitrarily set. This means that a reference voltage source with temperature characteristics can be easily added to a reference voltage source that does not have temperature characteristics, so it can be easily added to the circuit without increasing the hole width of the element. This means that the temperature characteristics can be corrected or set as desired, and can be said to be an effective means especially on integrated circuits.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing one embodiment of the present invention, FIG. 2 is a circuit diagram showing another embodiment, FIG. 3 is a graph showing the temperature characteristics of the reference voltage of the circuit shown in FIG. 1, and FIG. FIG. 4 is a graph showing the temperature characteristics of the reference voltage of the circuit shown in FIG. Agent Patent Attorney Oto Uchihara

Claims (1)

[Claims] a first transistor having a collector resistance and an emitter resistance and operating at a first current density; and a second transistor having a collector resistance and operating at a second current density, the first transistor having a base bias. a third transistor whose base is connected to the collector of the first transistor; a fourth transistor which supplies an operating current to the first and second transistors; an output terminal; A voltage source circuit comprising: a resistor connected to a terminal; a current source; and means for applying a conduction current between the current of the current source and the current flowing to the fourth transistor to the resistor.