| 摘要 |
Amplifier apparatus comprising a power amplifier ( 4 ) having an operating frequency in the radio frequency ('RF') or microwave or higher ranges and a pre-distorter ( 2 ), the characteristics of the power amplifier ( 4 ) comprising a distortion from a linear transfer function. The pre-distorter ( 2 ) comprises a non-linear path ( 7 ), a linear path ( 8 ), input means ( 6 ) responsive to an amplifier input signal for applying respective prre-distorter input signals to the paths ( 7,8 ) and combining means ( 13 ) for combining a linear signal from the linear path ( 8 ) with a non-linear signal from the non-linear path ( 7 ) to produce a pre-distorted signal. The characteristics of the pre-distorter ( 2 ) comprise a distortion relative to a linear transfer function such as to tend to compensate for the distortion of the transfer function of the power amplifier. The input means ( 6 ) is arranged to apply the pre-distorter input signals to the paths ( 7,8 ) substantially in relative phase opposition (+ 90 ) and the combining means ( 13 ) is arranged to combine the signals from the paths ( 7,8 ) without introducing any significant relative phase difference. The input means ( 6 ) and the combining means ( 13 ) consist substantially of passive components ( 16 to 21, 30 to 36 ) and substantially all the components of the pre-distorter ( 2 ) are formed in a common semiconductor substrate.
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