JPS5943849B2 - transistor amplifier circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a non-saturating transistor amplifier circuit suitable for amplifying pulse signals, etc., and is an excellent transistor amplifier circuit that has a simple configuration and performs good operation without transistor saturation. The purpose is to provide the following.

A commonly used transistor amplifier circuit is constructed as shown in FIG.

That is, in FIG. 1, 1 is a signal source, 2 is a circuit element having a voltage shift function, 3 and 4 are amplifying transistors, 5 is a load, and 6 and 7 are power supplies.

In FIG. 1, it is assumed that the signal obtained from the signal source 1 is in the form of a pulse and causes the transistors 3 and 4 to perform a switching operation.

In this case, when the transistors 3 and 4 are saturated, even if the signal from the signal source 1 disappears, the transistors 3 and 4 remain for a while.
4 remains in the on state, and this accumulation effect causes a time delay in the fall of the pulsed output appearing on the output side of the transistors 3 and 4, resulting in a problem that accurate amplification cannot be performed.

In particular, in the case of a push-pull amplifier as shown in FIG. 1, there is a period in which transistors 3 and 4 are turned on at the same time, which causes an excessive current to flow through transistor 14 and destroy transistors 3 and 4. Ta.

The present invention eliminates the above-mentioned conventional drawbacks and provides an excellent transistor amplifier circuit that has a simple configuration and operates well without transistor saturation.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A transistor amplifier circuit according to the present invention will be described below with reference to drawings of an embodiment.

FIG. 2 is an electrical connection diagram of one embodiment of the transistor amplifier circuit of the present invention, in which 11 is a signal source, 12 is a resistor, 13 and 14 are transistors connected to each other in Darlington, 15 is a load, 16 is a diode connected between the base of the transistor 13 at the front stage and the collector of the transistor 14 at the rear stage of the Darlington-connected transistors 13 and 14, and 17 is the transistor 1 at the front stage.
A second diode is connected between the collector of 3 and the collector of the transistor 14 in the subsequent stage, 18 is the emitter resistance of the transistor 13 in the previous stage, and 19 is a power supply.

In FIG. 2, it is assumed that a signal from the signal source 11 is now applied to the transistor 13 in the previous stage, and a signal amplified here is further applied to the transistor 14 in the latter stage.

In this case, transistors 13 and 14 are both in the on state, and if the current supplied to the base of transistor 14 is large enough, transistor 14 will naturally be saturated and its collector potential will fall below the base potential. become many.

However, in this case, the threshold voltage of the diode 16 D
1 and the base of transistor 13 in the previous stage.

The relationship with the emitter voltage v1 is ■.

, -VBB1B, as soon as the collector and base potentials of the subsequent transistor 14 become almost equal, current from the signal source 1 flows through the first diode 16 and flows out to the collector of the subsequent transistor 14. .

Therefore, this current causes the current supplied to the base of the transistor 13 in the previous stage to decrease, resulting in a decrease in the collector current of the transistor 14 in the latter stage, and settles when the collector and base potentials of the transistor 14 in the latter stage become approximately equal. It becomes like this.

On the other hand, the collector potential of the transistor 13 in the previous stage becomes higher than the collector potential of the transistor 13 in the previous stage by the threshold voltage value ■9□ due to the second diode 17. The potentials of the base and collector of 13 are approximately equal to each other.

In other words, the transistor 13 at the front stage and the transistor 14 at the rear stage are kept in an on state just before saturation in response to a sufficient current from the signal source 1.

Therefore, according to the embodiment shown in FIG. 2, even if the signal from the signal source 1 is in the form of a pulse, the signal can be accurately and accurately processed by the front and rear transistors 13 and 14 without deteriorating its falling characteristics. This can be reliably amplified.

FIG. 3 is an electrical wiring diagram of another embodiment configured as a push-pull amplifier, in which 21 is a signal source, 22 is a resistor, 23 and 24 are voltage shift transistors, and 25 to 2
8 is an amplification transistor, 29.30 is a high-speed switching diode, 31.32 is a silicon diode,
33 and 34 are load resistances, 35 and 36 are emitter resistances, 3
7 is a negative i, 38 and 39 are power supplies, and 40 is an emitter resistance.

As is clear from the above embodiments, the present invention connects a first diode between the base of the transistor in the previous stage and the collector of the transistor in the latter stage, which are Darlington connected,
A second transistor is connected between the collector of the former transistor and the collector of the latter transistor, and neither transistor enters the saturation region.
Even pulsed signals can be amplified accurately and reliably without affecting the falling characteristics.

In the embodiment, the case where an NPN transistor is used has been described, but the same applies to the case where a PNP transistor is used.

Furthermore, in the embodiments, the signal from the signal source is described as being in the form of a pulse, but the amplifier circuit of the present invention can also be used as a normal linear amplifier.

In this case, a good effect will be exhibited when clipping the signal.

[Brief explanation of drawings]

Figure 1 is an electrical wiring diagram of a conventional transistor amplifier circuit.
FIG. 2 is an electrical connection diagram of one embodiment of the transistor amplifier circuit of the present invention, and FIG. 3 is an electrical connection diagram of another embodiment. 11... Signal source, 13, 14... Transistor, 15... Load, 16, 17...
·diode.

Claims (1)

[Claims] 1 Of the two transistors connected in Darlington,
A first diode is connected between the base of the preceding transistor and the collector of the subsequent transistor, and a second diode is connected between the collector of the preceding transistor and the collector of the subsequent transistor. A transistor amplifier circuit configured to take out the output from the collector side.