JPS5821854B2 - SEPP Shutsuryoku Cairo - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a class B 5EPP output circuit that can flow a stable current when no signal is present and can reduce crossover distortion and unnecessary power consumption.

Class B 5EPP output circuits, whether formed using individual components or integrated into a semiconductor integrated circuit, are designed to eliminate the inconvenience of crossover distortion in the output signal. Consideration has been taken to flow an appropriate current when no signal is present.

However, the no-signal current is greatly affected by the characteristics of the transistors, resistors, etc. that make up the circuit, and the value of the no-signal current changes due to a slight change in characteristics, and when this current value becomes small, crossover distortion occurs. occurs, and conversely, when it becomes too large, it causes the inconvenience of consuming excess power.

Therefore, high precision is required for the parts that make up the circuit, and the circuit as a whole has the disadvantage of being expensive.

The present invention has been made to eliminate the above-mentioned disadvantages, and by adopting a circuit configuration in which a transistor is added whose emitter and base are commonly connected to the emitter and base of the output transistor constituting the 5EPP output circuit, the transistor 5E, which can flow stable current during no signal without being affected by the characteristics of
The purpose is to provide a PP output circuit.

FIG. 1 shows an embodiment of the 5EPP output circuit according to the present invention. As shown in the figure, a transistor 2, which is a second transistor, is arranged facing an output transistor 1, which is a first transistor, and 2
A configuration is adopted in which the emitter and base of the output transistor 1 and the output transistor 1 are connected in common.

The commonly connected emitters of transistors 1 and 2 are connected to the collector of a third transistor, transistor 7, whose emitter is grounded, and the base of transistor 7 is connected to the collector of transistor 7, whose emitter is connected to the collector of transistor 2. It is connected to the collector of transistor 4, which is transistor No. 4.

The collector of the transistor 7 is connected to a speaker 9 as a load via a capacitor 8 as a charging/discharging element.

Power supply terminal 6 is connected to the collector of transistor 1, to the collector of transistor 2 via resistor 5, and to the collector of transistor 4.
are connected to the base of each via a resistor 10,
The signal source terminal 3 is connected to the bases of the transistors 1, 2.4, respectively.

According to the 5EPP output circuit of the present invention having the above configuration, a stable non-signal special current flows through the transistor 1 through the operation described below, and the above-mentioned disadvantages can be avoided.

That is, when there is no AC signal at the signal source terminal 3 and the signal source terminal 3 is held at a normal DC potential, the emitter potential of the transistor 4 is determined according to this DC potential.

At this time, the current flowing through the resistor 5 has a value obtained by dividing the difference between the potential of the power supply terminal 6 and the emitter potential of the transistor 4 by the value of the resistor 5.

Here, if a transistor with a sufficiently high current amplification factor is selected for transistor 7, the current flowing to the base of transistor 7 will be sufficiently small compared to the current flowing to the collector of transistor 7, so that the collector of transistor 4 and the transistor The current flowing between the base of the circuit and the base of the circuit becomes negligible.

Therefore, if the current amplification factor of transistor 7 is sufficiently high, the current flowing to the collector of transistor 2 will be determined by the value of resistor 5.

By the way, the base of transistor 1 and the base of transistor 2 are commonly connected, and if the characteristics of transistor 1 and transistor 2 are substantially equal, the currents flowing through the respective collectors of both transistors will be equal.

Therefore, the current flowing to the collector of the output transistor 1 is also determined only by the value of the resistor 5, and the current can be made extremely stable when there is no signal.

Incidentally, the collector current of the transistor 4 is a small base current of the transistor 7, which is required to cause the collector current of the transistor 7 to flow.

Next, the operation of the 5EPP amplifier circuit according to the present invention will be explained.

When there is no signal, the capacitor 8 is charged to a potential lower than the DC potential held at the signal source terminal 3 by the base-emitter forward voltage of the transistor 1 or transistor 2.

FIG. 2 shows the state of the signal at the emitter of transistor 1 or transistor 2 when an alternating current signal is applied to signal source terminal 3.

In the same figure, E.

is the emitter potential of transistor 1 when there is no signal.

Now, when a signal that becomes higher than the DC potential when there is no signal is applied to the signal source terminal 3, that is, during the period A in FIG. 2, the collector current of the transistor 2 increases, and this current flows through the resistor 5. The collector potential of the transistor 2, that is, the emitter potential of the transistor 4 decreases, and the transistor 2 operates in a saturation region.

On the other hand, the bases of transistor 2 and transistor 4 are commonly connected, so when the collector current of transistor 2 increases and it operates in the saturation region, a voltage in the opposite direction is applied between the base and emitter of transistor 4. It turns out.

Therefore, the transistor 4 enters the cutoff region and the collector current of the transistor 4 becomes zero.

Since the collector current of transistor 4 is also the base current of transistor 7, when transistor 4 is cut off and the collector current of transistor 4 becomes zero, transistor 7 is also cut off and the collector current of transistor 7 stops flowing.

Therefore, during period A in FIG. 2, no current flows through the collector of transistor 7, and the saturated collector current of transistor 2 is limited by resistor 5, so only transistor 1 operates effectively against the load. and transistor 1
A signal current is supplied from the emitter of the transistor 1 to the load 9 via the capacitor 8, and the transistor 1 operates as an emitter follower.

Next, when a signal that is lower than the DC potential when there is no signal is applied to the signal source terminal 3, that is, during the period B in FIG. only works.

Since the base potential of the transistor 40 is lower than the DC potential when there is no signal, the transistor 4 operates in the active region, and a current flows through the collector of the transistor 4, driving the transistor 7 to 1 and causing a collector current to flow through the transistor 7.

Therefore, the collector potential of transistor 7 is
The electric potential E charged at.

As the voltage becomes lower, current flows from the capacitor 8 to the transistor 7 and supplies a signal current to the load 9.

That is, in the 5EPP output circuit of the present invention as described above, a signal current is supplied to the load 9 by the transistor 1 during the period A in FIG. A signal current is supplied, and therefore the circuit operation is the same as that of the 5EPP output circuit.

As explained above, the emitter of the first transistor whose collector is connected to the power supply terminal and the emitter of the second transistor whose collector is connected to the power supply terminal via a resistor are commonly connected, and the emitter of the first transistor whose collector is connected to the power supply terminal is commonly connected. A load is connected to the connected emitters via a charging/discharging element, and a fourth transistor has an emitter connected to the base of a third transistor whose collector is connected to the commonly connected emitter and a collector of the second transistor. The 5EPP output circuit of the present invention is characterized in that the collectors of the transistors are connected, and the bases of the first, second, and fourth transistors are commonly connected and connected to a signal source terminal. The setting of the quiescent current is done by selecting the value of the resistor connected between the second transistor and the power supply terminal, and the setting is easy and the quiescent current can be stabilized, so crossover distortion can be reduced. In addition, the circuit configuration itself is very simple and the number of parts can be reduced.

Furthermore, the 5EPP output circuit of the present invention has a configuration mainly consisting of a circuit section formed by an output transistor and a transistor whose base and emitter are commonly connected to the base and emitter of the output transistor, and is capable of semiconductor integration. In some cases, the characteristics of the circuit elements are uniform, and even greater effects can be expected, resulting in very large effects.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an embodiment of the 5EPP output circuit of the present invention, and FIG. 2 is a diagram showing the waveform of the potential at the emitter of the output transistor when a signal is applied. 1.2,4,7...transistor, 3...
...Signal source terminal, 5,10...Resistor, 6...
...Power terminal, 8...Capacitor, 9...
···load.

Claims (1)

[Claims] 1. An emitter of a first transistor whose collector is connected to the power supply terminal and an emitter of a second transistor of the same polarity as the first transistor whose collector is connected to the power supply terminal via a resistor are commonly connected. , a load is connected to the commonly connected emitters via a charging/discharging element, and the second transistor is connected to the base of a third transistor having the same polarity as the first transistor whose collector is connected to the commonly connected emitters. The emitter of a fourth transistor is connected to the collector of the first transistor, and the collector of a fourth transistor of opposite polarity is connected to the collector of the first transistor, and the bases of each of the first, second, and fourth transistors are commonly connected to generate a signal. A 5EPP output circuit characterized by being connected to a power source terminal.