JPS6033716A - Power amplifier - Google Patents

Abstract

PURPOSE:To miniaturize an external power switch by using independently the external power switch as a means for operating only a bias circuit supplying a bias voltage to an amplfier stage. CONSTITUTION:An electronic switch 7 is connected between a bias circuit 13 and a power supply 1 and the electronic switch 7 is made conductive through the turning-on of the external power switch 12 of mechanical contact whose one end is connected to a reference point, e.g., an earthing point 8. Then a bias circuit 13 is connected to a power supply 1 through the turning-on of the electronic switch 7 and activated, thereby activating an initial stage amplifier stage 4, a pre-driver stage 5 and a power amplifier stage 6. Since the on-current flowing to the external power supply 12 is a minute current to turn on the electronic switch 7, the switch is miniaturized.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of intermittent power supply from an external power source to a power amplifier.

Power is supplied from an external power supply to a conventional power amplifier by a mechanical switch (simply referred to as a switch) installed on a line that supplies the power amplifier and the external power. Therefore, the switch used therein needs to have a power capacity commensurate with the power supplied from the external power supply to the power amplifier, and naturally the size of the switch becomes larger depending on the power required. However, this restriction on the size of the switch is currently an obstacle to reducing the size and weight of the parts used to make the system smaller and lighter.

FIG. 1 shows a block diagram of a conventional power amplifier. 1st
In the figure, when the external power switch 2 is closed, power is supplied from the external power supply 1 to the bias circuit 3, and the bias circuit 3 becomes operational.

Next, the bias circuit 3 puts the first amplification stage 4 and the predriver stage 5 into operation, and then the output amplification stage 6
enters the operating state, and the entire power amplifier device enters the operating state.

In this way, conventional power amplifiers operate and deactivate depending on the opening and closing of the external power switch, but switch 2 can handle large transient currents at the rated output of the power amplifier and when switch 2 opens and closes. It needs to be durable, and is larger than a switch in a small signal system. Therefore,
This was a major obstacle to reducing the size and weight of system components.

SUMMARY OF THE INVENTION An object of the present invention is to provide a power amplifying device that solves the problem of the conventional power switch's large size.

The power amplification device of the present invention includes an initial amplification stage, a predriver stage, a power amplification stage, a bias circuit that supplies a bias voltage to these amplification stages, and two external power switches of mechanical contact. and the external power switch is
The present invention has a configuration in which only the bias circuit L path is operated independently.

Next, the present invention will be explained by examples.

FIG. 2 is a block diagram of one embodiment of the present invention.

In FIG. 2, an electronic switch 7 is connected between the bias circuit 13 and the power source 1, and the electronic switch 7 is an external power switch 120 with a mechanical contact that connects one end to a reference potential point, for example, the ground point 8. When turned on (closed), it becomes conductive. Then, by turning on the electronic switch 7, the bias circuit 13
is connected to the power supply 1 and operates, and this operation causes the first amplification stage 4. 1 driver stage 5. Power amplification stage 6 will now operate.

FIG. 3 shows an actual circuit diagram corresponding to the block circuit diagram of FIG. In FIG. 3, transistor 7 corresponds to electronic switch 7 of FIG. 2, and by turning on external switch 12, the transistor OFF base is grounded and transistor 7 is turned on. As a result, the transistor 21 of the bias circuit becomes conductive, and the bias circuit becomes operational. As a result, transistors 22, 23.2 of the first amplification stage
4 becomes operational, and at the same time, the transistor 25 of the pre-drino stage and the transistors 2G, 2'7, 28, and 29 of the power amplification stage including the dry no. The signal is amplified through each amplifier stage to provide the required output power to the load 30.

The power amplifier device of the present invention is powered on by turning on the external power switch 12, and the on-current flowing through the external power switch 12 is used to turn on the transistor 25 of the electronic switch. Since the current is minute, on the order of several to several hundred microamperes, an extremely small device is sufficient to turn this current on and off. Therefore, according to the present invention, the external power switch can be easily miniaturized.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional power amplifier, FIG. 2 is a block diagram of an embodiment of the present invention, and FIG. 3 is an actual circuit diagram corresponding to FIG. 1...Power supply, 2.12...External power switch, 3.13...Bias circuit, 4...
°°°First amplification stage, 5... Predriver stage, 6
...Power amplification stage, 7...Electronic switch (transistor), 8...Grounding, 21...
・・Bias circuit transistor, 22, 23° 24・・
...First stage amplification stage transistor, 25... Predriver stage transistor, 26, 27, 28, 29.
...Power amplification stage transistor, 30...
load.

Claims (1)

[Claims] It has an initial amplification stage, a pre-driver stage, an output amplification stage, a bias circuit that supplies a bias voltage to these amplification stages, and a roughly mechanical external power switch, and after the bias circuit becomes operational, A power amplifying device in which the first amplifying stage, the pre-driver stage, and the output amplifying stage are in an operating state, wherein the power switch causes only the bias circuit to operate independently.