JPH0338776B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to transistor logic circuits, and more particularly to transistor logic circuits useful in integrated circuits operated at low power.

Figure 1 shows an example of a conventional transistor logic circuit, so-called RTL (Resistor Transistor Logic).
It is a circuit connection diagram showing what is called. 1
is an input terminal, 2, 3, 4, 57 are transistors,
5, 6, 7, 55, and 56 are resistors, 8, 9 are output terminals, and 10 is a power supply. The signal input from terminal 1 is inverted by transistor 2, and from its collector is passed through resistors 6 and 7 to transistors 3 and 3, respectively.
It is input to the base of 4. The signal inverted by transistor 3 is output to terminal 9. Furthermore, the signal inverted by the transistor 4 is transmitted to the resistor 5.
6, the signal is further inverted by a transistor 57, and an output is taken out from a terminal 8. 10 is a power source.

Considering the case where the above circuit is created in an integrated circuit,
The value of resistor 5 is 50kΩ in terms of the area occupied by the element.
degree is the practical upper limit. Also, from the point of view of power consumption, it is preferable that the resistors 5 and 55 be larger.
Consider setting it to 50kΩ. The current consumption and power consumption of this circuit are approximately equal to the current and power consumed by the resistors 5 and 55. Furthermore, in actual operation, current flows only through either the resistor 5 or the resistor 55, so the power supply voltage is If it is 12 (V), the current consumption will be 240 (μA). Further, the power consumption is 12 ² (V) ² /50×10 ³ (Ω)≒0.00288 (W). When a large number of circuits as shown in FIG. 1 are used, power consumption increases. for example
If 100 were used, the output would be 288mW. This value is close to the maximum allowable loss determined by the integrated circuit package, and means that many other circuits cannot be integrated.

An object of the present invention is to provide a logic circuit with a simple circuit configuration and extremely low power consumption.

In the present invention, outputs are taken out separately from the collector and emitter of the input transistor.
A constant current source with a small current capacity is connected between the collector and the power supply, one output transistor is connected to this collector, and a current mirror circuit is connected to the emitter. By taking out the output independently from the circuit, the output fanout of the input transistor is distributed between the collector side and the emitter side, thereby reducing power consumption and circuit area.

Next, the present invention will be described in detail according to embodiments using drawings.

FIG. 2 is a circuit connection diagram showing an embodiment of the present invention, in which 1 is an input terminal, 2, 3', 4 are transistors,
5' is a constant current source, 8' and 9 are output terminals, and 10 is a power supply. The diode 11 and the transistor 3' constitute a current mirror circuit which receives the emitter current of the input transistor 2 as an input. diode 1
2 is a level shift diode.

In FIG. 1, if the resistor 5 is replaced with a constant current circuit with a small current, it is possible to reduce power consumption, but the voltage drop that occurs across the resistors 6 and 7 is also reduced, and the current hogging of the transistors 3 and 4 is reduced. This phenomenon occurs, and the collector currents of transistors 3 and 4 no longer flow in a balanced manner. For this reason, it is necessary to make the resistors 6 and 7 large to provide a predetermined voltage drop, which results in an increase in the area occupied by the resistors 6 and 7, which is impractical. In the present invention, in order to avoid this problem, one output is obtained from the output terminal 8' of the current mirror circuit. In other words, since only transistor 4 is connected to the collector of transistor 2 via level shift diode 12, current hogging does not occur, and when transistor 1 is conductive, a current that is the emitter current multiplied by the current amplification of the current mirror is generated. can flow through the transistor 3', so that the transistor 3' can be sufficiently driven.

It is assumed that the output terminals 8' and 9 are pulled up to a high potential by, for example, a constant current source (not shown). In this case, the emitter areas of the transistors 3' and 4 are set so that the collector current of the transistors 3' and 4 when they are conductive has a driving ability that can absorb all the current of the constant current source. (Normally 1:1 to 1:3 is sufficient) The input applied to the input terminal is at "H" level, that is, the forward voltage V _BE between the base and emitter of transistor 2 and the forward voltage V _F of diode 11 (= V _BE ) (V _BE +V _F )
When the voltage is larger, transistors 2 and 3' conduct, a low potential output equal to the collector-emitter saturation voltage V _CE (sat) of transistor 3' is obtained at terminal 8', and a high potential is obtained at terminal 9. Almost equal “H”
When a level output is obtained and the input is at the "L" level below (V _BE + V _F ), a high potential ("H") is applied to terminal 8'.
level), and a low potential (“L” level) output is obtained at terminal 9.

As described above, the present invention takes out an output from the collector and emitter of the first-stage transistor 2 that receives an input signal as shown in FIG.
Furthermore, 1 (μA) ~
By connecting a constant current circuit with a small current capacity of about 10 (μA), current hogging does not occur and the current is approximately 1/240 compared to the conventional Figure 1.
Logic circuits with low current consumption of ~1/24 can be realized. Furthermore, the logic circuit of the present invention has the feature that the plurality of constant current circuits can be realized using multi-collector PNP transistors, so that the logic circuit can be significantly smaller than the case where resistors are used.

FIG. 3 is a circuit connection diagram showing an example of a conventional RTL type R-S flip-flop. 31 is R
input, 32 is S input, 33 is Q output, 34
-38 are transistors, 39-43 are resistors, 44
is the power supply. For the purpose of explanation, first consider when the terminal 31 is at the "H" level and the terminal 32 is at the "L" level, the transistor 34 is turned on (conducting),
Its collector potential becomes “L”, transistor 36 turns off (blocks off), and transistor 37 also turns off.
Since it is OFF, the collector potential of transistors 36 and 37 becomes "H", and transistors 35 and 38 are turned off.
Turn on. Next, even if the terminal 31 is set to "L", since the transistor 35 is turned on as described above,
Other states remain unchanged. Next, when the terminal 32 is set to "H", the transistor 37 is turned on and its collector potential becomes "L", and the transistors 35 and 38
is turned off, and since the transistor 34 is also turned off, the collectors of the transistors 34 and 35 are at "H".
Therefore, the transistor 36 is turned on. Next, even if the terminal 32 is set to "L", the other states do not change because the transistor 36 is turned on as described above. The operation of the R-S flip-flop has been explained above. Similar to the circuit shown in FIG. 1, it is difficult to reduce the power consumption of this circuit.

FIG. 4 is a circuit connection diagram of a power-saving R-S flip-flop according to another embodiment of the present invention.
Components that are the same as in FIG. 3 are given the same numbers. In place of the load resistors 39 and 42 in FIG. 3, a constant current source formed by a transistor 47 is used in the present invention. In addition, in FIG. 3, transistors 36, 3
Since transistors 35 and 38 are connected to the collector of transistor 7, resistors 41 and 43 were required to prevent current hogging, but in the present invention, the above resistors can be replaced by changing the connection point of the base of transistor 38. Made unnecessary. Since the current flowing through the transistor 38 must be in a reciprocal relationship with the collector current of the transistors 36 and 37 ≒ the emitter current, the emitter current of the transistors 34 and 35 with inverted outputs is changed using a current mirror circuit consisting of a diode 45 and the transistor 38. I'm making it. Note that the diode 46 is for level shifting.

When the terminal 31 is at the "H" level and the terminal 32 is at the "L" level, the transistor 34 is turned on, its collector potential becomes "L", and the transistor 36
is off, and transistor 37 is also off, so
The collector potential of transistors 36 and 37 is “H”
Therefore, the transistor 35 is turned on. The transistor 38 is turned on when the transistor 34 is turned on. Next, even if the terminal 31 is set to "L", since the transistor 35 is turned on,
There are no other changes in status. Next, when the terminal 32 is set to "H", the transistor 37 is turned on, its collector potential becomes "L", and the transistor 35 is turned on.
Since it is turned off and the transistor 34 is also turned off, it becomes the transistor 38, and at the same time, the transistor 36 is also turned on. Next, even if the terminal 32 is set to "L", other states do not change because the transistor 36 is turned on.

In this R-S flip-flop, the power supply circuit 4
Since no resistors other than 8 are required, the power consumption of the R-S flip-flop stage can essentially be made as small as desired depending on the setting of the collector current of transistor 47. For example, by setting this current to 10 μA, it is possible to reduce the current to 1/20 or less of the conventional value. Inside the power supply circuit 48, a voltage of approximately 0.7V is generated from the power supply 44 to a diode 53 via a resistor 52, and a constant current is generated by a circuit consisting of a transistor 50 and a resistor 51, which is connected to a diode 4.
A desired current source is created by a current mirror circuit consisting of a transistor 9 and a transistor 47. For example, by setting the resistor 52 to 22.6 kΩ and the resistor 51 to 4.2 kΩ, each collector current of the transistor 47 is
Can be set to 10μA. These resistance values are suitable for integrated circuits. The power supply circuit 48 can supply not only the transistor 47 but also other logic circuits.

As described above, according to the present invention, a transistor logic circuit that can essentially save any amount of power can be configured, and is extremely useful industrially.

[Brief explanation of the drawing]

FIG. 1 shows an example of a conventional RTL circuit, FIG. 2 shows an embodiment of the present invention, FIG. 3 shows an example of a conventional RS flip-flop, and FIG. 4 shows an example of an RS flip-flop implementing the present invention. It is a diagram. 1, 31, 32...input terminal, 2, 3, 3',
4, 34, 35, 36, 37, 38, 47, 5
0,57...transistor, 5,6,7,39,
40, 41, 42, 43, 51, 52, 55, 5
6...Resistance, 5'... Constant current source, 8, 8', 9, 3
3, 33'...output terminal, 10,44...power supply,
11, 12, 45, 46, 49, 53...diode, 48...power supply circuit.

Claims (1)

[Claims] 1. In a transistor logic circuit that has an input transistor that receives an input signal as a base and performs a switching operation according to the input level, and takes out a plurality of outputs in response to the operation of the input transistor, one end is connected to the collector of the input transistor. a constant current source having a small current capacity, the other end of which is directly connected to the power source, and the other end of which is directly connected to a power supply; a transistor whose base is connected to the collector of the input transistor directly or only through a level shifting diode; and a current mirror circuit that is directly connected to the emitter of the transistor and receives the emitter current as input, and separately outputs a plurality of outputs responsive to the input signal from the transistor and the current mirror circuit without using a resistor element. A logic circuit characterized in that it can be taken out.