JPS5911924B2 - Parallel control type voltage stabilization circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a parallel control type voltage stabilizing circuit suitable for use in an integrated circuit (IC).

In an integrated circuit, a voltage stabilizing circuit is built into the integrated circuit and used as a stabilized power source for other circuits.

In this case, a circuit in which a Zener diode and a diode-connected transistor are connected in series is used as a temperature-compensated voltage stabilizing circuit. That is, as shown in FIG. 1, the anode of a Zener diode 1 is connected to the anode of a diode (silicon diode, actually a diode-connected transistor) 2, and the cathode of the diode 2 is grounded. The cathode of the Zener diode 1 is connected to a DC power supply +B via a high-resistance resistor 3, and also to an output terminal 4, which is connected to a load 5.
grounded via. In this case, Zener diode 1
(e.g. 5.5V across diode 2), 7
A voltage of 6.2 V is generated, and a constant voltage of 6.2 V is supplied to both ends of the load 5 despite fluctuations in the load current. In this case, the voltage of the power supply 10 is E, and the voltage across the series circuit of Zener diode 2 is V. , when the resistance value of resistor 2 is Rs, the current 10 flowing through resistor 2 is expressed as, and if E is constant, 10 15 is constant.

This voltage stabilizing circuit has a feature that the temperature characteristics of the constant voltage are good because the temperature characteristics of the Zener diode 1 and the diode 2 are opposite.

On the other hand, Zener diodes have a permissible current of 20% less, so they cannot be used when a large current that is more than sufficient to flow through a load is unusable. Therefore, by adding a diode T and a transistor 8 to the circuit shown in FIG. 1, such as the series-controlled voltage stabilizing circuit shown in FIG.
The current supplied to 25 can be increased.

That is, in this circuit, the cathode of diode 2 is connected to the anode of diode T, and the cathode of diode T is grounded. The midpoint of the connection between the resistor 3 and the Zener diode 1 is connected 30 to the base of the transistor 8 , its collector is connected to the power supply +B, and its emitter is connected to the load 5 via the output terminal 4 . In addition, the added diode T
is for compensating for changes in V of the transistor 8 due to temperature.

35 According to the circuit shown in Fig. 2, the Zener diode 1
A current that is hFE times the allowable current of can be supplied to the load 5.

However, the series control type voltage stabilization circuit shown in Fig. 2
It may not be suitable depending on the type of circuit connected to it.

That is, it is difficult to suppress white noise generated in the Zener diode 1. Also, the output impedance is somewhat high. Furthermore,
As a result of inserting transistor 7, the resistance value Rs of resistor 2
becomes smaller, which reduces the effect of suppressing ripples from the power supply. In view of these points, the present invention provides a novel parallel control type voltage stabilization circuit which has good temperature characteristics of the output voltage, can supply a large current to the load, and has improved the drawbacks of the above-mentioned conventional circuits. This is what I am trying to do.

Hereinafter, an example of the parallel control type voltage stabilizing circuit of the present invention will be explained in detail with reference to FIG.
The same reference numerals are given to parts corresponding to those in the figure and FIG. 2, and redundant explanation will be omitted.

In the present invention, a series circuit consisting of a high-resistance resistor 3, a Zener diode 1, and a diode-connected (collector-base connection) main transistor 10 is connected to both ends of the DC power supply +B. 1 - Sub-transistors Q, ~Qn (n=1), which have an emitter region having an equivalent emitter area greater than or equal to the equivalent emitter area of the emitter region of the main transistor 10 in the series circuit of the main transistor 10.
．． 2.3. ...) is connected between the collector and emitter of the main and sub transistors 10, 1.1 {Q
, ~Qn} are connected to each other, and a stabilized DC voltage is obtained across the series circuit of the Zener diode 1 and the main transistor 10, which is applied to the load 5 via the output terminal 4. It is designed so that

In this case, the collectors of the transistors Q, -Qn are connected to the midpoint between the resistor 3 and the Zener diode 1, and the emitters of the transistors are grounded. Transistor 10, Q
, ~Qn constitute a current mirror circuit. In this example, transistors having the same characteristics are used as transistors 10, Q, to Qn. Next, let's analyze the circuit shown in Figure 3. Assume that the current in load 5 is zero. The supply voltage is E1, the resistance of resistor 3 is RSl, the current flowing through Zener diode 1 is IZl, and the voltage between terminal 4 and ground is RS. , the common emitter current amplification rate of transistor 10, Q1 to Qn is H
If the base current of FEl is IB, then current 1 flows through resistor 3. is expressed as the following equation. Also, the Zener voltage of the Zener diode 1 is connected to the VZl transistor 10.
When the base-emitter voltage of is VBE, o is expressed as in the following equation. o=z+VBE・・・・・・・・・
(2) Also, IB is expressed as in the following equation.

Equations (1) to (3) to 12 are expressed as shown below.

Here, if HFE>n+1, equation 4 can be approximated as shown in the following equation. I from formulas (1) and (4).

can be made approximately n+1 times 12, and therefore the current flowing through the load 5 can be approximately n+1 times the allowable current of the Zener diode 1.
Can be doubled. It is already known that the emitter ground current amplification rate of a transistor can be changed by changing the area of the emitter during its manufacturing process.

That is, as shown in FIG. 4, the terminal from which the collector of the transistor 10 is led out is designated 12, the terminals from which the collectors of the transistors Q, .
If the terminal from which each emitter of QO is led out is 14, transistors 10, Q, to Qn can be constituted by two transistors, transistors 10 and 11, as shown in FIG. In FIG. 5, 15 is a P+ type semiconductor substrate;
16 is a collector region of an n-type semiconductor in the transistor 10, 17 is a base region of a p-type semiconductor, and 18 is an emitter region of an n+ type semiconductor. Also, 19 is transistor 1
1 is a collector region of an n-type semiconductor, 20 is a base region of a P-type semiconductor, and 21 is an emitter region of an n+ type semiconductor, and the equivalent emitter area of the emitter region 21 is larger than the equivalent emitter area of the emitter region 18 of the transistor 10. Selected. According to the parallel control type voltage stabilizing circuit of the present invention described above, the temperature characteristics of the output voltage are good and a large current can be supplied to the load.

Furthermore, since it is a parallel control type, white noise generated by Zener diodes can be suppressed, and the S/N ratio of the circuit can be improved.

Furthermore, since the resistor connected in series with the Zener diode can have a high resistance, ripples in the power supply can be effectively suppressed. Furthermore, output impedance can be reduced.

[Brief explanation of the drawing]

Figures 1 and 2 are circuit diagrams of conventional parallel and series control type voltage stabilizing circuits, Figure 3 is a circuit diagram of →1 of the parallel control type voltage stabilizing circuit of the present invention, and Figure 4 is Figure 3. Some circuit diagrams,
FIG. 5 is a perspective view showing a model in which a part of another example of the present invention is constructed on a semiconductor substrate. 1 is a Zener diode, 3 is a resistor, 10 is a diode-connected main transistor, and Q, -QO are sub transistors.

Claims (1)

[Claims] 1 A series circuit of a resistor-Zener diode-diode-connected main transistor is connected to both ends of the DC power supply, and the series circuit of the Zener diode-the main transistor has an equivalent emitter area greater than or equal to the equivalent emitter area of the emitter region of the main transistor. The collector and emitter of the sub-transistor having an emitter region of the emitter area are connected, and the bases of the main and sub-transistors are connected to each other, and the Zener diode and the main transistor are stabilized at both ends of the series circuit. 1. A parallel control type voltage stabilizing circuit characterized by being able to obtain a direct current voltage.