JPS6040737B2 - transistor circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present application relates to a transistor circuit that drives a plurality of amplifier circuits or switching circuits with the output of an amplifier provided with an output terminal.

Figure 1 is an example of the follower technology.

When a signal for supplying base current is applied to the base of transistor 1 from terminal a, transistor 1 becomes conductive, and the collector current causes a voltage drop across resistor 2, causing a voltage drop between the collector and the ground potential (ground). becomes small and transistor 1 operates in the saturation region, the power supply voltage applied to terminal b is divided by the voltage division ratio determined approximately by resistor 2 and resistor 3, and a certain voltage is applied between the collector and ground potential. occurs. This voltage is the sum of the base-emitter forward voltages of transistors 7 and 8, and this voltage is the sum of the forward voltages between the bases and emitters of transistors 7 and 8.
If the voltage divided by is set to be smaller than the forward voltage between the base and emitter of transistor 6, transistor 6 and transistors 7 and 8 will be controlled according to the operation of transistor 1 (here, ON-OFF operation). (in this case, ON-OFF operation). A load is connected to the collectors of transistor 6 and transistors 7 and 8, respectively, to obtain a predetermined output. In the case of such conventional technology, when transistor 6 and transistors 7 and 8 are operated simultaneously over a wide temperature range, half of the variation due to temperature characteristics of the sum of the base-emitter forward voltages of transistors 7 and 8 is Resistors 4 and 5 are connected between the base and emitter of transistor 6.
It is necessary to set the ratio 1:1.

By the way, if several more circuits such as the one made up of transistor 6 are connected in parallel between the collector of transistor 1 and the ground potential, in order to sufficiently drive them, the resistance value of resistor 2 should be reduced to increase the current. must be shed,
Further, the burden on the transistor 1 also increases. Therefore, considering operation at high temperatures, in order to ensure cutoff operation of transistor 6 and transistors 7 and 8,
This is very disadvantageous when applied to integrated circuits, where the conditions imposed on the saturation resistance of the transistor and the resistance 3 must take very limited and small values. That is,
The saturation resistance and the temperature coefficient of resistance are positive, and reducing this resistance value below a predetermined value is undesirable because it significantly increases the chip area in the case of integrated circuits. A transistor circuit for driving a plurality of amplifier circuits is obtained.

An embodiment of the present invention will be explained with reference to FIG.

That is, when a signal for supplying the base current of the transistor 11 is applied to the a terminal, the transistor 11 becomes conductive, the collector potential decreases, and the transistor 19 and the transistors 17 and 18 are cut off. When no signal is applied to the a terminal, the transistor 11 is cut off, a base current is supplied to the transistor 19 from the resistor 12, and a collector current flows through the transistor 19. transistor 1
The collector current of 9 is passed through the transistor 21 in a current mirror circuit composed of the diode 20 and the transistor 21.
is converted into a collector current to drive the transistor 16. In the circuit shown in FIG. 2, when transistor 11 is cut off, transistors 17, 18 and 19 are conductive, and the collector voltage of transistor 1 is equal to the sum of the base-emitter forward voltages of transistors 17 and 18 (VBE, 70VBE, 8).

Base-emitter forward voltage VB of transistor 19
8 and 9 and those of transistors 17 and 18 are substantially equal in their voltage and temperature characteristics. therefore,
Transistors 17 and 19 cancel out the temperature dependence of their respective base-emitter forward voltages.
Also, since VBE·7−VBB,9, the voltage drop VR,4 of the resistor 14 is the base-emitter forward voltage drop VBE·7 of the transistor. It becomes equal to 8. therefore,
The emitter current IE of transistor 9 is IE=VBE,
8/R. It becomes 4. Note that R,4 is the resistance value of the resistor 14. Since the emitter current and collector current of the transistor 19 can be considered to be substantially equal, VB, 8/R,
A collector current of 4 flows through the transistor 19. A current proportional to this current becomes the collector current of the transistor 21 due to the well-known characteristics of the current mirror circuit consisting of the diode 20 and the transistor 21, but the PN junction area of the diode 20 and the base-emitter junction area of the transistor 21 are :1 is selected so that a 1:1 current flows through these transistors, so transistor 2
The collector current of 1 becomes substantially equal to that of transistor 9. Therefore, the voltage drop across resistor 15 is V·v
The voltage drop across the false disconnection 15 of the transistor 16 is the base-to-dark forward voltage V of the transistor 16, so that v is equal to v.

If R,4=R,5, then VB. , 6=V88,8, and this relationship does not depend on the temperature characteristics of the resistors 14 and 15 by using resistors 14 and 15 with the same temperature characteristics (which can be easily realized in an integrated circuit). That is, the temperature dependence of the base-emitter forward voltage of transistor 16 is canceled out by that of transistor 8. As described above, the circuit shown in FIG. 2 is extremely suitable for integrated circuits, and temperature compensation can be realized extremely easily by integrating the circuits. According to this embodiment of the present invention, since only the base current of the transistor 19 is sufficient as the signal current for driving the transistor 16, even when a large number of circuits, such as the portion constituted by the transistor 6, are simultaneously driven, the processing can be performed by the transistor 1. The current flowing through the resistor 12 and the current flowing through the resistor 12 are extremely small (depending on the value of hFE of the transistor 9) compared to the conventional technology.

Therefore, the value of the resistor 12 can be increased, while the saturation voltage of the transistor 11 and the resistance value of the resistor 3 are 4
・Can be reduced. Therefore, transistor 1
1. The chip area of the resistor 3 can be reduced in stripes, and the transistor signals 16-19 can be reliably cut off even at high temperatures. Furthermore, there is the effect that their operating points can be changed by changing the ratio of the resistors 14 and 15, the ratio of the emitter current densities of the diode 20 and the transistor 21, or by using a resistor instead of the diode 20. That is, in the above explanation, it was assumed that the junction area ratio of the diode 20 and the transistor 21 is equal (the emitter current density is equal), but in general, the junction area of the diode 20 is
As is well known, if the emitter junction area is , then the input/output current ratio of the current mirror circuit consisting of the diode 20 and the transistor 21 is . Therefore, the voltage drop across resistor 15 is A2, . R・5. VBE18 VR・5=A20R,4.

Therefore, the area ratio A2,/n of the diode 20 and the transistor 21, the ratio R,5/R of the resistors 1 4, 1 5,
4, the operating point of the transistor 16 changes. Also, as is clear from this equation, the resistances 14 and 15 are 1:
Even if it is not 1, the area ratio is /n. By VR, 5=V
BE,6=VBE,8. That is,
Temperature compensation can also be achieved while operating temperature can be varied. When a resistor is used instead of the diode 20, the operating point can be changed by changing the value of this resistor and the ratio of the resistors 14 and 15. In FIG. 2, the transistor 16 and Darlington-connected transistors 17 and 18 have the basic configuration of a grounded emitter amplifier, but resistors are provided at the emitters of the transistor 16 and the emitter of the transistor 18, respectively, to provide current feedback. A grounded emitter amplifier may also be used. The power supply voltage in FIG. 2 is applied to the b terminal for transistor 11, and to the
Although the case where the voltage is applied to each terminal is shown, it goes without saying that the same power supply voltage may be applied to terminals B and B.
The present application also has the feature that by using a plurality of power supply voltages, it is possible to take a configuration according to the capacity of each power supply.

FIG. 3 is an example in which the present application is applied to a comparator.
The comparison output obtained at the load resistor 64 of the differential amplifier of transistors 61 and 62 using the resistor 63 as a constant current source drives the drive circuit of transistors 66, 67, and 70 and the transistors 71 and 71.
72 drive circuits. The outer part of the transistor 67 has an emitter resistor 68, and the collector has a current mirror circuit consisting of a diode 65 and a transistor 66, and its output controls the voltage generated across the resistor 15 to drive the transistor 70. ing. Such a circuit can also produce effects similar to those of the above embodiment. As described above, the present invention can be widely applied not only to the above-mentioned embodiments.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an example of the prior art. FIG. 2 is a circuit diagram showing an embodiment of the present invention. Third
The figure is a circuit diagram showing another embodiment of the present invention. 1,6
,7,8,11,19,21,16.17,18,61
, 62, 66, 67, 70, 71, 72}...transistor, 2, 3, 4, 5, 12, 13, 14, 15, 63
, 64, 68, 69}...Resistance, 20, 65...
·····diode. Strategy/Kanita Z Zuta J Garden

Claims (1)

[Claims] 1 an input terminal to which a switching signal is supplied; two Darlington-connected transistors that drive a first load in response to the switching signal, the base-emitter junctions of which are connected between the input terminal and a reference potential terminal; first and second transistors connected in series between them; at least one third transistor having a base connected to the input terminal; and a first resistor connected between the emitter of the third transistor and the reference potential terminal. , a current mirror circuit having a current input terminal connected to the collector of the third transistor, a second resistor connected between the current output terminal of the current mirror circuit and the reference potential input terminal, and the second resistor.
a fourth transistor that receives a voltage drop across the resistor as a base-emitter voltage to drive a second load connected to the collector, wherein the voltage drop across the second resistor is applied to the bases of the first and second transistors; - The resistance values of the first and second resistors and the input/output current ratio of the current mirror circuit are set so as to be substantially equal to the forward voltage drop of one of the emitter junctions. transistor circuit.