| 摘要 |
<p>Amplifier apparatus comprising a power amplifier (4) having an operating frequency in the radio frequency (1RF') 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) and a linear path (8) including amplifiers having substantially identical physical characteristics, an input divider (6) responsive to an amplifier input signal for applying respective pre-distorter input signals to the paths (7, 8), and an output coupler (13) for combining the signals from the linear path (8) and 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 that compensates for the distortion of the transfer function of the power amplifier. The input divider (6) and the output coupler (13) are each arranged to introduce substantially orthogonal relative phase shifts between the non-linear path (7) and the linear path (8) signals from the two paths are combined substantially in anti phase to produce the pre-distorted signal. One of the input divider (6) and the output coupler (13) presents high-pass and the other low-pass transfer characteristics whose variations with frequency tend to compensate each other. The input divider (6) and the output coupler (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.</p> |
