JPH0410762B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in stabilizing bias circuits.

As a conventional stabilizing bias circuit, for example, the first stabilizing bias circuit
Something like the one shown in the figure was known.

That is, the power line 24 and the ground line 25
A pnp transistor 13, an npn transistor 15, and a resistor 16 are connected in series between the transistors 13, 14, and a pnp transistor 14 and npn transistors 17, 18 are connected in series. The stabilizing bias circuit 2 includes a starting resistor 19 connected between the bases of the transistors 15 and 17 as well as between the bases of the transistors 15 and 17, and connecting the transistors 13, 17 and 18 as diodes. A device in which load circuits 1 and 3 are connected to circuit 2 is known.

The conventional stabilizing bias circuit 2 operates as follows. In other words, the power supply (+
When a voltage is applied to B), a current flows through the high-resistance starting resistor 19, current flows through diode-connected transistors 17 and 18, a voltage is generated at point D, and current flows through transistor 15. A current flows through the current mirror circuit of the transistors 13 and 14, and a current flows from the collector of the transistor 14 to the diode-connected transistors 17 and 18. This loop operates as a positive feedback operation in which the current gradually increases and the emitter of the transistor 15 The current is stabilized by the resistor 16.

In this circuit, the bases of transistors 15 and 17
Since the voltage between the emitters (VBE) is approximately the same, the voltage drop across the resistor 16 is approximately the same as the voltage between the base and emitter of the transistor 18.

For example, when the current of transistor 18 is 100μA, VBE is 0.6V, and resistor 16 is 6kΩ, transistors 15, 17, 18, 13,
A current of approximately 100 μA will flow through the resistor 14 and the resistor 16.

Even if the voltage of the power supply (+B) changes, the current flowing through these devices hardly changes. Therefore, if a base bias is applied to the transistor 20 in the load circuit 3 from point A, a current mirror operation will occur, and the load 21 on the collector of the transistor 20 will be approximately
A current of 100μA will flow.

Also, from point C, transistor 1 in load circuit 1
When a base bias is applied to transistor 1, it performs a current mirror operation and the load 12 on the collector of transistor 11 is
A current of approximately 100μA flows through the

In Fig. 1, the loads 21 and 12 can be biased from points A and C so that the current flows stably against fluctuations in the power supply voltage, but the drawback is that the current changes when the temperature changes. There is.

This operation will be explained below. FIG. 3 shows the characteristics of the emitter current and voltage flowing through the transistor using temperature as a parameter.

For example, if the current at point b is 100μA, and the temperature increases from 20℃, transistors 17, 18, 1
The value of the voltage (VBE) between the base and emitter of the transistor 5 becomes small, and the current flowing through the resistor 16 and the current flowing through the transistors 15, 13, 14, 17, and 18 also become small. The currents of 20, 11 and loads 12, 21 also become smaller. Conversely, when the temperature decreases, the voltage (VBE) increases from i to j, and the resistance 16
Current flowing through the transistors 13, 14, 1
The currents of the loads 12, 21 also become larger as the currents of the loads 12, 21 become larger.

As described above, the conventional circuit has the disadvantage that the current changes greatly with temperature changes.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a stabilizing bias circuit that can obtain a stable bias even against temperature changes.

In the configuration of the present invention, a current is supplied to two diodes or two diode-connected transistors using the potential between the base and emitter of the transistor, and a first voltage is applied to the base of the first transistor. A second voltage is applied to the second voltage obtained by connecting the emitter to the first resistor and supplying a current to one diode or one diode-connected transistor using the potential between the base and emitter of the transistor. A second resistor is connected between the base and emitter of the transistor, and the first resistor is connected to the second resistor.
A current source is configured by adding the collector current of the transistor and the collector current of the second transistor.

Hereinafter, embodiments of the present invention will be described in detail based on FIG. 2. In FIG. 2, the same parts as in FIG. 1 are given the same numbers and detailed explanations thereof are omitted.

That is, the base electrode is connected to the transistor 18.
A transistor 22 is provided, the collector of which is connected to the collector of the transistor 15, and the emitter of the transistor 22 is connected to the ground line 25 via a resistor 23.

Here, the transistor 22 is two npn type transistors connected in parallel.

Next, the operation of the above configuration will be explained.

Apply voltage to the power supply (+B), transistor 1
If a current of approximately 100 μA flows through transistors 13, 14, 17, and 18, a current of 200 μA flows through transistors 13, 14, 17, and 18, so the voltage between the base and emitter of transistor 18 is at point C (200 μA) in Figure 3. , and at a temperature of 20℃, the voltage at point l (for example, 0.61V)
is obtained, and in order to cause a current of 100 μA to flow through the resistor 16, the voltage between the base and emitter of transistors 17 and 18 at 20°C is changed from the voltage at point (l) (0.61×2) to the voltage between the base and emitter of transistor 15. Voltage (100 μA flows through transistor 15 at point i at 20°C
0.6V) is applied to the resistor 16,
Resistor 16 is 0.61V×2−0.6V/100×10 ^-6 ≒6.2kΩ, which is 6.2kΩ.

Also, when a current of 100 μA is passed through the transistor 22, since two transistors 22 are used,
The current flowing through each transistor is 50μA,
At point a in Figure 3, which is the point of 50μA, and the temperature is 20℃
For example, the voltage (VBE) is 0.59V at point f.
Assuming that, for resistor 23, 0.61−0.59=
It is necessary to obtain a voltage drop of 0.02V, and the resistor 23
The resistance value (R23) is R23 = 0.02/100 x 10 ^-6 = 200Ω.

Next, the temperature rises to 60℃, and the voltage (VBE) of transistors 17 and 18 becomes 0.61V x 2 at point (l).
If it becomes 0.50V x 2 at point (K), the voltage between the base and emitter of transistor 15 will be at point (i).
From 0.6V to 0.49V at point (h), transistor 15
The current (current of resistor 16) is 0.5×2−0.49/6.2×10 ³ ≒82μA, and the current decreases. On the other hand, transistor 2
Since the voltage (VBE) of transistor 2 changes from point f (0.59V) to point e (0.477V),
The current flowing through resistor 23 (current through resistor 23) is 0.5-0.477/200≒115μA, and the sum of the collector currents of transistors 15 and 22 is 82+115=197μA, so the current starts from 200μA.
The reduction to only 3 μA is a decrease of about 1.5%.

However, if the only change in the collector current of the conventional transistor 15 in FIG. The voltage between the base and emitter of transistor 15 changes from point i (0.6V) to point (h) (0.49V), and resistor 16 becomes
6.2kΩ, which is 0.61×2−0.6/6.2×10 ³ = 100μA, becomes 0.5×2−0.49/6.2×10 ³ = 82μA, which is a decrease of 18μA, and a change of 18%.

In this way, compared to conventional circuits, the current change rate when the temperature changes to a high temperature can be reduced.

In the above explanation, transistors 15 and 22
Since 100 μA is flowing, the current twice as much as before, that is, 200 μA flows through loads 12 and 21, but the resistance values of resistors 16 and 23 are selected so that a current of 50 μA flows through the collectors of transistors 15 and 22, respectively. By this, transistors 13, 14, 17,
A current of 100 μA can flow through the transistors 20 and 11 in the load circuits 1 and 3 and the load 12,
21 is also capable of passing a current of 100 μA, similar to the conventional one. In addition, in this embodiment, transistors 17, 18, 15, and 22 have the same emitter area, and transistor 22 has two transistors connected in parallel, but Even if it is used, it has the same effect as described above. That is, if one transistor 22 is used and the emitter area of the diode-connected transistor 22 is made to use the potential between the base and emitter of the transistor, which is twice the emitter area of the transistor 18, the current per unit area of the emitter of the transistor 22 is The density is halved and the transistor 22 is
This is the same as the base-emitter voltage VBE when the current is reduced by connecting the two in parallel, and has the same effect.

FIG. 4 shows another embodiment of the present invention, in which the connection position of the starting resistor 19 is changed.

With this connection position, when a voltage is applied to the power supply (+B) and a current flows through the diode-connected transistor 13, a current flows through the transistor 14, and then the diode-connected transistor 1
Current flows through transistors 7 and 18 and transistors 15 and 22 to start a stabilizing operation, and the same effects as in the previous embodiment are obtained.

As detailed above, the present invention provides a diode 2
A first voltage obtained by supplying current to two diode-connected transistors using the potential between the base and emitter of the first transistor and the potential between the base and emitter of the first transistor
A resistor is connected to the second voltage obtained by supplying current to one diode or one diode-connected transistor using the potential between the base and emitter of the transistor. Connect the emitter and the second resistor,
Since this is a stabilizing bias circuit characterized by configuring a current source by adding the collector current of the first transistor and the collector current of the second transistor, the rate of current change is small when the temperature changes. This has the effect of obtaining a stable bias.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram of a conventional example, Fig. 2 is a circuit diagram showing an embodiment of the present invention, Fig. 3 is a current-voltage characteristic diagram showing temperature as a parameter, and Fig. 4 is another embodiment of the present invention. FIG. 2 is a circuit diagram showing an example. 13, 14, 15, 16, 17, 18, 22...
...Transistor, 16,23...Resistor.

Claims (1)

[Claims] 1 Supplying current to the diode-connected first and second transistors 17 and 18 using the potential between the base and emitter of the first and second diodes or transistors connected in series; a third diode in parallel with the second diode or the series circuit of the first and second transistors;
between the base and emitter of the transistor 15 and the first
A diode-connected second transistor 18 is connected to the resistor 16 and uses the potential between the base and emitter of the second diode or transistor.
The second resistor 23 is connected between the base and emitter of the fourth transistor 22 in parallel with the above, and the collector current of the third transistor and the collector current of the fourth transistor are added to form a current source. 4, or one diode-connected third transistor using the potential between the base and emitter of the transistor. A stabilizing bias circuit characterized by a structure in which the chip area of the transistor is increased to reduce changes in current value due to temperature changes.