JPS60102003A - Power amplifier circuit capable of attaching and detaching one part of power amplifiers - Google Patents

Abstract

PURPOSE:To control outputs of power amplifiers by one gain control circuit even when the number of connection stages varies by switching the control input to one gain control circuit to the output of a final-stage power amplifier or the output of an intermediate-stage power amplifier. CONSTITUTION:Power amplifiers 12 and 15 are cascaded and an output is obtained only by the initial-stage power amplifier by making disconnections at points 13 and 14. When large electric power is necessary on the whole, two-stage constitution is used; and the signal 25 outputted from the final stage 15 is inputted from a terminal 20 to an automatic switch circuit 26 to lead the detection output 24 of the final stage 15 inputted from a terminal 22, and a control circuit 27 controls the output of the initial-stage power amplifier 12. When small electric power is necessary, the final stage 15 is disconnected, so no signal is inputted to the terminal 20 and a detection output 23 is led, so that the control circuit controls the output of the power amplifier 12, i.e. output at a terminal 13 according to the detection output 23.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a power amplifier circuit, more specifically, a power amplifier in which a part of the power amplifier is detachable so that a wide range of 4M power can be selected depending on the purpose of use. Regarding circuits.

Figure 1(a) is a circuit diagram showing the output power control method of a conventionally used power amplifier circuit, in which two power amplifiers (
n=2) is used.

An input from input terminal l is amplified by power amplifier 2 at the first stage and output to terminal 3. Output from terminal 3 is terminal 40
It becomes an input, is amplified by a power amplifier 5, and is output to a terminal 6. At this time, the output of the power amplifier 5 is controlled by the control circuit 8 which receives the detection amount cuff of the power amplifier 5 as an input, and as a result, the transmission power of the power amplifier circuit can be stabilized.

In the output control method of this circuit, the control circuit that controls the output power of the power amplifier circuit only controls the power amplifier 5, so the power amplifier 5 is essential to the circuit, and in order to lower the output power of the power amplifier circuit. Although it is necessary to disconnect the power amplifier 5, it is impossible to dismount it.

FIG. 1(b) shows another conventional example of a power amplifier circuit in which the power amplifier at the subsequent stage can be separated.

The input from input terminal l is amplified by power amplifier 2 and output to terminal 3. At this time, the output of the power amplifier 2 is controlled by a control circuit 9 which receives the detection output cuff of the power amplifier 2 as an input. Further, the output from the terminal 3 becomes the input to the terminal 4, is amplified by the power amplifier 5, and is output to the terminal 6. At this time, the output of the power amplifier 5 is controlled by a control circuit 10 which receives the detected output 8 of the magnetic amplifier 5 as an input.

In this method, each power amplifier has its own control circuit, and unlike the method shown in FIG. It is. Therefore, the variable range of output power can be widened, and it can be used for various output power applications.

However, there is a drawback that a control circuit is also required for each power amplifier.

An object of the present invention is to provide a power amplifier circuit with a wide output variable range, in which even if the number of connected stages of the power amplifier increases or decreases, the output can be fully controlled with a single control 4111 circuit by using an automatic gain control method. It's about doing.

In order to achieve the above object, n power amplifier circuits in which some of the power amplifiers are detachable according to the present invention are connected in series,
A group of power amplifiers in which the power amplifiers after the nl flea satisfying the relationship between the n and the following formula can be attached and detached, and the detection output of the n-th power amplifier is controlled by the signal from the n-th power amplifier, and the detected output of the n-th power amplifier is an automatic switching circuit that selects one of the m-1th detection output; and an automatic switching circuit that selects one of the detection outputs from the
It consists of a control circuit that controls the detection output of the n-th power amplifier when using the m-th and subsequent power amplifiers, and the detection output of the m-1-th power amplifier when the m-th and subsequent power amplifiers are disconnected. It is configured to select the output.

According to the above structure, the object of the present invention can be completely achieved.

Hereinafter, the present invention will be explained in more detail with reference to the drawings.

FIG. 2 is a circuit diagram showing an embodiment of the power amplifier circuit according to the present invention, and is an example where n=2.m=2.

In FIG. 2(a), 12 and 15 are power amplifiers;
26 is a means for switching between the detected output 23 of the power amplifier 12 which is manually input from the terminal 18 and the detected output 24 of the power amplifier 15 which is inputted from the terminal 22, and a signal 25 for controlling the automatic switching circuit 26 is output from the terminal 20. is input. 27
is a control circuit that controls the power amplifier 12.

First, when a large amount of power is required as the output of the entire power amplifier circuit, the human power from the terminal 11 is amplified by the power amplifier 22 and output to the terminal 13.

The output is input to a terminal 14, amplified by a power amplifier 15, and a large amount of power is outputted from a terminal 16. In this case, when the signal 25 output from the power amplifier 15 is input to the automatic switching circuit 26 from the terminal 20, the automatic switching circuit 26 connects the power amplifier 15 input from the terminal 22.
The detection outputs 24 of the two are connected in equal order, and the control circuit 27 controls the output of the magnetic force amplifier 12 and the output from the terminal 16 according to item (i).

Next, if a small power is required as the output of the power amplifier circuit, the power amplifier 15 is not mounted. Figure 2 (b
) shows the status. The input from the terminal 11 is amplified by the magnetic force amplifier 12, and a small force from the terminal 13 is output. In this case, since no signal is input from the child 20, the signal is input from the automatic switching circuit 26 from the terminal -18;
The detection output 23 of the power amplifier 21 is made equal to the signal 4Q, and the control circuit 27 controls the output of the power amplifier 12, that is, the output of the terminal 13 (7111).

As explained above, according to the present invention, by adding an automatic switching circuit to the control circuit of the power amplifier circuit, when all the power amplifiers are used for high power output, and some of the power amplifiers in the subsequent stage are disabled. A single control circuit can handle the small power output of the implementation, making it possible to obtain a wide range of transmission power.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a conventional power amplifier output control method, and FIG. 2 is a block diagram showing an embodiment of the power amplifier circuit according to the present invention. ], 4, 11, 14...Signal input terminal 2,
5, 12, 15...power amplifiers 3, 6, 13
, 16...Signal output terminals 7, 8, 23, 24
...-detection output 8, 9, 10, 27...control nl
A circuit 25...Signal 26 for controlling the automatic switching circuit...
・Automatic switching circuit patent applicant Hisashi Inoro, agent of Hiki Electric Co., Ltd., patent attorney

Claims (1)

[Claims] A power amplifier group in which n cascade-connected power amplifiers are capable of attaching and detaching the m-th and subsequent power amplifiers that satisfy the relationship between the n and the following formula, and a group of power amplifiers whose switching is controlled by a signal from the n-th power amplifier. ,
an automatic switching circuit that selects either the detection output of the n-th power amplifier or the m-1-th detection output; and control that controls the gain of the first-stage power amplifier based on the detection output selected by the automatic switching circuit. When using the m-th power amplifier or later, the detection output of the n-th power amplifier is used, and when the m-th or later power amplifier is disconnected, the detection output is m-1.
1. A power amplifier circuit to which some power amplifiers are detachable, characterized in that the detection output of the second power amplifier is selected. n≧m≧2 (n, m; positive integer)