Abstract: Disclosed is a distortion compensating and power amplifying apparatus including: a transistor to power amplifies an input signal; a branch circuit to branch the input signal into two signals; distortion compensation means for generating a second harmonic of a fundamental wave for one of branched signals and adding the generated second harmonic to the other branch signal from said branch circuit for input to an input terminal of said transistor; and a termination circuit connected to an output terminal of said transistor and grounding the second harmonic.

Abstract: Disclosed is a distortion compensating and power amplifying apparatus including: a transistor to power amplifies an input signal; a branch circuit to branch the input signal into two signals; distortion compensation means for generating a second harmonic of a fundamental wave for one of branched signals and adding the generated second harmonic to the other branch signal from said branch circuit for input to an input terminal of said transistor; and a termination circuit connected to an output terminal of said transistor and grounding the second harmonic.

Abstract: An amplitude compensator utilized in a distortion compensating device which compensates non-linearity in amplitude and phase of an input-output characteristic of a high frequency power amplifier incorporated in a mobile phone in which the input-output amplitude characteristic of the high frequency power amplifier is fitted by a hyperbolic tangent function, and an inverse hyperbolic tangent function is obtained by using two parameters, thereby providing amplitude compensation. A voltage input-output characteristic of the power amplifier is fitted to a hyperbolic function including predetermined parameters and a logarithmic function constituted by the parameters after the fitting and a linear gain of the power amplifier is obtained. An envelope voltage of an envelope signal obtained by detection of a modulated input signal is applied to the logarithmic function to obtain an amplitude compensating value.

Abstract: To make compact the constitution and to improve accuracy of an amplitude compensator utilized in a distortion compensating device which compensates non-linearity in amplitude and phase of an input-output characteristic of a high frequency power amplifier incorporated in a mobile phone and so on. The input-output amplitude characteristic of the high frequency power amplifier 5 is fitted by a hyperbolic tangent function, and an inverse hyperbolic tangent function is obtained by using two parameters, thereby providing amplitude compensators 2d, 2d1 and 2d2.