JPS5980023A - Supplying current source circuit working at low voltage - Google Patents

Abstract

PURPOSE:To ensure the stable working of a current source circuit down to a low level of voltage, by using the collector current of a transistor circuit containing an emitter-base diode circuit set in parallel to a constant voltage source as a reference current of a current mirror circuit and then applying the output of the current mirror circuit to an ILL. CONSTITUTION:A constant voltage source VREF is provided with a band gap reference circuit and used as a reference power supply having a temperature coefficient set approximately at zero. For an npn transistor TRQ1, the base, emitter and collector are connected to the source VREF, a resistance R1, and the base and the collector of a pnp TRQ2 as well as the base of a pnp TRQ3 respectively. The current I1 flowing to the resistance R1 connected between the emitter of the TRQ1 and an earth is set at (VREF-VBE1)/R1, where VBE1 shows the base-emitter voltage of the TRQ1. This current I1 flows to the TRQ2, and the injecting current Iinj is set equal to the current flowing through the R1 by TRQ2 and Q3 which constitute a current mirror. Thus an IIL circuit 1 can be made to have the stable working down to a low level of power supply voltage.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to an injection current source circuit for an IIL circuit.
In particular, it relates to an injection power supply circuit that can be driven to low voltages.

(Configuration of conventional example and its problems) Fig. 1 is a circuit diagram showing the configuration of an injection current source circuit of a conventionally known IIL circuit. A gap reference circuit is used, the voltage value of which is approximately 1.5V, IO is a constant current source, Q - Q7 are transistors, R1 + R2+
R3 is a resistor, and 1 indicates an IIL network.

- where transistors Ql-Q5, resistor R1;

The circuit consisting of R2, constant voltage source VR□, and constant current source ■o is a differential amplifier circuit with negative feedback.
).

Transistors Q6 and Q7 represent an equivalent circuit of an inverter circuit using IIL, and IIL circuit network 1 represents a collection of these equivalent circuits. The resistor R3 determines the injection current flowing into the entire IIL circuit, and the injection current is determined by the following equation.

(Vo-VBlc6)/R3211n.

However, *ln] is the injection current, and V16 is the V of transistor Q6. (Base-emitter voltage) In the circuit shown in FIG. 1, the minimum value of the power supply voltage (VCC) for ensuring the injection current is calculated from the following equation.

v-Vo 10v, 10VBE3 C:: 1.2v (1+R2/R,)+1.2v≧24v
(The lowest value when R2-0) However, VBE5 is the transistor Q5, and VBEVBg3 is the transistor Q3's BE. It is.

Tiger 7 Nosta Q1, Q2 - Q3, and resistor R1.

The output voltage vo becomes equal to the voltage vR□ of the constant voltage source by a differential circuit consisting of R2, a constant current source IO%, and a constant voltage source "REF."

Power supply voltage V. The lowest value of 0 is determined by the following formula.

Voo2 Vo + Vn, Ba + RI II = 1.8
+ RI II However, 11 is the current flowing through the resistor R1.

Assuming that the injection current l1nj tt is equal to the collector current of the transistor Q3, the current {circle around (1)} flowing through the resistor R1 will be determined. As an example, consider a case where the injection current I. is nj 2 ridges and the minimum voltage of the power supply voltage ■cc is 20V. If hFE of transistor Q3 is 50, the base current of transistor Q3 is 2mA 150 = 40μ
It becomes A. The value of the current I needs to be sufficiently larger than 40 μA; for example, if it is 100 μA, the resistance R
The value of 1 is (■cc 1-8) /I-=(2,0-1,8)
/2 k-Ω.

Although the circuit shown in FIG. 2 can operate with a low power supply voltage by determining the constants as described above, it has the following drawbacks.

One is that since it is a differential amplifier circuit with 100% angular feedback, it easily oscillates, and requires a capacitor to prevent oscillation, so it takes up a large area if it is made of semiconductor heavy C. . Another disadvantage is that when the power supply voltage range is wide, the current 11 changes greatly, so the current balance flowing through the transistors Ql and Q2 of the differential amplifier circuit is poor, the stability of the output voltage Vo is not good, and the constant current This is because the source Io requires a large current. For example, for the constant in the example above, the power supply voltage V. If 0 becomes 3, 11-3.吋””-=600μA 2Ω, and the power supply voltage is V. The change is six times greater than when 0 is 20V.

(Objective of the Invention) The present invention has been made in order to eliminate the drawbacks mentioned above. This provides a stable injection current source circuit in the circuit.

(Structure of the invention) FIG. 3 is a circuit diagram showing the configuration of an embodiment of the present invention.

The constant voltage source V8a is a reference voltage source with a temperature coefficient of approximately zero, which is constructed of a bandgap reference circuit as in the case of FIG. 1, and has a voltage value of about 12V.

QluNPN) Lannostar, the base is a constant voltage source VRE
F, the emitter is connected to the resistor R1, the collector is connected to the base and collector of the PNP trannostar Q2, and the base of the PNP trannostar Q3, respectively. Resistor R1 has one end connected to NPN) transistor Q! , the other end is connected to GND, and the PNP) transistors Q2 and Q
3 has a common emitter and a common base ζ, the common emitter is connected to the power supply VCC, the common base is connected to the collector of the NPN transistor Q1 along with the collector of the transistor Q2, and the collector of the transistor Q3 is connected to the IIL network 1.
is connected to the injection current terminal of

(Explanation of Example) The current 11 flowing through the resistor R connected between the emitter of the Touno Star Q1 and GND is ("REF 'nIi, 1
) 4, (L VREI u ) the base-emitter voltage of Lannostar Q]. This current flows through the transistor Q2, and due to the transistors Q2 and Q3 forming a current mirror, the injection current ■inj becomes equal to the current (VRgF +VBEI)/R1 flowing through the resistor R1.

The minimum power supply voltage of this circuit is the constant voltage source voltage “REI”
When is 12V, it is determined by the following formula.

VCCoVREF-VBE1+VCEI+VBE2≧1
．． 2-0.6o0.6+0.6-1.8However, VCK'
l is the collector-emitter voltage of Ql.

VBE2 is the voltage between the base and emitter of Q2 ◇ According to the configuration shown in Figure 3, I
It is possible to operate the IL circuit network 1 stably. Furthermore, regarding temperature characteristics, in semiconductor ICs, the temperature coefficient of resistance is approximately +2000 to +3000 ppm 7°C, so the temperature coefficient of resistor R1 (NPN) of Lannostar Qt is
The temperature coefficients of Bg cancel each other out, and together with the fact that the temperature coefficient of the reference voltage source is zero, the temperature coefficient of the injection current becomes almost zero, and an extremely stable injection current source can be constructed. Furthermore, since the number of elements is very small and there is no feedback, it can be said that it is an extremely simple and stable IIL injection current source with no fear of oscillation.

FIG. 4 shows another embodiment of the invention. In Figure 3, I
When the IL circuit network becomes large and requires a large injection current, the hFg of the PNP transistor at a large current is not large enough to alternating, so the base current of the transistor Q3 becomes large, and the current flowing through the resistor R1 and the injection current increase. The values of will be different. The configuration shown in FIG. 4 improves this.

In Fig. 4, the constant voltage source (REF%), the resistor Qi, Q2 + Q3, and the resistor R1 are the third
It is similar to the figure. NPN transistors Q4 and Q5 have a common emitter and a common base and form a current mirror, and are connected to the common emitter/1GNDK. Is the collector of transistor Q4 a transistor? Q
4 and Q5 common base and PNP) transistor Q3
is connected to the collector. The collector of transistor Q5 is the collector of PNP transistor Q6 and the collector of PNP)
Connected to the base of Lannostar Q7. PNP)
Transistors Q6 and Q8 have a common emitter and a common base, and constitute a current mirror. This common emitter is the power supply V. 0, the common base is connected to the emitter of the lannostar Q7 (PNP). PNP) The collector of the lannostar Q6 is connected to the collector of the transistor Q11 and the base of the transistor Q7. The collector of transistor Q8 is injecting current into the 115 circuit network. The collector of transistor Q7 is connected to GND.

In the circuit configuration as described above, the transistor Q1 ・
The collector currents of Q4, Q5, and Q7 are respectively I+
Let's find the relationship between each current as lI4 115 117. As stated in the case of Fig. 3, the current I is
-(”REF VBEI)/R1.PNP
l-Lannostar Q2. If we set the value of 11 in the region where hFE of Q3 is sufficiently large and the base current can be ignored, then the collector current of transistor Q3 is equal to I, which flows through transistor Q4, so ■4-■l
becomes. With transistor Q4. Since 5 constitutes a current mirror, it becomes 15-14.

Next, when we want to make the injection current l1nj n times I5, PN
N P transistors Q8 may be connected in parallel with the number of transistors Q6. At this time, PNP transistor. 80 The base current increases, but the transistor. The sum of the base currents of 6 and Q8 is the transistor. Flows into the emitter of 7. This value is equal to I7. The base current of transistor Q7 is I7. It is equal to the value divided by the current amplification factor of 7, which is a sufficiently small value. Therefore, the collector current 5 of the transistor Q5 is almost equal to the collector current of the transistor Q6, and as a result, the current for n times of Q6 becomes exactly the collector current of Q8, that is, the injection current.

In the circuit shown in Figure 4, the minimum operating power supply voltage is approximately 1.8 V, the same as in Figure 3.
This is effective as an injection current source for a semiconductor IC including an L circuit network. In addition, Figure 3,
Both of the devices shown in FIG. 4 can also be used in applications where the power supply voltage is high.

(Effects of the Invention) As described above, the present invention has the advantage of being able to drive to a low voltage with an extremely simple configuration and realizing a stable injection current source circuit.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing the configuration of a conventional IIL injection current source circuit, FIG. 2 is a conventional circuit diagram with slight modifications to the circuit in FIG. 1, and FIG. 3 is a circuit diagram of an embodiment of the present invention. A circuit diagram showing the configuration, FIG. 4 is another embodiment 1 of the present invention...IIL circuit network, vR
O... Constant voltage source, Vco... Power supply voltage, ■. ...
Output voltage, ■. ... Constant current source, Q1 to Q8... Transistor. Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. II

Claims (3)

[Claims] (1) A constant voltage source and a first NPN in parallel with this constant voltage source.
A series circuit of a diode and a resistor is formed between the base and emitter of the transistor, and the collector current of the NPN transnoster shown in 2-11 is passed as a reference current of the current mirror circuit constituted by the second and third PNP transistors, and the current mirror is A low voltage operated injection current source circuit characterized in that the output of the circuit is connected to the injection current terminal of an IIL network. (2) The low voltage operation injection current source circuit according to claim (1), wherein the constant voltage source is constituted by a bandgap reference circuit. (3) 2nd and 3rd PNP) A current mirror circuit made up of a runnostar, a current mirror circuit made up of a 4th and 5th NPN trannostar, and a 6th and 8th PNP) A current mirror made up of a transistor. A low voltage operation injection current source circuit according to claim 1, characterized in that the collector of the eighth PNP transistor is connected as an output to the injection current terminal of the IIL network. .