JPS62296609A - Quasi-complementary push-pull amplifier - Google Patents

Abstract

PURPOSE:To make an output waveform hardly being disturbed by providing the 1st and 2nd transistors (TRs) constituting an output stage and connecting a collector of the 3rd TR and a current source to the base of the 1st TR. CONSTITUTION:TRs 1, 2 constitute an output stage of a push-pull amplifier and a TR 3 drives the TR 2 and a TR 6 drives the TR 1. A TR 7, diodes 8, 9, 10, 11 and constant current sources 12, 13 constitute a base circuit. Moreover, a current source 5 is connected to a base of the TR 2. The base of the TR 2 receives current supply from the constant current source 5, then the base voltage of the TR 2 is not dropped up to zero V, the response of the TR 2 when the TR 3 is switched from OFF to ON is excellent and the disturbance of an output waveform, that is, the switching distortion is hardly caused.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention Field of Industrial Application This invention relates to a quasi-complementary push-pull amplifier.

Prior Art FIG. 3 is a diagram showing a conventional example of the output stage of a quasi-complementary push-pull amplifier. In the figure, 1 and 2 are transistors that constitute the output stage of the push-pull amplifier, and 3 is a transistor that drives transistor 2. It is a transistor that 4 is an output terminal. 6 is a transistor that drives transistor 1; Transistor 7, diode 8.9, 10.
11° and constant current sources 12 and 13 constitute a bias circuit, and 14 is an input signal source to this output stage.

In a quasi-complementary push-pull amplifier having a configuration that exceeds the problems that the invention aims to solve, when transistor 1 is on, transistor 2 is off. At this time, transistor 3 is in the off state, so the collector current of transistor 3 becomes zero, and the base potential of transistor 2 becomes O
It drops to v.

In this state, even if transistor 3 is turned on, the base potential of transistor 2 cannot rise rapidly, and transistor 2
Due to the delay in the on-operation, the falling waveform of the output terminal 4 has the disadvantage of causing a waveform disturbance as shown in FIG. 4, that is, so-called switching distortion.

The present invention has been made in order to eliminate the above-mentioned disadvantages, and an object of the present invention is to provide a quasi-complementary push-pull amplifier having a novel configuration in which disturbances in the output waveform are less likely to occur.

Means for Solving the Problems The quasi-complementary push-pull amplifier of the present invention comprises a first . It has each transistor shown in FIG.
The configuration is such that the collector of a third transistor and a current source are connected to the base of the second transistor.

Effect: With the circuit configuration described above, a minute current is supplied to the base of the second transistor through the current source, which prevents the collector of the third transistor from dropping to zero potential, and therefore prevents the second transistor from turning on. A quasi-complementary push-pull amplifier circuit that operates quickly and is less likely to cause disturbances in the falling output waveform can be realized.

Embodiment FIG. 1 shows an embodiment of a quasi-complementary push-pull amplifier according to the present invention, and the same parts as in FIG. 2 are designated by the same numbers. Current source 5 is connected to the base of transistor 2.

According to the above configuration, even when the transistor 3 is off, the base of the transistor 2 receives current supply from the constant current source 5, so that the base voltage of the transistor 2 does not drop to Ov, and the base voltage of the transistor 2 does not drop to Ov. The response of the transistor 2 when the transistor 3 is switched from off to on is good, and disturbance of the output waveform, that is, switching distortion is unlikely to occur.

In a conventional quasi-complementary push-pull amplifier as shown in Fig. 3, for example, if the output power is 10W class amplifier, in order to prevent switching distortion, the output power is connected from the emitter of transistor 1 to the collector of transistor 2 in a quiescent state. It was necessary to pass a current of about 10 mA (hereinafter, this current will be referred to as Icct). With the circuit shown in FIG. 1, switching distortion will not occur even if the lcQ is set as small as 2 to 3 mA even in a 10 W class amplifier. What is the setting of the current value of the constant current source 5 at this time, assuming that the current amplification factor of the transistor 2 is 100?
The current value is 30 μA or less.

FIG. 2 shows the waveform of the output terminal 4 at this time and the time change of the base potential of the transistor 2 superimposed on the same time axis.

Effects of the Invention As described above, the present invention can make it difficult to cause switching distortion, which is particularly likely to occur when the static circuit current is set to a small value, in a quasi-complementary push-pull amplifier, and realizes an amplifier with less unnecessary radiation. Since it becomes possible, its utility value is great.

[Brief explanation of drawings]

FIG. 1 is an output stage circuit configuration diagram of a quasi-complementary push-pull amplifier according to an embodiment of the present invention, FIG. 2 is a characteristic diagram of an embodiment of the present invention, and FIG. 3 is an output stage circuit diagram of a conventional quasi-complementary push-pull amplifier. 4 are characteristic diagrams of the conventional example. 1.2.3...Transistor, 4...
Output terminal, 5... constant current source. Figure 1 Figure 2 Lock

Claims (1)

[Claims] A quasi-complementary push device comprising first and second transistors constituting an output stage of a push-pull amplifier, the collector of a third transistor and a current source being connected to the base of the first transistor. pull amplifier.