JPS60103703A - Power amplifier circuit - Google Patents

Abstract

PURPOSE:To obtain a highly efficient power amplifier circuit of class F operation by short-circuiting both ends of a 1/2 wavelength transmission line in terms of high frequency, connecting an output side of an amplifier element and connecting a series resonance circuit extracting the fundamental wave to its midpoint. CONSTITUTION:When a fundamental wave signal is inputted to a GaAs FET4, since both ends (a), (b) of the 1/2 wavelength transmission line 5 are short-circuited to the fundamental wave and harmonics in terms of high frequencies, a voltage as shown in Fig. is distributed to the fundamental wave and the 2nd order harmonic on the line 5. That is, the fundamental wave is opened to the midpoint (c) and the 2nd order harmonic is short-circuited thereto. All odd number harmonics are opened to the midpoint (c) and all even number harmonics are short-circuited similarly with respect to harmonics of the 3rd order or over. The voltage waveform of the FET4 is formed as a rectangular wave and the current is formed as a half-wave rectified sinusoidal wave by connecting the line 5 having the impedance characteristic above as a load to the drain of the FET4 and the highly efficient power amplifier operated with the class F mode is attained.

Description

[Detailed description of the invention] (Technical field) The present invention relates to a highly efficient power amplifier circuit.

(Prior Art) Conventionally, a class F power amplifier has been used as a high-efficiency power amplification circuit, which is composed of an amplification element that mainly operates as a current source and a load circuit having a specific harmonic impedance.

FIG. 1 is a circuit diagram showing an example of a conventional class F power amplifier. In FIG. 1, the load on the amplifying element is composed of a quarter-wavelength transmission line 2 and a parallel resonant circuit 3 that is mutually limited to the fundamental wave. This class F power amplifier short-circuits the output side of the 1/4 wavelength transmission line 2 with respect to harmonics, and connects the load of the amplifying element 1 and the input side of the 1/4 wavelength transmission line 2 to the fundamental wave and odd-numbered harmonics. Highly efficient power amplification was achieved by opening to harmonics and shorting to even-order harmonics. However, since the output side of the 1/4 wavelength transmission line 2 uses the capacitor of the parallel resonant circuit 3 for short-circuiting, it cannot be sufficiently short-circuited against harmonics, and the parallel resonant circuit 3 is basically In order to extract the wave, it is necessary to resonate with the fundamental wave and create a high impedance, so in the end, the output side of the I'i 1/4 wavelength transmission line 2 is short-circuited to the fundamental wave and harmonics using the circuit configuration shown in Fig. 1. I couldn't do it. Otherwise, the input side of the 1/4 wavelength transmission line 2, that is, the amplification element 1
The load has the disadvantage that it is not open-circuited by the fundamental wave and odd-numbered harmonics, and is not short-circuited by even-numbered harmonics, and ideally efficient power amplification cannot be obtained.

(Object of the Invention) An object of the present invention is to provide a high-efficiency power amplifier circuit of class F operation that solves the above-mentioned drawbacks of the prior art.

(Structure of the Invention) The present invention provides a 1/1/2 fundamental wave whose both ends are short-circuited with high frequency.
A 2-wavelength transmission line, an amplifying element whose output side is connected to the midpoint of the 1/2 wavelength transmission line, and a series resonant circuit that resonates with a fundamental wave and whose one end is connected to the midpoint of the 172-wavelength transmission line. , a power amplifier circuit characterized in that a fundamental wave output is obtained from the other end of the series resonant circuit.

(Example) FIG. 2 is a circuit diagram showing an example of the present invention, and is 1/1
Both ends a and r b of the two-wavelength transmission line 5 are short-circuited at high frequency, and both ends a of the half-wavelength transmission line 5 are short-circuited.

An amplification element such as a gallium arsenide field effect transistor (GaAsFFT
) Connecting the drain of 4 and creating a series resonant circuit 6
One end of the series resonant circuit 6 is also connected to the output terminal 7, and the other end of the series resonant circuit 6 is connected to the output terminal 7. In addition, the 1/2 wavelength transmission line 5
The line length is 1/2 of the wavelength of the input fundamental wave on the transmission line 5, and the series resonant circuit 6 is a circuit for extracting the fundamental wave and resonates with the fundamental wave.

When a fundamental wave signal is input to the GaAsFFT 4, since both ends of the 1/2 wavelength transmission line are short-circuited at high frequency with respect to the fundamental wave and harmonics, the fundamental wave appears on the 172-wavelength transmission line. , the voltage is distributed as shown in FIG. 3 for the second harmonic. In FIG. 3, a.

b indicates both ends of the 1/2 wavelength transmission line 5, and C indicates the midpoint. At the center point C, the circuit is open to the fundamental wave and short-circuited to the second harmonic. Regarding harmonics of the third order or higher, similarly, at the midpoint C, there is an open circuit for all odd harmonics and a short circuit for all even harmonics. In this example, by connecting a 1/2 wavelength transmission line having such impedance characteristics to the drain of GaAsFET 4 as a load as shown in Fig. 2, the voltage waveform of GaAsFET 4 is changed to a rectangular wave and the current is changed to a half wave. This realizes a highly efficient power amplifier circuit that operates in class F mode using rectified sine waves. In addition,
The desired fundamental wave is obtained from the output terminal via the series resonant circuit 6.

(Effects of the Invention) The present invention short-circuits both ends of a 172-wavelength transmission line in terms of high frequency, connects the output side of an amplifying element to the midpoint, and connects a series resonant circuit for extracting the fundamental wave for amplification. Since the circuit is constructed, the load of the amplifying element is neither odd order open circuit nor even order short circuit, and a highly efficient power amplification circuit that performs a predetermined class F operation can be obtained. By using the power amplifier circuit, the heat sink and battery can be made smaller, and the device can be made smaller and lighter.

[Brief explanation of the drawing]

It is a voltage distribution diagram on a transmission line. 4- GaAsFET, 5-1/2 wavelength transmission line, 6
...Series resonant circuit, 7...Output terminal. Figure 3 1 Display of the case 1982 Patent Application No. 209965 2 Name of the invention Power amplifier circuit 3 Person making the amendment Relationship to the case Patent applicant Address (105) 1-7 Toranomon, Minato-ku, Tokyo 12
Address (105) 1-7 Kaoru, Toranomon, Minato-ku, Tokyo
No. 2 No. 5, “Detailed Description of the Invention” in the Amendment No. 7 Specification
Column (1) In the 17th column of the specification, page 1, ``F-class power amplifier'' should be corrected to ``F-class power amplifier circuit.'' (2) In the same book, page 2, lines 111 to 15, the phrase ``short-circuited to harmonics'' is corrected to ``ideally short-circuited to harmonics.'' (3) In the 19th line of page 4 of the same book, the phrase "rectangular wave" is corrected to "rectangular wave."

Claims (1)

[Claims] A fundamental wave 1/2 wavelength transmission line whose both ends are short-circuited at a high frequency, an amplification element whose output side is connected to the midpoint of the 1/2 wavelength transmission line, and one end connected to the midpoint of the 1/2 wavelength transmission line. A power amplification circuit comprising a series resonant circuit that resonates with a connected fundamental wave, and obtaining a fundamental wave output from the other end of the series resonant circuit.