| 摘要 |
PURPOSE: An apparatus for removing a DC offset of a feed-forward linear amplifier is provided to improve a linear characteristic of a circuit and an adaptive control characteristic by removing a DC offset of a correlation detector used based on an error detection method in a linear power amplifier of a feed-forward method. CONSTITUTION: A main amplifier(13) receives a data and a pilot signal from a pilot generator(30) and amplifies the received signal. An error amplifier(21) receives a signal amplified by the main amplifier(13) and amplifies to offset an error component. A pilot generator(30) generates a pilot signal and transmits to the main amplifier(13) and an IMD detector(40). An IMD detector(40) receives a pilot signal generated by the pilot generator(30) and an output of the main amplifier(13) for down-converting the same and detects an IMD by performing a band pass filtering operation. The IMD detector(40) includes a down converter(41) for receiving a pilot signal generated by the pilot generator(30) and an output of the main amplifier for thereby performing a down-converting operation, band pass filters(42,43) for receiving a DC signal down-converted by the down converter(41) and performs a band pass filtering operation and extracts an IF frequency component, and A/D converters(46,47) for performing a synchronous sampling in synchronization with a signal amplified by the amplifiers(44,45).
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