JPH0785534B2 - Pulse current output circuit - Google Patents

Description

Detailed Description of the Invention [Industrial applications]

The present invention relates to a pulse current output circuit that causes a load to output a pulse current based on an input pulse.

[Prior art]

Conventionally, a pulse current output circuit described below with reference to FIG. 2 has been proposed. That is, the collector is passed through the load L and one end is connected to the power supply end.
A pulse signal source connected to the power supply end E1 connected to the other end (positive side) of the drive power supply VD connected to E2 (ground) and one end connected to the power supply end E2 (ground) It has an NPN-type transistor Q1 connected to the other end of S. Further, it has an NPN transistor Q2 whose collector is connected to the power supply terminal E1 and whose base is connected to the other end (positive side) of the reference power supply VR whose one end is connected to the ground. Further, the collector is connected to the emitters of the transistors Q1 and Q2, and the base is connected through the resistor R1 to one end of the power source E2.
It has an NPN-type transistor Q3 connected to the other end (positive side) of the current setting power supply VS1 connected to (ground) and whose emitter is connected to the power supply end E2 through the constant current circuit H. Also, connect the collector to the power supply terminal E1 and connect the base to another resistor.
NP that connects one end to the other end (positive side) of the other current setting power supply VS2 whose one end is connected to the power supply end E2 (ground) through R2 and whose emitter is connected to the power supply end E2 through the constant current circuit H
It has an N-type transistor Q4. The above is an example of the configuration of the conventionally proposed pulse current output circuit. Further, conventionally, as shown in FIG. 3, in the conventional pulse current output circuit described above with reference to FIG.
Capacitor CS for suppressing voltage fluctuation is connected between the base of the
There is also proposed a pulse current output circuit having the same configuration as the conventional pulse current output circuit described above with reference to FIG. According to the conventional pulse current output circuit shown in FIGS. 2 and 3, the pulse signal is supplied from the pulse signal source S to the reference power source.
If a voltage value higher than the reference voltage applied from VR to the base of transistor Q2 is obtained, then transistor Q1 and
Q2 turns on and off respectively. At this time, the current setting voltage is applied to the bases of the transistors Q3 and Q4 from the current setting power supplies VS1 and VS2 through the resistors R1 and R2, respectively. Therefore, the pulse current I _P based on the pulse signal flows from the drive power source VD through the power source terminal E1, the load L, the transistor Q3, and the constant current circuit H in that order, and at this time, the transistor Q4 is driven. A current I ₄ flows from the power supply VD side through the constant current circuit H. A pulse current I _P flowing through the load L, and the current flowing through the transistors Q4, has a value of the ratio corresponding to the ratio of the value of the voltage current settings are given to the bases of the transistors Q3 and Q4. Also, when the pulse signal is obtained at a voltage value lower than the reference voltage, the transistor Q1 and Q2 are turned off and turned on, respectively, the load L, the pulse current I _P as described above
Does not flow. Therefore, according to the conventional pulse current output circuit shown in FIG. 2 and FIG. 3, the pulse current based on the pulse signal input to the load L is obtained from the current setting voltage sources VS1 and VS2, respectively. It has a function of outputting a value according to the value of the ratio of the working voltage.

[Problems to be Solved by the Invention]

However, in the case of the conventional pulse current output circuit shown in FIG. 2, the base-emitter resistance of the transistor Q1 is transiently pulsed during the rising transition of the pulse signal in which the transistors Q1 and Q2 are turned on and off, respectively. The collector voltage of the transistor Q3 is
Transiently, the pulse signal rises and fluctuates as compared with the case of a steady state other than the transition of the rising edge of the pulse signal. Then, the variation is given to the base of the transistor Q3 via the collector-base capacitance C3 of the transistor Q3. Therefore, in the case of the conventional pulse current output circuit shown in FIG. 2, the current flowing through the transistor Q3, and hence the pulse current I _P flowing through the load, transiently increases and changes more than in the steady state of the pulse signal. It had the drawback of. In the case of the conventional pulse current output circuit shown in FIG. 4,
Since the voltage fluctuation suppressing capacitive element CS is connected between the base of the transistor Q3 and the power supply terminal E2, the base voltage of the transistor Q3 transiently changes as described above at the transition of the rising edge of the pulse signal. When the fluctuations increase, the equivalent impedance between the base of the transistor Q3 and the power supply terminal E2 transiently decreases and decreases as compared with the case where the pulse signal is in the steady state. Therefore, in the case of the conventional pulse current output circuit described above with reference to FIG. 2, it is suppressed that the base voltage of the transistor Q3 transiently increases and changes,
Therefore, it is suppressed that the pulse current transiently increases and changes. However, the suppression effect is that the voltage fluctuation suppression element CS
In order to increase the capacitance value of the pulse current output circuit as a whole, a substrate having a small area is used to increase the capacitance value of the semiconductor integrated circuit. Since the above-described suppression effect cannot be sufficiently satisfied due to a certain limitation due to such factors, if the capacitance value of the current fluctuation suppression capacitive element CS is large, the currents of the current setting power supplies VS1 and VS2 are increased. If the value of the setting voltage is changed at high speed, the value of the voltage for their current settings can not be applied to the base of the transistor Q3 and Q4 rapidly follow the variation, thus, the value of the pulse current I _P at high speed It had the drawback that it could not be changed. Therefore, the present invention proposes a novel pulse current output circuit without the above-mentioned drawbacks.

[Means for Solving the Problems]

In the pulse current output circuit according to the present invention, as in the case of the conventional pulse current output circuit described above with reference to FIG. 2, the collector is connected to the first power supply terminal through the load and the base is connected to the pulse signal source. A first transistor and a second transistor whose collector is connected to the first power supply terminal and whose base is connected to the reference power supply; and a collector which is connected to the emitters of the first and second transistors, A third transistor having a base connected to a first current setting power source and an emitter connected to a second power source terminal paired with the first power source terminal through a constant current circuit, and a collector connected to the first power source terminal. And a base connected to a second current setting power supply, and an emitter connected to the second power supply end through the constant current circuit. However, in the pulse current output circuit according to the present invention, in the pulse current output circuit having such a configuration, the base is connected to the pulse signal source between the collector of the fourth transistor and the first power supply terminal. 5th doing
A transistor having a collector connected to the first power supply terminal and an emitter connected to the collector of the fourth transistor, and a base connected to the reference power supply. No. 6 transistor is inserted in such a relationship that its collector is connected to the first power supply terminal and its emitter is connected to the collector of the fourth transistor.

[Action / effect]

According to the pulse current output circuit of the present invention, when the pulse signal is obtained from the pulse signal source at a voltage value higher than the reference voltage applied to the second transistor from the reference power supply, the above-described operation is performed in FIG. As in the case of the conventional pulse current output circuit described above, the first and second transistors are in ON and OFF states, respectively, but in this case, the fifth and sixth transistors are also in ON and OFF states, respectively. When the pulse signal has a voltage value lower than the reference voltage, the first and second transistors are turned off and on, respectively, as in the case of the conventional pulse current output circuit described above with reference to FIG. However, in this case, the fifth and sixth transistors are also turned off and on, respectively. Therefore, in the transistor Q4, the transistors Q5 and Q6 are not inserted between the collector of the transistor Q4 and the power source terminal E1, and the collector of the transistor Q4 is connected to the power source terminal E1. As with the pulse current output circuit, current flows. Therefore, the pulse current output circuit according to the present invention will not be described in detail, but similarly to the case of the conventional pulse current output circuit described above with reference to FIG. 2, a pulse current based on the pulse signal input to the load is applied. , And a function of outputting with a value according to the ratio of the current setting voltages obtained from the first and second current setting power supplies, respectively. However, in the case of the pulse current output circuit according to the present invention, in the case of the conventional pulse current output circuit described above with reference to FIG. 2, during the rising transition of the pulse signal in which the first and second transistors are turned on and off, respectively. Similarly, the base-emitter resistance of the first transistor fluctuates transiently, so that the collector voltage of the third transistor fluctuates transiently, and the fluctuation is the collector-emitter of the third transistor. Is given to the base of the third transistor via the inter-capacitance, and the base voltage of the third transistor fluctuates transiently. At this time, the base-emitter resistance of the fifth transistor also fluctuates transiently. Therefore, the collector voltage of the fourth transistor also transiently fluctuates, and the variation is the collector voltage of the fourth transistor. Through the scan capacitance, it is applied to the base of the fourth transistor, whereby the base voltage of the fourth transistor also varies transiently. Therefore, the base voltage of the third transistor transiently changes, so that the pulse current flowing through the third transistor, and thus the load, transiently changes.
The current that flows through the fourth and fifth transistors transiently fluctuates and is suppressed. In this case, the characteristics of the first and fifth transistors and the like are appropriately selected in advance so that the third and fourth transistors are
Since the ratio of the base voltage value of the transistor in the transient state can be made substantially equal to the ratio in the steady state, the pulse current with respect to the load can be substantially not changed even in the transient state. Further, since such an effect can be obtained without using the current fluctuation suppressing capacitive element in the conventional pulse current output circuit described in FIG. 3, the conventional pulse current output described in FIG. 2 is used. It does not have the disadvantages described above for the circuit.

【Example】

Next, a first embodiment of the pulse current output circuit according to the present invention will be described with reference to FIG. In FIG. 1, parts corresponding to those in FIG. 2 are designated by the same reference numerals, and detailed description thereof will be omitted. The pulse current output circuit according to the present invention shown in FIG. 1 has the same configuration as the conventional pulse current output circuit described above with reference to FIG. 3, except for the following matters. That is, between the collector of the transistor Q4 and the power source end E1, the transistor Q5 having its base connected to the other end of the pulse signal source whose one end is connected to the power source end E2 (ground) is
The collector is connected to the power supply terminal E1 and the emitter is connected to the collector of the NPN transistor Q4. In addition, between the collector of the transistor Q4 and the power source end E1, there is an NPN transistor Q6 whose base is connected to the other end of the reference power source VR whose one end is connected to the power source end E2 (ground). , The collector of which is connected to the power supply terminal E1 and the emitter of which is connected to the collector of the transistor Q4. The above is the configuration of the embodiment of the pulse current output circuit according to the present invention. The pulse current output circuit according to the present invention having such a configuration has the same configuration as that of the conventional pulse current output circuit described above with reference to FIG. 2, except for the matters described above. When a pulse signal is obtained from the pulse signal source S at a voltage value higher than the reference voltage applied to the transistor Q2 from the reference power supply VR, the case of the conventional pulse current output circuit described above with reference to FIG. Similarly, transistors Q1 and
Q2 turns on and off respectively. However,
In this case, the transistors Q5 and Q6 are also turned on and off, respectively. When the pulse signal has a voltage value lower than the reference voltage, the transistors Q1 and Q2 are turned off and on, respectively, as in the case of the conventional pulse current output circuit described above with reference to FIG. However, in this case, the transistors Q5 and Q6 are also turned off and on, respectively. Therefore, the transistor Q4 has its collector and power supply terminal E1
Second transistor in which the collectors of the transistor Q4 are connected to the power supply terminal E1 without the transistors Q5 and Q6 being interposed between
A current flows as in the case of the conventional pulse current output circuit described above in the figure. Therefore, the detailed description of the pulse current output circuit according to the present invention shown in FIG. 1 is also omitted, but the pulse signal input to the load L is the same as in the conventional pulse current output circuit described above with reference to FIG. Pulse current based on
It is possible to obtain the function of outputting with a value according to the ratio of the current setting voltages obtained from 1 and VS2. However, in the case of the pulse current output circuit according to the present invention shown in FIG. 1, the conventional pulse current output circuit described above with reference to FIG. As in the case of, the base-emitter resistance of the transistor Q1 changes transiently, which causes the collector voltage of the transistor Q3 to change transiently, and this change is caused by the collector-emitter capacitance of the transistor Q3. Is applied to the base of transistor Q3, which causes the base voltage of transistor Q3 to change transiently, and the base-emitter resistance of transistor Q5 also changes transiently, which causes the collector voltage of transistor Q4 to change transiently. And the amount of the fluctuation is applied to the base of the transistor Q4 via the collector-base capacitance of the transistor Q4. This causes the base voltage of the transistor Q4 to change transiently. Therefore, the base voltage of the transistor Q3 fluctuates transiently, so that the pulse current flowing through the transistor Q3, and thus the load L, fluctuates transiently. The transient current flowing through the transistors Q4 and Q5 is transient. It is suppressed by fluctuating to. Then, in this case, by appropriately selecting the characteristics of the transistors Q1 and Q5 in advance,
Since the ratio of the value of the base voltage of Q4 in the transient state can be made substantially equal to the ratio in the steady state, the pulse current to the load L can be substantially unchanged even in the transient state. Further, since such an effect can be obtained without using the current fluctuation suppressing capacitive element CS in the conventional pulse current output circuit described above with reference to FIG. 3, the conventional pulse current described above with reference to FIG. It does not involve the drawbacks described above for the output circuit. In the above description, only one embodiment of the pulse current output circuit according to the present invention is shown, and in the configuration of the pulse current output circuit according to the present invention described above with reference to FIG.
Replace each of the NPN type transistors Q1 to Q6 with a PNP type transistor, and according to this, drive power supply VD, reference power supply
It is also possible to replace the polarities of VR and the current setting power supplies VS1 and VS2 with the polarities opposite to those described above with reference to FIG. 1 so as to obtain the same effects as those described above with reference to FIG. Various modifications and changes may be made without departing from the spirit of the invention.

[Brief description of drawings]

FIG. 1 is a connection diagram showing an embodiment of a pulse current output circuit according to the present invention. 2 and 3 are connection diagrams showing a conventional pulse current output circuit. Q1 to Q6 …… Transistor S …… Pulse signal source L …… Load VR …… Reference power supply VS1, VS2 …… Current setting power supply H …… Constant current circuit C3, C4 …… Collector-base capacitance R1, R2 ……resistance

Claims (1)

[Claims] 1. A first transistor having a collector connected to a first power supply terminal through a load and a base connected to a pulse signal source; and a collector connected to the first power supply terminal, and a base for reference. A second transistor connected to the power supply, a collector connected to the emitters of the first and second transistors, a base connected to the first current setting power supply, and an emitter connected to the first current setting circuit through a constant current circuit. A third transistor connected to a second power supply terminal paired with the power supply terminal of
A fourth transistor having a collector connected to the first power supply terminal, a base connected to a second current setting power supply, and an emitter connected to the second power supply terminal through the constant current circuit. In the pulse current output circuit, a fifth transistor whose base is connected to the pulse signal source is provided between the collector of the fourth transistor and the first power supply terminal, and the collector of the fifth transistor is connected to the first power supply terminal. A sixth transistor connected to the power supply end and having an emitter connected to the collector of the fourth transistor and a base connected to the reference power supply has a collector connected to the first transistor. A pulse current output circuit connected to the power supply end of the second transistor and having an emitter connected to the collector of the fourth transistor.