| 摘要 |
A wireless communication unit (100) comprises a transmitter (120) arranged to transmit an envelope modulated signal. The transmitter (120) comprises a radio frequency power amplifier (124) operably coupled to a logarithmic detector (210, 310) and a bias control circuit (126) arranged to set a direct current bias level of the radio frequency power amplifier (124) via a bias signal. The logarithmic detector (210, 310) is arranged to detect the envelope modulated signal and provide the detected envelope modulated signal to the bias control circuit such that the bias signal applied to the radio frequency power amplifier (124) comprises both a direct current and a low frequency component based on the detected envelope modulated signal. In this manner, the present invention supports a tradeoff of linearity for additional efficiency, as well as providing more margin on adjacent channel power levels, whilst maintaining a good overall power added efficiency.
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