JPS6162213A - Amplitude modulation high frequency power amplifier - Google Patents

Abstract

PURPOSE:To increase the power efficiency by applying digital conversion to an input signal, varying an output level of plural power amplifiers in response to the code of the digital and combining the outputs so as to eliminate the need for a modulator thereby eliminating modulation distortion. CONSTITUTION:After an input voice signal is converted into a digital signal having 0-4,095 steps by an A/D converter 12, the result is outputted in parallel to carrier amplifiers 13-15. Then the amplifiers 13-15 apply respectively power amplification a high frequency signal in phase by 0-15[W], 0-240[W] and 0-3840[W] in response to the input level of the voice signal. In adding outputs of the amplifiers 13-15 by a combiner 17, the high frequency power subject to amplitude modulation in the range of 0-4,095[W] in 1[W] step is obtained in response to the input level of the voice signal.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an amplitude modulation high frequency power amplification device that amplitude modulates high frequency power according to an input signal.

[Technical background of the invention and its problems] In general, in a high frequency power amplification device that generates 1q AM (amplitude modulated) waves, an AM modulator such as a modulation tube is used to input the power supply voltage to an audio signal, etc. AM waves are obtained by amplitude modulating the signal, and methods such as plate modulation and PWM (pulse width modulation) are used, but since both require a modulator, these linearity distortions There are problems such as deterioration of characteristics due to generation of , circuit complexity, and deterioration of power efficiency.

For example, when using the final plate modulation method, the modulation tube is used in a push-pull circuit configuration, and a modulation transformer and modulation choke are also required, which is not only economically disadvantageous, but also modulation The idle current in the tube increases dead loss, which also reduces power efficiency.

In addition, when using the PWM method, there is a problem with the fidelity of pulse transmission, resulting in characteristic deterioration, and the circuit configuration is very difficult, as it is necessary to perform PWM modulation and then demodulate it through a low-pass filter. It becomes complicated.

[Purpose of the invention] This invention was made to improve the above-mentioned problems, and it is possible to eliminate the need for a modulator, eliminate modulation distortion, increase power efficiency, and obtain extremely good AM waves. An object of the present invention is to provide an amplitude modulated high frequency power amplification device.

[Summary of the Invention] That is, the amplitude modulation power amplification device according to the present invention converts an analog input signal into a digital signal using an analog-to-digital converter, and uses a plurality of amplifiers that power-amplify a high-frequency signal according to the code of the digital signal. The present invention is characterized in that the output level of the power amplifier is varied and the outputs thereof are combined by a combiner to obtain amplitude modulated high frequency power.

[Embodiment of the Invention] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows its configuration, and numeral 11 in the figure is an input terminal for audio signals. This input terminal 11 is connected to the input end of a 12-bit output analog-to-digital (hereinafter abbreviated as A/D) converter 12, and each output end 2° to 211 of this A/D converter 12 is connected to a □ It is connected to each control input terminal PAI to PA 12 of the first to third carrier amplifiers 13 to 15 each having a 4-bit control input. The input terminals of the first to third carrier amplifiers 13 to 15 are connected to the output terminal of an oscillator 16 that generates a high frequency signal.
The carrier amplifier 13 outputs the high frequency signal from the excavator 16 according to the first to fourth bit outputs 20 to 23 of the A/D converter 12.
The second carrier amplifier 14 digitally amplifies the power of the fifth to eighth bits 24 to 2 of the A/D converter 12.
The high frequency signal from the oscillator 16 is digitally amplified to a power of O [W] to 240 [W] in 16 [W] steps in accordance with T. The high frequency signal from the oscillator 16 is 0 [W] in 256 [W] steps according to the 12th bit output 28 to 2+1.
]~3840[W power is digitally amplified,
Each output terminal of the first to third carrier amplifiers 13 to 15 is connected to each input terminal of a combiner 17. This combiner 17 is connected to the first to third carrier amplifiers 13 to 15.
The output terminal is output terminal 1 through pass filter 18.
9 is connected.

That is, the audio signal input through the input terminal 11 is converted into a digital signal of 0 to 4095 levels by the A/D converter 12, and then sent to the first to third carrier amplifiers 13.
~15 are output in parallel. For this reason, the first to third
The carrier amplifiers 13 to 15 each have a power of 0 to 15[W], ○ to 240[W] depending on the input level of the audio signal.
W], O~3840 [W], the high frequency signals are power amplified in the same phase and output, so each output of the first to third carrier amplifiers 13 to 15 is sent to the combiner 17.
If added at , 1 [W
] step, it is possible to obtain high frequency power that is amplitude modulated in the range of O [W] to 4095 [W], and harmonic components of this high frequency power are removed by the low pass filter 18 and appear at the output terminal 19.

Therefore, the amplitude modulation high frequency power amplifier configured as described above converts the input signal into a digital signal, and sets the output power level of the high frequency signal with good linearity according to this digital signal. First, with a relatively simple configuration, modulation distortion can be eliminated and power efficiency can be increased.

In the above embodiment, the number of bits is 12, but the circuit may be configured with an arbitrary number of pits from the viewpoint of characteristics and economy.

In this case, it is necessary to set the power supply voltage of each carrier amplifier 13 to 15 so that the output power becomes a predetermined value.

Fig. 2 shows another embodiment, and in the figure 21.22°2
3, 24. ...is 1 [W], 2 [W], 4 [W]
], 8 [W], ... output power amplifier, 25.26.
27.28°... is each output 2 of the A/D converter 12
Switches that are controlled on and off according to °, 21.22.23, ..., Vl, V2, V3, V4,
...indicate the power supply voltages of the power amplifiers 21, 22, 23, and 24, respectively. The power amplifier 21.
22.23.24. . . . power amplifies the high frequency signal from the oscillator 16 at the output level and sends it to the combiner 17.
It is designed to output to .

That is, according to the above configuration, the switches 25.2G, 27.28, . ... are controlled on/off, so that the power amplifiers 21, 22, 23, 24, . ...
Each power supply voltage V1 , V2 , V3 , V4 ,
. . . are selectively supplied, and thereby the power amplifiers 21, 22, 23
．． 24. ... will be selected. Here, each power amplifier 21, 22.23.24. ... all amplify the high frequency signals in the same phase, so from the combiner 18,
Similar to the above-described embodiment, high-frequency power is modulated in imaging width in a range up to the total wattage of the output level of all power amplifiers in steps of 1 [, W] according to the input level of the audio signal. . In this way, the same implementation can be achieved by converting the input signal into a digital signal and controlling the power supply voltages of power amplifiers with different output levels according to the code.

[Effects of the Invention] As detailed above, according to the present invention, there is provided an amplitude modulation high frequency power amplifier device that eliminates the need for a modulator, eliminates modulation distortion, increases power efficiency, and can obtain extremely good AM waves. can be provided.

[Brief explanation of the drawing]

FIG. 1 is a block circuit diagram showing one embodiment of an amplitude modulation high frequency power amplification device according to the present invention, and FIG. 2 is a block circuit diagram showing another embodiment of the invention. 11...Input terminal, 12...A/D converter, 13~
15... Carrier amplifier, 16... Oscillator, 17.
...Synthesizer, 18...Low pass filter, 19...
Output terminals, 21-24. ...Power amplifier, 25
~28.・・・・・・Switch, ■1～V4゜・・・・
··Power-supply voltage. Applicant's representative Patent attorney Takehiko Suzue? , duck 1

Claims (1)

[Claims] Analog converter that converts analog input signals into digital signals.
It is characterized by comprising a digital converter, a plurality of power amplifiers that power amplify a high frequency signal and vary the output level according to the code of the digital signal, and a synthesizer that combines the outputs of the plurality of power amplifiers. Amplitude modulated high frequency power amplification device.