| 摘要 |
A high-frequency power amplifier is provided, which suppresses effectively the distortion induced by gain deviation or fluctuation occurring in at least one of the amplifier stages without using the back-off of the operating point. The amplifier comprises first to n-th amplifier stages connected in cascade, where n is an integer greater than unity. A k-th one of the amplifier stages receives a k-th input signal power to produce a k-th output signal power, where k is an integer satisfying a relationship of 1<=k<=n. The k-th amplifier stage includes a transistor with an amplification function. The transistor has a gain change in a range of the k-th input signal power or the k-th output signal power. A m-th one of the amplifier stages receives a m-th output signal to produce a m-th output signal, where m is an integer satisfying a relationship of 1<=m<=n and m<> k. The m-th amplifier stage includes a transistor with an amplification function. The transistor has a gain change in a range of the m-th input signal power or the m-th output signal power. The gain change of the transistor of the m-th amplifier stage is decreased or cancelled by the gain change or the transistor of the k-th amplifier stage.
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