JPH0247623Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a power amplification circuit such as an audio amplifier.

[Prior Art] As is well known, class A amplifier circuits have relatively small distortion components in their output signals, but have low efficiency, while class B amplifier circuits have good efficiency, but have low distortion in their output signals compared to class A amplifier circuits. Each had its advantages and disadvantages, such as large components.

Therefore, a circuit as shown in FIG. 2 has been devised to have distortion characteristics comparable to that of a class A amplifier circuit and achieve efficiency comparable to that of a class B amplifier circuit.

The circuit consists of a class A amplifier circuit 01a driven by a low voltage source 02a and a class A amplifier circuit 01a driven by a high voltage source 02b.
A class amplification circuit 01b is provided, and an input signal e _s is applied to each amplifier circuit, and the voltage of a low voltage source 02a is changed according to the magnitude of the input signal by the output of the class B amplification circuit 01b. This is intended to improve the efficiency of the circuit 01a.

Note that 03 is an output terminal.

[Problems to be solved by the invention] In the conventional amplifier circuit described above, the class A amplifier circuit 01a and the low voltage source 02a move significantly with respect to the ground due to the signal, so there are problems such as withstand voltage between the ground and leakage impedance of the power transformer, etc. becomes a problem.

Furthermore, since the load return current returns to ground,
This may have a common impedance with the ground current of other circuits or the charging current of the power supply capacitor, causing an increase in distortion components of the output signal.

[Means for Solving the Problem] This invention has a class B amplifier circuit and a class 1A amplifier circuit connected to the input signal terminal, and a feedback signal of the class B amplifier circuit and an output of the class 1A amplifier circuit, respectively. The power amplifier circuit includes a class 2A amplifier circuit as an input, the output of the class B amplifier circuit being a + output terminal, and the output of the class 2A amplifier circuit being a - output terminal.

[Example] In FIG. 1, e _s is a signal source, 1 and 2 are a class B amplifier circuit and a class 1A amplifier circuit connected to the signal source, respectively, and 3 is a feedback signal of the class B amplifier circuit 1. a 2nd class A amplifier circuit having a non-inverting input and the output of the class A amplifier circuit as an inverting input; 4 and 5;
are a high voltage source and a low voltage source for driving the class B amplifier circuit and the class 2A amplifier circuit, respectively;
6a is connected to the output terminal of the class B amplifier circuit.
An output terminal 6b is connected to the output terminal of the second A class amplifier circuit, and 7 is a load.

According to the above configuration, the input signal is subjected to class B amplification and class A amplification in the class B amplifier circuit 1 and the first class A amplifier circuit, respectively.

In other words, a signal with a high output level but a relatively large distortion component is output from the class B amplifier circuit 1, while a signal with a relatively large distortion component is output from the
Each of the 1A class amplifier circuits 2 outputs signals having a low output level but relatively low distortion components.

Then, the feedback signal of the class B amplifier circuit, that is, the voltage-divided signal of the output signal, and the output signal of the class 1A amplifier circuit are applied to the non-inverting input and the inverting input terminal of the class 2A amplifier circuit, respectively.

The class 2A amplifier circuit operates as a differential amplifier circuit, so if you set each resistance and amplification factor so that the levels of both input signals are the same (for example, set the resistance value to the value shown in the diagram), The amplifier circuit 3 outputs a signal corresponding to the difference between both input signals, that is, a distortion component included in the output of the class B amplifier circuit 1.

Therefore, when the signal is applied to the - output terminal, the distortion component in the output of the class B amplifier circuit is canceled at the load (speaker, etc.) 7 connected between both terminals.

[Effects of the invention] As described above, according to this invention, the distortion characteristics, which are a drawback of class B amplifier circuits, are significantly improved, and it also has the good efficiency of class B amplifier circuits, which cannot be achieved with conventional examples. It has excellent advantages.

[Brief explanation of the drawing]

FIG. 1 is a block circuit diagram of a power amplifier circuit according to an embodiment of the invention, and FIG. 2 is a block circuit diagram of a conventional power amplifier circuit. 1 is a class B amplifier circuit, 2 is a class 1A amplifier circuit, 3
is the class 2A amplifier circuit, 6a is the + output terminal, 6b is the -
This is the output end.

Claims (1)

[Scope of utility model registration request] A class B amplifier circuit 1 and a class 1A amplifier circuit 2 are connected to the input signal terminal, and a class 2A amplifier circuit receives the feedback signal of the class B amplifier circuit 1 and the output of the class 1A amplifier circuit 2, respectively. 3, the output of the B class amplifier circuit 1 is connected to the + output terminal 6a, and
A power amplifier circuit characterized in that the output terminal 6b of the 2A class amplifier circuit 3 is used as one output terminal.