| 摘要 |
A method and apparatus for efficient power amplification with low distortion includes an envelope detector (220), a difference amplifier (130), an envelope amplifier (270), and a power amplifier (260). A feedback path is provided from the output through a second envelope detector (120) to the difference amplifier (130). The feedback circuit operates on the bandwidth of the envelope of the RF signal rather than at the RF bandwidth. An envelope amplifier (270) includes a difference amplifier (272), a pulsewidth modulator (275), a driver (280), switching transistors (285), a low pass filter (290), and a voltage scaler (292). A feedback path within the envelope amplifier reduces the time delay introduced by low pass filter (290). The combined feedback loops work together to reduce distortion and lower intermodulation products.
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