JP2000049542A - Amplifier circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an amplifier circuit which is attained in high efficiency and also is improved in following property to the steep start of an input signal which is high pass (high frequency) and also large amplitude (large output). SOLUTION: An amplifier circuit which has power supplies 22 and 26, a power amplifier 12 that amplifies an input signal and DC-DC converters 24 and 28 for power supply which are connected between the power supplies and the power amplifier, lower the power supply voltage of the power supplies and supply it to the power amplifier has power supply circuits 30 and 32 for high pass and large amplitude which are connected between the power supplies and the power amplifier in parallel with the DC-DC converters for power supply, and when a signal that has high pass and large amplitude is inputted, the power supply circuits for high pass and large amplitude supply the power supply voltage of the power supplies to the power amplifier without lowering it instead of the DC-DC converters for power supply.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an amplifier circuit,
More specifically, the present invention relates to an amplifier circuit used for power amplification of an audio signal or the like, and particularly to improving the efficiency and suppressing a sharp rise in an input signal having a high frequency (high frequency) and a large amplitude (large output). The present invention relates to an amplifier circuit with improved tracking.

[0002]

2. Description of the Related Art As a conventional amplifier circuit for amplifying an audio signal with high efficiency, for example, one having a circuit configuration shown in FIG. 1 is known.

This amplifier circuit inputs a signal (audio input signal) output from a signal source 10 to a power amplifier 12, amplifies the signal in a voltage amplifier circuit 14 of the power amplifier 12, and is an output transistor of the power amplifier 12. +
-Side power transistor 16, −side power transistor 1
8 is supplied to supply necessary power to the speaker 20 as a load.

The power supply voltage + B generated by the power supply 22 for driving the + power transistor 16 is supplied by a + power supply DC-DC converter 24 connected between the power supply 22 and the + power transistor 16. Be lowered. That is, the + -side power transistor 16 is driven by lowering the power supply voltage + B by the + -side power supply DC-DC converter 24.

Similarly, a power supply voltage B generated by the power supply 26 for driving the negative power transistor 18 is supplied to a DC power supply DC-DC converter 28 connected between the power supply 26 and the negative power transistor 18. Is reduced by That is, the power supply voltage -B is reduced by the DC power supply 28 for the negative side power supply to drive the negative side power transistor 18.

That is, in the conventional amplifier circuit shown in FIG. 1, the power supply voltage + B and the power supply voltage -B are respectively used by using the + side power supply DC-DC converter 24 and the-side power supply DC-DC converter 28. And driving the power amplifier 12 to reduce the loss due to heat generation in the power amplifier 12 while improving the efficiency.

FIG. 2 shows voltage waveforms at various parts of the amplifier circuit shown in FIG. 1 when a large-amplitude signal having a frequency of 1 kHz is output from the signal source 10 and input to the power amplifier 12. The operation of the amplifier circuit shown in FIG. 1 will be further described with reference to this.

Here, the DC-DC converter 24 for the + power supply and the DC-DC converter 28 for the-power supply have an on / off ratio variable according to the output of the power amplifier 12 (control input by a control voltage signal). Is switched.

Accordingly, in the + side circuit, the +/− power supply DC-DC converter 24 variably switches the on / off ratio in accordance with the output of the power amplifier 12 (control input by a control voltage signal), thereby providing the power supply. Voltage + B
(A) is reduced to a voltage (B) necessary and sufficient to extract necessary power from the power amplifier 12.

On the negative side, a DC power supply for the negative side
The DC converter 28 variably switches the ON / OFF ratio in accordance with the output of the power amplifier 12 (control input based on the control voltage signal), so that the power supply voltage −B (E) is extracted from the power amplifier 12 as necessary power. To a voltage (D) that is necessary and sufficient.

That is, according to this amplifier circuit, as shown in FIG. 2, the output voltage (B) of the DC-DC converter 24 for the + power supply and the output voltage (D) of the DC-DC converter 28 for the-power supply. Is changed following the output voltage (C) of the power amplifier 12, so that loss due to heat of the power transistor in the power amplifier 12 can be greatly reduced regardless of the magnitude of the output of the power amplifier 12. it can.

Also, a DC-DC converter 2 for the + side power supply
Since the DC-DC converter 4 and the-side power supply DC-DC converter 28 are driven by switching, the loss here is also small, and the efficiency of the whole amplifier circuit is extremely high.

However, in the above-described amplifier circuit, the + side power supply DC-DC converter 24 and the − side power supply DC-DC converter 28 are smoothed to smooth the switching output waveform and supply it to the power amplifier 12. Built-in circuit. For this reason, when a high-frequency (high-frequency) and large-amplitude (large-output) signal is input to the power amplifier 12, the power supply cannot follow the sharp rise of the input signal, and the power amplifier 12 Twelve outputs were clipping.

That is, FIG. 3 shows a voltage waveform at each part of the amplifier circuit shown in FIG. 1 when a large-amplitude signal having a frequency of 10 kHz is output as a high-band and large-amplitude signal and input to the power amplifier 12. When a large amplitude signal having a frequency of 10 kHz is output and input to the power amplifier 12, the power supply follows the steep rise of the input signal. (B, D), and the output (C) of the power amplifier 12 is clipped.

[0015]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the conventional amplifier circuit, and has as its object to improve the efficiency and to improve the high frequency range. It is an object of the present invention to provide an amplifier circuit with improved followability to a steep rising of an input signal having a high frequency and a large amplitude (a large output).

[0016]

According to one aspect of the present invention, there is provided a power supply, a power amplifier for amplifying an input signal, and a power amplifier for amplifying an input signal. An amplifier circuit connected between the power supply and a power supply DC-DC converter for reducing the power supply voltage of the power supply and supplying the power supply to the power amplifier, wherein the power supply DC-DC converter is provided between the power supply and the power amplifier. And a high-frequency / large-amplitude power supply circuit connected in parallel with the high-frequency / large-amplitude power supply circuit when the high-frequency / large-amplitude signal is input. In place of the DC converter, the power is supplied to the power amplifier without lowering the power supply voltage of the power supply.

Therefore, according to the first aspect of the present invention, when a high-frequency (high-frequency) and large-amplitude (large-output) signal is input, the DC-DC converter for power supply is used instead. The high-frequency / large-amplitude power supply circuit supplies power to the power amplifier without lowering the power supply voltage of the power supply, so high-frequency (high-frequency) and large-amplitude (large-output)
The follow-up performance for a steep rising of the input signal is improved.

When a signal that is not in a high frequency range (high frequency) and has a large amplitude (large output) is input, the power supply DC-
Since the DC converter reduces the power supply voltage of the power supply and supplies the power supply to the power amplifier, it is possible to suppress a decrease in efficiency of the entire amplifier circuit.

Here, the power supply circuit for high frequency and large amplitude is
A high-frequency and large-amplitude detection circuit for detecting whether or not an input signal is a high-frequency and large-amplitude signal, according to the second aspect of the present invention, A power FET control signal generation circuit for generating an FET control signal; a power FET drive circuit; and a power FET. When the power FET control signal is generated by the power FET control signal generation circuit, the power FET drive circuit drives the power FET drive circuit. The power supply voltage is supplied to the power amplifier without lowering the power supply voltage of the power supply. When detecting the non-signal, it is possible to restrict the driving of the power FET drive circuit according to the power FET control signal generated by the power FET control signal generating circuit.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of an amplifier circuit according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 4 is a block diagram showing an example of an embodiment of the amplifier circuit according to the present invention. In the amplifier circuit shown in FIG. 4, the same or corresponding components as those of the conventional amplifier circuit shown in FIG. 1 are denoted by the same reference numerals as those used in FIG. Description is omitted.

That is, the amplifying circuit shown in FIG. 4 differs from the conventional amplifying circuit shown in FIG. 1 in that a DC-DC converter for the + side power supply is provided between the power supply 22 and the power transistor 16 in the + side circuit. For high frequency and large amplitude in parallel with 24+
Side power supply circuit 30 is connected, and in the − side circuit, between the power supply 26 and the power transistor 18.
The difference is that a high-frequency / large-amplitude negative power supply circuit 32 is connected in parallel with the negative power DC-DC converter 28.

Since the negative circuit has the same configuration as the positive circuit, in the following description, the description of the negative circuit will be omitted, and only the positive circuit will be described.

In the amplifier circuit shown in FIG. 4, in accordance with the output of the power amplifier 12 (control input by the control voltage signal), the + side circuit is connected to the + side power supply DC-DC converter 24 and the The + side power supply circuit 30 for amplitude is switched and driven by performing a switching operation. In the − side circuit, the DC-DC for − side power supply is used.
Converter 28 and negative side power supply circuit 32 for high range and large amplitude
Are switched and driven by switching operation.

That is, in the amplifying circuit shown in FIG. 4, the low-frequency (low-frequency) or middle-frequency (middle-frequency) small-amplitude (small output) and large-amplitude (large output) signals and high When a signal of small amplitude (small output) is input even in the high frequency range (high frequency), the output is switched to the DC-DC converter 24 for the + side power supply by the output of the power amplifier 12 (control input by the control voltage signal). As in the conventional amplifier circuit (FIG. 1), the power supply voltage + B is reduced using the DC power supply 24 for the + side power supply to drive the + side power transistor 16 and the output (control) of the power amplifier 12. Control input by voltage signal)
It is switched to the DC-DC converter 28 for the -side power supply, and the DC-DC for the -side power supply is
The power supply voltage −B is lowered by using the converter 28 to drive the − side power transistor 18. The flow of the power supply current at this time corresponds to “the flow of the power supply current during normal operation” in FIG.

As described above, the DC-DC converter 2 for the + side power supply is used instead of the + side power supply circuit 30 for the high range and large amplitude.
4 is used, and the DC-DC converter 28 for the-side power supply is used instead of the-side power supply circuit 32 for the high frequency and large amplitude, as shown in FIG. When a signal is output from the signal source 10 and input to the power amplifier 12, the DC-DC converter 24 for the + side power supply turns on / off ratio according to the output of the power amplifier 12 (control input by a control voltage signal). , The power supply voltage + B (A) is reduced to a voltage (B) necessary and sufficient for extracting necessary power from the power amplifier 12, and the DC-D
The C-converter 28 variably switches the on / off ratio in accordance with the output (control input by the control voltage signal) of the power amplifier 12 to extract the power supply voltage −B (E) from the power amplifier 12 as necessary power. To a voltage (D) that is necessary and sufficient.

That is, the DC-DC converter 2 for the + side power supply
4 and the output voltage (D) of the negative side power supply DC-DC converter 28 follow the output voltage (C) of the power amplifier 12 and change.

On the other hand, in the amplifier circuit shown in FIG. 4, when a signal of a high band (high frequency) and large amplitude (large output) is input to the power amplifier 12, the output of the power amplifier 12 (control voltage The input is switched to the high-frequency / large-amplitude + power supply circuit 30 by a signal (control input by a signal). Unlike the conventional amplifier circuit (FIG. 1), the power is supplied using the high-frequency / large-amplitude + power supply circuit 30. The voltage + B is supplied to the + side power transistor 16 to drive the + side power transistor 16, and is switched to the − side power supply circuit 32 for high frequency and large amplitude by the output of the power amplifier 12 (control input by the control voltage signal). Unlike the conventional amplifier circuit (FIG. 1), the power supply voltage -B is supplied to the -side power transistor 18 using the -band power supply circuit 32 for high frequency and large amplitude, and the-side power transistor 18 is supplied. It is intended to drive the motor 18.
The flow of the power supply current at this time corresponds to "the flow of the power supply current at the time of high frequency and large amplitude" in FIG.

As described above, instead of the DC-DC converter 24 for the + side power supply, the + side power supply circuit 3 for the high range and large amplitude is used.
0 and the negative-side power supply DC-DC converter 28 is used instead of the high-frequency / large-amplitude negative side power supply circuit 32, as shown in FIG.
When the large-amplitude signal is output from the signal source 10 and input to the power amplifier 12, the high-frequency / large-amplitude + side power supply circuit 30 does not decrease the power supply voltage + B so much that the frequency of 10 kHz The voltage (B) that can sufficiently follow the steep rising of the large-amplitude input signal is applied to the + side power transistor 1
6, a voltage which can sufficiently follow the steep rise of a large-amplitude input signal having a frequency of 10 kHz without causing the high-frequency / large-amplitude-side power supply circuit 32 to decrease the power supply voltage -B so much. (D) is a negative side power transistor 18
Is to be supplied to

The "high band (high frequency)" can be set to any frequency. Similarly, the "large amplitude (large output)" is an arbitrary amplitude value (output value). Can of course be set.

FIG. 7 shows an example of the maximum output frequency characteristic of the conventional amplifier circuit (FIG. 1), and FIG. 8 shows an example of the maximum output frequency characteristic of the amplifier circuit of the present invention (FIG. 4). In FIG. 8, the maximum output frequency characteristic of the conventional amplifier circuit (FIG. 1) is indicated by a broken line for comparison with the maximum output frequency characteristic of the amplifier circuit (FIG. 4) according to the present invention. There.)

As is clear from the example of the maximum output frequency characteristic shown in FIG.
The maximum output voltage starts to fall from around kHz and the frequency once rises from around 5 kHz, but suddenly starts to fall again from around 10 kHz.

On the other hand, as is clear from the example of the maximum output frequency characteristic shown in FIG. 8, in the amplifier circuit (FIG. 4) according to the present invention, the flat output characteristic does not fall until the frequency becomes about 20 kHz. Can be obtained.

FIG. 9 shows a + side power supply circuit 30 for high band and large amplitude, a − side power supply circuit 32 for high band and large amplitude, a DC-DC converter 24 for + side power supply and a DC − FIG. 3 is a block diagram showing a detailed configuration of an output unit of the DC converter 28.

The + side power supply circuit 30 for high band and large amplitude
A power FET (POWER FET) control signal generation circuit 30a and a high-pass filter (HP
F) built-in high frequency & large amplitude detection circuit 30b and power FET (POWER FET) drive circuit 30c
And a power FET (POWER FET) 30d. Similarly, the negative side power supply circuit 32 for high band and large amplitude is a power FET (POWER FET).
A control signal generation circuit 32a, a high frequency & large amplitude detection circuit 32b incorporating a high-pass filter (HPF) for high frequency detection, a power FET (POWER FET) drive circuit 32c, and a power FET (POWER FE)
T) 32d.

The DC-DC converter 2 for the + power supply
4 is supplied to the power transistor 16 of the power amplifier 12 and the fluctuating output is represented by “+ SOURCE (source)”.
And the fluctuating output supplied from the negative-side power supply DC-DC converter 28 to the power transistor 18 of the power amplifier 12 is referred to as "-SINK (sink)".

In the + side circuit, a power FET
30d source and power supply 22 are connected, and power FET
DC-DC converter 2 for 30d drain and + side power supply
+ Source power supply path (source power supply path) of output section 4
34 are connected. In the negative circuit,
The source of the power FET 32d and the power supply 26 are connected,
Drain of power FET 32d and DC-DC for-side power supply
The −SINK power supply path (sink power supply path) 36 of the output unit of the converter 28 is connected.

In the case of an input signal other than a high-frequency and large-amplitude signal, + SO is supplied from the power FET 24a at the output of the DC-DC converter 24 for the + side power supply to the source power supply path 34.
URCE is output, and DC-DC
-SINK is output from the power FET 28a at the output of the converter 28 to the sink power supply path 36.

On the other hand, in the case of an input signal having a high frequency and a large amplitude, the power FE of the + side power supply circuit 30 for the high frequency and the large amplitude is used.
+ SOURCE is output from T30d to the source power supply path 34, and the − side power supply circuit 32 for high range and large amplitude is used.
-SIN from the power FET 32d to the sink power supply path 36
K will be output.

FIG. 10 shows an example of the characteristics of the high-pass frequency detection high-pass filter incorporated in the high-frequency and large-amplitude detection circuit 30b.

That is, in the high-pass filter for detecting high-frequency components, the attenuation is small (−10 dB) at high frequencies, the attenuation starts gradually from about 10 kHz, and the attenuation is about −30 dB from about 1 kHz. .

In the high-frequency / large-amplitude + side power supply circuit 30, when the output of the power amplifier 12 is input as a control input, the power FET control signal generation circuit 30a outputs the power in accordance with the control input waveform. An FET control signal is generated.

On the other hand, the power amplifier 12 as a control input
Is also input to the high-frequency and large-amplitude detection circuit 30b, and the high-frequency filter and high-amplitude detection circuit 30b incorporates a high-pass filter to extract only the high-frequency component. Further, the high frequency and large amplitude detection circuit 30b rectifies and holds the signal extracted only in the high frequency and detects the voltage (amplitude).

The high frequency and large amplitude detection circuit 30
In b, when the output of the power amplifier 12 as the control input is detected as a high-band and large-amplitude signal,
From the power FET control signal generation circuit 30a to the power FET
A control signal is supplied to the power FET drive circuit 30c, and + SO is supplied from the power FET 30d to the source power supply path 34.
URCE will be output.

On the other hand, the high frequency and large amplitude detection circuit 30b
In the case where the output of the power amplifier 12 as the control input is not detected as a high-frequency and large-amplitude signal, the power FET control signal from the power FET control signal generation circuit 30a to the power FET drive circuit 30c Supply is suppressed, and the + side power supply circuit 30 for high range and large amplitude
+ SOURCE to the source power supply path 34 will not be output. In this case, the DC-D for the + power supply is used.
+ SOURCE is output from the power FET 24a at the output of the C converter 24 to the source power supply path 34.

Next, referring to FIG. 11, which shows the voltage waveforms at various parts in the + side circuit shown in FIG. 9, the voltage waveforms accompanying the operation of the above-mentioned high-frequency / large-amplitude + side power supply circuit 30 will be described. The change will be described. Note that FIG.
The voltage waveform of each part in the side circuit is a waveform symmetrical with respect to the + side voltage waveform shown in FIG.

First, at point A, the power amplifier 12
Is provided, and the waveform is, for example, a sine wave having a frequency of 10 kHz.

In the power FET control signal generation circuit 30a, the waveform shown at point A is clipped,
The switching waveform of the square wave obtained at the point B is generated. Since the waveform at the point B takes a value of 0V to -2V, if it is assumed that the power FET control signal generation circuit 30a does not exist, the power FE
Since the input stage transistor incorporated in the T drive circuit 30c cannot be turned on, the power FET drive circuit 30c
No drive signal is output from c to the power FET 30d, and the power FET 30d does not operate.

On the other hand, the high frequency and large amplitude detection circuit 30b
In the above, when the waveform shown at the point A is input, only the high band is passed through a high-pass filter, and further rectified and held, thereby generating a waveform having a voltage of about 4 V at the point C. The high frequency and large amplitude detection circuit 3
At 0b, when the waveform at point A has a low frequency, the voltage of the waveform at point A is almost 0V,
Only when the waveform at point A has a high frequency and a large amplitude, a waveform as shown at point C is obtained.

When the waveform at the point B and the waveform at the point C are combined, a waveform indicated by a broken line at the point D is obtained.
The waveform is locked at 0.6 V by the base voltage ( _Vbe ) of the transistor in the input stage of c).

Therefore, the power FET drive circuit 30c
Of the input stage repeats the on / off operation, and the gate voltage is supplied from the power FET drive circuit 30c to the power FET 30d.

Therefore, only when the output from the power amplifier 12 is a high-frequency and large-amplitude signal, the power FET 3
0d is supplied with a gate voltage, the power FET 30d operates, and + S is supplied from the power FET 30d to the source power supply path 34.
OURC will be output.

FIG. 12 shows a high-frequency / large-amplitude power supply circuit (a high-frequency / large-amplitude + power supply circuit 30 and a high-frequency / large-amplitude − power supply circuit 32). "High frequency
This is referred to as a “large amplitude power supply circuit”. 2) shows a characteristic diagram illustrating an example of the operation region.

In the example shown in FIG. 10, the high-frequency / large-amplitude power supply circuit starts to operate at a frequency of about 5 kHz, but the output voltage is 15 Vrms even at a high frequency of 10 kHz or more. It works from about.

Since a normal audio signal does not belong to the shaded area in FIG. 12, the high-frequency / large-amplitude power supply circuit does not normally operate. That is, since the high-frequency / large-amplitude power supply circuit does not operate frequently, even if the high-frequency / large-amplitude power supply circuit operates, the time is very short. It does not lower.

FIG. 13 shows an example of a specific configuration of the + side power supply circuit for high frequency and large amplitude, and FIG. 14 shows a high-pass filter (H) for the + side power supply and the − side power supply.
FIG. 4 is a detailed circuit diagram of a high-frequency / large-amplitude power supply circuit when a common power supply (PF) is used.

As shown in FIGS. 13 and 14, a high-frequency / large-amplitude power supply circuit can be formed. In particular, when the circuit configuration shown in FIG. 14 is used, the + side power supply circuit 30 for high frequency and large amplitude and the high frequency
The high-pass and large-amplitude detection circuits 30b and 32b can share a high-pass filter with the large-amplitude-side power supply circuit 32, so that the circuit scale can be reduced.

Although the above embodiment has been described with reference to a monaural amplifier circuit, it is a matter of course that the present invention can be applied to a stereo amplifier circuit.

[0059]

Since the present invention is configured as described above, it is possible to improve the efficiency and follow the steep rising of an input signal having a high frequency (high frequency) and a large amplitude (large output). This provides an excellent effect of being able to provide an amplifier circuit with improved characteristics.

[Brief description of the drawings]

FIG. 1 is a block diagram of a conventional amplifier circuit.

FIG. 2 is a voltage waveform diagram of each part of the conventional amplifier circuit (FIG. 1) when a large amplitude signal having a frequency of 1 kHz is input.

FIG. 3 is a voltage waveform diagram of each part of the conventional amplifier circuit (FIG. 1) when a large amplitude signal having a frequency of 10 kHz is input.

FIG. 4 is a block diagram showing an example of an embodiment of an amplifier circuit according to the present invention.

FIG. 5 is a voltage waveform diagram of each part of the amplifier circuit (FIG. 4) according to the present invention when a large amplitude signal having a frequency of 1 kHz is input.

FIG. 6 is a voltage waveform diagram of each part of the amplifier circuit (FIG. 4) according to the present invention when a large amplitude signal having a frequency of 10 kHz is input.

FIG. 7 is a characteristic diagram showing an example of a maximum output frequency characteristic of a conventional amplifier circuit (FIG. 1).

FIG. 8 is a characteristic diagram showing an example of a maximum output frequency characteristic of the amplifier circuit (FIG. 4) according to the present invention.

FIG. 9 is a detailed block diagram of a main part of an amplifier circuit (FIG. 4) according to the present invention.

FIG. 10 is a characteristic diagram of a high-pass frequency detection high-pass filter (HPF) of the high-frequency and large-amplitude detection circuit.

FIG. 11 is a voltage waveform diagram of each part of the + side power supply circuit for high frequency and large amplitude.

FIG. 12 is an operation area diagram of a high-frequency / large-amplitude power supply circuit.

FIG. 13 is a detailed circuit diagram of a + side power supply circuit for high frequency and large amplitude.

FIG. 14 is a detailed circuit diagram of a high-frequency / large-amplitude power supply circuit when a high-pass filter (HPF) for the + side power supply and the − side power supply is commonly used.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Signal source 12 Power amplifier 14 Voltage amplifier circuit 16, 18 Power transistor 20 Speaker 22 Power supply (+ B) 24 DC-DC converter for + side power supply 24a, 28a, 30d, 32d Power FET 26 Power supply (-B) 28-side power supply DC-DC converter 30 High-frequency / large-amplitude + side power supply circuit 32 High-frequency / large-amplitude + -side power supply circuit 30a, 32a POWER FET (power FET)
Control signal generation circuit 30b, 32b High frequency and large amplitude detection circuit 30c, 32c POWER FET (power FET)
Drive circuit

Claims (2)

[Claims] 1. A power supply, a power amplifier for amplifying an input signal, and a power supply DC-DC connected between the power supply and the power amplifier, for reducing the power supply voltage of the power supply and supplying the power supply to the power amplifier. An amplifier circuit having a converter, wherein the power supply DC- is provided between the power supply and the power amplifier.
A high-frequency / large-amplitude power supply circuit connected in parallel with a DC converter, wherein the high-frequency / large-amplitude power supply circuit is configured to output the power when a high-frequency / large-amplitude signal is input. An amplifying circuit that supplies the power amplifier without lowering a power supply voltage of the power supply instead of a DC-DC converter for use. 2. The amplifier circuit according to claim 1, wherein the high-frequency / high-amplitude power supply circuit detects a high-frequency / high-amplitude signal for detecting whether or not the input signal is a high-frequency and large-amplitude signal. An amplitude detection circuit, a power FET control signal generation circuit that generates a power FET control signal in accordance with the input signal, a power FET drive circuit, and a power FET. When the circuit detects that the input signal is a high-frequency and large-amplitude signal, the power FE generated by the power FET control signal generation circuit is generated.
Driving the power FET drive circuit with a T control signal, further driving a power FET with the power FET drive circuit, and supplying the power FET to the power amplifier without lowering the power supply voltage of the power supply. When the frequency & large amplitude detection circuit detects that the input signal is not a signal having a high frequency and a large amplitude, the power FE generated by the power FET control signal generation circuit is used.
An amplifier circuit which limits driving of the power FET drive circuit by a T control signal.